1
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Jarvis-Lowry B, Harrington KC, Ghanizadeh H, Robertson AW. Viability and dormancy of the Clematis vitalba aerial seed bank. Plant Biol (Stuttg) 2024; 26:457-466. [PMID: 38407522 DOI: 10.1111/plb.13629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 01/17/2024] [Indexed: 02/27/2024]
Abstract
Old man's beard (Clematis vitalba L.) is a liana species that has become invasive in many areas of its introduced range. Seeds are produced in abundance and are both physiologically and morphologically dormant upon maturity. To understand the importance of seeds to its invasiveness, changes in viability and dormancy of the aerial seed bank were tracked throughout the after-ripening period and during storage. Seeds collected every second month for 2 years were subjected to germination tests. Other seeds stored in outdoor ambient conditions or in a dry, chilled state were dissected before, during, and after imbibition, as well as during incubation, to measure embryo size. Less than 72% of seeds on the mother plant were viable. Viable seeds remained completely morpho-physiologically dormant throughout autumn, even when treated with nitrate. Physiological dormancy declined in response to seasonal changes, yet morphological dormancy did not change until seeds had been exposed to appropriate germination conditions for several days. Fully dormant autumn seeds decayed at higher rates during incubation than partially or fully after-ripened seeds, which were also more germinable and less dormant. Furthermore, seeds incubated in complete darkness were more likely to decay or remain dormant than those exposed to light. This study demonstrates that fewer than three-quarters of seeds produced are viable and further decay occurs after dispersal, yet total fertility is still very high, with enormous propagule pressure from seeds alone. Viable seeds are protected with two forms of dormancy; morphological dormancy requires additional germination cues in order to break after seasonal changes break physiological dormancy.
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Affiliation(s)
- B Jarvis-Lowry
- School of Agriculture and Environment, Massey University, Palmerston North, New Zealand
| | - K C Harrington
- School of Agriculture and Environment, Massey University, Palmerston North, New Zealand
| | - H Ghanizadeh
- School of Agriculture and Environment, Massey University, Palmerston North, New Zealand
| | - A W Robertson
- School of Natural Sciences, Massey University, Palmerston North, New Zealand
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2
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Marie JJ, House RA, Rees GJ, Robertson AW, Jenkins M, Chen J, Agrestini S, Garcia-Fernandez M, Zhou KJ, Bruce PG. Trapped O 2 and the origin of voltage fade in layered Li-rich cathodes. Nat Mater 2024:10.1038/s41563-024-01833-z. [PMID: 38429520 DOI: 10.1038/s41563-024-01833-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/06/2024] [Indexed: 03/03/2024]
Abstract
Oxygen redox cathodes, such as Li1.2Ni0.13Co0.13Mn0.54O2, deliver higher energy densities than those based on transition metal redox alone. However, they commonly exhibit voltage fade, a gradually diminishing discharge voltage on extended cycling. Recent research has shown that, on the first charge, oxidation of O2- ions forms O2 molecules trapped in nano-sized voids within the structure, which can be fully reduced to O2- on the subsequent discharge. Here we show that the loss of O-redox capacity on cycling and therefore voltage fade arises from a combination of a reduction in the reversibility of the O2-/O2 redox process and O2 loss. The closed voids that trap O2 grow on cycling, rendering more of the trapped O2 electrochemically inactive. The size and density of voids leads to cracking of the particles and open voids at the surfaces, releasing O2. Our findings implicate the thermodynamic driving force to form O2 as the root cause of transition metal migration, void formation and consequently voltage fade in Li-rich cathodes.
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Affiliation(s)
- John-Joseph Marie
- Department of Materials, University of Oxford, Oxford, UK
- The Faraday Institution, Didcot, UK
| | - Robert A House
- Department of Materials, University of Oxford, Oxford, UK.
- The Faraday Institution, Didcot, UK.
| | - Gregory J Rees
- Department of Materials, University of Oxford, Oxford, UK
- The Faraday Institution, Didcot, UK
| | | | - Max Jenkins
- Department of Materials, University of Oxford, Oxford, UK
| | - Jun Chen
- Department of Materials, University of Oxford, Oxford, UK
| | | | | | | | - Peter G Bruce
- Department of Materials, University of Oxford, Oxford, UK.
- The Faraday Institution, Didcot, UK.
- Department of Chemistry, University of Oxford, Oxford, UK.
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3
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Yuan Y, Pu SD, Pérez-Osorio MA, Li Z, Zhang S, Yang S, Liu B, Gong C, Menon AS, Piper LFJ, Gao X, Bruce PG, Robertson AW. Diagnosing the Electrostatic Shielding Mechanism for Dendrite Suppression in Aqueous Zinc Batteries. Adv Mater 2024; 36:e2307708. [PMID: 37879760 DOI: 10.1002/adma.202307708] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 10/17/2023] [Indexed: 10/27/2023]
Abstract
Aqueous zinc electrolytes offer the potential for cheaper rechargeable batteries due to their safe compatibility with the high capacity metal anode; yet, they are stymied by irregular zinc deposition and consequent dendrite growth. Suppressing dendrite formation by tailoring the electrolyte is a proven approach from lithium batteries; yet, the underlying mechanistic understanding that guides such tailoring does not necessarily directly translate from one system to the other. Here, it is shown that the electrostatic shielding mechanism, a fundamental concept in electrolyte engineering for stable metal anodes, has different consequences for the plating morphology in aqueous zinc batteries. Operando electrochemical transmission electron microscopy is used to directly observe the zinc nucleation and growth under different electrolyte compositions and reveal that electrostatic shielding additive suppresses dendrites by inhibiting secondary zinc nucleation along the (100) edges of existing primary deposits and encouraging preferential deposition on the (002) faces, leading to a dense and block-like zinc morphology. The strong influence of the crystallography of Zn on the electrostatic shielding mechanism is further confirmed with Zn||Ti cells and density functional theory modeling. This work demonstrates the importance of considering the unique aspects of the aqueous zinc battery system when using concepts from other battery chemistries.
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Affiliation(s)
- Yi Yuan
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Shengda D Pu
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | | | - Zixuan Li
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Shengming Zhang
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Sixie Yang
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Boyang Liu
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Chen Gong
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | | | | | - Xiangwen Gao
- Future Battery Research Center, Global Institute of Future Technology, Shanghai Jiaotong University, Shanghai, 200240, China
| | - Peter G Bruce
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK
| | - Alex W Robertson
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
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4
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Deng R, Chen J, Chu F, Qian M, He Z, Robertson AW, Maier J, Wu F. "Soggy-Sand" Chemistry for High-Voltage Aqueous Zinc-Ion Batteries. Adv Mater 2023:e2311153. [PMID: 38095834 DOI: 10.1002/adma.202311153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/01/2023] [Indexed: 12/22/2023]
Abstract
The narrow electrochemical stability window, deleterious side reactions, and zinc dendrites prevent the use of aqueous zinc-ion batteries. Here, aqueous "soggy-sand" electrolytes (synergistic electrolyte-insulator dispersions) are developed for achieving high-voltage Zn-ion batteries. How these electrolytes bring a unique combination of benefits, synergizing the advantages of solid and liquid electrolytes is revealed. The oxide additions adsorb water molecules and trap anions, causing a network of space charge layers with increased Zn2+ transference number and reduced interfacial resistance. They beneficially modify the hydrogen bond network and solvation structures, thereby influencing the mechanical and electrochemical properties, and causing the Mn2+ in the solution to be oxidized. As a result, the best performing Al2 O3 -based "soggy-sand" electrolyte exhibits a long life of 2500 h in Zn||Zn cells. Furthermore, it increases the charging cut-off voltage for Zn/MnO2 cells to 2 V, achieving higher specific capacities. Even with amass loading of 10 mgMnO2 cm-2 , it yields a promising specific capacity of 189 mAh g-1 at 1 A g-1 after 500 cycles. The concept of "soggy-sand" chemistry provides a new approach to design powerful and universal electrolytes for aqueous batteries.
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Affiliation(s)
- Rongyu Deng
- School of Metallurgy and Environment, Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Hunan Provincial Key Laboratory of Nonferrous Value-added Metallurgy, Central South University, Changsha, 410083, China
| | - Jieshuangyang Chen
- School of Metallurgy and Environment, Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Hunan Provincial Key Laboratory of Nonferrous Value-added Metallurgy, Central South University, Changsha, 410083, China
| | - Fulu Chu
- School of Metallurgy and Environment, Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Hunan Provincial Key Laboratory of Nonferrous Value-added Metallurgy, Central South University, Changsha, 410083, China
| | - Mingzhi Qian
- School of Metallurgy and Environment, Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Hunan Provincial Key Laboratory of Nonferrous Value-added Metallurgy, Central South University, Changsha, 410083, China
| | - Zhenjiang He
- School of Metallurgy and Environment, Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Hunan Provincial Key Laboratory of Nonferrous Value-added Metallurgy, Central South University, Changsha, 410083, China
| | - Alex W Robertson
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - Joachim Maier
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569, Stuttgart, Germany
| | - Feixiang Wu
- School of Metallurgy and Environment, Engineering Research Center of the Ministry of Education for Advanced Battery Materials, Hunan Provincial Key Laboratory of Nonferrous Value-added Metallurgy, Central South University, Changsha, 410083, China
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Lv Z, Hao L, Yao Z, Li W, Robertson AW, Sun Z. Rigorous Assessment of Cl - -Based Anolytes on Electrochemical Ammonia Synthesis. Adv Sci (Weinh) 2022; 9:e2204205. [PMID: 36253143 PMCID: PMC9685447 DOI: 10.1002/advs.202204205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/14/2022] [Indexed: 06/16/2023]
Abstract
Many challenges in the electrochemical synthesis of ammonia have been recognized with most effort focused on delineating false positives resulting from unidentified sources of nitrogen. However, the influence of oxidizing anolytes on the crossover and oxidization of ammonium during the electrolysis reaction remains unexplored. Here it is reported that the use of analytes containing halide ions (Cl- and Br- ) can rapidly convert the ammonium into N2 , which further intensifies the crossover of ammonium. Moreover, the extent of migration and oxidation of ammonium is found to be closely associated with external factors, such as applied potentials and the concentration of Cl- . These findings demonstrate the profound impact of oxidizing anolytes on the electrochemical synthesis of ammonia. Based on these results, many prior reported ammonia yield rates are calibrated. This work emphasizes the significance of avoiding selection of anolytes that can oxidize ammonium, which is believed to promote further progress in electrochemical nitrogen fixation.
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Affiliation(s)
- Zengxiang Lv
- State Key Laboratory of Organic‐Inorganic CompositesBeijing University of Chemical TechnologyBeijing100029P. R. China
| | - Leiduan Hao
- State Key Laboratory of Organic‐Inorganic CompositesBeijing University of Chemical TechnologyBeijing100029P. R. China
| | - Zhibo Yao
- State Key Laboratory of Organic‐Inorganic CompositesBeijing University of Chemical TechnologyBeijing100029P. R. China
| | - Weixiang Li
- State Key Laboratory of Organic‐Inorganic CompositesBeijing University of Chemical TechnologyBeijing100029P. R. China
| | | | - Zhenyu Sun
- State Key Laboratory of Organic‐Inorganic CompositesBeijing University of Chemical TechnologyBeijing100029P. R. China
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6
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Yao Z, Zhan X, Ruan Y, Li W, Xu Y, Chen Y, Robertson AW, Tao R, Hong S, Hao L, Sun Z. Atomically dispersed Mn for electrochemical CO2 reduction with tunable performance. Chem Asian J 2022; 17:e202200997. [DOI: 10.1002/asia.202200997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/25/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Zhibo Yao
- Beijing University of Chemical Technology College of Chemical Engineering Department of Chemical Engineering CHINA
| | - Xinyu Zhan
- Beijing University of Chemical Technology College of Chemical Engineering College of Chemical Engineering Beijing Third Ring Road, Chaoyang District, Beijing 100029 Beijing CHINA
| | - Yukun Ruan
- Beijing University of Chemical Technology College of Chemical Engineering College of Chemical Engineering CHINA
| | - Weixiang Li
- Beijing University of Chemical Technology College of Chemical Engineering College of Chemical Engineering CHINA
| | - Yiwen Xu
- Beijing University of Chemical Technology College of Chemical Engineering College of Chemical Engineering CHINA
| | - Yuxin Chen
- Beijing University of Chemical Technology College of Chemical Engineering College of Chemical Engineering CHINA
| | | | - Ranting Tao
- Beijing University of Chemical Technology College of Chemical Engineering College of Chemical Engineering CHINA
| | - Song Hong
- Beijing University of Chemical Technology College of Chemical Engineering College of Chemical Engineering CHINA
| | - Leiduan Hao
- Beijing University of Chemical Technology College of Chemical Engineering College of Chemical Engineering CHINA
| | - Zhenyu Sun
- Beijing University of Chemical Technology Department of Chemical Engineering North Third Ring Road 15, Chaoyang District, Beijing, China 100029 Beijing CHINA
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7
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Pu SD, Gong C, Tang YT, Ning Z, Liu J, Zhang S, Yuan Y, Melvin D, Yang S, Pi L, Marie JJ, Hu B, Jenkins M, Li Z, Liu B, Tsang SCE, Marrow TJ, Reed RC, Gao X, Bruce PG, Robertson AW. Achieving Ultrahigh-Rate Planar and Dendrite-Free Zinc Electroplating for Aqueous Zinc Battery Anodes. Adv Mater 2022; 34:e2202552. [PMID: 35560650 DOI: 10.1002/adma.202202552] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 04/21/2022] [Indexed: 06/15/2023]
Abstract
Despite being one of the most promising candidates for grid-level energy storage, practical aqueous zinc batteries are limited by dendrite formation, which leads to significantly compromised safety and cycling performance. In this study, by using single-crystal Zn-metal anodes, reversible electrodeposition of planar Zn with a high capacity of 8 mAh cm-2 can be achieved at an unprecedentedly high current density of 200 mA cm-2 . This dendrite-free electrode is well maintained even after prolonged cycling (>1200 cycles at 50 mA cm- 2 ). Such excellent electrochemical performance is due to single-crystal Zn suppressing the major sources of defect generation during electroplating and heavily favoring planar deposition morphologies. As so few defect sites form, including those that would normally be found along grain boundaries or to accommodate lattice mismatch, there is little opportunity for dendritic structures to nucleate, even under extreme plating rates. This scarcity of defects is in part due to perfect atomic-stitching between merging Zn islands, ensuring no defective shallow-angle grain boundaries are formed and thus removing a significant source of non-planar Zn nucleation. It is demonstrated that an ideal high-rate Zn anode should offer perfect lattice matching as this facilitates planar epitaxial Zn growth and minimizes the formation of any defective regions.
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Affiliation(s)
- Shengda D Pu
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Chen Gong
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Yuanbo T Tang
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Ziyang Ning
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Junliang Liu
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Shengming Zhang
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Yi Yuan
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Dominic Melvin
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Sixie Yang
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Liquan Pi
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - John-Joseph Marie
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
- The Faraday Institution, Quad One, Becquerel Avenue, Harwell Campus, Didcot, OX11 0RA, UK
| | - Bingkun Hu
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Max Jenkins
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Zixuan Li
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Boyang Liu
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - S C Edman Tsang
- The Wolfson Catalysis Centre, Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK
| | - T James Marrow
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Roger C Reed
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
- Department of Engineering Science, University of Oxford, Parks Road, Oxford, OX1 3PJ, UK
| | - Xiangwen Gao
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Peter G Bruce
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
- The Faraday Institution, Quad One, Becquerel Avenue, Harwell Campus, Didcot, OX11 0RA, UK
- Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK
- The Henry Royce Institute, Parks Road, Oxford, OX1 3PH, UK
| | - Alex W Robertson
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
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8
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Wang L, Li X, Hao L, Hong S, Robertson AW, Sun Z. Integration of ultrafine CuO nanoparticles with two-dimensional MOFs for enhanced electrochemicgal CO2 reduction to ethylene. Chinese Journal of Catalysis 2022. [DOI: 10.1016/s1872-2067(21)63947-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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9
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Zhao Z, Park J, Choi C, Hong S, Hui X, Zhang H, Benedict Lo TW, Robertson AW, Lv Z, Jung Y, Sun Z. Engineering vacancy and hydrophobicity of two-dimensional TaTe 2 for efficient and stable electrocatalytic N 2 reduction. Innovation (N Y) 2022; 3:100190. [PMID: 34984409 PMCID: PMC8693264 DOI: 10.1016/j.xinn.2021.100190] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 11/23/2021] [Indexed: 01/23/2023] Open
Abstract
Demand for ammonia continues to increase to sustain the growing global population. The direct electrochemical N2 reduction reaction (NRR) powered by renewable electricity offers a promising carbon-neutral and sustainable strategy for manufacturing NH3, yet achieving this remains a grand challenge. Here, we report a synergistic strategy to promote ambient NRR for ammonia production by tuning the Te vacancies (VTe) and surface hydrophobicity of two-dimensional TaTe2 nanosheets. Remarkable NH3 faradic efficiency of up to 32.2% is attained at a mild overpotential, which is largely maintained even after 100 h of consecutive electrolysis. Isotopic labeling validates that the N atoms of formed NH4+ originate from N2. In situ X-ray diffraction indicates preservation of the crystalline structure of TaTe2 during NRR. Further density functional theory calculations reveal that the potential-determining step (PDS) is ∗NH2 + (H+ + e–) → NH3 on VTe-TaTe2 compared with that of ∗ + N2 + (H+ + e–) → ∗N–NH on TaTe2. We identify that the edge plane of TaTe2 and VTe serve as the main active sites for NRR. The free energy change at PDS on VTe-TaTe2 is comparable with the values at the top of the NRR volcano plots on various transition metal surfaces. 2D TaTe2 is produced in large quantities Jointly tuning the Te vacancies (VTe) and surface hydrophobicity of 2D TaTe2 enables efficient and stable electrocatalytic NRR with remarkable NH3 faradic efficiency The edge plane of TaTe2 and VTe serve as the main active sites for NRR The free energy change at the potential-determining step on VTe-TaTe2 is comparable with the values at the top of the NRR volcano plots on various transition metal surfaces
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Affiliation(s)
- Zhenqing Zhao
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
| | - Jongseo Park
- Department of Chemical and Biomolecular Engineering (BK21 four), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Changhyeok Choi
- Department of Chemical and Biomolecular Engineering (BK21 four), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Song Hong
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xiangchao Hui
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
| | - Hao Zhang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China
| | - Tsz Woon Benedict Lo
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hong Kong, China
| | - Alex W Robertson
- Department of Materials, University of Oxford, Oxford OX1 3PH, UK
| | - Zengxiang Lv
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
| | - Yousung Jung
- Department of Chemical and Biomolecular Engineering (BK21 four), Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea
| | - Zhenyu Sun
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
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10
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Chen Y, Wang L, Yao Z, Hao L, Tan X, Masa J, W. Robertson A, Sun Z. Tuning the Coordination Structure of Single Atoms and Their Interaction with the Support for Carbon Dioxide Electroreduction. ACTA PHYS-CHIM SIN 2022. [DOI: 10.3866/pku.whxb202207024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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11
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Zhang Y, Gong C, Li D, Wang ZW, Pu SD, Robertson AW, Yu H, Parrington J. A prognostic dynamic model applicable to infectious diseases providing easily visualized guides: a case study of COVID-19 in the UK. Sci Rep 2021; 11:8412. [PMID: 33863958 PMCID: PMC8052322 DOI: 10.1038/s41598-021-87882-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 03/19/2021] [Indexed: 12/14/2022] Open
Abstract
A reasonable prediction of infectious diseases’ transmission process under different disease control strategies is an important reference point for policy makers. Here we established a dynamic transmission model via Python and realized comprehensive regulation of disease control measures. We classified government interventions into three categories and introduced three parameters as descriptions for the key points in disease control, these being intraregional growth rate, interregional communication rate, and detection rate of infectors. Our simulation predicts the infection by COVID-19 in the UK would be out of control in 73 days without any interventions; at the same time, herd immunity acquisition will begin from the epicentre. After we introduced government interventions, a single intervention is effective in disease control but at huge expense, while combined interventions would be more efficient, among which, enhancing detection number is crucial in the control strategy for COVID-19. In addition, we calculated requirements for the most effective vaccination strategy based on infection numbers in a real situation. Our model was programmed with iterative algorithms, and visualized via cellular automata; it can be applied to similar epidemics in other regions if the basic parameters are inputted, and is able to synthetically mimic the effect of multiple factors in infectious disease control.
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Affiliation(s)
- Yuxuan Zhang
- Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK.,Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, 200030, People's Republic of China
| | - Chen Gong
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Dawei Li
- Department of Physics, University of California, San Diego, La Jolla, CA, USA
| | - Zhi-Wei Wang
- Computer Science, University of York, York, YO10 5GH, UK.,College of Physics, Jilin University, Changchun, 130012, People's Republic of China
| | - Shengda D Pu
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Alex W Robertson
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Hong Yu
- Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, 200030, People's Republic of China.
| | - John Parrington
- Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, UK.
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12
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Hua X, Allan PK, Gong C, Chater PA, Schmidt EM, Geddes HS, Robertson AW, Bruce PG, Goodwin AL. Non-equilibrium metal oxides via reconversion chemistry in lithium-ion batteries. Nat Commun 2021; 12:561. [PMID: 33495443 PMCID: PMC7835223 DOI: 10.1038/s41467-020-20736-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 12/07/2020] [Indexed: 11/09/2022] Open
Abstract
Binary metal oxides are attractive anode materials for lithium-ion batteries. Despite sustained effort into nanomaterials synthesis and understanding the initial discharge mechanism, the fundamental chemistry underpinning the charge and subsequent cycles-thus the reversible capacity-remains poorly understood. Here, we use in operando X-ray pair distribution function analysis combining with our recently developed analytical approach employing Metropolis Monte Carlo simulations and non-negative matrix factorisation to study the charge reaction thermodynamics of a series of Fe- and Mn-oxides. As opposed to the commonly believed conversion chemistry forming rocksalt FeO and MnO, we reveal the two oxide series topotactically transform into non-native body-centred cubic FeO and zincblende MnO via displacement-like reactions whose kinetics are governed by the mobility differences between displaced species. These renewed mechanistic insights suggest avenues for the future design of metal oxide materials as well as new material synthesis routes using electrochemically-assisted methods.
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Affiliation(s)
- Xiao Hua
- Inorganic Chemistry Laboratory, University of Oxford, Oxford, OX1 3QR, UK.
| | - Phoebe K Allan
- School of Chemistry, University of Birmingham, Birmingham, B15 2TT, UK
| | - Chen Gong
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Philip A Chater
- Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Ella M Schmidt
- Inorganic Chemistry Laboratory, University of Oxford, Oxford, OX1 3QR, UK
| | - Harry S Geddes
- Inorganic Chemistry Laboratory, University of Oxford, Oxford, OX1 3QR, UK
| | - Alex W Robertson
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Peter G Bruce
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Andrew L Goodwin
- Inorganic Chemistry Laboratory, University of Oxford, Oxford, OX1 3QR, UK
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13
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Lee GD, Robertson AW, Lee S, Lin YC, Oh JW, Park H, Joo YC, Yoon E, Suenaga K, Warner JH, Ewels CP. Direct observation and catalytic role of mediator atom in 2D materials. Sci Adv 2020; 6:eaba4942. [PMID: 32577521 PMCID: PMC7286694 DOI: 10.1126/sciadv.aba4942] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 04/15/2020] [Indexed: 06/11/2023]
Abstract
The structural transformations of graphene defects have been extensively researched through aberration-corrected transmission electron microscopy (AC-TEM) and theoretical calculations. For a long time, a core concept in understanding the structural evolution of graphene defects has been the Stone-Thrower-Wales (STW)-type bond rotation. In this study, we show that undercoordinated atoms induce bond formation and breaking, with much lower energy barriers than the STW-type bond rotation. We refer to them as mediator atoms due to their mediating role in the breaking and forming of bonds. Here, we report the direct observation of mediator atoms in graphene defect structures using AC-TEM and annular dark-field scanning TEM (ADF-STEM) and explain their catalytic role by tight-binding molecular dynamics (TBMD) simulations and image simulations based on density functional theory (DFT) calculations. The study of mediator atoms will pave a new way for understanding not only defect transformation but also the growth mechanisms in two-dimensional materials.
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Affiliation(s)
- Gun-Do Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, Republic of Korea
| | - Alex W. Robertson
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Sungwoo Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea
| | - Yung-Chang Lin
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Jeong-Wook Oh
- Department of Chemistry, Seoul National University, Seoul, Republic of Korea
| | - Hwanyeol Park
- Memory Thin Film Technology Team, Giheung Hwaseong Complex, Samsung Electronics, 445-701, Republic of Korea
| | - Young-Chang Joo
- Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, Republic of Korea
| | - Euijoon Yoon
- Department of Materials Science and Engineering, Seoul National University, Seoul, Republic of Korea
- Research Institute of Advanced Materials, Seoul National University, Seoul, Republic of Korea
| | - Kazu Suenaga
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Jamie H. Warner
- Department of Mechanical Engineering, University of Texas at Austin, 204 Dean Keeton Street, Austin, TX 78712, USA
| | - Christopher P. Ewels
- Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, CNRS UMR 6502, 2 Rue de la Houssinière, F-44322 Nantes, France
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14
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Liu H, Huang X, Lu Z, Wang T, Zhu Y, Cheng J, Wang Y, Wu D, Sun Z, Robertson AW, Chen X. Trace metals dramatically boost oxygen electrocatalysis of N-doped coal-derived carbon for zinc-air batteries. Nanoscale 2020; 12:9628-9639. [PMID: 32319453 DOI: 10.1039/c9nr10800a] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The commercialization of metal-air batteries requires efficient, low-cost, and stable bifunctional electrocatalysts for reversible electrocatalysis of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). The modification of natural coal by heteroatoms such as N and S, or metal oxide species, has been demonstrated to form very promising electrocatalysts for the ORR and OER. However, it remains elusive and underexplored as to how the impurity elements in coal may impact the electrocatalytic properties of coal-derived catalysts. Herein, we explore the influence of the presence of various trace metals that are notable impurities in coal, including Al, Si, Ca, K, Fe, Mg, Co, Mn, Ni, and Cu, on the electrochemical performance of the prepared catalysts. The constructed Zn-air batteries are further shown to be able to power green LED lights for more than 80 h. The charge-discharge polarization curves exhibited excellent and durable rechargeability over 500 (ca. 84 h) continuous cycles. The promotional effect of the trace elements is believed to accrue from a combination of electronic structure modification of the active sites, enhancement of the active site density, and formation of a conductive 3-dimensional hierarchical network of carbon nanotubes.
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Affiliation(s)
- Huimin Liu
- Research Group of Functional Materials for Electrochemical Energy Conversion, School of Chemical Engineering, University of Science and Technology Liaoning, Qianshan Middle Road 185, 114051 Anshan, P. R. China.
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15
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Chu S, Li X, W. Robertson A, Sun Z. Electrocatalytic CO<sub>2</sub> Reduction to Ethylene over CeO<sub>2</sub>-Supported Cu Nanoparticles: Effect of Exposed Facets of CeO<sub>2</sub>. ACTA PHYS-CHIM SIN 2020. [DOI: 10.3866/pku.whxb202009023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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16
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Yang L, Choi C, Hong S, Liu Z, Zhao Z, Yang M, Shen H, Robertson AW, Zhang H, Lo TWB, Jung Y, Sun Z. Single yttrium sites on carbon-coated TiO2 for efficient electrocatalytic N2 reduction. Chem Commun (Camb) 2020; 56:10910-10913. [DOI: 10.1039/d0cc01136c] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a facile synthesis of single yttrium sites anchored on carbon-coated TiO2 for efficient and stable electrocatalytic N2 fixation.
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Affiliation(s)
- Lianghao Yang
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | - Changhyeok Choi
- Department of Chemical and Biomolecular Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Song Hong
- Analysis Technology R&D Center
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | - Zhiming Liu
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | - Zhenqing Zhao
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | - Mengmeng Yang
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | - Huidong Shen
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
| | | | - Hao Zhang
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University
- P. R. China
| | - Tsz Woon Benedict Lo
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University
- P. R. China
| | - Yousung Jung
- Department of Chemical and Biomolecular Engineering
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Zhenyu Sun
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- P. R. China
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17
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Pu S, Gong C, Robertson AW. Liquid cell transmission electron microscopy and its applications. R Soc Open Sci 2020; 7:191204. [PMID: 32218950 PMCID: PMC7029903 DOI: 10.1098/rsos.191204] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 11/19/2019] [Indexed: 06/10/2023]
Abstract
Transmission electron microscopy (TEM) has long been an essential tool for understanding the structure of materials. Over the past couple of decades, this venerable technique has undergone a number of revolutions, such as the development of aberration correction for atomic level imaging, the realization of cryogenic TEM for imaging biological specimens, and new instrumentation permitting the observation of dynamic systems in situ. Research in the latter has rapidly accelerated in recent years, based on a silicon-chip architecture that permits a versatile array of experiments to be performed under the high vacuum of the TEM. Of particular interest is using these silicon chips to enclose fluids safely inside the TEM, allowing us to observe liquid dynamics at the nanoscale. In situ imaging of liquid phase reactions under TEM can greatly enhance our understanding of fundamental processes in fields from electrochemistry to cell biology. Here, we review how in situ TEM experiments of liquids can be performed, with a particular focus on microchip-encapsulated liquid cell TEM. We will cover the basics of the technique, and its strengths and weaknesses with respect to related in situ TEM methods for characterizing liquid systems. We will show how this technique has provided unique insights into nanomaterial synthesis and manipulation, battery science and biological cells. A discussion on the main challenges of the technique, and potential means to mitigate and overcome them, will also be presented.
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18
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Johnson SD, Butler HC, Robertson AW. Breeding systems in Cyrtanthus (Amaryllidaceae): variation in self-sterility and potential for ovule discounting. Plant Biol (Stuttg) 2019; 21:1008-1015. [PMID: 31271495 DOI: 10.1111/plb.13025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 07/01/2019] [Indexed: 06/09/2023]
Abstract
Breeding systems of plants determine their reliance on pollinators and ability to produce seeds following self-pollination. Self-sterility, where ovules that are penetrated by self-pollen tubes that do not develop into seeds, is usually considered to represent either a system of late-acting self-incompatibility or strong early inbreeding depression. Importantly, it can lead to impaired female function through ovule or seed discounting when stigmas receive mixtures of self and cross pollen, unless cross pollen is able to reach the ovary ahead of self pollen ('prepotency'). Self-sterility associated with ovule penetration by self-pollen tubes appears to be widespread among the Amaryllidaceae. We tested for self-sterility in three Cyrtanthus species - C. contractus, C. ventricosus and C. mackenii - by means of controlled hand-pollination experiments. To determine the growth rates and frequency of ovule penetration by self- versus cross-pollen tubes, we used fluorescence microscopy to examine flowers of C. contractus harvested 24, 48 and 72 h after pollination, in conjunction with a novel method of processing these images digitally. To test the potential for ovule discounting (loss of cross-fertilisation opportunities when ovules are disabled by self-pollination), we pollinated flowers of C. contractus and C. mackenii with mixtures of self- and cross pollen. We recorded full self-sterility for C. contractus and C. ventricosus, and partial self-sterility for C. mackenii. In C. contractus, we found no differences in the growth rates of self- and cross-pollen tubes, nor in the proportions of ovules penetrated by self- and cross-pollen tubes. In this species, seed set was depressed (relative to cross-pollinated controls) when flowers received a mixture of self and cross pollen, but this was not the case for C. mackenii. These results reveal variation in breeding systems among Cyrtanthus species and highlight the potential for gender conflict in self-sterile species in which ovules are penetrated and disabled by pollen tubes from self pollen.
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Affiliation(s)
- S D Johnson
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
| | - H C Butler
- Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
| | - A W Robertson
- Wildlife & Ecology, School of Agriculture & Environment, Massey University, Palmerston North, New Zealand
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19
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Robertson AW, Lee GD, Lee S, Buntin P, Drexler M, Abdelhafiz AA, Yoon E, Warner JH, Alamgir FM. Atomic Structure and Dynamics of Epitaxial Platinum Bilayers on Graphene. ACS Nano 2019; 13:12162-12170. [PMID: 31553564 DOI: 10.1021/acsnano.9b06701] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Platinum atomic layers grown on graphene were investigated by atomic resolution transmission electron microscopy (TEM). These TEM images reveal the epitaxial relationship between the atomically thin platinum layers and graphene, with two optimal epitaxies observed. The energetics of these epitaxies influences the grain structure of the platinum film, facilitating grain growth via in-plane rotation and assimilation of neighbor grains, rather than grain coarsening from the movement of grain boundaries. This growth process was enabled due to the availability of several possible low-energy intermediate states for the rotating grains, the Pt-Gr epitaxies, which are minima in surface energy, and coincident site lattice grain boundaries, which are minima in grain boundary energy. Density functional theory calculations reveal a complex interplay of considerations for minimizing the platinum grain energy, with free platinum edges also having an effect on the relative energetics. We thus find that the platinum atomic layer grains undergo significant reorientation to minimize interface energy (via epitaxy), grain boundary energy (via low-energy orientations), and free edge energy. These results will be important for the design of two-dimensional graphene-supported platinum catalysts and obtaining large-area uniform platinum atomic layer films and also provide fundamental experimental insight into the growth of heteroepitaxial thin films.
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Affiliation(s)
- Alex W Robertson
- Department of Materials , University of Oxford , Parks Road , Oxford , OX1 3PH , United Kingdom
| | - Gun-Do Lee
- Department of Materials Science and Engineering , Seoul National University , Gwanak-gu , Seoul 08826 , South Korea
- Research Institute of Advanced Materials , Seoul National University , Gwanak-gu , Seoul 08826 , Republic of Korea
| | - Sungwoo Lee
- Department of Materials Science and Engineering , Seoul National University , Gwanak-gu , Seoul 08826 , South Korea
- Research Institute of Advanced Materials , Seoul National University , Gwanak-gu , Seoul 08826 , Republic of Korea
| | - Parker Buntin
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Matthew Drexler
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Ali A Abdelhafiz
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
| | - Euijoon Yoon
- Department of Materials Science and Engineering , Seoul National University , Gwanak-gu , Seoul 08826 , South Korea
- Research Institute of Advanced Materials , Seoul National University , Gwanak-gu , Seoul 08826 , Republic of Korea
| | - Jamie H Warner
- Department of Materials , University of Oxford , Parks Road , Oxford , OX1 3PH , United Kingdom
| | - Faisal M Alamgir
- School of Materials Science and Engineering , Georgia Institute of Technology , Atlanta , Georgia 30332 , United States
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20
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Govind Rajan A, Silmore KS, Swett J, Robertson AW, Warner JH, Blankschtein D, Strano MS. Addressing the isomer cataloguing problem for nanopores in two-dimensional materials. Nat Mater 2019; 18:129-135. [PMID: 30643239 DOI: 10.1038/s41563-018-0258-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 11/20/2018] [Indexed: 06/09/2023]
Abstract
The presence of extended defects or nanopores in two-dimensional (2D) materials can change the electronic, magnetic and barrier membrane properties of the materials. However, the large number of possible lattice isomers of nanopores makes their quantitative study a seemingly intractable problem, confounding the interpretation of experimental and simulated data. Here we formulate a solution to this isomer cataloguing problem (ICP), combining electronic-structure calculations, kinetic Monte Carlo simulations, and chemical graph theory, to generate a catalogue of unique, most-probable isomers of 2D lattice nanopores. The results demonstrate remarkable agreement with precise nanopore shapes observed experimentally in graphene and show that the thermodynamic stability of a nanopore is distinct from its kinetic stability. Triangular nanopores prevalent in hexagonal boron nitride are also predicted, extending this approach to other 2D lattices. The proposed method should accelerate the application of nanoporous 2D materials by establishing specific links between experiment and theory/simulations, and by providing a much-needed connection between molecular design and fabrication.
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Affiliation(s)
- Ananth Govind Rajan
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kevin S Silmore
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | | | - Jamie H Warner
- Department of Materials, University of Oxford, Oxford, UK
| | - Daniel Blankschtein
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Michael S Strano
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
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21
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Sun Z, Zhang Y, Yu H, Yan C, Liu Y, Hong S, Tao H, Robertson AW, Wang Z, Pádua AAH. New solvent-stabilized few-layer black phosphorus for antibacterial applications. Nanoscale 2018; 10:12543-12553. [PMID: 29932193 DOI: 10.1039/c8nr03513j] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Discovering highly efficient, environmentally friendly, and low-cost exfoliating media that can both disperse and protect black phosphorus (BP) remains a challenge. Herein, we demonstrate such a new molecule, N,N'-dimethylpropyleneurea (DMPU), for effective exfoliation and dispersion of two-dimensional BP nanosheets. A very high exfoliation efficiency of up to 16% was achieved in DMPU, significantly surpassing other good solvents. Exfoliated flakes are free from structural disorder or oxidation. Nanosheets retain high stability in DMPU even after addition of 25 vol% of common solvents. The solvation shell appears to protect the nanosheets from reacting with water and air, more remarkably than the best solvent N-cyclohexyl-2-pyrrolidone reported so far. Molecular dynamics simulations of the exfoliation process show that DMPU is among the effective solvents, although energetically it does not appear as favorable as some other amides. We also demonstrate that our exfoliated BP nanosheets exhibit excellent antimicrobial activities against both Escherichia coli and Staphylococcus aureus, outperforming other common two-dimensional materials of graphene and MoS2, suggesting promise in biomedical applications.
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Affiliation(s)
- Zhenyu Sun
- State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China.
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22
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Robertson AW, Zhu G, Mehdi BL, Jacobs RMJ, De Yoreo J, Browning ND. Nanoparticle Immobilization for Controllable Experiments in Liquid-Cell Transmission Electron Microscopy. ACS Appl Mater Interfaces 2018; 10:22801-22808. [PMID: 29882653 DOI: 10.1021/acsami.8b03688] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We demonstrate that silanization can control the adhesion of nanostructures to the SiN windows compatible with liquid-cell transmission electron microscopy (LC-TEM). Formation of an (3-aminopropyl)triethoxysilane (APTES) self-assembled monolayer on a SiN window, producing a surface decorated with amino groups, permits strong adhesion of Au nanoparticles to the window. Many of these nanoparticles remain static, undergoing minimal translation or rotation during LC-TEM up to high electron beam current densities due to the strong interaction between the APTES amino group and Au. We then use this technique to perform a direct comparative LC-TEM study on the behavior of ligand and nonligand-coated Au nanoparticles in a Au growth solution. While the ligand coated nanoparticles remain consistent even under high electron beam current densities, the naked nanoparticles acted as sites for secondary Au nucleation. These nucleated particles decorated the parent nanoparticle surface, forming consecutive monolayer assemblies of ∼2 nm diameter nanoparticles, which sinter into the parent particle when the electron beam was shut off. This method for facile immobilization of nanostructures for LC-TEM study will permit more sophisticated and controlled in situ experiments into the properties of solid-liquid interfaces in the future.
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Affiliation(s)
- Alex W Robertson
- Physical & Computational Science Directorate , Pacific Northwest National Laboratory , Richland , Washington 99352 United States
- Department of Materials , University of Oxford , Parks Road , Oxford , OX1 3PH , United Kingdom
| | - Guomin Zhu
- Physical & Computational Science Directorate , Pacific Northwest National Laboratory , Richland , Washington 99352 United States
- Department of Materials Science and Engineering , University of Washington , Seattle , Washington 98195 , United States
| | - B Layla Mehdi
- Physical & Computational Science Directorate , Pacific Northwest National Laboratory , Richland , Washington 99352 United States
- School of Engineering , University of Liverpool , Liverpool , L69 3GH , United Kingdom
| | - Robert M J Jacobs
- Department of Chemistry, Chemistry Research Laboratory , University of Oxford , Mansfield Road , Oxford OX1 3TA , United Kingdom
| | - James De Yoreo
- Physical & Computational Science Directorate , Pacific Northwest National Laboratory , Richland , Washington 99352 United States
- Department of Materials Science and Engineering , University of Washington , Seattle , Washington 98195 , United States
| | - Nigel D Browning
- Physical & Computational Science Directorate , Pacific Northwest National Laboratory , Richland , Washington 99352 United States
- School of Engineering , University of Liverpool , Liverpool , L69 3GH , United Kingdom
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23
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Han Z, Choi C, Tao H, Fan Q, Gao Y, Liu S, Robertson AW, Hong S, Jung Y, Sun Z. Tuning the Pd-catalyzed electroreduction of CO2to CO with reduced overpotential. Catal Sci Technol 2018. [DOI: 10.1039/c8cy01037d] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The electrochemical CO2reduction to CO can be greatly enhanced by controlling the Pd–ceria interface and doping with tellurium atoms.
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Affiliation(s)
- Zishan Han
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Changhyeok Choi
- Graduate School of EEWS
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Hengcong Tao
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Qun Fan
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Yuannan Gao
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Shizhen Liu
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | | | - Song Hong
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Yousung Jung
- Graduate School of EEWS
- Korea Advanced Institute of Science and Technology (KAIST)
- Daejeon 34141
- Republic of Korea
| | - Zhenyu Sun
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
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24
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Tao H, Sun X, Back S, Han Z, Zhu Q, Robertson AW, Ma T, Fan Q, Han B, Jung Y, Sun Z. Doping palladium with tellurium for the highly selective electrocatalytic reduction of aqueous CO 2 to CO. Chem Sci 2017; 9:483-487. [PMID: 29629117 PMCID: PMC5868300 DOI: 10.1039/c7sc03018e] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Accepted: 11/03/2017] [Indexed: 11/21/2022] Open
Abstract
The doping of Pd with a small amount of Te can selectively convert CO2 to CO with a low overpotential.
Designing highly selective and energy-efficient electrocatalysts to minimize the competitive hydrogen evolution reaction in the electrochemical reduction of aqueous CO2 remains a challenge. In this study, we report that doping Pd with a small amount of Te could selectively convert CO2 to CO with a low overpotential. The PdTe/few-layer graphene (FLG) catalyst with a Pd/Te molar ratio of 1 : 0.05 displayed a maximum CO faradaic efficiency of about 90% at –0.8 V (vs. a reversible hydrogen electrode, RHE), CO partial current density of 4.4 mA cm–2, and CO formation turnover frequency of 0.14 s–1 at –1.0 V (vs. a RHE), which were 3.7-, 4.3-, and 10-fold higher than those of a Pd/FLG catalyst, respectively. Density functional calculations showed that Te adatoms preferentially bind at the terrace sites of Pd, thereby suppressing undesired hydrogen evolution, whereas CO2 adsorption and activation occurred on the high index sites of Pd to produce CO.
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Affiliation(s)
- Hengcong Tao
- State Key Laboratory of Organic-Inorganic Composites , Beijing University of Chemical Technology , Beijing 100029 , China .
| | - Xiaofu Sun
- Beijing National Laboratory for Molecular Sciences , Key Laboratory of Colloid and Interface and Thermodynamics , Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China .
| | - Seoin Back
- Graduate School of EEWS , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea .
| | - Zishan Han
- State Key Laboratory of Organic-Inorganic Composites , Beijing University of Chemical Technology , Beijing 100029 , China .
| | - Qinggong Zhu
- Beijing National Laboratory for Molecular Sciences , Key Laboratory of Colloid and Interface and Thermodynamics , Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China .
| | - Alex W Robertson
- Department of Materials , University of Oxford , Oxford , OX1 3PH , UK
| | - Tao Ma
- State Key Laboratory of Organic-Inorganic Composites , Beijing University of Chemical Technology , Beijing 100029 , China .
| | - Qun Fan
- State Key Laboratory of Organic-Inorganic Composites , Beijing University of Chemical Technology , Beijing 100029 , China .
| | - Buxing Han
- Beijing National Laboratory for Molecular Sciences , Key Laboratory of Colloid and Interface and Thermodynamics , Institute of Chemistry , Chinese Academy of Sciences , Beijing 100190 , China .
| | - Yousung Jung
- Graduate School of EEWS , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea .
| | - Zhenyu Sun
- State Key Laboratory of Organic-Inorganic Composites , Beijing University of Chemical Technology , Beijing 100029 , China .
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25
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Fan Y, Robertson AW, Zhou Y, Chen Q, Zhang X, Browning ND, Zheng H, Rümmeli MH, Warner JH. Electrical Breakdown of Suspended Mono- and Few-Layer Tungsten Disulfide via Sulfur Depletion Identified by in Situ Atomic Imaging. ACS Nano 2017; 11:9435-9444. [PMID: 28829575 DOI: 10.1021/acsnano.7b05080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The high-bias and breakdown behavior of suspended mono- and few-layer WS2 was explored by in situ aberration-corrected transmission electron microscopy. The suspended WS2 devices were found to undergo irreversible breakdown at sufficiently high biases due to vaporization of the WS2. Simultaneous to the removal of WS2 was the accompanying formation of few-layer graphene decorated with W and WS2 nanoparticles, with the carbon source attributed to organic residues present on the WS2 surface. The breakdown of few-layer WS2 resulted in the formation of faceted S-depleted WS2 tendrils along the vaporization boundary, which were found to exhibit lattice contraction indicative of S depletion, alongside pure W phases incorporated into the structure, with the interfaces imaged at atomic resolution. The combination of observing the graphitization of the amorphous carbon surface residue, W nanoparticles, and S-depleted WS2 phases following the high-bias WS2 disintegration all indicate a thermal Joule heating breakdown mechanism over an avalanche process, with WS2 destruction promoted by preferential S emission. The observation of graphene formation and the role the thin amorphous carbon layer has in the prebreakdown behavior of the device demonstrate the importance of employing encapsulated heterostructure device architectures that exclude residues.
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Affiliation(s)
- Ye Fan
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
- Physical & Computational Science Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
| | - Yingqiu Zhou
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Qu Chen
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Xiaowei Zhang
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Nigel D Browning
- Physical & Computational Science Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States
- Department of Materials Science and Engineering, University of Washington , Seattle, Washington 98195, United States
| | - Haimei Zheng
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Mark H Rümmeli
- Soochow Institute for Energy and Materials Innovations, College of Physics, Optoelectronics and Energy, Collaborative Innovation Center of Suzhou Nano Science and Technology, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University , Suzhou 215006, China
- Centre of Polymer and Carbon Materials, Polish Academy of Sciences , M. Curie-Sklodowskiej 34, Zabrze 41-819, Poland
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
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26
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Lee S, Kim D, Robertson AW, Yoon E, Hong S, Ihm J, Yu J, Warner JH, Lee GD. Graphene as a flexible template for controlling magnetic interactions between metal atoms. J Phys Condens Matter 2017; 29:085001. [PMID: 28081016 DOI: 10.1088/1361-648x/aa5167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Metal-doped graphene produces magnetic moments that have potential application in spintronics. Here we use density function theory computational methods to show how the magnetic interaction between metal atoms doped in graphene can be controlled by the degree of flexure in a graphene membrane. Bending graphene by flexing causes the distance between two substitutional Fe atoms covalently bonded in graphene to gradually increase and these results in the magnetic moment disappearing at a critical strain value. At the critical strain, a carbon atom can enter between the two Fe atoms and blocks the interaction between relevant orbitals of Fe atoms to quench the magnetic moment. The control of interactions between doped atoms by exploiting the mechanical flexibility of graphene is a unique approach to manipulating the magnetic properties and opens up new opportunities for mechanical-magnetic 2D device systems.
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Affiliation(s)
- Sungwoo Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Korea
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27
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Dave SH, Gong C, Robertson AW, Warner JH, Grossman JC. Correction to Chemistry and Structure of Graphene Oxide via Direct Imaging. ACS Nano 2017; 11:1121. [PMID: 28026164 DOI: 10.1021/acsnano.6b07705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
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28
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Tao H, Yan C, Robertson AW, Gao Y, Ding J, Zhang Y, Ma T, Sun Z. N-Doping of graphene oxide at low temperature for the oxygen reduction reaction. Chem Commun (Camb) 2017; 53:873-876. [DOI: 10.1039/c6cc08776k] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Nitrogen doping of graphene oxide was demonstrated for the first time at 5 °C in ammonia solution via ultrasonication.
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Affiliation(s)
- Hengcong Tao
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Chao Yan
- School of Material Science & Engineering
- Jiangsu University of Science and Technology
- Zhenjiang 212003
- China
| | | | - Yunnan Gao
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Jingjing Ding
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Yuqin Zhang
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Tao Ma
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
| | - Zhenyu Sun
- State Key Laboratory of Organic–Inorganic Composites
- Beijing University of Chemical Technology
- Beijing 100029
- China
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29
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Wang X, Hooper TN, Kumar A, Priest IK, Sheng Y, Samuels TOM, Wang S, Robertson AW, Pacios M, Bhaskaran H, Weller AS, Warner JH. Oligomeric aminoborane precursors for the chemical vapour deposition growth of few-layer hexagonal boron nitride. CrystEngComm 2017. [DOI: 10.1039/c6ce02006b] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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30
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Li S, Wang S, Salamone MM, Robertson AW, Nayak S, Kim H, Tsang SCE, Pasta M, Warner JH. Edge-Enriched 2D MoS2 Thin Films Grown by Chemical Vapor Deposition for Enhanced Catalytic Performance. ACS Catal 2016. [DOI: 10.1021/acscatal.6b02663] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Sha Li
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Shanshan Wang
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Matteo M. Salamone
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Alex W. Robertson
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Simantini Nayak
- Department
of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K
| | - Heeyeon Kim
- Convergence
Materials Laboratory, Korean Institute of Energy Research, 152
Gajeong-ro, Yuseong-gu, Daejeon 305-343, Korea
| | - S. C. Edman Tsang
- Department
of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K
| | - Mauro Pasta
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Jamie H. Warner
- Department
of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
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31
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Fan Y, Robertson AW, Zhang X, Tweedie M, Zhou Y, Rummeli MH, Zheng H, Warner JH. Negative Electro-conductance in Suspended 2D WS 2 Nanoscale Devices. ACS Appl Mater Interfaces 2016; 8:32963-32970. [PMID: 27934195 DOI: 10.1021/acsami.6b11480] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We study the in situ electro-conductance in nanoscale electronic devices composed of suspended monolayer WS2 with metal electrodes inside an aberration-corrected transmission electron microscope. Monitoring the conductance changes when the device is exposed to the electron beam of 80 keV energy reveals a reversible decrease in conductivity with increasing beam current density. The response time of the electro-conductance when exposed to the electron beam is substantially faster than the recovery time when the beam is turned off. We propose a charge trap model that accounts for excitation of electrons into the conduction band and localized trap states from energy supplied by inelastic scattering of incident 80 keV electrons. These results show how monolayer transition metal dichalcogenide 2D semiconductors can be used as transparent direct electron detectors in ultrathin nanoscale devices.
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Affiliation(s)
- Ye Fan
- Department of Materials, University of Oxford , Parks Rd, Oxford, OX1 3PH, United Kingdom
| | - Alex W Robertson
- Department of Materials, University of Oxford , Parks Rd, Oxford, OX1 3PH, United Kingdom
| | - Xiaowei Zhang
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Martin Tweedie
- Department of Materials, University of Oxford , Parks Rd, Oxford, OX1 3PH, United Kingdom
| | - Yingqiu Zhou
- Department of Materials, University of Oxford , Parks Rd, Oxford, OX1 3PH, United Kingdom
| | - Mark H Rummeli
- IFW Dresden , P.O. Box D-01171 Dresden, Germany
- College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , Suzhou 215006, China
- Centre of Polymer and Carbon Materials, Polish Academy of Sciences , M. Curie-Sklodowskiej 34, Zabrze 41-819, Poland
| | - Haimei Zheng
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Rd, Oxford, OX1 3PH, United Kingdom
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32
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Chen Q, He K, Robertson AW, Kirkland AI, Warner JH. Atomic Structure and Dynamics of Epitaxial 2D Crystalline Gold on Graphene at Elevated Temperatures. ACS Nano 2016; 10:10418-10427. [PMID: 27934079 DOI: 10.1021/acsnano.6b06274] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The atomic level dynamics of gold on graphene is studied at temperatures up to 800 °C using an in situ heating holder within an aberration-corrected transmission electron microscope. At this high temperature, individual gold atoms and nanoclusters are mobile across the surface of graphene and attach to defect sites and migrate along the edges of holes in graphene. Gold nanoclusters on clean graphene show crystallinity at temperatures above their predicted melting point for equivalent sized clusters due to strong epitaxial interactions with the underlying graphene lattice. Gold nanoclusters anchored to defect sites in graphene exhibit discrete rotations between fixed orientations while maintaining epitaxial correlations to the graphene. We show that gold nanoclusters can be two-dimensional with monolayer thickness and switch their crystal structure between two different phases. These results have important implications on the use of gold nanoclusters on graphene at elevated temperatures for applications, such as catalysis and plasmonics.
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Affiliation(s)
- Qu Chen
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Kuang He
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Angus I Kirkland
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
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33
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Robertson AW, Lin YC, Wang S, Sawada H, Allen CS, Chen Q, Lee S, Lee GD, Lee J, Han S, Yoon E, Kirkland AI, Kim H, Suenaga K, Warner JH. Atomic Structure and Spectroscopy of Single Metal (Cr, V) Substitutional Dopants in Monolayer MoS 2. ACS Nano 2016; 10:10227-10236. [PMID: 27934090 DOI: 10.1021/acsnano.6b05674] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Dopants in two-dimensional dichalcogenides have a significant role in affecting electronic, mechanical, and interfacial properties. Controllable doping is desired for the intentional modification of such properties to enhance performance; however, unwanted defects and impurity dopants also have a detrimental impact, as often found for chemical vapor deposition (CVD) grown films. The reliable identification, and subsequent characterization, of dopants is therefore of significant importance. Here, we show that Cr and V impurity atoms are found in CVD grown MoS2 monolayer 2D crystals as single atom substitutional dopants in place of Mo. We attribute these impurities to trace elements present in the MoO3 CVD precursor. Simultaneous annular dark field scanning transmission electron microscopy (ADF-STEM) and electron energy loss spectroscopy (EELS) is used to map the location of metal atom substitutions of Cr and V in MoS2 monolayers with single atom precision. The Cr and V are stable under electron irradiation at 60 to 80 kV, when incorporated into line defects, and when heated to elevated temperatures. The combined ADF-STEM and EELS differentiates these Cr and V dopants from other similar contrast defect structures, such as 2S self-interstitials at the Mo site, preventing misidentification. Density functional theory calculations reveal that the presence of Cr or V causes changes to the density of states, indicating doping of the MoS2 material. These transferred impurities could help explain the presence of trapped charges in CVD prepared MoS2.
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Affiliation(s)
- Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Yung-Chang Lin
- Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST) , AIST Central 5, Tsukuba 305-8564, Japan
| | - Shanshan Wang
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Hidetaka Sawada
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
- JEOL Limited, 3-1-2 Musashino, Akishima, Tokyo 196-8558, Japan
- Electron Physical Sciences Imaging Center, Diamond Light Source Limited, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Christopher S Allen
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
- Electron Physical Sciences Imaging Center, Diamond Light Source Limited, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Qu Chen
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Sungwoo Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Gun-Do Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Joohee Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Seungwu Han
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Euijoon Yoon
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Angus I Kirkland
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
- Electron Physical Sciences Imaging Center, Diamond Light Source Limited, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Heeyeon Kim
- Convergence Materials Laboratory, Korea Institute of Energy Research , 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343, Korea
| | - Kazu Suenaga
- Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST) , AIST Central 5, Tsukuba 305-8564, Japan
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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34
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Gong C, He K, Chen Q, Robertson AW, Warner JH. In Situ High Temperature Atomic Level Studies of Large Closed Grain Boundary Loops in Graphene. ACS Nano 2016; 10:9165-9173. [PMID: 27661200 DOI: 10.1021/acsnano.6b04959] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We use an in situ heating holder within an aberration corrected transmission electron microscope (AC-TEM) to study the structure and dynamics of large closed grain boundary (GB) loops in graphene at the atomic level. Temperatures up to 800 °C are used to accelerate dynamic evolution of the defect clusters, increasing bond rotation and atomic addition/loss. Our results show that the large closed GB loops relax under electron beam irradiation into several isolated dislocations far apart from each other. Line defects composed of several adjacent excess-atom clusters can be found during the reconfiguration process. Dislocation ejection from the closed GB loops are seen in real time and are shown to help the reduction in loop size. These results show detailed information about the stability and behavior of large GB loops in 2D materials that have importance in the high temperature processing of these materials.
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Affiliation(s)
- Chuncheng Gong
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Kuang He
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Qu Chen
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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35
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Gong C, He K, Lee GD, Chen Q, Robertson AW, Yoon E, Hong S, Warner JH. In Situ Atomic Level Dynamics of Heterogeneous Nucleation and Growth of Graphene from Inorganic Nanoparticle Seeds. ACS Nano 2016; 10:9397-9410. [PMID: 27643716 DOI: 10.1021/acsnano.6b04356] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An in situ heating holder inside an aberration-corrected transmission electron microscope (AC-TEM) is used to investigate the real-time atomic level dynamics associated with heterogeneous nucleation and growth of graphene from Au nanoparticle seeds. Heating monolayer graphene to an elevated temperature of 800 °C removes the majority of amorphous carbon adsorbates and leaves a clean surface. The aggregation of Au impurity atoms into nanoparticle clusters that are bound to the surface of monolayer graphene causes nucleation of secondary graphene layers from carbon feedstock present within the microscope chamber. This enables the in situ study of heterogeneous nucleation and growth of graphene at the atomic level. We show that the growth mechanism consists of alternating C cluster attachment and indentation filling to maintain a uniform growth front of lowest energy. Back-folding of the graphene growth front is observed, followed by a process that involves flipping back and attaching to the surrounding region. We show how the highly polycrystalline graphene seed evolves with time into a higher order crystalline structure using a combination of AC-TEM and tight-binding molecular dynamics (TBMD) simulations. This helps understand the detailed lowest-energy step-by-step pathways associated with grain boundaries (GB) migration and crystallization processes. We find the motion of the GB is discontinuous and mediated by both bond rotation and atom evaporation, supported by density functional theory calculations and TBMD. These results provide insights into the formation of crystalline seed domains that are generated during bottom-up graphene synthesis.
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Affiliation(s)
- Chuncheng Gong
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Kuang He
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Gun-Do Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Qu Chen
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Euijoon Yoon
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Suklyun Hong
- Department of Physics and Graphene Research Institute, Sejong University , Seoul 143-747, Korea
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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36
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Choi DS, Robertson AW, Warner JH, Kim SO, Kim H. Low-Temperature Chemical Vapor Deposition Synthesis of Pt-Co Alloyed Nanoparticles with Enhanced Oxygen Reduction Reaction Catalysis. Adv Mater 2016; 28:7115-7122. [PMID: 27276337 DOI: 10.1002/adma.201600469] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 05/04/2016] [Indexed: 06/06/2023]
Abstract
Novel Pt-Co alloyed nanocatalysts are generated via chemical vapor deposition-assisted facile one-pot synthesis. The method guarantees highly monodisperse Pt-Co alloy nanoparticles with precise control of metallic compositions within 1 at%. A significant features is that a perfectly alloyed single-crystal structure is obtained at temperatures as low as 500 °C, which is much lower than conventional alloying temperatures.
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Affiliation(s)
- Dong Sung Choi
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Alex W Robertson
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Jamie H Warner
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK
| | - Sang Ouk Kim
- National Creative Research Initiative Center for Multi-Dimensional Directed Nanoscale Assembly, Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Heeyeon Kim
- Energy Materials Laboratory, Korea Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon, 34129, Republic of Korea
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Abstract
Graphene oxide (GO) and reduced GO (rGO) are the only variants of graphene that can be manufactured at the kilogram scale, and yet the widely accepted model for their structure has largely relied on indirect evidence. Notably, existing high-resolution transmission electron microscopy (HRTEM) studies of graphene oxide report long-range order of sp(2) lattice with isolated defect clusters. Here, we present HRTEM evidence of a different structural form of GO, where nanocrystalline regions of sp(2) lattice are surrounded by regions of disorder. The presence of contaminants that adsorb to the surface of the material at room temperature normally prevents direct observation of the intrinsic atomic structure of this defective GO. To overcome this, we use an in situ heating holder within an aberration-corrected TEM (AC-TEM) to study the atomic structure of this nanocrystalline graphene oxide from room temperature to 700 °C. As the temperature increases to above 500 °C, the adsorbates detach from the GO and the underlying atomic structure is imaged to be small 2-4 nm crystalline domains within a polycrystalline GO film. By combining spectroscopic evidence with the AC-TEM data, we support the dynamic interpretation of the structural evolution of graphene oxide.
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Affiliation(s)
| | - Chuncheng Gong
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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38
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Wu X, Zhong G, D'Arsié L, Sugime H, Esconjauregui S, Robertson AW, Robertson J. Growth of Continuous Monolayer Graphene with Millimeter-sized Domains Using Industrially Safe Conditions. Sci Rep 2016; 6:21152. [PMID: 26883292 PMCID: PMC4756286 DOI: 10.1038/srep21152] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 01/18/2016] [Indexed: 11/24/2022] Open
Abstract
We demonstrate the growth of continuous monolayer graphene films with millimeter-sized domains on Cu foils under intrinsically safe, atmospheric pressure growth conditions, suitable for application in roll-to-roll reactors. Previous attempts to grow large domains in graphene have been limited to isolated graphene single crystals rather than as part of an industrially useable continuous film. With both appropriate pre-treatment of the Cu and optimization of the CH4 supply, we show that it is possible to grow continuous films of monolayer graphene with millimeter scale domains within 80 min by chemical vapour deposition. The films are grown under industrially safe conditions, i.e., the flammable gases (H2 and CH4) are diluted to well below their lower explosive limit. The high quality, spatial uniformity, and low density of domain boundaries are demonstrated by charge carrier mobility measurements, scanning electron microscope, electron diffraction study, and Raman mapping. The hole mobility reaches as high as ~5,700 cm2 V−1 s−1 in ambient conditions. The growth process of such high-quality graphene with a low H2 concentration and short growth times widens the possibility of industrial mass production.
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Affiliation(s)
- Xingyi Wu
- Department of Engineering, University of Cambridge, Cambridge, CB 3 0FA, United Kingdom
| | - Guofang Zhong
- Department of Engineering, University of Cambridge, Cambridge, CB 3 0FA, United Kingdom
| | - Lorenzo D'Arsié
- Department of Engineering, University of Cambridge, Cambridge, CB 3 0FA, United Kingdom
| | - Hisashi Sugime
- Department of Engineering, University of Cambridge, Cambridge, CB 3 0FA, United Kingdom
| | | | - Alex W Robertson
- Department of Materials, University of Oxford, Oxford, OX 1 3 PH, United Kingdom
| | - John Robertson
- Department of Engineering, University of Cambridge, Cambridge, CB 3 0FA, United Kingdom
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Abstract
We study the bond lengths of silicon (Si) atoms attached to both armchair and zigzag edges using aberration corrected transmission electron microscopy with monochromation of the electron beam. An in situ heating holder is used to perform imaging of samples at 800 °C in order to reduce chemical etching effects that cause rapid structure changes of graphene edges at room temperature under the electron beam. We provide detailed bond length measurements for Si atoms both attached to edges and also as near edge substitutional dopants. Edge reconstruction is also involved with the addition of Si dopants. Si atoms bonded to the edge of graphene are compared to substitutional dopants in the bulk lattice and reveal reduced out-of-plane distortion and bond elongation. An extended linear array of Si atoms at the edge is found to be energy-favorable due to inter-Si interactions. These results provide detailed structural information about the Si-C bonds in graphene, which may have importance in future catalytic and electronic applications.
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Affiliation(s)
- Qu Chen
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Kuang He
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Chuncheng Gong
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Euijoon Yoon
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Angus I Kirkland
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Gun-Do Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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40
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Abstract
The atomic structure of subnanometer pores in graphene, of interest due to graphene's potential as a desalination and gas filtration membrane, is demonstrated by atomic resolution aberration corrected transmission electron microscopy. High temperatures of 500 °C and over are used to prevent self-healing of the pores, permitting the successful imaging of open pore geometries consisting of between -4 to -13 atoms, all exhibiting subnanometer diameters. Picometer resolution bond length measurements are used to confirm reconstruction of five-membered ring projections that often decorate the pore perimeter, knowledge which is used to explore the viability of completely self-passivated subnanometer pore structures; bonding configurations where the pore would not require external passivation by, for example, hydrogen to be chemically inert.
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Affiliation(s)
- Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Gun-Do Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul, Korea
| | - Kuang He
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Chuncheng Gong
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Qu Chen
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Euijoon Yoon
- Department of Materials Science and Engineering, Seoul National University , Seoul, Korea
| | - Angus I Kirkland
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
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41
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Gong C, Robertson AW, He K, Lee GD, Yoon E, Allen CS, Kirkland AI, Warner JH. Thermally Induced Dynamics of Dislocations in Graphene at Atomic Resolution. ACS Nano 2015; 9:10066-10075. [PMID: 26461042 DOI: 10.1021/acsnano.5b05355] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Thermally induced dislocation movements are important in understanding the effects of high temperature annealing on modifying the crystal structure. We use an in situ heating holder in an aberration corrected transmission electron microscopy to study the movement of dislocations in suspended monolayer graphene up to 800 °C. Control of temperature enables the differentiation of electron beam induced effects and thermally driven processes. At room temperature, the dynamics of dislocation behavior is driven by the electron beam irradiation at 80 kV; however at higher temperatures, increased movement of the dislocation is observed and provides evidence for the influence of thermal energy to the system. An analysis of the dislocation movement shows both climb and glide processes, including new complex pathways for migration and large nanoscale rapid jumps between fixed positions in the lattice. The improved understanding of the high temperature dislocation movement provides insights into annealing processes in graphene and the behavior of defects with increased heat.
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Affiliation(s)
- Chuncheng Gong
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Kuang He
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Gun-Do Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Euijoon Yoon
- Department of Materials Science and Engineering, Seoul National University , Seoul 151-742, Korea
| | - Christopher S Allen
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Angus I Kirkland
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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42
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Abstract
With increasing possibilities for applications of graphene, it is essential to fully characterize the rich topological variations in graphene edge structures. Using aberration-corrected transmission electron microscopy, dangling carbon doublets at the edge of monolayer graphene crystals have been observed. Unlike the single-atom Klein edge often found at zigzag edges, these carbon dimers were observed in various edge structure environments, but most frequently on the more stable armchair edges. Observation of this Klein edge doublet over time reveals that its existence enhances the stability of armchair edges and is a route to atom abstraction on zigzag edges.
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Affiliation(s)
- Judy S Kim
- Department of Materials, University of Oxford , Parks Road, Oxford, OX13PH, U.K
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford, OX13PH, U.K
| | - Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford, OX13PH, U.K
| | - Angus I Kirkland
- Department of Materials, University of Oxford , Parks Road, Oxford, OX13PH, U.K
- Research Complex at Harwell (RCaH), Rutherford Appleton Laboratory Harwell , Didcot, Oxon, OX11 0FA, U.K
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43
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Robertson AW, Lee GD, He K, Fan Y, Allen CS, Lee S, Kim H, Yoon E, Zheng H, Kirkland AI, Warner JH. Partial Dislocations in Graphene and Their Atomic Level Migration Dynamics. Nano Lett 2015; 15:5950-5955. [PMID: 26313338 DOI: 10.1021/acs.nanolett.5b02080] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We demonstrate the formation of partial dislocations in graphene at elevated temperatures of ≥500 °C with single atom resolution aberration corrected transmission electron microscopy. The partial dislocations spatially redistribute strain in the lattice, providing an energetically more favorable configuration to the perfect dislocation. Low-energy migration paths mediated by partial dislocation formation have been observed, providing insights into the atomistic dynamics of graphene during annealing. These results are important for understanding the high temperature plasticity of graphene and partial dislocation behavior in related crystal systems, such as diamond cubic materials.
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Affiliation(s)
- Alex W Robertson
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Gun-Do Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul, Korea
| | - Kuang He
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Ye Fan
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Christopher S Allen
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Sungwoo Lee
- Department of Materials Science and Engineering, Seoul National University , Seoul, Korea
| | - Heeyeon Kim
- Energy Materials Laboratory, Korean Institute of Energy Research , 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343, Korea
| | - Euijoon Yoon
- Department of Materials Science and Engineering, Seoul National University , Seoul, Korea
| | - Haimei Zheng
- Materials Science Division, Lawrence Berkeley National Lab , Berkeley, California 94720, United States
| | - Angus I Kirkland
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Jamie H Warner
- Department of Materials, University of Oxford , Parks Road, Oxford, OX1 3PH, United Kingdom
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44
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Sugime H, Esconjauregui S, D'Arsié L, Yang J, Robertson AW, Oliver RA, Bhardwaj S, Cepek C, Robertson J. Low-Temperature Growth of Carbon Nanotube Forests Consisting of Tubes with Narrow Inner Spacing Using Co/Al/Mo Catalyst on Conductive Supports. ACS Appl Mater Interfaces 2015; 7:16819-16827. [PMID: 26176167 DOI: 10.1021/acsami.5b04846] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We grow dense carbon nanotube forests at 450 °C on Cu support using Co/Al/Mo multilayer catalyst. As a partial barrier layer for the diffusion of Co into Mo, we apply very thin Al layer with the nominal thickness of 0.50 nm between Co and Mo. This Al layer plays an important role in the growth of dense CNT forests, partially preventing the Co-Mo interaction. The forests have an average height of ∼300 nm and a mass density of 1.2 g cm(-3) with tubes exhibiting extremely narrow inner spacing. An ohmic behavior is confirmed between the forest and Cu support with the lowest resistance of ∼8 kΩ. The forest shows a high thermal effusivity of 1840 J s(-0.5) m(-2) K(-1), and a thermal conductivity of 4.0 J s(-1) m(-1) K(-1), suggesting that these forests are useful for heat dissipation devices.
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Affiliation(s)
- Hisashi Sugime
- †Department of Engineering, University of Cambridge, Cambridge CB3 0FA, United Kingdom
| | | | - Lorenzo D'Arsié
- †Department of Engineering, University of Cambridge, Cambridge CB3 0FA, United Kingdom
| | - Junwei Yang
- †Department of Engineering, University of Cambridge, Cambridge CB3 0FA, United Kingdom
| | - Alex W Robertson
- ‡Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Rachel A Oliver
- §Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB3 0FS, United Kingdom
| | - Sunil Bhardwaj
- ∥Istituto Officina dei Materiali-CNR, Laboratorio TASC, Trieste I-34149, Italy
| | - Cinzia Cepek
- ∥Istituto Officina dei Materiali-CNR, Laboratorio TASC, Trieste I-34149, Italy
| | - John Robertson
- †Department of Engineering, University of Cambridge, Cambridge CB3 0FA, United Kingdom
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45
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He K, Robertson AW, Gong C, Allen CS, Xu Q, Zandbergen H, Grossman JC, Kirkland AI, Warner JH. Controlled formation of closed-edge nanopores in graphene. Nanoscale 2015; 7:11602-11610. [PMID: 26088477 DOI: 10.1039/c5nr02277k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Dangling bonds at the edge of a nanopore in monolayer graphene make it susceptible to back-filling at low temperatures from atmospheric hydrocarbons, leading to potential instability for nanopore applications, such as DNA sequencing. We show that closed edge nanopores in bilayer graphene are robust to back-filling under atmospheric conditions for days. A controlled method for closed edge nanopore formation starting from monolayer graphene is reported using an in situ heating holder and electron beam irradiation within an aberration-corrected transmission electron microscopy. Tailoring of closed-edge nanopore sizes is demonstrated from 1.4-7.4 nm. These results should provide mechanisms for improving the stability of nanopores in graphene for a wide range of applications involving mass transport.
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Affiliation(s)
- Kuang He
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, UK.
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46
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Kim H, Robertson AW, Kim SO, Kim JM, Warner JH. Resilient High Catalytic Performance of Platinum Nanocatalysts with Porous Graphene Envelope. ACS Nano 2015; 9:5947-5957. [PMID: 26027750 DOI: 10.1021/acsnano.5b00678] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Despite the innumerable developments of nanosized and well dispersed noble metal catalysts, the degradation of metal nanoparticle catalysts has proven to be a significant obstacle for the commercialization of the hydrogen fuel cell. Here, the formation of Pt nanoparticle catalysts with a porous graphene envelope has been achieved using a single step low temperature vaporization process. While these Pt-Gr core-shell nanoparticles possess superior resilience to degradation, it comes at the cost of degraded overall catalyst efficacy. However, it is possible to combat this lower overall performance through inclusion of low concentrations of nitrogen precursor in the initial stage of single-step synthesis, inhibiting the formation of complete graphene shells, as verified by atomic resolution aberration-corrected transmission electron microscopy (AC-TEM) imaging. The resultant porous graphene encapsulated Pt catalysts are found to have both the high peak performance of the bare Pt nanoparticle catalysts and the increased resilience of the fully shielded Pt-Gr core-shells, with the optimal N-doped Pt-Gr yielding a peak efficiency of 87% compared to bare Pt, and maintaining 90% of its catalytic activity after extended potential cycling. The nitrogen treated Pt-Gr core-shells thus act as an effective substitute catalyst for conventional bare Pt nanoparticles, maintaining their catalytic performance over prolonged use.
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Affiliation(s)
- Heeyeon Kim
- †Energy Materials Laboratory, Korean Institute of Energy Research, 152 Gajeong-ro, Yuseong-gu, Daejeon 305-343, Korea
| | - Alex W Robertson
- ‡Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Sang Ouk Kim
- §Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Korea
| | - Jong Min Kim
- ∥Department of Engineering, University of Oxford, Parks Road, Oxford OX1 3PJ, United Kingdom
| | - Jamie H Warner
- ‡Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
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47
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He K, Robertson AW, Fan Y, Allen CS, Lin YC, Suenaga K, Kirkland AI, Warner JH. Temperature dependence of the reconstruction of zigzag edges in graphene. ACS Nano 2015; 9:4786-95. [PMID: 25880335 DOI: 10.1021/acsnano.5b01130] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We examine the temperature dependence of graphene edge terminations at the atomic scale using an in situ heating holder within an aberration-corrected transmission electron microscope. The relative ratios of armchair, zigzag, and reconstructed zigzag edges from over 350 frames at each temperature are measured. Below 400 °C, the edges are dominated by zigzag terminations, but above 600 °C, this changes dramatically, with edges dominated by armchair and reconstructed zigzag edges. We show that at low temperature chemical etching effects dominate and cause deviation to the thermodynamics of the system. At high temperatures (600 and 800 °C), adsorbates are evaporated from the surface of graphene and chemical etching effects are significantly reduced, enabling the thermodynamic distribution of edge types to be observed. The growth rate of holes at high temperature is also shown to be slower than at room temperature, indicative of the reduced chemical etching process. These results provide important insights into the role of chemical etching effects in the hole formation, edge sputtering, and edge reconstruction in graphene.
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Affiliation(s)
- Kuang He
- †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Alex W Robertson
- †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Ye Fan
- †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Christopher S Allen
- †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Yung-Chang Lin
- ‡Nanotube Research Center, Advanced Institute for Industrial Science and Technology, Tsukuba 305-8561, Japan
| | - Kazu Suenaga
- ‡Nanotube Research Center, Advanced Institute for Industrial Science and Technology, Tsukuba 305-8561, Japan
| | - Angus I Kirkland
- †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
| | - Jamie H Warner
- †Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K
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48
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Rong Y, He K, Pacios M, Robertson AW, Bhaskaran H, Warner JH. Controlled preferential oxidation of grain boundaries in monolayer tungsten disulfide for direct optical imaging. ACS Nano 2015; 9:3695-3703. [PMID: 25870912 DOI: 10.1021/acsnano.5b00852] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Synthetic 2D crystal films grown by chemical vapor deposition are typically polycrystalline, and determining grain size within domains and continuous films is crucial for determining their structure. Here we show that grain boundaries in the 2D transition metal dichalcogenide WS2, grown by CVD, can be preferentially oxidized by controlled heating in air. Under our developed conditions, preferential degradation at the grain boundaries causes an increase in their physical size due to oxidation. This increase in size enables their clear and rapid identification using a standard optical microscope. We demonstrate that similar treatments in an Ar environment do no show this effect, confirming that oxidation is the main role in the structural change. Statistical analysis of grain boundary (GB) angles shows dominant mirror formation. Electrical biasing across the GB is shown to lead to changes at the GB and their observation under an optical microscope. Our approach enables high-throughput screening of as-synthesized WS2 domains and continuous films to determine their crystallinity and should enable improvements in future CVD growth of these materials.
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Affiliation(s)
- Youmin Rong
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Kuang He
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Mercè Pacios
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Alex W Robertson
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Harish Bhaskaran
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
| | - Jamie H Warner
- Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom
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49
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Abstract
Graphene edges and their functionalization influence the electronic and magnetic properties of graphene nanoribbons. Theoretical calculations predict saturating graphene edges with hydrogen lower its energy and form a more stable structure. Despite the importance, experimental investigations of whether graphene edges are always hydrogen-terminated are limited. Here we study graphene edges produced by sputtering in vacuum and direct measurements of the C-C bond lengths at the edge show ~86% contraction relative to the bulk. Density functional theory reveals the contraction is attributed to the formation of a triple bond and the absence of hydrogen functionalization. Time-dependent images reveal temporary attachment of a single atom to the arm-chair C-C bond in a triangular configuration, causing expansion of the bond length, which then returns back to the contracted value once the extra atom moves on and the arm-chair edge is returned. Our results provide confirmation that non-functionalized graphene edges can exist in vacuum.
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Affiliation(s)
- Kuang He
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Gun-Do Lee
- Department of Materials Science and Engineering, Seoul National University, Seoul 151-742, Korea
| | - Alex W Robertson
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
| | - Euijoon Yoon
- Department of Materials Science and Engineering, Seoul National University, Seoul 151-742, Korea
| | - Jamie H Warner
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, UK
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50
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Gong C, He K, Robertson AW, Yoon E, Lee GD, Warner JH. Spatially dependent lattice deformations for dislocations at the edges of graphene. ACS Nano 2015; 9:656-662. [PMID: 25496495 DOI: 10.1021/nn505996c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We show that dislocations located at the edge of graphene cause different lattice deformations to those located in the bulk lattice. When a dislocation is located near an edge, a decrease in the rippling and increase of the in-plane rotation occurs relative to the dislocations in the bulk. The increased in-plane rotation near the edge causes bond rotations at the edge of graphene to reduce the overall strain in the system. Dislocations were highly stable and remained fixed in their position even when located within a few lattice spacings from the edge of graphene. We study this behavior at the atomic level using aberration-corrected transmission electron microscopy. These results show detailed information about the behavior of dislocations in 2D materials and the strain properties that result.
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Affiliation(s)
- Chuncheng Gong
- Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom
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