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Xu J, Xing S, Hu J, Shi Z. Stepwise on-surface synthesis of nitrogen-doped porous carbon nanoribbons. Commun Chem 2024; 7:40. [PMID: 38402282 PMCID: PMC10894233 DOI: 10.1038/s42004-024-01123-4] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 02/07/2024] [Indexed: 02/26/2024] Open
Abstract
Precise synthesis of carbon-based nanostructures with well-defined structural and chemical properties is of significance towards organic nanomaterials, but remains challenging. Herein, we report on a synthesis of nitrogen-doped porous carbon nanoribbons through a stepwise on-surface polymerization. Scanning tunneling microscopy revealed that the selectivity in molecular conformation, intermolecular debrominative aryl-aryl coupling and inter-chain dehydrogenative cross-coupling determined the well-defined topology and chemistry of the final products. Density functional theory calculations predict that the ribbons are semiconductors, and the band gap can be tuned by the width of the ribbons.
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Affiliation(s)
- Jin Xu
- Center for Soft Condensed Matter Physics & Interdisciplinary Research, School of Physical Science and Technology, Soochow University, Suzhou, 215006, China
| | - Shuaipeng Xing
- Center for Soft Condensed Matter Physics & Interdisciplinary Research, School of Physical Science and Technology, Soochow University, Suzhou, 215006, China
| | - Jun Hu
- School of Physical Science and Technology, Ningbo University, Ningbo, 315112, China.
| | - Ziliang Shi
- Center for Soft Condensed Matter Physics & Interdisciplinary Research, School of Physical Science and Technology, Soochow University, Suzhou, 215006, China.
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2
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Qin T, Guo D, Xiong J, Li X, Hu L, Yang W, Chen Z, Wu Y, Ding H, Hu J, Xu Q, Wang T, Zhu J. Synthesis of a Porous [14]Annulene Graphene Nanoribbon and a Porous [30]Annulene Graphene Nanosheet on Metal Surfaces. Angew Chem Int Ed Engl 2023; 62:e202306368. [PMID: 37401637 DOI: 10.1002/anie.202306368] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 07/05/2023]
Abstract
The electrical and mechanical properties of graphene-based materials can be tuned by the introduction of nanopores, which are sensitively related to the size, morphology, density, and location of nanopores. The synthesis of low-dimensional graphene nanostructures containing well-defined nonplanar nanopores has been challenging due to the intrinsic steric hindrance. Herein, we report the selective synthesis of one-dimensional (1D) graphene nanoribbons (GNRs) containing periodic nonplanar [14]annulene pores on Ag(111) and two-dimensional (2D) porous graphene nanosheet containing periodic nonplanar [30]annulene pores on Au(111), starting from a same precursor. The formation of distinct products on the two substrates originates from the different thermodynamics and kinetics of coupling reactions. The reaction mechanisms were confirmed by a series of control experiments, and the appropriate thermodynamic and kinetic parameters for optimizing the reaction pathways were proposed. In addition, the combined scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations revealed the electronic structures of porous graphene structures, demonstrating the impact of nonplanar pores on the π-conjugation of molecules.
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Affiliation(s)
- Tianchen Qin
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Dezhou Guo
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing, 100081, P. R. China
| | - Juanjuan Xiong
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Xingyu Li
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Lei Hu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Weishan Yang
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Zijie Chen
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Yulun Wu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Honghe Ding
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Jun Hu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Qian Xu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
| | - Tao Wang
- Donostia International Physics Center, 20018, San Sebastián, Spain
| | - Junfa Zhu
- National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei, 230029, P. R. China
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3
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Gammelgaard JJ, Sun Z, Vestergaard AK, Zhao S, Li Z, Lock N, Daasbjerg K, Bagger A, Rossmeisl J, Lauritsen JV. A Monolayer Carbon Nitride on Au(111) with a High Density of Single Co Sites. ACS Nano 2023; 17:17489-17498. [PMID: 37643209 DOI: 10.1021/acsnano.3c05996] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Carbon nitrides that expose atomically dispersed single-atom metals in the form of M-N-C (M = metal) sites are attractive earth-abundant catalyst materials that have been demonstrated in electrocatalytic conversion reactions. The catalytic performance is determined by the abundance of N-doped sites and the type of metal coordination to N, but challenges remain to synthesize pristine carbon nitrides with a high concentration of the most active sites and prepare homogeneously doped materials that allow for in-depth characterization of the M-N-C sites and quantitative evaluation of their catalytic performance. Herein, we have synthesized and characterized a well-defined monolayer carbon nitride phase on a Au(111) surface that exposes an exceedingly high concentration of Co-N4 sites. The crystalline monolayer carbon nitride, whose formation is controlled by an on-surface reaction between Co atoms and melamine on Au(111), is characterized by a dense array of 4- and 6-fold N-terminated pockets, whereof only the 4-fold pocket is found to be holding Co atoms. Through detailed characterization using scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory modeling, we determine the atomic structure and chemical state of the carbon nitride network. Furthermore, we show that the monolayer carbon nitride structure is stable and reactive toward the electrocatalytic oxygen reduction reaction in alkaline electrolyte, with a quantitative performance metric that significantly exceeds comparable M-N-C-based catalyst types. The work demonstrates that high-density active catalytic sites can be created using common precursor materials, and the formed networks themselves offer an excellent platform for onward studies addressing the characteristics of M-N-C sites.
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Affiliation(s)
| | - Zhaozong Sun
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - Anders K Vestergaard
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
| | - Siqi Zhao
- Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
- Novo Nordisk Foundation (NNF) CO2 Research Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Zheshen Li
- Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark
| | - Nina Lock
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
- Novo Nordisk Foundation (NNF) CO2 Research Center, Aarhus University, 8000 Aarhus C, Denmark
- Department of Biological and Chemical Engineering, Aarhus University, 8200 Aarhus N, Denmark
| | - Kim Daasbjerg
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
- Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
- Novo Nordisk Foundation (NNF) CO2 Research Center, Aarhus University, 8000 Aarhus C, Denmark
| | - Alexander Bagger
- Department of Chemistry, University of Copenhagen, 2100 Copenhagen, Denmark
- Department of Physics, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Jan Rossmeisl
- Department of Chemistry, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Jeppe V Lauritsen
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, 8000 Aarhus C, Denmark
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4
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Wu X, Fan H, Wang W, Lei L, Chang X, Ma L. Segmented Structure Design of Carbon Ring In-Plane Embedded in g-C 3 N 4 Nanotubes for Ultra-High Hydrogen Production. ChemSusChem 2022; 15:e202201268. [PMID: 36031750 DOI: 10.1002/cssc.202201268] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 08/25/2022] [Indexed: 06/15/2023]
Abstract
The photocatalytic water splitting capability of metal-free graphitic carbon nitride (g-C3 N4 ) photocatalyst is determined by its microstructure and photoexcited electrons transfer. Herein, a segmented structure was developed, consisting of alternant g-C3 N4 nanotubes and graphitic carbon rings (denoted as Cr -CN-NT). The Cr -CN-NT showed ordered structure and ultralong length/diameter ratio of 150 nm in diameter and a few microns in lengths, which promoted electron transport kinetics and elongated photocarrier diffusion length and lifetime. Meanwhile, the local in-plane π-conjugation was formed and extended in Cr -CN-NT, which could improve charge carrier density and prohibit electron-hole recombination. Accordingly, the average hydrogen evolution rate of Cr -CN-NT reached 9245 μmol h-1 g-1 , which was 61.6 times that of pristine CN, and the remarkable apparent quantum efficiency (AQE) of Cr -CN-NT reached up to 12.86 % at 420 nm. This work may provide a pathway for simultaneous morphology regulation and in-plane modification of high-performance photocatalysts.
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Affiliation(s)
- Xiaobo Wu
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, 710072, P. R. China
| | - Huiqing Fan
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, 710072, P. R. China
| | - Weijia Wang
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, 710072, P. R. China
| | - Lin Lei
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, 710072, P. R. China
| | - Xinye Chang
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an, 710072, P. R. China
| | - Longtao Ma
- Frontiers Science Center for Flexible Electronics, Institute of Flexible Electronics, Northwestern Polytechnical University, Xi'an, 710072, P. R. China
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5
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Wang W, Li Q, Yang J. High thermoelectric figure of merit in rhombic porous carbon nitride nanoribbons. J CHIN CHEM SOC-TAIP 2022. [DOI: 10.1002/jccs.202200359] [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] [Indexed: 11/10/2022]
Affiliation(s)
- Weiyi Wang
- Department of Chemical Physics & Hefei National Research Center for Physical Sciences at Microscale University of Science and Technology of China Hefei China
| | - Qunxiang Li
- Department of Chemical Physics & Hefei National Research Center for Physical Sciences at Microscale University of Science and Technology of China Hefei China
| | - Jinlong Yang
- Department of Chemical Physics & Hefei National Research Center for Physical Sciences at Microscale University of Science and Technology of China Hefei China
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6
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Wang D, Wang Z, Wu S, Yin X, Tang CS, Feng YP, Wu J, Wee ATS. Realizing Two-Dimensional Supramolecular Arrays of a Spin Molecule via Halogen Bonding. ACS Nanosci Au 2022; 2:333-340. [PMID: 37102064 PMCID: PMC10125333 DOI: 10.1021/acsnanoscienceau.2c00005] [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] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Well-ordered spin arrays are desirable for next-generation molecule-based magnetic devices, yet their synthetic method remains a challenging task. Herein, we demonstrate the realization of two-dimensional supramolecular spin arrays on surfaces via halogen-bonding molecular self-assembly. A bromine-terminated perchlorotriphenylmethyl radical with net carbon spin was synthesized and deposited on Au(111) to achieve two-dimensional supramolecular spin arrays. By taking advantage of the diversity of halogen bonds, five supramolecular spin arrays form and are probed by low-temperature scanning tunneling microscopy at the single-molecule level. First-principles calculations verify that the formation of three distinct types of halogen bonds can be used to tailor supramolecular spin arrays via molecular coverage and annealing temperature. Our work suggests that supramolecular self-assembly can be a promising method to engineer two-dimensional molecular spin arrays.
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Affiliation(s)
- Dingguan Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Zishen Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Shaofei Wu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Xinmao Yin
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, Singapore 117603, Singapore
- Shanghai Key Laboratory of High Temperature Superconductors, Physics Department, Shanghai University, Shanghai 200444, China
| | - Chi Sin Tang
- Singapore Synchrotron Light Source (SSLS), National University of Singapore, Singapore 117603, Singapore
- Institute of Materials Research and Engineering, ASTAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Singapore 138634, Singapore
| | - Yuan Ping Feng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Jishan Wu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Andrew T S Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
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7
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Zhang Y, Lu J, Li B, Chen W, Xiong W, Ruan Z, Zhang H, Sun S, Chen L, Gao L, Cai J. On-surface synthesis and characterization of nitrogen-doped covalent-organic frameworks on Ag(111) substrate. J Chem Phys 2022; 157:031103. [DOI: 10.1063/5.0099995] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Atomically precise fabrication of covalent-organic frameworks with well-defined heteroatom-dopant sites and further understanding of their electronic properties at the atomic level remain a challenge. Herein, we demonstrate the bottom-up synthesis of well-organized covalent-organic frameworks doped by nitrogen atoms on an Ag(111) substrate. Using high-resolution scanning tunneling microscopy and non-contact atomic force microscopy, the atomic structures of the intermediate metal–organic frameworks and the final covalent-organic frameworks are clearly identified. Scanning tunneling spectroscopy characterization reveals that the electronic bandgap of the as-formed N-doped covalent-organic framework is 2.45 eV, in qualitative agreement with the theoretical calculations. The calculated band structure together with the projected density of states analysis clearly unveils that the incorporation of nitrogen atoms into the covalent-organic framework backbone will remarkably tune the bandgap owing to the fact that the foreign nitrogen atom has one more electron than the carbon atom. Such covalent-organic frameworks may offer an atomic-scale understanding of the local electronic structure of heteroatom-doped covalent-organic frameworks and hold great promise for all relevant wide bandgap semiconductor technologies, for example, electronics, photonics, high-power and high-frequency devices, and solar energy conversion.
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Affiliation(s)
- Yong Zhang
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, No. 68 Wenchang Road, Kunming 650093, China
| | - Jianchen Lu
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, No. 68 Wenchang Road, Kunming 650093, China
| | - Baijin Li
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, No. 68 Wenchang Road, Kunming 650093, China
| | - Weiben Chen
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Wei Xiong
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, No. 68 Wenchang Road, Kunming 650093, China
| | - Zilin Ruan
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, No. 68 Wenchang Road, Kunming 650093, China
| | - Hui Zhang
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, No. 68 Wenchang Road, Kunming 650093, China
| | - Shijie Sun
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, No. 68 Wenchang Road, Kunming 650093, China
| | - Long Chen
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China
| | - Lei Gao
- Faculty of Science, Kunming University of Science and Technology, No. 727 Jingming South Road, Kunming 650500, China
| | - Jinming Cai
- Faculty of Materials Science and Engineering, Kunming University of Science and Technology, No. 68 Wenchang Road, Kunming 650093, China
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Wang D, Wang Z, Liu W, Zhong S, Feng YP, Loh KP, Wee ATS. Real-Space Investigation of the Multiple Halogen Bonds by Ultrahigh-Resolution Scanning Probe Microscopy. Small 2022; 18:e2202368. [PMID: 35719029 DOI: 10.1002/smll.202202368] [Citation(s) in RCA: 2] [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] [Received: 04/30/2022] [Indexed: 06/15/2023]
Abstract
The chemical bond is of central interest in chemistry, and it is of significance to study the nature of intermolecular bonds in real-space. Herein, non-contact atomic force microscopy (nc-AFM) and low-temperature scanning tunneling microscopy (LT-STM) are employed to acquire real-space atomic information of molecular clusters, i.e., monomer, dimer, trimer, tetramer, formed on Au(111). The formation of the various molecular clusters is due to the diversity of halogen bonds. DFT calculation also suggests the formation of three distinct halogen bonds among the molecular clusters, which originates from the noncovalent interactions of Br-atoms with the positive potential H-atoms, neutral potential Br-atoms, and negative potential N-atoms, respectively. This work demonstrates the real-space investigation of the multiple halogen bonds by nc-AFM/LT-STM, indicating the potential use of this technique to study other intermolecular bonds and to understand complex supramolecular assemblies at the atomic/sub-molecular level.
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Affiliation(s)
- Dingguan Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Zishen Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Wei Liu
- School of Physics, Southeast University, 2 Southeast University Road, Nanjing, China
| | - Siying Zhong
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Yuan Ping Feng
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
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9
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Wang D, Lu X, Cai L, Zhang L, Feng S, Zhang W, Yang M, Wu J, Wang Z, Wee ATS. Low-Dimensional Porous Carbon Networks Using Single-/Triple-Coupling Polycyclic Hydrocarbon Precursors. ACS Nano 2022; 16:9843-9851. [PMID: 35657207 DOI: 10.1021/acsnano.2c03909] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Polycyclic hydrocarbons (PHs) share the same hexagonal structure of sp2 carbons as graphene but possess an energy gap due to quantum confinement effect. PHs can be synthesized by a bottom-up strategy starting from small building blocks covalently bonded into large 2D organic sheets. Further investigation of the role of the covalent bonding/coupling ways on their electronic properties is needed. Here, we demonstrate a surface-mediated synthesis of hexa-peri-hexabenzocoronene (HBC) and its extended HBC oligomers (dimers, trimers, and tetramers) via single- and triple-coupling ways and reveal the implication of different covalent bonding on their electronic properties. High-resolution low-temperature scanning tunneling microscopy and noncontact atomic force microscopy are employed to in situ determine the atomic structures of as-synthesized HBC oligomers. Scanning tunneling spectroscopy measurements show that the length extension of HBC oligomers narrows the energy gap between highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO). Furthermore, the energy gaps of triple-coupling HBC oligomers are smaller and decrease more significantly than that of the single-coupling ones. We hypothesize that the triple coupling promotes a more effective delocalization of π-electrons than the single coupling, according to density functional theory calculations. We also demonstrate that the HBC oligomers can further extend across the substrate steps to achieve conjugated polymers and large-area porous carbon networks.
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Affiliation(s)
- Dingguan Wang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Xuefeng Lu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
- Department of Materials Science, Fudan University, Shanghai 200438, China
| | - Liangliang Cai
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Lei Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
| | - Shuo Feng
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Wenjing Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Ming Yang
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Jishan Wu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Zhuo Wang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Andrew T S Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore
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10
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Abstract
Significant efforts are focused on defect-engineering of metal-free graphitic carbon nitride (g-C3N4) to amplify its efficacy. A conceptually new multidefect-modified g-C3N4 having simultaneously two or more defects has attracted strong attention for its enhanced photocatalytic properties. We model and compare the excited state dynamics in g-C3N4 with (i) nitrogen defects (N vacancy and CN group) and (ii) dual defects (N vacancy, CN group, and O doping) and show that the nonradiative recombination of charge carriers in these systems follows the Shockley-Read-Hall mechanism. The nitrogen defects create three midgap states that trap charges and act as recombination centers. The dual-defect modified systems exhibit superior properties compared with pristine g-C3N4 because the defects facilitate rapid charge separation and extend the spectrum of absorbed light. The system doped with O shows better performance due to enhanced carrier lifetime and higher oxidation potential caused by a downshifted valence band. The study provides guidance for rational design of stable and efficient photocatalytic materials.
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Affiliation(s)
- Shriya Gumber
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Sraddha Agrawal
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Oleg V Prezhdo
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
- Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, United States
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11
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Wang D, Lu X, Yang M, Wu J, Wee ATS. On-Surface Synthesis of Variable Bandgap Nanoporous Graphene. Small 2021; 17:e2102246. [PMID: 34535956 DOI: 10.1002/smll.202102246] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/26/2021] [Indexed: 06/13/2023]
Abstract
Tuning the bandgap of nanoporous graphene is desirable for applications such as the charge transport layer in organic-hybrid devices. The holy grail in the field is the ability to synthesize 2D nanoporous graphene with variable pore sizes, and hence tunable band gaps. Herein, the on-surface synthesis of nanoporous graphene with variable bandgaps is demonstrated. Two types of nanoporous graphene are synthesized via hierarchical CC coupling, and are verified by low-temperature scanning tunneling microscopy and non-contact atomic force microscopy. Nanoporous graphene-1 is non-planar, and nanoporous graphene-2 is a single-atom thick planar sheet. Scanning tunneling spectroscopy measurements reveal that nanoporous graphene-2 has a bandgap of 3.8 eV, while nanoporous graphene-1 has a larger bandgap of 5.0 eV. Corroborated by first-principles calculations, it is proposed that the large bandgap opening is governed by the confinement of π-electrons induced by pore generation and the non-planar structure. The finding shows that by introducing nanopores or a twisted structure, semi metallic graphene is converted into semiconducting nanoporous graphene-2 or insulating wide-bandgap nanoporous graphene-1.
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Affiliation(s)
- Dingguan Wang
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Xuefeng Lu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
- Department of Materials Science, Fudan University, Shanghai, 200438, China
| | - Ming Yang
- Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Jishan Wu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore, 117543, Singapore
| | - Andrew T S Wee
- Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore, 117551, Singapore
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Tang D, Shao C, Jiang S, Sun C, Song S. Graphitic C 2N 3: An Allotrope of g-C 3N 4 Containing Active Azide Pentagons as Metal-Free Photocatalyst for Abundant H 2 Bubble Evolution. ACS Nano 2021; 15:7208-7215. [PMID: 33871961 DOI: 10.1021/acsnano.1c00477] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A g-C3N4 allotrope, a curved leaf-like graphitic C2N3 (g-C2N3) with an intrinsic spontaneous polarization electric field (ISPEF), has been constructed for efficient solar energy conversion into H2 energy via photocatalytic H2O splitting. The curved leaf-like π-delocalization g-C2N3 was composed of aromatic azide pentagons and normal triazine hexagons obtained by cycloaddition between -C≡N groups from dicyandiamide polymerization and azide from the heat-treated polypyrrole fibers. Under light irradiation (λ > 420 nm), photo-generated charges are driven to separate efficiently and transfer from bulk to active sites of the surface under ISPEF that is opposite to the Coulomb field. Consequently, without any cocatalyst, g-C3N4 allotrope demonstrates a very high H2-production activity of 14.9 mmol g-1 h-1 accompanied by a lot of H2 bubbles, which is 2.6 times of g-C3N4 loading with Pt. In comparison with the reported metal-free photocatalysts or those supported with noble metals, g-C3N4 allotrope (i.e., leaf-like g-C2N3) is confirmed to be the best metal-free photocatalyst for H2O splitting into H2 fuel so far. The contructed leaf-like g-C2N3 with SPEF supplies a suitable platform for solar energy conversion into H2 fuel, which actively contributes to clean energy production.
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Affiliation(s)
- Dongmei Tang
- School of Material Science and Chemical Engineering, Ningbo University, Fenghua Road 818, Ningbo 315211, People's Republic of China
| | - Chengtian Shao
- Department of Chemistry, Chung Yuan Christian University, Taoyuan City 32033, Taiwan
| | - Shujuan Jiang
- School of Material Science and Chemical Engineering, Ningbo University, Fenghua Road 818, Ningbo 315211, People's Republic of China
| | - Chuanzhi Sun
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan 250014, People's Republic of China
| | - Shaoqing Song
- School of Material Science and Chemical Engineering, Ningbo University, Fenghua Road 818, Ningbo 315211, People's Republic of China
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