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Tetteh EB, Krysiak OA, Savan A, Kim M, Zerdoumi R, Chung TD, Ludwig A, Schuhmann W. Long-Range SECCM Enables High-Throughput Electrochemical Screening of High Entropy Alloy Electrocatalysts at Up-To-Industrial Current Densities. Small Methods 2023:e2301284. [PMID: 38155148 DOI: 10.1002/smtd.202301284] [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: 09/22/2023] [Revised: 12/18/2023] [Indexed: 12/30/2023]
Abstract
High-entropy alloys (HEAs), especially in the form of compositional complex solid solutions (CCSS), have gained attention in the field of electrocatalysis. However, exploring their vast composition space concerning their electrocatalytic properties imposes significant challenges. Scanning electrochemical cell microscopy (SECCM) offers high-speed electrochemical analysis on surface areas with a lateral resolution down to tens of nm. However, high-precision piezo positioners often used for the motion of the tip limit the area of SECCM scans to the motion range of the piezo positioners which is typically a few tens of microns. To bridge this experimental gap, the study proposes a long-range SECCM system with a rapid gas-exchange environmental cell for high-throughput electrochemical characterization of 100 mm diameter HEA thin-film material libraries (ML) obtained by combinatorial co-sputtering. Due to the gas-liquid interface at the positioned SECCM droplet on the sample, high-throughput evaluation under industrial current density conditions becomes feasible. This allows the direct correlation between electrocatalytic activity and material composition with high statistical reliability. The multidimensional data obtained accelerates materials discovery, development, and optimization.
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Affiliation(s)
- Emmanuel Batsa Tetteh
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Olga A Krysiak
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Alan Savan
- Chair for Materials Discovery and Interfaces, Institute for Materials, Faculty of Mechanical Engineering, Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Moonjoo Kim
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
- Department of Chemistry, Seoul National University, Seoul, 08826, Republic of Korea
| | - Ridha Zerdoumi
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Taek Dong Chung
- Department of Chemistry, Seoul National University, Seoul, 08826, Republic of Korea
- Advanced Institute of Convergence Technology, Suwon-si, Gyeonggi-do, 16229, Republic of Korea
| | - Alfred Ludwig
- Chair for Materials Discovery and Interfaces, Institute for Materials, Faculty of Mechanical Engineering, Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
- Center for Interface-Dominated High-Performance Materials, ZGH; Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
| | - Wolfgang Schuhmann
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr University Bochum, Universitätsstr. 150, D-44780, Bochum, Germany
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2
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Lee H, Matthews KC, Zhan X, Warner JH, Ren H. Precision Synthesis of Bimetallic Nanoparticles via Nanofluidics in Nanopipets. ACS Nano 2023; 17:22499-22507. [PMID: 37926957 DOI: 10.1021/acsnano.3c06011] [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: 11/07/2023]
Abstract
Bimetallic nanoparticles often show properties superior to their single-component counterparts. However, the large parameter space, including size, structure, composition, and spatial arrangement, impedes the discovery of the best nanoparticles for a given application. High-throughput methods that can control the composition and spatial arrangement of the nanoparticles are desirable for accelerated materials discovery. Herein, we report a methodology for synthesizing bimetallic alloy nanoparticle arrays with precise control over their composition and spatial arrangement. A dual-channel nanopipet is used, and nanofluidic control in the nanopipet further enables precise tuning of the electrodeposition rate of each element, which determines the final composition of the nanoparticle. The composition control is validated by finite element simulation as well as electrochemical and elemental analyses. The scope of the particles demonstrated includes Cu-Ag, Cu-Pt, Au-Pt, Cu-Pb, and Co-Ni. We further demonstrate surface patterning using Cu-Ag alloys with precise control of the location and composition of each pixel. Additionally, combining the nanoparticle alloy synthesis method with scanning electrochemical cell microscopy (SECCM) allows for fast screening of electrocatalysts. The method is generally applicable for synthesizing metal nanoparticles that can be electrodeposited, which is important toward developing automated synthesis and screening systems for accelerated material discovery in electrocatalysis.
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Affiliation(s)
- Heekwon Lee
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Kevin C Matthews
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Xun Zhan
- Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jamie H Warner
- Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Hang Ren
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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3
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Kang M, Bentley CL, Mefford JT, Chueh WC, Unwin PR. Multiscale Analysis of Electrocatalytic Particle Activities: Linking Nanoscale Measurements and Ensemble Behavior. ACS Nano 2023; 17:21493-21505. [PMID: 37883688 PMCID: PMC10655184 DOI: 10.1021/acsnano.3c06335] [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: 07/11/2023] [Accepted: 09/18/2023] [Indexed: 10/28/2023]
Abstract
Nanostructured electrocatalysts exhibit variations in electrochemical properties across different length scales, and the intrinsic catalytic characteristics measured at the nanoscale often differ from those at the macro-level due to complexity in electrode structure and/or composition. This aspect of electrocatalysis is addressed herein, where the oxygen evolution reaction (OER) activity of β-Co(OH)2 platelet particles of well-defined structure is investigated in alkaline media using multiscale scanning electrochemical cell microscopy (SECCM). Microscale SECCM probes of ∼50 μm diameter provide voltammograms from small particle ensembles (ca. 40-250 particles) and reveal increasing dispersion in the OER rates for samples of the same size as the particle population within the sample decreases. This suggests the underlying significance of heterogeneous activity at the single-particle level that is confirmed through single-particle measurements with SECCM probes of ∼5 μm diameter. These measurements of multiple individual particles directly reveal significant variability in the OER activity at the single-particle level that do not simply correlate with the particle size, basal plane roughness, or exposed edge plane area. In combination, these measurements demarcate a transition from an "individual particle" to an "ensemble average" response at a population size of ca. 130 particles, above which the OER current density closely reflects that measured in bulk at conventional macroscopic particle-modified electrodes. Nanoscale SECCM probes (ca. 120 and 440 nm in diameter) enable measurements at the subparticle level, revealing that there is selective OER activity at the edges of particles and highlighting the importance of the three-phase boundary where the catalyst, electrolyte, and supporting carbon electrode meet, for efficient electrocatalysis. Furthermore, subparticle measurements unveil heterogeneity in the OER activity among particles that appear superficially similar, attributable to differences in defect density within the individual particles, as well as to variations in electrical and physical contact with the support material. Overall this study provides a roadmap for the multiscale analysis of nanostructured electrocatalysts, directly demonstrating the importance of multilength scale factors, including particle structure, particle-support interaction, presence of defects, etc., in governing the electrochemical activities of β-Co(OH)2 platelet particles and ultimately guiding the rational design and optimization of these materials for alkaline water electrolysis.
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Affiliation(s)
- Minkyung Kang
- School
of Chemistry, The University of Sydney, Camperdown 2006 NSW, Australia
- Department
of Chemistry, The University of Warwick, Coventry CV4 7AL, U.K.
| | | | - J. Tyler Mefford
- Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States
| | - William C. Chueh
- Department
of Materials Science and Engineering, Stanford
University, Stanford, California 94305, United States
| | - Patrick R. Unwin
- Department
of Chemistry, The University of Warwick, Coventry CV4 7AL, U.K.
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4
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Kawabe Y, Ito Y, Hori Y, Kukunuri S, Shiokawa F, Nishiuchi T, Jeong S, Katagiri K, Xi Z, Li Z, Shigeta Y, Takahashi Y. 1T/1H-SnS 2 Sheets for Electrochemical CO 2 Reduction to Formate. ACS Nano 2023. [PMID: 37272845 DOI: 10.1021/acsnano.2c12627] [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] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Understanding the catalytic mechanism of highly active two-dimensional electrocatalysts is crucial to their rational design. Herein, we reveal the element dependence of the reactivity of two-dimensional metal dichalcogenide sheets for electrocatalytic CO2 reduction. We found that tin(IV) disulfide (SnS2) and molybdenum(IV) disulfide (MoS2) sheets exhibited Faradaic efficiencies of 63.3% and ∼0%, respectively, for formic acid. Scanning electrochemical cell microscopy and theoretical calculations were used to identify the catalytically active sites of SnS2 as terraces and edges. Owing to the effective utilization of the entire surface area, SnS2 can effectively accelerate catalytic reactions. This finding provides a direction for material research in two-dimensional electrocatalysts for energy-efficient chemical production from electrochemical CO2 reduction, as well as for other energy devices.
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Affiliation(s)
- Yusuke Kawabe
- Department of Electronics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Yoshikazu Ito
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Yuta Hori
- Center for Computational Sciences, University of Tsukuba, Ibaraki 305-8577, Japan
| | - Suresh Kukunuri
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Fumiya Shiokawa
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Tomohiko Nishiuchi
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Samuel Jeong
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Kosuke Katagiri
- Division of Electrical Engineering and Computer Science, Kanazawa University, Kanazawa 920-1192, Japan
| | - Zeyu Xi
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Zhikai Li
- Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan
| | - Yasuteru Shigeta
- Center for Computational Sciences, University of Tsukuba, Ibaraki 305-8577, Japan
| | - Yasufumi Takahashi
- Department of Electronics, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
- WPI Nano Life Science Institute (NanoLSI, WPI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan
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5
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Zhao J, Wang M, Peng Y, Ni J, Hu S, Zeng J, Chen Q. Exploring the Strain Effect in Single Particle Electrochemistry using Pd Nanocrystals. Angew Chem Int Ed Engl 2023:e202304424. [PMID: 37225678 DOI: 10.1002/anie.202304424] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 05/11/2023] [Accepted: 05/22/2023] [Indexed: 05/26/2023]
Abstract
Tuning the surface strain of heterogeneous catalysts are recognized as a powerful strategy for tailoring their catalytic activity. However, a clear understanding of the strain effect in electrocatalysis at single-particle resolution is still lacking. Here, we explore the electrochemical hydrogen evolution reaction (HER) of single Pd octahedra and icosahedra with the same surface bounded {111} crystal facets and similar sizes using scanning electrochemical cell microscopy (SECCM). It is revealed that tensely strained Pd icosahedra display significantly superior HER electrocatalytic activity. The estimated turnover frequency at -0.87 V vs RHE on Pd icosahedra is about two times higher than that on Pd octahedra. Our single-particle electrochemistry study using SECCM at Pd nanocrystals ambiguously highlights the importance of tensile strain on electrocatalytic activity and may offer new strategy for understanding the fundamental relationship between surface strain and reactivity.
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Affiliation(s)
- Jiao Zhao
- Donghua University, College of Chemistry and Chemical Engineering, CHINA
| | - Menglin Wang
- USTC: University of Science and Technology of China, Hefei National Research Center for Physical Sciences at the Microscale, CHINA
| | - Yu Peng
- Donghua University, College of Chemistry and Chemical Engineering, CHINA
| | - Jie Ni
- USTC: University of Science and Technology of China, Hefei National Research Center for Physical Sciences at the Microscale, CHINA
| | - Sunpei Hu
- USTC: University of Science and Technology of China, Hefei National Research Center for Physical Sciences at the Microscale, CHINA
| | - Jie Zeng
- USTC: University of Science and Technology of China, Hefei National Research Center for Physical Sciences at the Microscale, 96 Jinzhai Road, 230026, Hefei, CHINA
| | - Qianjin Chen
- Donghua University, College of Chemistry and Chemical Engineering, CHINA
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6
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Varhade S, Tetteh EB, Saddeler S, Schumacher S, Aiyappa HB, Bendt G, Schulz S, Andronescu C, Schuhmann W. Crystal Plane-Related Oxygen-Evolution Activity of Single Hexagonal Co 3 O 4 Spinel Particles. Chemistry 2023; 29:e202203474. [PMID: 36423237 DOI: 10.1002/chem.202203474] [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] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 11/24/2022] [Accepted: 11/24/2022] [Indexed: 11/26/2022]
Abstract
The electrocatalytic activity for the oxygen evolution reaction in alkaline electrolyte of hexagonal spinel Co3 O4 nanoparticles derived using scanning electrochemical cell microscopy (SECCM) is correlated with scanning electron microscopy and atomic force microscopy images of the droplet landing sites. A unique way to deconvolute the intrinsic catalytic activity of individual crystal facets of the hexagonal Co3 O4 spinel particle is demonstrated in terms of the turnover frequency (TOF) of surface Co atoms. The top surface exposing 111 crystal planes displayed a thickness-dependent TOF with a TOF of about 100 s-1 at a potential of 1.8 V vs. RHE and a particle thickness of 100 nm. The edge of the particle exposing (110) planes, however, showed an average TOF of 270±68 s-1 at 1.8 V vs. RHE and no correlation with particle thickness. The higher atomic density of Co atoms on the edge surface (2.5 times of the top) renders the overall catalytic activity of the edge planes significantly higher than that of the top planes. The use of a free-diffusing Os complex in the alkaline electrolyte revealed the low electrical conductivity through individual particles, which explains the thickness-dependent TOF of the top planes and could be a reason for the low activity of the top (111) planes.
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Affiliation(s)
- Swapnil Varhade
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Emmanuel Batsa Tetteh
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Sascha Saddeler
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780, Bochum, Germany.,Inorganic Chemistry, Faculty of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45141, Essen, Germany
| | - Simon Schumacher
- Chemical Technology III, Faculty of Chemistry, University of Duisburg Essen, Carl-Benz-Strasse 199, 47057, Duisburg, Germany
| | - Harshitha Barike Aiyappa
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780, Bochum, Germany
| | - Georg Bendt
- Inorganic Chemistry, Faculty of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45141, Essen, Germany
| | - Stephan Schulz
- Inorganic Chemistry, Faculty of Chemistry, University of Duisburg-Essen, Universitätsstrasse 7, 45141, Essen, Germany.,Center for Nanointegration (CENIDE), University of Duisburg-Essen, Carl-Benz-Strasse 199, 47057, Duisburg, Germany
| | - Corina Andronescu
- Chemical Technology III, Faculty of Chemistry, University of Duisburg Essen, Carl-Benz-Strasse 199, 47057, Duisburg, Germany.,Center for Nanointegration (CENIDE), University of Duisburg-Essen, Carl-Benz-Strasse 199, 47057, Duisburg, Germany
| | - Wolfgang Schuhmann
- Analytical Chemistry - Center for Electrochemical Sciences (CES), Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780, Bochum, Germany
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7
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Tao B, McPherson IJ, Daviddi E, Bentley CL, Unwin PR. Multiscale Electrochemistry of Lithium Manganese Oxide (LiMn 2O 4): From Single Particles to Ensembles and Degrees of Electrolyte Wetting. ACS Sustain Chem Eng 2023; 11:1459-1471. [PMID: 36743391 PMCID: PMC9890564 DOI: 10.1021/acssuschemeng.2c06075] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [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: 10/10/2022] [Revised: 12/16/2022] [Indexed: 06/18/2023]
Abstract
Scanning electrochemical cell microscopy (SECCM) facilitates single particle measurements of battery materials using voltammetry at fast scan rates (1 V s-1), providing detailed insight into intrinsic particle kinetics, otherwise obscured by matrix effects. Here, we elucidate the electrochemistry of lithium manganese oxide (LiMn2O4) particles, using a series of SECCM probes of graded size to determine the evolution of electrochemical characteristics from the single particle to ensemble level. Nanometer scale control over the SECCM meniscus cell position and height further allows the study of variable particle/substrate electrolyte wetting, including comparison of fully wetted particles (where contact is also made with the underlying glassy carbon substrate electrode) vs partly wetted particles. We find ensembles of LiMn2O4 particles show voltammograms with much larger peak separations than those of single particles. In addition, if the SECCM meniscus is brought into contact with the substrate electrode, such that the particle-support contact changes from dry to wet, a further dramatic increase in peak separation is observed. Finite element method modeling of the system reveals the importance of finite electronic conductivity of the particles, contact resistance, surface kinetics, particle size, and contact area with the electrode surface in determining the voltammetric waveshape at fast scan rates, while the responses are relatively insensitive to Li+ diffusion coefficients over a range of typical values. The simulation results explain the variability in voltammetric responses seen at the single particle level and reveal some of the key factors responsible for the evolution of the response, from ensemble, contact, and wetting perspectives. The variables and considerations explored herein are applicable to any single entity (nanoscale) electrochemical study involving low conductivity materials and should serve as a useful guide for further investigations of this type. Overall, this study highlights the potential of multiscale measurements, where wetting, electronic contact, and ionic contact can be varied independently, to inform the design of practical composite electrodes.
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Affiliation(s)
- Binglin Tao
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Ian J. McPherson
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Enrico Daviddi
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | | | - Patrick R. Unwin
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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8
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Li M, Wang Y, Blount B, Gordon E, Muñoz-Castañeda JA, Ye Z, Ren H. Stochastic Local Breakdown of Oxide Film on Ni from Identical-Location Imaging: One Single Site at a Time. Nano Lett 2022; 22:6313-6319. [PMID: 35877081 DOI: 10.1021/acs.nanolett.2c02018] [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] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The electrochemical breakdown of a metal oxide film can directly affect the performance of functional electrochemical devices. However, revealing the structural insight into the breakdown sites is challenging because of heterogeneity: different breakdown sites are spatially distributed over the surface. Herein, we combine scanning electrochemical cell microscopy with identical-location microscopies to reveal the heterogeneity in the breakdown of NiO film on Ni in a site-by-site manner. Local critical breakdown potential varies by ∼500 mV, corresponding to an excess energy of 0.02-0.12 J/m2. Correlative composition imaging using time-of-flight secondary ion mass spectrometry shows Ni crystal grains with thinner NiO films are more resistant to breakdown. This high resistance is explained using classical nucleation theory, where the electrical energy is affected by the film thickness through the local interfacial capacitance. The correlative imaging approach overcomes the issue of heterogeneity, providing conclusive insight into the stability of the electrochemical interfaces.
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Affiliation(s)
- Mingyang Li
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Yufei Wang
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Brandon Blount
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Emma Gordon
- Department of Chemistry, Miami University, Oxford, Ohio 45056, United States
| | | | - Zhijiang Ye
- Department of Mechanical and Manufacturing Engineering, Miami University, Oxford, Ohio 45056, United States
| | - Hang Ren
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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9
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Bentley CL, Kang M, Bukola S, Creager SE, Unwin PR. High-Resolution Ion-Flux Imaging of Proton Transport through Graphene|Nafion Membranes. ACS Nano 2022; 16:5233-5245. [PMID: 35286810 PMCID: PMC9047657 DOI: 10.1021/acsnano.1c05872] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Accepted: 11/29/2021] [Indexed: 05/18/2023]
Abstract
In 2014, it was reported that protons can traverse between aqueous phases separated by nominally pristine monolayer graphene and hexagonal boron nitride (h-BN) films (membranes) under ambient conditions. This intrinsic proton conductivity of the one-atom-thick crystals, with proposed through-plane conduction, challenged the notion that graphene is impermeable to atoms, ions, and molecules. More recent evidence points to a defect-facilitated transport mechanism, analogous to transport through conventional ion-selective membranes based on graphene and h-BN. Herein, local ion-flux imaging is performed on chemical vapor deposition (CVD) graphene|Nafion membranes using an "electrochemical ion (proton) pump cell" mode of scanning electrochemical cell microscopy (SECCM). Targeting regions that are free from visible macroscopic defects (e.g., cracks, holes, etc.) and assessing hundreds to thousands of different sites across the graphene surfaces in a typical experiment, we find that most of the CVD graphene|Nafion membrane is impermeable to proton transport, with transmission typically occurring at ≈20-60 localized sites across a ≈0.003 mm2 area of the membrane (>5000 measurements total). When localized proton transport occurs, it can be a highly dynamic process, with additional transmission sites "opening" and a small number of sites "closing" under an applied electric field on the seconds time scale. Applying a simple equivalent circuit model of ion transport through a cylindrical nanopore, the local transmission sites are estimated to possess dimensions (radii) on the (sub)nanometer scale, implying that rare atomic defects are responsible for proton conductance. Overall, this work reinforces SECCM as a premier tool for the structure-property mapping of microscopically complex (electro)materials, with the local ion-flux mapping configuration introduced herein being widely applicable for functional membrane characterization and beyond, for example in diagnosing the failure mechanisms of protective surface coatings.
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Affiliation(s)
- Cameron L. Bentley
- School
of Chemistry, Monash University, Clayton, Victoria 3800, Australia
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Minkyung Kang
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Saheed Bukola
- Department
of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
| | - Stephen E. Creager
- Department
of Chemistry, Clemson University, Clemson, South Carolina 29634, United States
| | - Patrick R. Unwin
- Department
of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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10
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Bentley CL, Agoston R, Tao B, Walker M, Xu X, O'Mullane AP, Unwin PR. Correlating the Local Electrocatalytic Activity of Amorphous Molybdenum Sulfide Thin Films with Microscopic Composition, Structure, and Porosity. ACS Appl Mater Interfaces 2020; 12:44307-44316. [PMID: 32880446 DOI: 10.1021/acsami.0c11759] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Thin-film electrodes, produced by coating a conductive support with a thin layer (nanometer to micrometer) of active material, retain the unique properties of nanomaterials (e.g., activity, surface area, conductivity, etc.) while being economically scalable, making them highly desirable as electrocatalysts. Despite the ever-increasing methods of thin-film deposition (e.g., wet chemical synthesis, electrodeposition, chemical vapor deposition, etc.), there is insufficient understanding on the nanoscale electrochemical activity of these materials in relation to structure/composition, particularly for those that lack long-range order (i.e., amorphous thin-film materials). In this work, scanning electrochemical cell microscopy (SECCM) is deployed in tandem with complementary, colocated compositional/structural analysis to understand the microscopic factors governing the electrochemical activity of amorphous molybdenum sulfide (a-MoSx) thin films, a promising class of hydrogen evolution reaction (HER) catalyst. The a-MoSx thin films, produced under ambient conditions by electrodeposition, possess spatially heterogeneous electrocatalytic activity on the tens-of-micrometer scale, which is not attributable to microscopic variations in elemental composition or chemical structure (i.e., Mo and/or S bonding environments), shown through colocated, local energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analysis. A new SECCM protocol is implemented to directly correlate electrochemical activity to the electrochemical surface area (ECSA) in a single measurement, revealing that the spatially heterogeneous HER response of a-MoSx is predominantly attributable to variations in the nanoscale porosity of the thin film, with surface roughness ruled out as a major contributing factor by complementary atomic force microscopy (AFM). As microscopic composition, structure, and porosity (ECSA) are all critical factors dictating the functional properties of nanostructured materials in electrocatalysis and beyond (e.g., battery materials, electrochemical sensors, etc.), this work further cements SECCM as a premier tool for structure-function studies in (electro)materials science.
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Affiliation(s)
- Cameron L Bentley
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Roland Agoston
- School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD 4001, Australia
| | - Binglin Tao
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Marc Walker
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | - Xiangdong Xu
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Anthony P O'Mullane
- School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD 4001, Australia
| | - Patrick R Unwin
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
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11
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Thompson AC, Simpson BH, Lewis NS. Macroscale and Nanoscale Photoelectrochemical Behavior of p-Type Si(111) Covered by a Single Layer of Graphene or Hexagonal Boron Nitride. ACS Appl Mater Interfaces 2020; 12:11551-11561. [PMID: 32040911 DOI: 10.1021/acsami.9b21134] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Two-dimensional (2D) materials may enable a general approach to the introduction of a dipole at a semiconductor surface as well as control over other properties of the double layer at a semiconductor/liquid interface. Vastly different properties can be found in the 2D materials currently studied due in part to the range of the distribution of density-of-states. In this work, the open-circuit voltage (Voc) of p-Si-H, p-Si/Gr (graphene), and p-Si/h-BN (hexagonal boron nitride) in contact with a series of one-electron outer-sphere redox couples was investigated by macroscale measurements as well as by scanning electrochemical cell microscopy (SECCM). The band gaps of Gr and h-BN (0-5.97 eV) encompass the wide range of band gaps for 2D materials, so these interfaces (p-Si/Gr and p-Si/h-BN) serve as useful references to understand the behavior of 2D materials more generally. The value of Voc shifted with respect to the effective potential of the contacting solution, with slopes (ΔVoc/ΔEEff) of -0.27 and -0.38 for p-Si/Gr and p-Si/h-BN, respectively, indicating that band bending at the p-Si/h-BN and p-Si/Gr interfaces responds at least partially to changes in the electrochemical potential of the contacting liquid electrolyte. Additionally, SECCM is shown to be an effective method to interrogate the nanoscale photoelectrochemical behavior of an interface, showing little spatial variance over scales exceeding the grain size of the CVD-grown 2D materials in this work. The measurements demonstrated that the polycrystalline nature of the 2D materials had little effect on the results and confirmed that the macroscale measurements reflected the junction behavior at the nanoscale.
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Affiliation(s)
- Annelise C Thompson
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Burton H Simpson
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Nathan S Lewis
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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12
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Takahashi Y, Kobayashi Y, Wang Z, Ito Y, Ota M, Ida H, Kumatani A, Miyazawa K, Fujita T, Shiku H, Korchev YE, Miyata Y, Fukuma T, Chen M, Matsue T. High-Resolution Electrochemical Mapping of the Hydrogen Evolution Reaction on Transition-Metal Dichalcogenide Nanosheets. Angew Chem Int Ed Engl 2020; 59:3601-3608. [PMID: 31777142 DOI: 10.1002/anie.201912863] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Indexed: 11/10/2022]
Abstract
High-resolution scanning electrochemical cell microscopy (SECCM) is used to image and quantitatively analyze the hydrogen evolution reaction (HER) catalytically active sites of 1H-MoS2 nanosheets, MoS2 , and WS2 heteronanosheets. Using a 20 nm radius nanopipette and hopping mode scanning, the resolution of SECCM was beyond the optical microscopy limit and visualized a small triangular MoS2 nanosheet with a side length of ca. 130 nm. The electrochemical cell provides local cyclic voltammograms with a nanoscale spatial resolution for visualizing HER active sites as electrochemical images. The HER activity difference of edge, terrace, and heterojunction of MoS2 and WS2 were revealed. The SECCM imaging directly visualized the relationship of HER activity and number of MoS2 nanosheet layers and unveiled the heterogeneous aging state of MoS2 nanosheets. SECCM can be used for improving local HER activities by producing sulfur vacancies using electrochemical reaction at the selected region.
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Affiliation(s)
- Yasufumi Takahashi
- WPI Nano Life Science Institute (NanoLSI, WPI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan.,Precursory Research for Embryonic Science and Technology, (PRESTO) (Japan), Science and Technology Agency (JST), Saitama, 332-0012, Japan
| | - Yu Kobayashi
- Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Ziqian Wang
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Yoshikazu Ito
- Precursory Research for Embryonic Science and Technology, (PRESTO) (Japan), Science and Technology Agency (JST), Saitama, 332-0012, Japan.,Institute of Applied Physics, Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8573, Japan
| | - Masato Ota
- WPI Nano Life Science Institute (NanoLSI, WPI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Hiroki Ida
- Graduate School of Environmental Studies, Tohoku University, 6-6-11-604, Aramaki Aoba, Aoba-ku, Sendai, 980-8579, Japan
| | - Akichika Kumatani
- Graduate School of Environmental Studies, Tohoku University, 6-6-11-604, Aramaki Aoba, Aoba-ku, Sendai, 980-8579, Japan.,WPI-Advanced Institute for Materials Research (AIMR), Tohoku University, 2-1-1-509, Katahira, Aoba-ku, Sendai, 980-8577, Japan
| | - Keisuke Miyazawa
- WPI Nano Life Science Institute (NanoLSI, WPI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Takeshi Fujita
- School of Environmental Science and Engineering, Kochi University of Technology, Kochi, 782-8502, Japan
| | - Hitoshi Shiku
- Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, Sendai, 980-8579, Japan
| | - Yuri E Korchev
- WPI Nano Life Science Institute (NanoLSI, WPI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan.,Department of Medicine, Imperial College London, London, W12 0NN, UK
| | - Yasumitsu Miyata
- Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan
| | - Takeshi Fukuma
- WPI Nano Life Science Institute (NanoLSI, WPI), Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan
| | - Mingwei Chen
- Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.,WPI-Advanced Institute for Materials Research (AIMR), Tohoku University, 2-1-1-509, Katahira, Aoba-ku, Sendai, 980-8577, Japan.,Core Research for Evolutional Science and Technology (CREST) (Japan), Science and Technology Agency (JST), Saitama, 332-0012, Japan
| | - Tomokazu Matsue
- Graduate School of Environmental Studies, Tohoku University, 6-6-11-604, Aramaki Aoba, Aoba-ku, Sendai, 980-8579, Japan.,WPI-Advanced Institute for Materials Research (AIMR), Tohoku University, 2-1-1-509, Katahira, Aoba-ku, Sendai, 980-8577, Japan
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13
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Choi M, Siepser NP, Jeong S, Wang Y, Jagdale G, Ye X, Baker LA. Probing Single-Particle Electrocatalytic Activity at Facet-Controlled Gold Nanocrystals. Nano Lett 2020; 20:1233-1239. [PMID: 31917592 PMCID: PMC7727918 DOI: 10.1021/acs.nanolett.9b04640] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [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] [Indexed: 05/25/2023]
Abstract
Electrocatalytic reduction reactions (i.e., the hydrogen evolution reaction (HER) and oxygen reduction reaction) at individual, faceted Au nanocubes (NCs) and nano-octahedra (ODs) expressing predominantly {100} and {111} crystal planes on the surface, respectively, were studied by nanoscale voltammetric mapping. Cyclic voltammograms were collected at individual nanoparticles (NPs) with scanning electrochemical cell microscopy (SECCM) and correlated with particle morphology imaged by electron microscopy. Nanoscale measurements from a statistically informative set of individual NPs revealed that Au NCs have superior HER electrocatalytic activity compared to that of Au ODs, in good agreement with macroscale cyclic voltammetry measurements. Au NCs exhibited more particle-to-particle variation in catalytic activity compared to that with Au ODs. The approach of single-particle SECCM imaging coupled with macroscale CV on well-defined NPs provides a powerful toolset for the design and activity assessment of nanoscale electrocatalysts.
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Affiliation(s)
- Myunghoon Choi
- Department of Chemistry , Indiana University , 800 E. Kirkwood Avenue , Bloomington , Indiana 47405 , United States
| | - Natasha P Siepser
- Department of Chemistry , Indiana University , 800 E. Kirkwood Avenue , Bloomington , Indiana 47405 , United States
| | - Soojin Jeong
- Department of Chemistry , Indiana University , 800 E. Kirkwood Avenue , Bloomington , Indiana 47405 , United States
| | - Yi Wang
- Department of Chemistry , Indiana University , 800 E. Kirkwood Avenue , Bloomington , Indiana 47405 , United States
| | - Gargi Jagdale
- Department of Chemistry , Indiana University , 800 E. Kirkwood Avenue , Bloomington , Indiana 47405 , United States
| | - Xingchen Ye
- Department of Chemistry , Indiana University , 800 E. Kirkwood Avenue , Bloomington , Indiana 47405 , United States
| | - Lane A Baker
- Department of Chemistry , Indiana University , 800 E. Kirkwood Avenue , Bloomington , Indiana 47405 , United States
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14
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Daviddi E, Chen Z, Beam Massani B, Lee J, Bentley CL, Unwin PR, Ratcliff EL. Nanoscale Visualization and Multiscale Electrochemical Analysis of Conductive Polymer Electrodes. ACS Nano 2019; 13:13271-13284. [PMID: 31674763 DOI: 10.1021/acsnano.9b06302] [Citation(s) in RCA: 34] [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: 05/12/2023]
Abstract
Conductive polymers are exceptionally promising for modular electrochemical applications including chemical sensors, bioelectronics, redox-flow batteries, and photoelectrochemical systems due to considerable synthetic tunability and ease of processing. Despite well-established structural heterogeneity in these systems, conventional macroscopic electroanalytical methods-specifically cyclic voltammetry-are typically used as the primary tool for structure-property elucidation. This work presents an alternative correlative multimicroscopy strategy. Data from laboratory and synchrotron-based microspectroscopies, including conducting-atomic force microscopy and synchrotron nanoscale infrared spectroscopy, are combined with potentiodynamic movies of electrochemical fluxes from scanning electrochemical cell microscopy (SECCM) to reveal the relationship between electrode structure and activity. A model conductive polymer electrode system of tailored heterogeneity is investigated, consisting of phase-segregated domains of poly(3-hexylthiophene) (P3HT) surrounded by contiguous regions of insulating poly(methyl methacrylate) (PMMA), representing an ultramicroelectrode array. Isolated domains of P3HT are shown to retain bulk-like chemical and electronic structure when blended with PMMA and possess approximately equivalent electron-transfer rate constants compared to pure P3HT electrodes. The nanoscale electrochemical data are used to model and predict multiscale electrochemical behavior, revealing that macroscopic cyclic voltammograms should be much more kinetically facile than observed experimentally. This indicates that parasitic resistances rather than redox kinetics play a dominant role in macroscopic measurements in these conductive polymer systems. SECCM further demonstrates that the ambient degradation of the P3HT electroactivity within P3HT/PMMA blends is spatially heterogeneous. This work serves as a roadmap for benchmarking the quality of conductive polymer films as electrodes, emphasizing the importance of nanoscale electrochemical measurements in understanding macroscopic properties.
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Affiliation(s)
- Enrico Daviddi
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Zhiting Chen
- Department of Materials Science and Engineering , University of Arizona , Tucson , Arizona 85721 , United States
| | - Brooke Beam Massani
- Department of Chemistry and Biochemistry , University of Arizona , Tucson , Arizona 85721 , United States
| | - Jaemin Lee
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Cameron L Bentley
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Patrick R Unwin
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , United Kingdom
| | - Erin L Ratcliff
- Department of Materials Science and Engineering , University of Arizona , Tucson , Arizona 85721 , United States
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15
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Tarnev T, Aiyappa HB, Botz A, Erichsen T, Ernst A, Andronescu C, Schuhmann W. Scanning Electrochemical Cell Microscopy Investigation of Single ZIF-Derived Nanocomposite Particles as Electrocatalysts for Oxygen Evolution in Alkaline Media. Angew Chem Int Ed Engl 2019; 58:14265-14269. [PMID: 31347751 PMCID: PMC6790716 DOI: 10.1002/anie.201908021] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [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: 06/27/2019] [Indexed: 11/11/2022]
Abstract
"Single entity" measurements are central for an improved understanding of the function of nanoparticle-based electrocatalysts without interference arising from mass transfer limitations and local changes of educt concentration or the pH value. We report a scanning electrochemical cell microscopy (SECCM) investigation of zeolitic imidazolate framework (ZIF-67)-derived Co-N-doped C composite particles with respect to the oxygen evolution reaction (OER). Surmounting the surface wetting issues as well as the potential drift through the use of a non-interfering Os complex as free-diffusing internal redox potential standard, SECCM could be successfully applied in alkaline media. SECCM mapping reveals activity differences relative to the number of particles in the wetted area of the droplet landing zone. The turnover frequency (TOF) is 0.25 to 1.5 s-1 at potentials between 1.7 and 1.8 V vs. RHE, respectively, based on the number of Co atoms in each particle. Consistent values at locations with varying number of particles demonstrates OER performance devoid of macroscopic film effects.
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Affiliation(s)
- Tsvetan Tarnev
- Analytical Chemistry-Center for Electrochemical Sciences (CES), Faculty for Chemistry and Biochemistry, Ruhr University Bochum, 44780, Bochum, Germany
| | - Harshitha Barike Aiyappa
- Analytical Chemistry-Center for Electrochemical Sciences (CES), Faculty for Chemistry and Biochemistry, Ruhr University Bochum, 44780, Bochum, Germany
| | - Alexander Botz
- Analytical Chemistry-Center for Electrochemical Sciences (CES), Faculty for Chemistry and Biochemistry, Ruhr University Bochum, 44780, Bochum, Germany
| | - Thomas Erichsen
- Analytical Chemistry-Center for Electrochemical Sciences (CES), Faculty for Chemistry and Biochemistry, Ruhr University Bochum, 44780, Bochum, Germany
| | - Andrzej Ernst
- Analytical Chemistry-Center for Electrochemical Sciences (CES), Faculty for Chemistry and Biochemistry, Ruhr University Bochum, 44780, Bochum, Germany
| | - Corina Andronescu
- Chemical Technology III, Faculty of Chemistry and CENIDE, Center for Nanointegration University Duisburg Essen, Carl-Benz-Str. 199, 47057, Duisburg, Germany
| | - Wolfgang Schuhmann
- Analytical Chemistry-Center for Electrochemical Sciences (CES), Faculty for Chemistry and Biochemistry, Ruhr University Bochum, 44780, Bochum, Germany
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16
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Abstract
Spatial variations in photoelectrochemical reaction rates within individual p-type WSe2 nanosheets were mapped through the application of scanning electrochemical cell microscopy (SECCM). The simultaneous topographical and electrochemical information provided via SECCM directly revealed how both sheet thickness and the presence of defect structures affect the local rate of photoelectrochemical reactions for both outer sphere and inner sphere redox couples. Sheet thickness was found to play a dramatic role in reaction rates, with onset potentials shifting by as much as 0.5 V over thicknesses of 20-120 nm, attributable to the inability of thin sheets to support independent space charge layers. Step/edge features were found to play a detrimental role for the outer sphere redox couple investigated (Ru(NH3)63+ reduction), with taller steps having larger effects on performance. Shorter step features were found to be beneficial for hydrogen evolution, showing a controlled density of defect features is desirable for inner sphere processes. The studies presented here not only provide valuable, quantitative insights into the behavior of transitional metal dichalcogenide materials but also demonstrate the power of applying SECCM to the study of photoelectrochemical systems, particularly those involving two-dimensional (2D) materials.
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Affiliation(s)
- Joshua W Hill
- Department of Chemistry , University of Wyoming , 1000 E. University Ave , Laramie , Wyoming 82071 , United States
| | - Caleb M Hill
- Department of Chemistry , University of Wyoming , 1000 E. University Ave , Laramie , Wyoming 82071 , United States
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17
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Kumatani A, Miura C, Kuramochi H, Ohto T, Wakisaka M, Nagata Y, Ida H, Takahashi Y, Hu K, Jeong S, Fujita J, Matsue T, Ito Y. Chemical Dopants on Edge of Holey Graphene Accelerate Electrochemical Hydrogen Evolution Reaction. Adv Sci (Weinh) 2019; 6:1900119. [PMID: 31131204 PMCID: PMC6524082 DOI: 10.1002/advs.201900119] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/07/2019] [Indexed: 05/20/2023]
Abstract
Carbon-based metal-free catalysts for the hydrogen evolution reaction (HER) are essential for the development of a sustainable hydrogen society. Identification of the active sites in heterogeneous catalysis is key for the rational design of low-cost and efficient catalysts. Here, by fabricating holey graphene with chemically dopants, the atomic-level mechanism for accelerating HER by chemical dopants is unveiled, through elemental mapping with atomistic characterizations, scanning electrochemical cell microscopy (SECCM), and density functional theory (DFT) calculations. It is found that the synergetic effects of two important factors-edge structure of graphene and nitrogen/phosphorous codoping-enhance HER activity. SECCM evidences that graphene edges with chemical dopants are electrochemically very active. Indeed, DFT calculation suggests that the pyridinic nitrogen atom could be the catalytically active sites. The HER activity is enhanced due to phosphorus dopants, because phosphorus dopants promote the charge accumulations on the catalytically active nitrogen atoms. These findings pave a path for engineering the edge structure of graphene in graphene-based catalysts.
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Affiliation(s)
- Akichika Kumatani
- WPI Advanced Institute for Materials Research (AIMR)Tohoku UniversitySendai980‐8577Japan
- Graduate School of Environmental StudiesTohoku UniversitySendai980‐856Japan
| | - Chiho Miura
- Graduate School of Environmental StudiesTohoku UniversitySendai980‐856Japan
| | - Hirotaka Kuramochi
- Institute of Applied PhysicsGraduate School of Pure and Applied SciencesUniversity of TsukubaTsukuba305‐8573Japan
| | - Tatsuhiko Ohto
- Graduate School of Engineering ScienceOsaka University1‐3 MachikaneyamaToyonaka560‐8531Japan
| | - Mitsuru Wakisaka
- Graduate School of EngineeringToyama Prefectural University5180 KurokawaImizuToyama939‐0398Japan
| | - Yuki Nagata
- Max Planck Institute for Polymer ResearchAckermannweg 1055128MainzGermany
| | - Hiroki Ida
- Graduate School of Environmental StudiesTohoku UniversitySendai980‐856Japan
| | - Yasufumi Takahashi
- PRESTOJapan Science and Technology AgencySaitama332‐0012Japan
- Division of Electrical Engineering and Computer ScienceKanazawa UniversityKanazawa920‐1192Japan
| | - Kailong Hu
- Institute of Applied PhysicsGraduate School of Pure and Applied SciencesUniversity of TsukubaTsukuba305‐8573Japan
| | - Samuel Jeong
- Institute of Applied PhysicsGraduate School of Pure and Applied SciencesUniversity of TsukubaTsukuba305‐8573Japan
| | - Jun‐ichi Fujita
- Institute of Applied PhysicsGraduate School of Pure and Applied SciencesUniversity of TsukubaTsukuba305‐8573Japan
| | - Tomokazu Matsue
- Graduate School of Environmental StudiesTohoku UniversitySendai980‐856Japan
| | - Yoshikazu Ito
- Institute of Applied PhysicsGraduate School of Pure and Applied SciencesUniversity of TsukubaTsukuba305‐8573Japan
- PRESTOJapan Science and Technology AgencySaitama332‐0012Japan
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18
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E SP, Kim YR, Perry D, Bentley CL, Unwin PR. Nanoscale Electrocatalysis of Hydrazine Electro-Oxidation at Blistered Graphite Electrodes. ACS Appl Mater Interfaces 2016; 8:30458-30466. [PMID: 27739301 DOI: 10.1021/acsami.6b10940] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
There is great interest in finding and developing new, efficient, and more active electrocatalytic materials. Surface modification of highly oriented pyrolytic graphite, through the introduction of surface "blisters", is demonstrated to result in an electrode material with greatly enhanced electrochemical activity. The increased electrochemical activity of these blisters, which are produced by electro-oxidation in HClO4, is revealed through the use of scanning electrochemical cell microscopy (SECCM), coupled with complementary techniques (optical microscopy, field emission-scanning electron microscopy, Raman spectroscopy, and atomic force microscopy). The use of a linear sweep voltammetry (LSV)-SECCM scan regime allows for dynamic electrochemical mapping, where a voltammogram is produced at each pixel, from which movies consisting of spatial electrochemical currents, at a series of applied potentials, are produced. The measurements reveal significantly enhanced electrocatalytic activity at blisters when compared to the basal planes, with a significant cathodic shift in the onset potential of the hydrazine electro-oxidation reaction. The improved electrochemical activity of the hollow structure of blistered graphite could be explained by the increased adsorption of protonated hydrazine at oxygenated defect sites, the ease of ion-solvent intercalation/deintercalation, and the reduced susceptibility to N2 nanobubble attachment (as a product of the reaction). This study highlights the capability of electrochemistry to tailor the surface structure of graphite and presents a new electrocatalyst for hydrazine electro-oxidation.
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Affiliation(s)
| | - Yang-Rae Kim
- Department of Chemistry, Kwangwoon University , Seoul 01897, Republic of Korea
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Abstract
The design, development, and application of high-speed scanning electrochemical probe microscopy is reported. The approach allows the acquisition of a series of high-resolution images (typically 1000 pixels μm(-2)) at rates approaching 4 seconds per frame, while collecting up to 8000 image pixels per second, about 1000 times faster than typical imaging speeds used up to now. The focus is on scanning electrochemical cell microscopy (SECCM), but the principles and practicalities are applicable to many electrochemical imaging methods. The versatility of the high-speed scan concept is demonstrated at a variety of substrates, including imaging the electroactivity of a patterned self-assembled monolayer on gold, visualization of chemical reactions occurring at single wall carbon nanotubes, and probing nanoscale electrocatalysts for water splitting. These studies provide movies of spatial variations of electrochemical fluxes as a function of potential and a platform for the further development of high speed scanning with other electrochemical imaging techniques.
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Affiliation(s)
- Dmitry Momotenko
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, United Kingdom
| | - Joshua C Byers
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, United Kingdom
| | - Kim McKelvey
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, United Kingdom
| | - Minkyung Kang
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, United Kingdom
| | - Patrick R Unwin
- Department of Chemistry, University of Warwick , Coventry CV4 7AL, United Kingdom
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