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Maurya R, Das R, Sharma S, Neergat M. Estimation of the electrochemical active site density of a metal-free carbon-based catalyst using phosphomolybdate (PMo 12) as an adsorbate. Phys Chem Chem Phys 2024; 26:10091-10100. [PMID: 38482929 DOI: 10.1039/d3cp06008j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
A method to estimate the electrochemical active site density (SD) of carbon (C) and nitrogen-doped carbon (N/C-900) using phosphomolybdate (PMo12) as a probe molecule is proposed. The complete coverage of the active sites by the probe molecules is established irrespective of the adsorbate concentration (1, 5, or 10 mM), potential cycling (1 or 10 cycles) and cleaning time (2, 5, or 10 min). A conversion factor derived from a smooth and polished glassy carbon disk of known geometrical area is used to estimate the electrochemical active surface area (ECSA) of the carbon catalyst from the SD. The relatively higher SD values estimated from DC voltammetry than from large-amplitude Fourier-transform alternating-current voltammetry (FTacV) is indicative of the contribution of capacitive charge in the former. Adsorbed probe molecules (PMo12) can readily be desorbed from the catalyst surface by cycling the electrode to lower potentials. The active site density of N/C-900 (∼0.36 × 1019 sites g-1) is higher than that of C (∼0.17 × 1019 sites g-1).
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Affiliation(s)
- Rajan Maurya
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay (IITB), Powai, Mumbai 400076, India.
| | - Rubul Das
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay (IITB), Powai, Mumbai 400076, India.
| | - Shreya Sharma
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay (IITB), Powai, Mumbai 400076, India.
| | - Manoj Neergat
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay (IITB), Powai, Mumbai 400076, India.
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Feng Y, Fang C, Zhang X, Zhang Q, Cui X, Li Y, Xu J, Shi C. Transition Metal Functionalized C 30N 12S 6 as High-Performance Trifunctional Catalysts with Integrated Descriptors toward Hydrogen Evolution, Oxygen Evolution, and Oxygen Reduction Reactions: A Case of High-Throughput First-Principles Screening within the Framework of TM-N 2@C 30N 10S 6. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:489-503. [PMID: 38145890 DOI: 10.1021/acs.langmuir.3c02758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
In energy conversion and storage technologies, the design of highly efficient trifunctional electrocatalysts integrating with the high hydrogen evolution reaction (HER) and oxygen evolution/reduction reaction (OER/ORR) activities is highly desirable. Herein, utilizing first-principles computations, a novel periodically ordered macropore C30N12S6 monolayer was proposed, and the stability analysis attests to its good stability. Single transition metal (TM) atom anchored onto this newly proposed C30N12S6 monolayer to form single-atom catalysts, as achieved by TM-N2@C30N10S6, among which the Co-N2@C30N10S6 is the most promising multifunctional catalyst toward HER/OER/ORR with low overpotential of 0.01/0.59/0.3 V; meanwhile, the Rh-N2@C30N10S6 can be used as a bifunctional OER/ORR catalyst with low overpotential of 0.37/0.44 V, overmatching the landmark Pt (111) and IrO2/RuO2 catalysts. Particularly, the TM-d orbital in TM@CNS is remarkably hybridized with the O-p orbital of oxygenated intermediates, so that the lone electrons initially located at the antibonding orbital pair up and fill the downward bonding orbital, allowing OH* to be suitably adsorbed on TM@CNS, enhancing the catalytic performance. The relevant attributes, such as good stabilities and metallic features, ensured their applications in ambient conditions. Moreover, multilevel descriptors were constructed to clarify the origin of activity on TM@CNS, such as ΔGOH* (Gibbs free energy of OH*), εd (d-band center), COHP (crystal orbital Hamilton population), Nd/Nd + s (number of d/d + s electrons) and φ (descriptor), among which the filling of outer d-electrons of TM atom significantly affects the value of ΔGOH* that can determine the overpotential and, thus, become a key descriptor.
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Affiliation(s)
- Yajuan Feng
- Research Center of Silicon Target and Silicon-Carbon Negative, Materials Engineering Technology, School of Materials Science & Engineering, North Minzu University, Yinchuan 750021, People's Republic of China
| | - Chunyao Fang
- Department of Physics, College of Science, University of Shanghai for Science and Technology, Shanghai 200093, People's Republic of China
| | - Xihang Zhang
- Department of Physics, College of Science, University of Shanghai for Science and Technology, Shanghai 200093, People's Republic of China
| | - Qiang Zhang
- Department of Physics, College of Science, University of Shanghai for Science and Technology, Shanghai 200093, People's Republic of China
| | - Xiaomeng Cui
- Department of Physics, College of Science, University of Shanghai for Science and Technology, Shanghai 200093, People's Republic of China
| | - Yuanrui Li
- Department of Physics, College of Science, University of Shanghai for Science and Technology, Shanghai 200093, People's Republic of China
| | - Jingcheng Xu
- School of Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, People's Republic of China
| | - Chenglong Shi
- Department of Physics, College of Science, University of Shanghai for Science and Technology, Shanghai 200093, People's Republic of China
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Choudhury D, Das R, Maurya R, Kumawat H, Neergat M. Kinetics of the Oxygen Evolution Reaction (OER) on Amorphous and Crystalline Iridium Oxide Surfaces in Acidic Medium. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:13748-13757. [PMID: 37695734 DOI: 10.1021/acs.langmuir.3c02293] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/13/2023]
Abstract
Amorphous and crystalline IrO2 catalysts are synthesized by the Adams method and characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The oxygen evolution reaction (OER) is investigated on both the catalyst surfaces in 0.5 M H2SO4 electrolyte. The Tafel slope estimated in the temperature range of 293-333 K on the two surfaces indicates a change in the rate-limiting steps. The data are also analyzed in terms of the Eyring equation to estimate the activation enthalpy (ΔH#) and pre-exponential factor (Af) as a function of overpotential and therefore the charge-transfer coefficient (α). The estimated α values suggest strong electrocatalysis on both the surfaces. While the ΔH# plays a decisive role in the electrocatalysis on the amorphous sample, the trend of Af indicates that an increase in the entropy on the crystalline surface is pivotal in reducing the reaction barrier.
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Affiliation(s)
- Debittree Choudhury
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Rubul Das
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Rajan Maurya
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Himanshu Kumawat
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Manoj Neergat
- Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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