Journal
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Volume 143, Issue 46, Pages 19341-19355Publisher
AMER CHEMICAL SOC
DOI: 10.1021/jacs.1c07276
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Funding
- U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, Catalysis Science Program
- Knut and Alice Wallenberg Foundation [2019.0586]
- Alexander von Humboldt Foundation (AvH)
- Office of Science of the U.S. Department of Energy [DE-AC02-05CH11231]
- Stanford University
- Stanford Research Computing Center
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Accurate theoretical simulation of electrochemical activation barriers is crucial for understanding electrocatalysis. By developing an analytical approach based on charge conservation and decoupled potential energy surfaces, we successfully simulated the Pt-catalyzed alkaline hydrogen evolution reaction with consideration of solvent thermal fluctuations, showing the significant impact of water-metal distances on charge transfer barriers.
Accurate theoretical simulation of electrochemical activation barriers is key to understanding electrocatalysis and guides the design of more efficient catalysts. Providing a detailed picture of proton transfer processes encounters several challenges: the constant potential requirement during charge transfer, the different time scales involved in the processes, and the thermal fluctuation of the solvent. Hence, it is prohibitively expensive computationally to apply density functional theory (DFT) calculations in modeling the potential-dependent activation barrier at the electrode-solvent interface, and the results are dubious. To address these challenges, we have developed an analytical approach based on charge conservation and decoupled potential energy surfaces to compute charge transfer barriers. The method makes it possible to simulate an electrochemical process at different potentials and explicitly include thermal fluctuations of the solvent at the electrode-solvent interface. We use the Pt-catalyzed alkaline hydrogen evolution reaction (HER) as our benchmark reaction, and we model the microkinetics of HER with consideration of the spatial fluctuations between the metal surface and the first solvent layer at room temperature. The distribution of water-metal distances has a large effect on the barriers of the charge transfer processes, and an accurate account of the statistical fluctuation in the reaction network leads to a several orders of magnitude increase in HER current as compared to transfer from a static solvent. The trends of the different reaction mechanisms in HER were successfully simulated with our model, and the theoretical I-V curves obtained are in good qualitative agreement with experimental results.
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