Trapped Platinum Single-Site Catalysts for the Hydrogen Evolution Reaction

Abstract

Trapped platinum single-site catalysts (Pt-SSCs) in defective carbon substrates are of particular interest for polymer-electrolyte membrane (PEM) water electrolysers due to their high Pt atom utilization for the hydrogen evolution reaction (HER). However, their intrinsic catalytic activity compared with metallic Pt nanoparticles remains a topic of debate in the field with opposing results reported. [1, 2] A detailed investigation of the bonding environment of Pt and its evolution at HER working conditions is therefore warranted in order to corelate the Pt single-site structure to its catalytic activity and stability.Here, we present a detailed analysis on trapped Pt-SSC prepared by pyrolysing H2PtCl6 adsorbed on a polyaniline substrate. [3] We used in-situ heated scanning transmission electron microscopy, temperature-dependent X-ray photoelectron spectroscopy and operando X-ray absorption spectroscopy to follow the evolution of Pt’s bonding environment during pyrolysis and HER. We demonstrate that the trapped Pt-SSC is stable under HER potentials but with lower catalytic activity relative to commercial Pt nanoparticles. We also perform first principles calculations to elucidate the origin of the inferior activity.Our results promote the understanding of the relationship between the structure of trapped Pt-SSC and its HER performance, and calls for a techno-economic analysis to assess the practicality of using Pt-SSCs in commercial PEM water electrolyzers.References Q. Yang, H. Liu, P. Yuan, Y. Jia, L. Zhuang, H. Zhang, X. Yan, G. Liu,Y. Zhao, J. Liu, S. Wei, L. Song, Q. Wu, B. Ge, L. Zhang, K. Wang, X. Wang, C.-R. Chang, and X. Yao, J. Am. Chem. Soc., 144, 2171 (2022).J. Wang, H. Y. Tan, T. R. Kuo, S. C. Lin, C. S. Hsu, Y. Zhu, Y. C. Chu, T. L. Chen, J. F. Lee, and H. M. Chen, Small, 17, 2005713 (2021).P. Tang, P.-Y. Huang, J. E. N. Swallow, C. Wang, D. Gianolio, H. Guo, J. H. Warner, R. S. Weatherup and M. Pasta, “Structure- property relationship of defect-trapped Pt single-site electrocatalysts for the hydrogen evolution reaction” Reasearch Square (2023), doi: 10.21203/rs.3.rs-2397818/v1.