1. Identification of K+-determined reaction pathway for facilitated kinetics of CO2 electroreduction
- Author
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Feng Wu, Xiaokang Liu, Shiqi Wang, Longfei Hu, Sebastian Kunze, Zhenggang Xue, Zehao Shen, Yaxiong Yang, Xinqiang Wang, Minghui Fan, Hongge Pan, Xiaoping Gao, Tao Yao, and Yuen Wu
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Science - Abstract
Abstract Cations such as K+ play a key part in the CO2 electroreduction reaction, but their role in the reaction mechanism is still in debate. Here, we use a highly symmetric Ni-N4 structure to selectively probe the mechanistic influence of K+ and identify its interaction with chemisorbed CO2 −. Our electrochemical kinetics study finds a shift in the rate-determining step in the presence of K+. Spectral evidence of chemisorbed CO2 − from in-situ X-ray absorption spectroscopy and in-situ Raman spectroscopy pinpoints the origin of this rate-determining step shift. Grand canonical potential kinetics simulations - consistent with experimental results - further complement these findings. We thereby identify a long proposed non-covalent interaction between K+ and chemisorbed CO2 −. This interaction stabilizes chemisorbed CO2 − and thus switches the rate-determining step from concerted proton electron transfer to independent proton transfer. Consequently, this rate-determining step shift lowers the reaction barrier by eliminating the contribution of the electron transfer step. This K+-determined reaction pathway enables a lower energy barrier for CO2 electroreduction reaction than the competing hydrogen evolution reaction, leading to an exclusive selectivity for CO2 electroreduction reaction.
- Published
- 2024
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