Chinese Journal of Catalysis ›› 2025, Vol. 71: 128-137.DOI: 10.1016/S1872-2067(24)60243-3

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Accelerating C-C coupling in alkaline electrochemical CO2 reduction by optimized local water dissociation kinetics

Qingfeng Huaa,1, Hao Meia,1, Guang Fenga,1, Lina Sua, Yanan Yanga, Qichang Lia, Shaobo Lia, Xiaoxia Changb,*(), Zhiqi Huanga,*()   

  1. aBeijing Key Laboratory for Chemical Power Source and Green Catalysis, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
    bCollege of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
  • Received:2024-12-31 Accepted:2025-01-15 Online:2025-04-18 Published:2025-04-13
  • Contact: * E-mail:changxx@pku.edu.cn(X. Chang),huangzhiqi@bit.edu.cn(Z. Huang).
  • About author:

    1Contributed to this work equally.

  • Supported by:
    National Natural Science Foundation of China(22208019);National Natural Science Foundation of China(22278002)

Abstract:

Electrochemical carbon dioxide reduction reaction (CO2RR) produces valuable chemicals by consuming gaseous CO2 as well as protons from the electrolyte. Protons, produced by water dissociation in alkaline electrolyte, are critical for the reaction kinetics which involves multiple proton coupled electron transfer steps. Herein, we demonstrate that the two key steps (CO2-*COOH and *CO-*COH) efficiency can be precisely tuned by introducing proper amount of water dissociation center, i.e., Fe single atoms, locally surrounding the Cu catalysts. In alkaline electrolyte, the Faradaic efficiency (FE) of multi-carbon (C2+) products exhibited a volcano type plot depending on the density of water dissociation center. A maximum FE for C2+ products of 73.2% could be reached on Cu nanoparticles supported on N-doped Carbon nanofibers with moderate Fe single atom sites, at a current density of 300 mA cm-2. Experimental and theoretical calculation results reveal that the Fe sites facilitate water dissociation kinetics, and the locally generated protons contribute significantly to the CO2 activation and *CO protonation process. On the one hand, in-situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (in-situ ATR-SEIRAS) clearly shows that the *COOH intermediate can be observed at a lower potential. This phenomenon fully demonstrates that the optimized local water dissociation kinetics has a unique advantage in guiding the hydrogenation reaction pathway of CO2 molecules and can effectively reduce the reaction energy barrier. On the other hand, abundant *CO and *COH intermediates create favorable conditions for the asymmetric *CO-*COH coupling, significantly increasing the selectivity of the reaction for C2+ products and providing strong support for the efficient conversion of related reactions to the target products. This work provides a promising strategy for the design of a dual sites catalyst to achieve high FE of C2+ products through the optimized local water dissociation kinetics.

Key words: CO2 reduction, Proton, Microenvironment, Optimized local water dissociation kinetics, CO2 activation, Asymmetric coupling