Although the electron-withdrawing effect of gold (Au) is highlighted in catalytic reactions, its enhancement mechanism for electron transport, especially in the electrochemical process, is still unclear. Herein, Au-decorated Bi2 O3 (Au-Bi2 O3 ) is proposed as a proof-of-concept to investigate the electron-withdrawing effect in the electrocatalytic CO2 reduction reaction (eCO2 RR) process. Evidence from in situ Raman spectra and in situ XRD tests reveals that, compared to Bi2 O3 , Bi species in Au-Bi2 O3 can be reduced to metallic Bi more rapidly and more easily driven by the electron-withdrawing effect of Au. The XPS tests after eCO2 RR further validates the transformation from Bi3+ to Bi0 in Au-Bi2 O3 is more complete. Meanwhile, in the in situ Fourier transform infrared (FTIR) spectra, the key intermediates (CO2 *- and OCHO*- ) appear at the more positive potential, indicating that metallic Bi is favorable for eCO2 RR due to the lower energy barrier as corroborated by density function theory (DFT) calculations. Au don't directly participate in the conversion from CO2 to formate as the reaction sites, but utilize the electron-withdrawing effect to motivate Bi-sites to deliver higher catalytic activity and higher selectivity to formate at a lower applied potential. This study not only has an insight into the electron-withdrawing effect of Au on the eCO2 RR process, but also develops a new perspective for engineering electron-withdrawing effect in electrocatalysts for high-efficient CO2 -to-formate conversion.
Keywords: Au-Bi2O3; electrocatalytic CO2 reduction reaction; electron-withdrawing effect; in situ Raman spectra; in situ Fourier transform infrared (FTIR) spectra.
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