Decrypting the Electron-Withdrawing Effect of Au-Decorated Bi2O3 for Efficient CO2-to-Formate Electroreduction

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 Bi 2 O 3 (Au-Bi 2 O 3 ) is proposed as a proof-of-concept to investigate the electron-withdrawing effect in the electrocatalytic CO 2 reduction reaction (eCO 2 RR) process. Evidence from in situ Raman spectra and in situ XRD tests reveals that, compared to Bi 2 O 3 , Bi species in Au-Bi 2 O 3 can be reduced to metallic Bi more rapidly and more easily driven by the electron-withdrawing effect of Au. The XPS tests after eCO 2 RR further validates the transformation from Bi 3+ to Bi 0 in Au-Bi 2 O 3 is more complete. Meanwhile, in the in situ Fourier transform infrared (FTIR) spectra, the key intermediates (CO 2 * − and OCHO* − ) appear at the more positive potential, indicating that metallic Bi is favorable for eCO 2 RR due to the lower energy barrier as corroborated by density function theory (DFT) calculations. Au don't directly participate in the conversion from CO 2 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 eCO 2 RR process, but also develops a new perspective for engineering electron-withdrawing effect in electrocatalysts for high-efficient CO 2 -to-formate conversion.