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

Abstract 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 Bi₂O₃ (Au‐Bi₂O₃) is proposed as a proof‐of‐concept to investigate the electron‐withdrawing effect in the electrocatalytic CO₂ reduction reaction (eCO₂RR) process. Evidence from in situ Raman spectra and in situ XRD tests reveals that, compared to Bi₂O₃, Bi species in Au‐Bi₂O₃ can be reduced to metallic Bi more rapidly and more easily driven by the electron‐withdrawing effect of Au. The XPS tests after eCO₂RR further validates the transformation from Bi³⁺ to Bi⁰ in Au‐Bi₂O₃ 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 eCO₂RR 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 eCO₂RR process, but also develops a new perspective for engineering electron‐withdrawing effect in electrocatalysts for high‐efficient CO₂‐to‐formate conversion.