Synergistic Geometric and Electronic Effects in Bi–Cu Bimetallic Catalysts for CO₂ Electroreduction to Formate over a Wide Potential Window

Electrochemical CO2 reduction to formate provides a prospective avenue to produce more valuable products. Compared to pure Bi and Cu, the Bi–Cu (2:1) bimetallic catalyst optimizes the interfacial electronic structure through the electronic interaction between Bi and Cu. The Bi–Cu (2:1) catalyst exhibits a high faradaic efficiency of 94.1% at −1.0 V vs RHE, high faradaic efficiency (>90%) toward formate in a wide potential window (500 mV), and long-term stability of 20 h. The electrocatalytic mechanism is identified by combining in situ FT-IR and DFT calculations, which demonstrates that formate prefers to be formed through the HCOO* pathway. High faradaic efficiency in a wide potential window can be ascribed to stable active sites and the decreased energy barrier in HCOO* and formate. This study further provides inspirations for promoting the electrocatalytic selectivity of bimetallic catalysts through effective interfacial electronic modulation.