Restructuring-Resistant BiCuOS Superlattice Stabilizing Bi-O Coordination for Highly Selective CO2 Electroreduction to Formate

Abstract

Bismuth-based catalysts are promising for electrochemical CO2 reduction (eCO2R). However, structural restructuring under operating conditions undermines catalytic stability and obscures intrinsic activity. Herein, we report a BiCuOS superlattice catalyst with a stable Bi–O coordination environment during eCO2R, effectively suppressing structural restructuring. The catalyst delivers a wide operating window (−0.3 to −0.9 VRHE) with a formate Faradaic efficiency of 96.6% at −0.7 VRHE, benefiting from a large electrochemically active surface area and abundant active sites. Combined experimental and theoretical studies reveal *OCHO as the key intermediate, with its conversion to *HCOOH identified as the rate-determining step for formate production. This work elucidates the catalytic role of the stable Bi–O framework in eCO2R.