Electron‐deficient ZnO induced by heterointerface engineering as the dominant active component to boost CO₂‐to‐formate conversion

Abstract Electrocatalytic CO₂‐to‐formate conversion is considered an economically viable process. In general, Zn‐based nanomaterials are well‐known to be highly efficient electrocatalysts for the conversion of CO₂ to CO, but seldom do they exhibit excellent selectivity toward formate. In this article, we demonstrate that a heterointerface catalyst ZnO/ZnSnO₃ with nanosheet morphology shows enhanced selectivity with a maximum Faradaic efficiency (FE) of 86% at −0.9 V versus reversible hydrogen electrode and larger current density for the conversion of CO₂ to formate than pristine ZnO and ZnSnO₃. In particular, the FEs of the C₁ products (CO + HCOO⁻) exceed 98% over the potential window. The experimental measurements combined with theoretical calculations revealed that the ZnO in ZnO/ZnSnO₃ heterojunction delivers the valence electron depletion and accordingly optimizes Zn d‐band center, which results in moderate Zn–O hybridization of HCOO* and weakened Zn–C hybridization of competing COOH*, thus greatly boosting the HCOOH generation. Our study highlights the importance of charge redistribution in catalysts on the selectivity of electrochemical CO₂ reduction.