Enhancing the selectivity of CO₂-to-HCOOH conversion by constructing tensile-strained Cu catalyst

Heterogeneous interface engineering endows catalyst with the possibility to enhance the activity and tune the selectivity of electrochemical CO₂ reduction reaction (CO₂RR) by induced surface strain and interfacial charges transfer. Herein, a novel In₂O₃/Cu heterojunction catalyst with 3D succulents-like morphology significantly enhance the selectivity and activity for electrochemical CO₂-to-HCOOH conversion as compared to the In₂O₃ and Cu counterparts, achieving a maximum faraday efficiency (FE) of 87.5 % at −1.1 V vs RHE with corresponding formate partial current density of −70 mA cm⁻² at −1.4 V vs RHE. The combined DFT calculation and experimental studies revealed that electrons transfer from interfacial In to Cu via O bridge preserves the metallic state of Cu, which facilitates the capture and activation of CO₂ molecules. Furthermore, the surface tensile strain together with interfacial electronic interaction lowers the energy barrier for the formation of *HCOO intermediate, thus boosting the selectivity for HCOOH production. This work demonstrates a feasible strategy for advanced catalyst design by implanted heterogeneous interfaces to manipulate the lattice strain and electronic coupling. © 2023 Elsevier Ltd. All rights reserved.