Engineering Cu-In Dual-Site Catalysts by Dynamic Reconstruction of Cu-In-S Quantum Dots for Efficient Electrochemical CO2 Conversion to Formate

With the increasing consumption of fossil fuels emitting a large amount of CO₂, electrocatalytic CO₂ reduction (CO₂RR) has become a promising way to reduce carbon emissions. Dual-site catalysts have been identified as attractive materials for CO₂RR, however, suffering from low selectivity and activity. Herein, Cu-In-S quantum dots have undergone in situ dynamic restructuring to construct Cu-In dual-site catalysts (Cu_0.15In_0.85 NPs) with highly catalytic activity toward CO₂ electrochemical conversion. Cu_0.15In_0.85 NPs achieved a high Faraday efficiency of 92.3% for formate production at −1.45 V versus RHE, and a high formate partial current density of 245.4 mA cm⁻² at −1.82 V versus RHE in a flow cell. In situ ATR-SEIRAS spectroscopy and theoretical calculations indicated Cu dopants induced the charge transfer from Cu to In atoms to form the Cu-In synergistic active sites, thus decreasing the formation energy of OCHO^* and HCOOH^* intermediates, as well as inhibiting the dissociation of water molecules. This work elucidates the optimization mechanism of the electronic structure for dual-site catalysts and guides the fabrication of highly efficient electrocatalysts for formate production.