Suppressing Catalyst Reconstruction via Electric-Field-Enhanced Cu-Sn Alloying for Stable CO2 Electroreduction.

The electrochemical reduction of carbon dioxide (CO2RR) on copper (Cu) catalysts holds great promise for the sustainable production of value-added carbonaceous chemicals and fuels. However, these Cu nanostructures suffer from severe surface reconstruction due to Cu's oxidation, dissolution, and redeposition during electrolysis, resulting in rapid deactivation and poor product selectivity. Here, we report an efficient strategy to suppress Cu catalyst reconstruction by alloying with tin (Sn) to form a Cu-Sn alloy catalyst layer (ACL), in which an in situ electrochemically generated oxidized Sn layer plays an essential role in preventing the oxidation and dissolution of Cu during CO2RR. Moreover, by tuning the geometry of Cu mesh substrates, we exploit electric-field-induced reactant distribution (EIRD) to enhance the proposed alloying effect further, achieving improved CO selectivity and suppressed hydrogen evolution. The optimized Cu-Sn ACL exhibits a CO Faradaic efficiency (FE) of 93% at an overpotential (η) of 0.58 V, with an ultralow current density decay rate of 0.4% h-1, representing a 15-fold improvement in selectivity and 14-fold enhancement in durability compared to pristine Cu. Furthermore, tunable CO/H2 ratios of 0.4-9.3 further enable a broad range of syngas tailoring. This combined alloying and electric-field design principle offers a generalizable strategy for stabilizing catalysts under dynamic electrochemical conditions, with implications for CO2 conversion, fuel cells, and hydrogen production.