Unlocking high-performance CO2 electroreduction to CO with dual-doped CuO catalysts: Synergistic effects of Sn and Ga for enhanced selectivity and activity

Polymetallic electrocatalysts represent as a promising strategy for steering the electrocatalytic CO₂ reduction reactions (eCO₂RR) toward valuable products. However, achieving simultaneous high selectivity and activity remains challenging. Here, we report a dual-doped CuO catalyst (CuO-Sn_0.02-Ga_0.005) that synergistically combines Sn and Ga to achieve exceptional performance for CO₂-to-CO conversion. Electrochemical evaluations demonstrate that the optimized catalyst exhibits a Faradaic efficiency (FE) of 99.37 % for CO at -0.7 V_RHE with a current density of -132.8 mA cm^-2, significantly outperforming pristine CuO (54.21 %, -47.6 mA cm^-2 and single-doped counterparts (93.50 %, -55.3 mA cm^-2 for CuO-Sn_0.02 and 46.76 %, -94.2 mA cm^-2 for CuO-Ga_0.02, respectively). Sn doping suppresses hydrogen evolution and enhances CO selectivity, while Ga doping boosts catalytic activity. In situ Raman spectroscopy reveals that Sn incorporation facilitates the stabilization of key intermediates (e.g., *COOH), whereas Ga introduces lattice strain and defects, enlarging the electrochemically active surface area. The catalyst also demonstrates remarkable stability, maintaining >95 % FE for CO over 75 h. This work provides a rational design strategy for non-precious metal catalysts through dual-element doping, highlighting the critical role of electronic and structural modulation in eCO₂RR.