Pd-Induced Surface Reconstruction on Sputtered Cu Electrodes for Selective CO ₂ Electroreduction to C ₂₊ Products

The electrocatalytic CO2 conversion offers a sustainable pathway for generating ecofriendly chemicals and fuels while simultaneously enabling the storage of intermittent renewable energy. Herein, CuPd bimetallic catalysts were specifically designed through displacement reaction, with a magnetron sputtering Cu film as a substrate. The optimized CuPd catalyst achieved an ethylene Faradaic efficiency (FE) of 51.07% and a C2+ FE of 82.18% at a 200 mA/cm2 current density. In situ Raman spectroscopy indicates that the CuPd electrode exhibited a high local surface pH during the CO2 reduction reaction, which was favorable for C–C coupling. The observation of the *OCCOH intermediate by in situ FTIR, combined with density functional theory calculations, confirms that the CuPd surface promotes C–C coupling instead of direct hydrogenation. This mechanistic insight explains why the addition of Pd enhances the selectivity for C2+ products.