• • CuCe10Ox delivers a CH4 Faradaic efficiency of 61.7% at -1.6 V vs. RHE, demonstrating that isolated Cu centers surrounded by Ce-Ov sites favor deep hydrogenation, a key metric for renewable methane production.
• • Cu10CeOx achieves a C2 Faradaic efficiency of 61.5% at -1.4 V vs. RHE, showing that dense Cu sites enhance *CO coverage and C-C coupling, critical for producing multi-carbon fuels.
• • The *CO stripping charge measurements confirm higher *CO coverage on Cu10CeOx than on CuCe10Ox, directly linking local active-site density to intermediate availability and product distribution.
• • The molten salt-assisted synthesis enables precise tuning of Cu and Ce-Ov site concentrations, providing a scalable method to engineer catalyst selectivity for industrial CO2 valorization.