Bifunctional core–shell co-catalyst for boosting photocatalytic CO2 reduction to CH4

Solar-light-driven CO2 reduction CO to CH4 and C2H6 is a complex process involving multiple elementary reactions and energy barriers. Therefore, achieving high CH4 activity and selectivity remains a significant challenge. Here, we integrate bifunctional Cu2O and Cu-MOF (MOF = metal-organic framework) core–shell co-catalysts (Cu2O@Cu-MOF) with semiconductor TiO2. Experiments and theoretical calculations demonstrate that Cu2O (Cu+ facilitates charge separation) and Cu-MOF (Cu2+ improves the CO2 adsorption and activation) in the core–shell structure have a synergistic effect on photocatalytic CO2 reduction, reducing the formation barrier of the key intermediate ⋆COOH and ⋆CHO. The photocatalyst exhibits high CH4 yield (366.0 µmol·g−1·h−1), efficient electron transfer (3283 µmol·g−1·h−1) and hydrocarbon selectivity (95.5%), which represents the highest activity of Cu-MOF-based catalysts in photocatalytic CO2 reduction reaction. This work provides a strategy for designing efficient photocatalysts from the perspective of precise regulation of components.