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.