Influence of Copper Valence in CuO/TiO Catalysts on the Selectivity of Carbon Dioxide Photocatalytic Reduction Products.

The Cu cocatalyst supported on the surface of TiO photocatalysts has demonstrated unique activity and selectivity in photocatalytic CO reduction. The valence state of copper significantly influences the catalytic process; however, due to the inherent instability of copper's valence states, the precise role of different valence states in CO reduction remains inadequately understood. In this study, CuO/TiO catalysts were synthesized using an in situ growth reduction method, and we investigated the impact of various valence copper species on CO photocatalytic reduction. Our results indicate that Cu and Cu serve as primary active sites, with the selectivity for CH and CO products during CO photoreduction being closely related to their respective ratios on the catalyst surface. The adsorption and activation mechanisms of CO on both Cu and Cu surfaces are identified as critical factors determining product selectivity in photocatalytic processes. Furthermore, it is confirmed that Cu primarily facilitates CH production while Cu is responsible for generating CO. This study provides valuable insights into developing highly selective photocatalysts.