Influence of Copper Valence in CuOx/TiO2 Catalysts on the Selectivity of Carbon Dioxide Photocatalytic Reduction Products

The Cu cocatalyst supported on the surface of TiO2photocatalysts has demonstrated unique activity and selectivity in photocatalytic CO2reduction. 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 CO2reduction remains inadequately understood. In this study, CuOx/TiO2catalysts were synthesized using an in situ growth reduction method, and we investigated the impact of various valence copper species on CO2photocatalytic reduction. Our results indicate that Cu+and Cu0serve as primary active sites, with the selectivity for CH4and CO products during CO2photoreduction being closely related to their respective ratios on the catalyst surface. The adsorption and activation mechanisms of CO on both Cu+and Cu0surfaces are identified as critical factors determining product selectivity in photocatalytic processes. Furthermore, it is confirmed that Cu+primarily facilitates CH4production while Cu0is responsible for generating CO. This study provides valuable insights into developing highly selective photocatalysts.