Z-Scheme ZnO/ZnAl2O4 Heterojunction with Synergistic Effects for Enhanced Photocatalytic CO2 Reduction

The photocatalytic reduction of CO2into valuable hydrocarbons presents significant potential. In this research, a ZnO/ZnAl2O4composite photocatalyst was synthesized using the hydrothermal method, resulting in a marked enhancement in CO yield—approximately three times greater than that achieved with pure ZnAl2O4nanoparticles. The formation of a Z-scheme heterojunction between ZnO and ZnAl2O4was observed, characterized by low interfacial charge transfer resistance, an abundance of reaction sites, and optimized charge transport pathways. Within this composite, ZnO contributes additional vacancies, thereby increasing active sites and enhancing the separation and migration of photogenerated carriers. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analysis indicates that ZnAl2O4facilitates the formation of key intermediates, such as *COOH and HCO3−, thus promoting the conversion of CO2to CO. This study offers valuable insights into the design of heterogeneous catalysts with diverse active components to enhance the performance of CO2photocatalytic reduction through synergistic effects.