Enhanced photocatalytic CO2 reduction in a twin reactor by separating triphase CO2 reduction and water oxidation reactions

Harnessing solar energy for photocatalytic CO2 reduction represents a highly promising technology for mitigating CO2 emissions. In this study, a novel twin reactor that efficiently reduces CO2 via a triphase system on the reduction side while simultaneously generating oxygen on the oxidation side was developed. Pt/TiO2 and Pt/ WO3 were employed as the catalysts for CO2 reduction and water oxidation, respectively. The results indicate that the Z-scheme spatial separation structure, together with the triphase system integrated in the twin reactor, effectively enhances the mass transfer of gaseous reactants to the catalyst surface, inhibits reverse reactions, promotes charge separation and substantially increases the efficiency of photocatalytic reaction. Upon illumination, the maximum CO2 reduction rate reached 48.2 mu mol g-1h- 1, approximately 5 times higher than that achieved in conventional diphase single reactor. Meanwhile, CO, CH4 and O2 were generated in a stoichiometric ratio over a long period of photocatalytic reaction. This work offers a viable strategy for the design of photo- catalytic CO2 reduction reactors.