Synergistic effects of Cu2O-decorated CeO2 on photocatalytic CO2 reduction: Surface Lewis acid/base and oxygen defect.

• Cu 2 O-decorated CeO 2 was prepared for the photocatalytic CO 2 reduction. • Cu 2 O modified Lewis acid/base and surface oxygen defect content of CeO 2. • More medium basic sites on Cu 2 O/CeO 2 improved CO 2 adsorption/activation. • The synergistic effect of Cu 2 O/CeO 2 on photocatalytic mechanism was proposed. Ceria (CeO 2) with abundant oxygen defects, surface alkalinity, low cost effectiveness and admirable redox ability could be used in the photoreduction of CO 2. However, little attention has been paid to the interaction of reactant CO 2 molecules on CeO 2 –based photocatalysts. In this work, Cu 2 O nanoparticles were applied to the modification of the properties of Lewis acid/base, surface oxygen defect content and visible light adsorption of CeO 2 , and the adsorption/activation abilities of CO 2 reactant on Cu 2 O/CeO 2 and CeO 2 photocatalysts were investigated in comparison. The photocatalytic performance showed that Cu 2 O/CeO 2 had better activity than CeO 2. And the loading of Cu 2 O resulted in more oxygen defects and Ce3+ species, which was helpful for available visible light adsorption and higher charge-separation efficiency. Furthermore, CO 2 -TPD, CO 2 -adsorption DRIFTS and in-situ ESR results demonstrated that the synergistic effects of Cu 2 O/CeO 2 were beneficial for more generated carboxylate and CO 2 − radicals, instead of carbonate species which promoted CO 2 reduction to CO. [ABSTRACT FROM AUTHOR]