Integrating Au@TiOx and Co sites in a tandem photocatalyst for efficient C-C coupling synthesis of ethane

Herein, a series of Au@TiOx-Co catalysts were constructed for photocatalytic reduction of CO2 with H2O. Structural characterizations found separate Co and Au nanoparticles (NPs) are produced, and their ratios are variable with different reduction temperatures. Especially Au NPs were coated with oxygen vacancy(VO)-rich TiOx overlayers due to the high-temperature induced topological transition, resulting in interfacial electron transfer to generate Au delta--VO sites. In the photocatalytic reduction of CO2 , the ratios of Au@TiOx and Co sites strongly influenced the activity and product selectivity. The Au@TiOx-Co(650) catalyst with matched Au delta--VO and Co0 sites is efficient for C-C coupling with a C2H6 production rate of 58.65 mu mol center dot h- 1 center dot gcat- 1 and selectivity of 25.10%. In situ FTIR demonstrated the Au delta--VO sites are responsible for the H2O oxidation process and the conversion of CO2 to CO via CO2 center dot-species, and syngas is further coupled into C2H6 at the Co0 surface sites via CHO* intermediate.