Enhanced Hydrogen Production from Ethanol Photoreforming by Site-Specific Deposition of Au on Cu2O/TiO2 p-n Junction

Hydrogen production by photoreforming of biomass-derived ethanol is a renewable way of obtaining clean fuel. We developed a site-specific deposition strategy to construct supported Au catalysts by rationally constructing Ti(3+)defects inTiO(2)nanorods and Cu2O-TiO(2)p-n junction across the interface of two components. The Au nanoparticles (similar to 2.5 nm) were selectively anchored onto either TiO(2)nanorods (Au@TiO2/Cu2O) or Cu2O nanocubes (Au@Cu2O/TiO2) or both TiO(2)and Cu2O (Au@TiO2/Cu2O@Au) with the same Au loading. The electronic structure of supported Au species was changed by forming Au@TiO(2)interface due to the adjacent Ti(3+)defects and the associated oxygen vacancies while unchanged in Au@Cu2O/TiO(2)catalyst. The p-n junction of TiO2/Cu2O promoted charge separation and transfer across the junction. During ethanol photoreforming, Au@TiO2/Cu2O catalyst possessing both the Au@TiO(2)interface and the p-n junction showed the highest H(2)production rate of 8548 mu mol g(cat)(-1)h(-1)under simulated solar light, apparently superior to both Au@TiO(2)and Au@Cu2O/TiO(2)catalyst. The acetaldehyde was produced in liquid phase at an almost stoichiometric rate, and C-C cleavage of ethanol molecules to form CH(4)or CO(2)was greatly inhibited. Extensive spectroscopic results support the claim that Au adjacent to surface Ti(3+)defects could be active sites for H(2)production and p-n junction of TiO2/Cu2O facilitates photo-generated charge transfer and further dehydrogenation of ethanol to acetaldehyde during the photoreforming.