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 Ti3+defects inTiO2nanorods and Cu2O-TiO2p-n junction across the interface of two components. The Au nanoparticles (~2.5 nm) were selectively anchored onto either TiO2nanorods (Au@TiO2/Cu2O) or Cu2O nanocubes (Au@Cu2O/TiO2) or both TiO2and Cu2O (Au@TiO2/Cu2O@Au) with the same Au loading. The electronic structure of supported Au species was changed by forming Au@TiO2interface due to the adjacent Ti3+defects and the associated oxygen vacancies while unchanged in Au@Cu2O/TiO2catalyst. 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@TiO2interface and the p-n junction showed the highest H2production rate of 8548 μmol gcat−1h−1under simulated solar light, apparently superior to both Au@TiO2and Au@Cu2O/TiO2catalyst. The acetaldehyde was produced in liquid phase at an almost stoichiometric rate, and C−C cleavage of ethanol molecules to form CH4or CO2was greatly inhibited. Extensive spectroscopic results support the claim that Au adjacent to surface Ti3+defects could be active sites for H2production and p-n junction of TiO2/Cu2O facilitates photo-generated charge transfer and further dehydrogenation of ethanol to acetaldehyde during the photoreforming.Keywords:ethanol reforming;hydrogen production;Au catalyst;Ti3+defect;site-specific deposition