Enhanced hydrogen production from ethanol photoreforming by site-specific deposition of Au on CCu2O/TiO2 p-n junction

Abstract

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 inTiO2 nanorods and Cu2 O-TiO2 p-n junction across the interface of two components. The Au nanoparticles (~2.5 nm) were selectively anchored onto either TiO2 nanorods (Au@TiO2 /Cu2 O) or Cu2 O nanocubes (Au@Cu2 O/TiO2) or both TiO2 and Cu2 O (Au@TiO2 /Cu2 O@Au) with the same Au loading. The electronic structure of supported Au species was changed by forming Au@TiO2 interface due to the adjacent Ti3+ defects and the associated oxygen vacancies while unchanged in Au@Cu2 O/TiO2 catalyst. The p-n junction of TiO2 /Cu2 O promoted charge separation and transfer across the junction. During ethanol photoreforming, Au@TiO2 /Cu2 O catalyst possessing both the Au@TiO2 interface and the p-n junction showed the highest H2 production rate of 8548 µmol gcat−1 h−1 under simulated solar light, apparently superior to both Au@TiO2 and Au@Cu2 O/TiO2 catalyst. The acetaldehyde was produced in liquid phase at an almost stoichiometric rate, and C−C cleavage of ethanol molecules to form CH4 or CO2 was greatly inhibited. Extensive spectroscopic results support the claim that Au adjacent to surface Ti3+ defects could be active sites for H2 production and p-n junction of TiO2 /Cu2 O facilitates photo-generated charge transfer and further dehydrogenation of ethanol to acetaldehyde during the photoreforming.