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

• Main Authors: Lan Luo, Tingting Zhang, Xin Zhang, Rongping Yun, Yanjun Lin, Bing Zhang, Xu Xiang
• Format: Article
• Language: English
• Published: MDPI AG 2020-05-01
• Series: Catalysts
• Subjects: ethanol reforming; hydrogen production; Au catalyst; Ti³⁺ defect; site-specific deposition
• Online Access: https://www.mdpi.com/2073-4344/10/5/539

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 Cu₂O-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/Cu₂O) or Cu₂O nanocubes (Au@Cu₂O/TiO₂) or both TiO₂ and Cu₂O (Au@TiO₂/Cu₂O@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@Cu₂O/TiO₂ 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@TiO₂ interface and the p-n junction showed the highest H₂ production rate of 8548 μmol g_cat⁻¹ h⁻¹ under simulated solar light, apparently superior to both Au@TiO₂ and Au@Cu₂O/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/Cu₂O facilitates photo-generated charge transfer and further dehydrogenation of ethanol to acetaldehyde during the photoreforming.