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 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 gcat−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.
Highlights
Hydrogen is extensively used in various industrial processes, e.g., in the petrochemical industry, metallurgy, fine chemical engineering, etc. [1]
Cu2 O nanocubes with an average size of ~40 nm were grown on TiO2 nanorods with a lateral size of 80~120 nm
Cu2O nanocubes with an average size of ~40 nm were grown on TiO2 nanorods with a lateral size of 80~120 nm
Summary
Hydrogen is extensively used in various industrial processes, e.g., in the petrochemical industry, metallurgy, fine chemical engineering, etc. [1]. Hydrogen is extensively used in various industrial processes, e.g., in the petrochemical industry, metallurgy, fine chemical engineering, etc. As a clean and renewable fuel, has aroused tremendous attention from both academic and industrial perspectives in the past decades because its energy-extraction process produces only water as a byproduct and emits no greenhouse gases, e.g., CO2 or any pollutants [2,3]. Industrial production of hydrogen depends predominantly on steam reforming of CH4 , an energy-consuming process accompanied by CO2 emissions. It is highly desirable to develop efficient, economical and energy-neutral processes for sustainable H2 production. Ethanol could be produced in a sustainable way from huge-amount, low-grade biomass, e.g., lignocelluloses and agriculture waste besides from the conventional petrochemical route [4].
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