Tightly Interfaced Cu₂O with In₂O₃ to Promote Hydrogen Evolution in Presence of Biomass‐Derived Alcohols

Abstract

By a mild and straightforward synthetic protocol in aqueous solution and without surfactants, hierarchical Cu2O nanospheres were grown on preformed In2O3 nanostructures, varying the ratio In:Cu (2.5, 0.5). Accordingly, two different binary compounds In2O3‐Cu2O were prepared and afterwards they were integrated with TiO2 NPs. The ternary composites having a loading of 2.0, 5.0 and 10.0 wt.% respectively of binary In2O3‐Cu2O, were tested as photocatalysts in the solar‐driven production of hydrogen from water, using as sacrificial agents alcohols derived from the biomass. Satisfyingly, the rate of H2 evolution (20.5 mmol/g h) resulted two orders of magnitude higher respect to bare TiO2 (0.2 mmol/g h). Electrochemical impedance spectroscopy and photoluminescence measurements revealed the formation of a tight heterojunction between In2O3 and Cu2O, which is responsible for the improved charge carrier density and transfer and for the diminished electron‐hole recombination.