New photocatalysts based on Cd_0.3Zn_0.7S and Ni(OH)₂ for hydrogen production from ethanol aqueous solutions under visible light

The Cd_0.3Zn_0.7S photocatalysts modified by nickel hydroxide were prepared and characterized by different experimental techniques including X-ray diffraction, UV–vis spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The obtained photocatalysts were tested in the photocatalytic hydrogen evolution from ethanol aqueous solutions under visible light irradiation (λ = 450 nm). The nickel-modified photocatalysts were found to be more active than the zinc-modified ones. The reasons of high activity of Ni-contained photocatalysts and their transformations during the photocatalytic hydrogen production were discussed. The dependences of hydrogen production rate on ethanol and NaOH concentrations were obtained, the highest value of the photocatalytic activity was 27 mmol h⁻¹ g⁻¹ for 1%Pt/10% Ni(OH)₂/Cd_0.3Zn_0.7S (50% vol. ethanol, 1 M NaOH), apparent quantum efficiency exceeded 90%. A kinetic model describing the experimental data was proposed.