Novel photocatalysts Pt/Cd1-xZnxS/ZnO/Zn(OH)2: Activation during hydrogen evolution from aqueous solutions of ethanol under visible light

The transformations of single-phase Pt/Cd1-xZnxS and multiphase Pt/Cdd(1-x)Zn(x)S/ZnO/Zn(OH)(2) and Pt/Cd1-xZnS/Zn(OH)(2) during photocatalytic hydrogen evolution from aqueous solutions of ethanol under visible light (lambda = 450 nm) were investigated. Cyclic tests including long-term experiments were conducted for all photocatalysts. The photocatalysts were investigated before and after the photocatalytic reaction by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy techniques. Activation during photocatalytic hydrogen evolution was observed for all multiphase photocatalysts, whereas single phase Pt/Cd1-xZnxS was shown to exhibit a strong deactivation. The activation is likely caused by the formation of the epsilon-Zn(OH)(2) phase in a basic medium. The highest exhibited rate of hydrogen evolution on the composite photocatalyst was 3400 mu mol g(-1) h(-1), and stability during ten 5-hour photocatalytic runs was observed. (C) 2015 Elsevier B.V. All rights reserved.