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The transformations of single-phase Pt/Cd 1− x Zn x S and multiphase Pt/Cd 1− x Zn x S/ZnO/Zn(OH) 2 and Pt/Cd 1− x Zn x S/Zn(OH) 2 during photocatalytic hydrogen evolution from aqueous solutions of ethanol under visible light ( λ = 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/Cd 1− x Zn x S was shown to exhibit a strong deactivation. The activation is likely caused by the formation of the ϵ-Zn(OH) 2 phase in a basic medium. The highest exhibited rate of hydrogen evolution on the composite photocatalyst was 3400 μmol g −1 h −1 , and stability during ten 5-hour photocatalytic runs was observed. [ABSTRACT FROM AUTHOR]

A series of solid solutions of cadmium and manganese sulfides, Cd1−xMnxS (x = 0–0.35), and composite photocatalysts, CdS-β-Mn3O4-MnOOH, were synthesized by precipitation with sodium sulfide from soluble cadmium and manganese salts with further hydrothermal treatment at 120 °C. The obtained photocatalysts were studied by the X-ray diffraction method (XRD), UV-vis diffuse reflectance spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and N2 low temperature adsorption. The photocatalysts were tested in hydrogen production using a Na2S/Na2SO3 aqueous solution under visible light (λ = 450 nm). It was shown for the first time that both kinds of photocatalysts possess high activity in hydrogen evolution under visible light. The solid solution Cd0.65Mn0.35S has an enhanced photocatalytic activity due to its valence and conduction band position tuning, whereas the CdS-β-Mn3O4-MnOOH (40–60 at% Mn) samples were active due to ternary heterojunction formation. Further, the composite CdS-β-Mn3O4-MnOOH photocatalyst had much higher stability in comparison to the Cd0.65Mn0.35S solid solution. The highest activity was 600 mmol g−1 h−1, and apparent quantum efficiency of 2.9% (λ = 450 nm) was possessed by the sample of CdS-β-Mn3O4-MnOOH (40 at% Mn). [ABSTRACT FROM AUTHOR]