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

• Platinized Cd1−xZnxS, Cd1−xZnxS/ZnO/Zn(OH)2, and Cd1−xZnxS/Zn(OH)2 were prepared.
• Transformations of samples during H2 evolution were studied by XRD and XPS.
• Activation during H2 evolution was observed for all multiphase photocatalysts.
• Pt/Cd0.6Zn0.4S was shown to exhibit a strong deactivation due to CdCO3 formation.
• Photocatalytic activity (λ = 450 nm) 3.4 mmol H2 g−1 h−1 was achieved.

The transformations of single-phase Pt/Cd1−xZnxS and multiphase Pt/Cd1−xZnxS/ZnO/Zn(OH)2 and Pt/Cd1−xZnxS/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/Cd1−xZnxS 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.

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