The influence of the sacrificial agent nature on transformations of the Zn(OH)₂/Cd_0.3Zn_0.7S photocatalyst during hydrogen production under visible light

Abstract

Photocatalysts based on zinc hydroxide and a solid solution of CdS and ZnS were prepared <i>via</i> the precipitation method and used for photocatalytic hydrogen production from aqueous solutions of inorganic (Na₂S/Na₂SO₃) and organic (ethanol) sacrificial agents. The photocatalysts were tested in cyclic experiments for hydrogen evolution and studied using X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy, high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS) techniques. Different transformations of the β-Zn(OH)₂ co-catalyst were observed in the presence of inorganic and organic sacrificial agents; namely, ZnS was formed in Na₂S/Na₂SO₃ solution, whereas the formation of ε-Zn(OH)₂ was detected in solution with ethanol. The composite Zn(OH)₂/Cd_1-<i>x</i> Zn _<i>x</i> S photocatalysts have great potential in various photocatalysis processes (<i>e.g.</i>, hydrogen production, CO₂ reduction, and the oxidation of organic contaminants) under visible light.