Highly boosted photocatalytic H₂ production from ZnS particles assisted by Cd-Cu co-doping

Cd-Cu co-doping was applied to improve photocatalytic H₂ evolution efficiency of the ZnS photocatalyst. This study confirms that an optimal Cd-Cu dopant ratio enhances the photocatalytic activity by improving light absorbance and minimizing charge recombination. Furthermore, the optimum Cd-Cu ratio plays a significant role in inducing a uniform spherical morphology and CdS-CuS crystalline structure. The drawbacks of the ZnS photocatalysts can be overcome by reducing the band gap with an increased charge carrier concentration. In the type-II heterojunction system of the best C2C5 (Cd:Cu = 2:5) photocatalyst sample, electrons are effectively transferred through hierarchical band alignment while blocking the separated holes to reduce charge recombination. The content-optimized C2C5 sample greatly accelerated the charge transfers during the photocatalytic reactions. Thus, ZnS photocatalyst assisted by Cd-Cu co-doping is a promising material for overpowering the inherent problems of the metal sulfides for solar hydrogen productions.