Zn and Ni dual hydrogen evolution sites integrated onto CdS for effective photocatalytic hydrogen production

Effective and affordable photocatalysts play an important role in the cost reduction of solar hydrogen production through photocatalytic water splitting. In this research, a Zn²⁺ and Ni²⁺ modified carbon hydrogen evolution cocatalyst (ZnNi-C) were synthesized and immobilized onto the surface of CdS (CdS@ZnNi-C) for photocatalytic hydrogen evolution (PHE). The preparation used an ethylenediaminetetraacetic acid disodium (EDTA)-assisted method. The hydrogen evolution rate and apparent quantum efficiency (AQE) at 420 nm for an optimized CdS@ZnNi-C photocatalyst are15.7 mmol/h/g and 31.4 %, respectively. The rate is 2.4 times and 3.7 times greater than those of Zn²⁺ and Ni²⁺ modified carbon cocatalysts (Zn-C) and (Ni-C) on CdS (CdS@Zn-C) and (CdS@Ni-C), respectively. Density functional theory calculations indicate that the elevated catalytic performance of CdS@ZnNi-C is due to the co-anchored Zn²⁺ and Ni²⁺ in carbon layers that lead to a favorable Gibbs free energy (ΔG_H*) for hydrogen evolution. This approach is valuable for the design of stable and efficient photocatalysts for renewable hydrogen production.