Escalating the synergism on CdZnS via Ag₂S/Cu₂S co-catalysts: Boosts hydrogen evolution from water splitting under sunlight

Photocatalytic hydrogen production through water splitting is one of the effective ways to fulfill future energy demands. In current study, Ag and Cu were simultaneously incorporated into CdZnS through hydrothermal reaction to synthesize 1 % Ag₂S/Cu₂S codoped-CdZnS. The catalysts were characterized via XRD, FT-IR, SEM, EDX, UV–Vis/DRS, XPS, BET, PL and EIS techniques. It has been observed that 1 % Ag₂S/Cu₂S is optimized amount of dopants that enables CdZnS to produce hydrogen with 9.76 mmol g⁻¹h⁻¹ rate. This amount of H₂ is 3 times higher than that of bare CdZnS (2.91 mmol g⁻¹h⁻¹). Photocatalytic activity shown by 1 % Ag₂S/Cu₂S-CdZnS is due the incorporation of Ag and Cu which exist in the form of Ag₂S and Cu₂S clusters respectively and causes synergistic effect during photoreaction. During the photoreactions, oxidation half reactions occur at Ag₂S, while reduction half reaction at Cu₂S (i.e. conversion of H⁺ ions to H₂). On the basis of the results, it can be concluded that Cu₂S acts as reduction co-catalyst while Ag₂S serves as oxidation co-catalyst in water reduction reaction. This work could offer efficient and low cost photocatalysts for hydrogen production from the water splitting reactions.