Nickel (II) complex decorated zinc-cadmium sulfide type-II heterojunction for enhanced photocatalytic hydrogen production

The binary metal sulfide Zn0.5Cd0.5S has emerged as a promising photocatalyst for hydrogen (H2) production via visible-light-driven water splitting. However, its practical application is limited by rapid charge carrier recombination and insufficient stability. In this study, nickel (II)-(3-pyridyl) benzimidazole (NPBIm) complexes were synthesized and employed an ultrasonic-assisted method to decorate the surface of Zn0.5Cd0.5S, forming a novel metal-complex semiconductor heterostructure system (Zn0.5Cd0.5S/NPBIm). This hybrid system significantly enhances photocatalytic H2 evolution under visible light irradiation. Experimental findings reveal that the incorporation of NPBIm molecules improves the optical absorption of Zn0.5Cd0.5S and facilitates more efficient separation and migration of photogenerated charge carriers. The optimized Zn₀.₅Cd₀.₅S/NPBIm hybrid heterostructure exhibits a remarkable hydrogen production rate of 272.22 µmol h⁻¹ under visible light irradiation (λ ≥ 420 nm), which is more than three times higher than that of pure Zn₀.₅Cd₀.₅S (92.54 µmol h⁻¹). This significant enhancement demonstrates the potential of combining semiconductor materials with metal-complex structures to improve photocatalytic performance. Furthermore, the hybrid photocatalyst exhibits excellent stability, an essential criterion for long-term energy applications. These findings highlight the effectiveness of integrating semiconductor materials with metal-complex structures to enhance photocatalytic performance. This study contributes to the advancement of solar-driven hydrogen production and offers a promising strategy for developing next-generation photocatalysts, with broader relevance to renewable energy and environmental sustainability.