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

Abstract

The binary metal sulfide Zn_0.5Cd_0.5S 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 Zn_0.5Cd_0.5S, forming a novel metal-complex semiconductor heterostructure system (Zn_0.5Cd_0.5S/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 Zn_0.5Cd_0.5S 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.