Visible light-induced H<inf>2</inf> production and pollutant degradation by copper oxide nanosphere embedded zinc-cadmium-sulfide composite

Abstract

Green hydrogen production using solar water splitting and solving water pollution issues are intricately intertwined global goals which are hindered by the scarcity of highly active photocatalytic materials. Herein, we have presented a simple strategy to couple two semiconductors (Cu2O and ZnCdS) to form a type-I heterojunction with high visible light response. The as-synthesized heterojunction was well characterized by the battery techniques, such as TEM, HAADF-STEM elemental mapping, XRD and XPS. The visible light response was higher for composite than individual components, as was also supported by UV–vis DRS. The Cu2O-ZnCdS composite showed a higher visible light-driven photocatalytic H2 production rate (78.5 µmol g–1 h–1). The catalyst was also active for photocatalytic degradation of a model dye-methylene blue (MB)-with a degradation rate constant of 0.079 min−1. The enhanced performance of the Cu2O-loaded ZnCdS catalysts can be ascribed to both factors, such as enhancement of the visible light absorption and the growth of Cu2O-ZnCdS heterojunction. The heterojunction formation facilitates efficient charge separation with smaller charge resistance, as evidenced by transient photocurrent response and electrochemical impedance spectroscopy (EIS) studies. This study strongly indicates that the photocatalytic reactions with this catalyst material are kinetically favoured by coupling the two semiconductors. Graphical abstract: (Figure presented.)