Macroporous ZnO/ZnS/CdS composite spheres as efficient and stable photocatalysts for solar-driven hydrogen generation

Abstract

Solar-driven hydrogen (H2) generation utilizing photocatalysts has received extensive attention because of its potential to mitigate the global energy crisis and environmental problem. The implementation of efficient H2 production strongly relies on stable, active, and low-cost photocatalysts. In this work, we report the designed synthesis of macroporous ZnO/ZnS/CdS composite spheres as a highly active photocatalyst for H2 production via solar-driven water splitting. The composite spheres were synthesized by a facile solvothermal reaction paired with controllable ion-exchange processes. The resulting material exhibits superior photocatalytic activity, delivering a high H2 production rate of ~11.37 mmol h−1 g−1 under light illumination (250–780 nm, with an ultraviolet light intensity of 34 mW cm−2 and visible light intensity of 158 mW cm−2). Such performance enhancement can be mainly ascribed to the synergic effects of the composite structure: (1) formation of coherent ZnO/CdS and ZnS/CdS heterojunctions at nanoscale, facilitating charge separation of photoinduced electron/hole pairs, (2) highly accessible inner surface of the meso/macroporous ZnO/ZnS/CdS composites for rapid mass transfer of electrolyte, and (3) enhanced visible light scattering capability induced by their large particle size.