Fabricating sandwich-shelled ZnCdS/ZnO/ZnCdS dodecahedral cages with “one stone” as Z-scheme photocatalysts for highly efficient hydrogen production

Abstract

Affording two semiconductors with one template in one step to construct a composite with delicate structures may endow low-cost photocatalysts with desired characteristics, i.e., high activity, stability and recyclability. Herein, novel sandwich-shelled ZnCdS/ZnO/ZnCdS cages are fabricated with “one stone”—zeolitic-imidazolate-framework-8. ZnS and ZnO are formed simultaneously in the sulfidation stage, where ZnS serves as a barrier to localize the ZnO particles filling up the voids between the ZnS layers. It could therefore be very advantageous in photocatalysis that the ZnCdS, derived from cation-exchanged ZnS, and ZnO with well-defined interfaces also have staggered band structure configurations by virtue of the fine adjustment of the composition. The Zn_0.5Cd_0.5S/ZnO/Zn_0.5Cd_0.5S cages exhibit a H₂ production rate of 28.6 mmol g⁻¹ h⁻¹ and long-term durability, achieving the highest activities among the ZnCdS and ZnO families under noble-metal-free conditions. This remarkable performance could be ascribed to the unique morphology of the sandwich-shell and hollow interior integrating multiple vital merits for photocatalysis, including the enhanced light-harvesting ability, abundant active sites, shortened charge diffusion distances, and Z-scheme mechanism featuring preserved strong redox ability and improved charge separation and migration. This facile strategy may offer great opportunities in developing highly active metal sulfide/oxide-based photocatalysts for practical applications.