Visible-light responsive MOF encapsulation of noble-metal-sensitized semiconductors for high-performance photoelectrochemical water splitting

Abstract

A strategy that visible-light responsive zeolitic-imidazolate-framework-67 (ZIF-67) encapsulates noble-metal sensitized semiconductors, ZnO@M (M = Au, Pt, and Ag) to fabricate composite catalysts for photoelectrochemical (PEC) water splitting is proposed. The obtained ZnO@M@ZIF-67 catalysts have good catalytic performance, particularly, the ZnO@Au@ZIF-67 exhibits quite improved photoconversion efficiency and photocurrent density, superior to most of the reported photoelectrode catalysts. This can be attributed to the wider solar spectra harvesting capability originating from visible-light responsive ZIF-67 and UV-light active ZnO. Simultaneously, their integration enables interfacial electrons in the ZIF-67 shell to easily transfer to the ZnO@Au core, providing good electron–hole separation. In addition, the porous ZIF-67 as a protective shell ensures structural robustness, while maintaining fast ion or gas bubble diffusion through its pores, accounting for stable and excellent PEC performance.