Fabrication of high-surface-area mesoporous frameworks of β-Ni(OH)2–CdIn2S4 p–n nano-heterojunctions for improved visible light photocatalytic hydrogen production

Abstract

Photocatalytic water splitting holds promise as a cost-effective method for renewable hydrogen production. To this end, synthesising high-performance and robust semiconductor photocatalysts is highly desired. In this study, an interfacial engineering strategy of mesoporous p–n heterojunction frameworks comprising CdIn₂S₄ assembled nanocrystals (ca. 5–7 nm in size) and β-Ni(OH)₂ nanoparticles (ca. 7–8 nm in size) with significantly improved photocatalytic hydrogen evolution activity is described. The promotional effect of β-Ni(OH)₂ on the electronic band structure and interfacial charge transfer kinetics of heterostructures is systematically elucidated through a combination of spectroscopic and (photo)electrochemical studies. Incorporating β-Ni(OH)₂ effectively accelerates the charge separation process and enhances the utilization of surface-reaching photoexcited carriers for redox reactions. Benefiting from the superior charge transfer and mass transport kinetics, the Ni-modified CdIn₂S₄ mesostructures release H₂ at a rate of ∼20 mmol h⁻¹ g_cat⁻¹ under visible light illumination, corresponding to a 52% apparent quantum efficiency at 420 nm.