A ZrO₂-Based Ternary Photocatalyst with Highly Reduced Defects for Visible-Light-Driven Hydrogen Production

Photocatalytic hydrogen production has emerged as one of the most promising strategies for addressing current energy and ecological environment issues. Optimizing charge transport pathways and reducing internal defects in semiconductor catalysts are crucial to enhancing catalytic performance. Herein, a ZrO₂-based ternary-structured photocatalyst was successfully constructed by fabricating ZnIn₂S₄ (ZIS) nanosheets on the surface of Pt-ZrO₂ derived from UiO-66-NH₂. The composite catalyst exhibits a significantly improved photocatalytic hydrogen evolution activity of 14.2 mmol/h/g under visible light (≥420 nm), with an apparent quantum efficiency of 26.5% at 420 nm. This activity is 17.0 times and 5.4 times higher than that of ZIS-ZrO₂ and Pt-ZIS, respectively. In situ-irradiated XPS results confirmed that, under visible light, the ternary heterojunction photocatalyst follows a sensitization-heterojunction model; specifically, electrons migrate from ZIS to ZrO₂ and then to Pt to complete the hydrogen evolution reaction. The close positioning of ZIS, ZrO₂, and Pt facilitates charge separation and transfer via a shortening of the charge migration distance. Moreover, Pt NPs not only provide excellent active sites for hydrogen evolution but also drastically mitigate defects in ZrO₂ by regulating the annealing process of UiO-66-NH₂. This work demonstrates the significant role of metal nanoparticles in the MOF transformation process and provides an excellent ternary heterojunction photocatalyst that promotes interfacial charge transfer and utilization in photocatalysis.