MIL-125(Ti)@ZIF-67-derived MIL-125(Ti)@TiO2 hollow nanodiscs decorated with Co3S4 for remarkable photocatalytic CO2 reduction

Abstract

Fabricating photocatalysts with customizable structure and composition using different metal–organic framework (MOF) building blocks has intriguing implications in chemistry and material science, but it is challenging to do so. Here, a two-step synthetic strategy was designed to prepare MIL-125(Ti)@TiO₂ hollow nanodiscs decorated with Co₃S₄ nanoparticles for CO₂ photoreduction. The Co-based zeolite imidazolium ester backbone (ZIF-67) nanolayer was first loaded on the prepared MIL-125(Ti) nanodiscs to form core@shell MIL-125(Ti)@ZIF-67 nanodiscs. The following sulfidation process under solvothermal condition led to the production of MIL-125(Ti)@TiO₂ hollow nanodiscs decorated with Co₃S₄ nanoparticles (MIL-125(Ti)@TiO₂\Co₃S₄). This ternary hybrid catalyst with hollow nanodisc structure possessed a significantly enhanced charge separation efficiency and visible light absorption, along with offering a huge number of active sites. Considering the above advantages, the CO₂ photoreduction activity of the optimized MIL-125(Ti)@TiO₂\Co₃S₄ catalyst was significantly increased when compared to single-component catalysts (MIL-125(Ti), TiO₂, and Co₃S₄) and binary hybrid catalysts (MIL-125(Ti)@TiO₂ and TiO₂\Co₃S₄) under simulated sunlight irradiation. CO is the main product with a productivity of 587.50 μmol g⁻¹ h⁻¹, which is almost seven times higher than that of pure MIL-125(Ti). The potential photocatalytic mechanism of the hybrid photocatalyst has also been demonstrated. This study presents a simple and effective technique for fabricating MOF-based hybrid catalysts for photocatalytic applications.