Enhancing photocatalytic H2 evolution on In2S3/mesoporous TiO2 nanocomposites via one-pot microwave-assisted synthesis using an ionic liquid

Abstract

Charge transfer and surface photocatalytic reactions are two crucial factors that determine the efficiency of photocatalysts in converting light energy to hydrogen energy. Herein, a fast and green strategy composed of a one-pot microwave-assisted solvothermal synthesis followed by a heat treatment process is developed for synthesizing In₂S₃/mesoporous TiO₂ nanocomposites, using a mixture of tetra-butyl titanate, H₂O, In-S-ionic liquid precursor solution (In-S-ILs) and [Bmim]Cl as the reactants. The ionic liquid cations act not only as a microwave absorbent during the solvothermal process, but also as a morphology-controlling agent via a dissolution-recrystallization process, leading to the formation of nanocomposites consisting of small and uniform sized In₂S₃ and mesoporous TiO₂. The optimum In₂S₃/mesoporous TiO₂ nanocomposite with an In₂S₃ content of 1.01 mol% exhibits a H₂ evolution rate of 637.9 μmol g⁻¹ h⁻¹, which is over 10 times that of commercial P25, and is 5.7 and 2.6 times that of neat mesoporous TiO₂ and the milled In₂S₃/mesoporous TiO₂ with the same component, respectively. The improved H₂ evolution activity is predominantly attributed to the small size of In₂S₃, special mesoporous structure of TiO₂, and their intimate heterojunction interface, which guaranteed effective charger transfer between In₂S₃ and mesoporous TiO₂ as well as abundant active sites for photocatalytic reactions. This work provides a novel and simple strategy for obtaining special structures of semiconductor-based nanocomposites for efficient energy conversion.