Enhancing photocatalytic H₂ evolution on In₂S₃/mesoporous TiO₂ nanocomposites via one-pot microwave-assisted...

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.