Photosensitization of TiO2 nanosheets with ZnIn2S4 for enhanced visible photocatalytic activity toward hydrogen production

TiO 2 nanosheet is a fruitful paradigm for a wide variety of photocatalytic applications due to its characteristics of high photoactivity, robust stability, and environmental friendliness. However, its pragmatic utilization for visible light photocatalytic energy conversion still remains challenging owing to the wide bandgap. Herein, a 2D/3D TiO 2 /ZnIn 2 S 4 nanostructure was purposively constructed via a microwave-assisted synthesis, with ZnIn 2 S 4 functioned as a photosensitizer to overcome the lack of visible light response capacity for TiO 2 . The optimal TiO 2 /ZnIn 2 S 4 sample exhibits an excellent photocatalytic H 2 evolution activity with a rate of 1167.38 μmol/g/h under visible light illumination, far beyond that of pristine TiO 2 nanosheet (6.78 μmol/g/h) and ZnIn 2 S 4 (378.51 μmol/g/h). The enhanced photocatalytic performance can be attributed to synergy effects of the extended visible light response, compatible band alignment, and fast charge carrier separation. The in situ irradiated X-ray photoelectron spectroscopy (XPS) was used to systematically study the transfer behavior of photo-induced electrons; the results highlighted that the flow direction of photoexcited charges is from ZnIn 2 S 4 to TiO 2 nanosheets due to the strong interfacial contact. Then both ZnIn 2 S 4 and TiO 2 nanosheets can act as the active sites for proton reduction, which therefore boosts the hydrogen production under visible irradiation. This work opens a new venue for the development of flexible photosensitization systems for solar-driven energy conversion.