In₂S₃ nanoparticles dispersed on g-C₃N₄ nanosheets: role of heterojunctions in photoinduced charge transfer and photoelectrochemical and photocatalytic performance

Fast recombination of photogenerated charge carriers is a major problem in the photoelectrochemical and photocatalytic processes. In this work, we report significantly improved PEC performance of a nanocomposite consists of In₂S₃ nanoparticles dispersed on g-C₃N₄ nanosheets synthesized by a simple and facile wet chemical route. The results of high-resolution TEM study show that the obtained In₂S₃ nanoparticles of size 10–20 nm exist in cubic phase and are uniformly dispersed on the surface of g-C₃N₄ nanosheets. The In₂S₃/g-C₃N₄ nanocomposite with 25 weight percentage of In₂S₃ exhibits 8.5 times higher photocurrent density than the single-phase g-C₃N₄ under visible light illumination. The enhanced photocurrent density exhibited by the In₂S₃/g-C₃N₄ nanocomposite is attributed to the efficient separation of photogenerated charge carriers. The charge transfer mechanism in In₂S₃/g-C₃N₄ heterojunction was studied by a series of experiments, such as electrochemical impedance spectroscopy, photoelectrochemical measurement and photoluminescence emission spectroscopy. The intimate interface promotes the charge transfer and inhibits the recombination rate of photogenerated electron–hole pairs, which significantly improves the photoelectrochemical performance. A detailed charge transfer mechanism is discussed based on the Mott–Schottky plot study. This heterojunction material is found to be an efficient photocatalyst for the degradation of both cationic rhodamine B dye and anionic methyl orange dye as the lifetime of photogenerated charge carriers is higher in the composite than in single-phase In₂S₃ and g-C₃N₄. A strong correlation between the photoelectrochemical and the photocatalytic performances is observed in this composite.