Low-temperature preparation of AgIn5S8/TiO2 heterojunction nanocomposite with efficient visible-light-driven hydrogen production

AgIn5S8 and AgIn5S8/TiO2 heterojunction nanocomposite with efficient photoactivity for H2 production were prepared by a low-temperature water bath deposition process. The resultant AgIn5S8 shows an absorption edge at ∼720 nm, corresponding to a bandgap of ∼1.72 eV, and its visible-light-driven photoactivity (100.1 μmol h−1) for H2 evolution is 9 times higher than that (11 μmol h−1) of the product derived from a hydrothermal process, while the obtained AgIn5S8/TiO2 heterojunction nanocomposites prepared by using commercially available TiO2 nanoparticles (P25) as TiO2 source exhibit remarkably improved photoactivity as compared to the pristine AgIn5S8, and the AgIn5S8/TiO2 nanocomposite with molar ratio of 1:10 shows a maximum photocatalytic H2 evolution rate (371.1 μmol h−1), which is 4.3 times higher than that (85 μmol h−1) of the corresponding AgIn5S8/TiO2 nanocomposite derived from a hydrothermal method. This significant enhancement in the photocatativity of the present AgIn5S8/TiO2 nanocomposite can be ascribed to the better dispersion of the AgIn5S8 formed on TiO2 nanoparticle surfaces and the more intimate AgIn5S8/TiO2 heterojunction structure during the water bath deposition process under continuously stirring as compared to the corresponding nanocomposite derived from a hydrothermal method. This configuration of nanocomposite results in fast diffusion of the photogenerated carriers in AgIn5S8 towards TiO2, which is beneficial for separating spatially the photogenerated carriers and improving the photoactivity. The present findings shed light on the tuning strategy of spectral responsive region and photoactivity of photocatalysts for efficient light-to-energy conversion.