Low-temperature preparation of AgIn_5S_8/TiO_2 heterojunction nanocomposite with efficient visible-light-driven hydrogen production

摘要

AgIn_5S_8 and AgIn_5S_8/TiO_2 heterojunction nanocomposite with efficient photoactivity for H_2 production were prepared by a low-temperature water bath deposition process. The resultant AgIn_5S_8 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 H_2 evolution is 9 times higher than that (11 μmol h~(-1)) of the product derived from a hydrothermal process, while the obtained AgIn_5S_8/TiO_2 heterojunction nanocomposites prepared by using commercially available TiO_2 nanoparticles (P25) as TiO_2 source exhibit remarkably improved photoactivity as compared to the pristine AgIn_5S_8, and the AgIn_5S_8/TiO_2 nanocomposite with molar ratio of 1:10 shows a maximum photocatalytic H_2 evolution rate (371.1 μmol h~(-1)), which is 4.3 times higher than that (85 μmol h~(-1)) of the corresponding AgIn_5S_8/TiO_2 nanocomposite derived from a hydrothermal method. This significant enhancement in the photocatativity of the present AgIn_5S_8/TiO_2 nanocomposite can be ascribed to the better dispersion of the AgIn_5S_8 formed on TiO_2 nanoparticle surfaces and the more intimate AgIn_5S_8/TiO_2 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 AgIn_5S_8 towards TiO_2, 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.