MoS quantum dots@TiO nanotube composites with enhanced photoexcited charge separation and high-efficiency visible-light driven photocatalysis.

MoS quantum dots (QDs) that are 5 nm in size were deposited on the surface of ultrathin TiO nanotubes (TNTs) with 5 nm wall thickness by using an improved hydrothermal method to form a MoS QDs@TNT visible-light photocatalyst. The ultrathin TNTs with high percentage of photocatalytic reactive facets were fabricated by the commercially available TiO nanoparticles (P25) through an improved hydrothermal method, and the MoS QDs were acquired by using a surfactant-assisted technique. The novel MoS QDs@TNT photocatalysts showed excellent photocatalytic activity with a decolorization rate of 92% or approximately 3.5 times more than that of pure TNTs for the high initial concentration of methylene blue solution (20 mg l) within 40 min under visible-light irradiation. MoS as the co-catalysts favored the broadening of TNTs into the visible-light absorption scope. The quantum confinement and edge effects of the MoS QDs and the heterojunction formed between the MoS QDs and TNTs efficiently extended the lifetime of photoinduced charges, impeded the recombination of photoexcited electron-hole pairs, and improved the visible-light-driven high-efficiency photocatalysis.