MoS ₂ quantum dots@TiO ₂ nanotube composites with enhanced photoexcited charge separation and high-efficiency visible-light driven photocatalysis

MoS 2 quantum dots (QDs) that are 5 nm in size were deposited on the surface of ultrathin TiO 2 nanotubes (TNTs) with 5 nm wall thickness by using an improved hydrothermal method to form a MoS 2 QDs@TNT visible-light photocatalyst. The ultrathin TNTs with high percentage of photocatalytic reactive facets were fabricated by the commercially available TiO 2 nanoparticles (P25) through an improved hydrothermal method, and the MoS 2 QDs were acquired by using a surfactant-assisted technique. The novel MoS 2 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 −1 ) within 40 min under visible-light irradiation. MoS 2 as the co-catalysts favored the broadening of TNTs into the visible-light absorption scope. The quantum confinement and edge effects of the MoS 2 QDs and the heterojunction formed between the MoS 2 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.