MoS₂ quantum dots@TiO₂ nanotube composites with enhanced photoexcited charge separation and high-efficiency...

MoS₂ quantum dots (QDs) that are 5 nm in size were deposited on the surface of ultrathin TiO₂ nanotubes (TNTs) with 5 nm wall thickness by using an improved hydrothermal method to form a MoS₂ QDs@TNT visible-light photocatalyst. The ultrathin TNTs with high percentage of photocatalytic reactive facets were fabricated by the commercially available TiO₂ nanoparticles (P25) through an improved hydrothermal method, and the MoS₂ QDs were acquired by using a surfactant-assisted technique. The novel MoS₂ 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. MoS₂ as the co-catalysts favored the broadening of TNTs into the visible-light absorption scope. The quantum confinement and edge effects of the MoS₂ QDs and the heterojunction formed between the MoS₂ 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.