One-step synthesis of oxygen vacancy-rich SnO2 quantum dots with ultrahigh visible-light photocatalytic activity

In this work, the oxygen vacancy-rich SnO2 quantum dots (QDs) have been synthesized via facile vapor hydrolysis method and employed as an efficient visible-light photocatalyst for MO degradation. The as-prepared oxygen vacancy-rich SnO2 QDs showed ultrahigh visible light photocatalytic activity for MO degradation (k = 1.1699 min(-1)), which was about 182.13 and 259.26 times as high as that of P25 TiO2 (k = 0.00642 min(-1)) and commercial SnO2 (k = 0.00451 min(-1)). Besides, the SnO2 QDs-160 photocatalyst had a bandgap of 2.29 eV, much narrower than that of commercial SnO2 ((similar to)3.56 eV), mainly because of the formation of oxygen vacancy defects in the SnO2 QDs. The photocatalytic MO degradation under visible-light irradiation here was mainly attributed to the oxidation of the superoxide radicals and holes. This work also indicated that the as-prepared SnO2 QDs could serve as a promising visible-light photocatalyst for efficient environmental photocatalysis.