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 (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.