Graphene quantum dot modified Bi2WO6 with enhanced photocatalytic activity by reinforcing the charge separation

Abstract

The poor light-harvesting capability and fast charge recombination of Bi-based photocatalysts weaken their photocatalytic activity. In this study, graphene quantum dot (GQD) modified Bi₂WO₆ (BWO) composites (GQDs/BWO) were prepared by a facile microwave-assisted hydrothermal method. GQDs/BWO exhibited an excellent photocatalytic activity by degrading 97.3% of phenol in 60 min under visible-light irradiation. The mechanism of reinforcing the separation of hole–electron (h⁺/e⁻) pairs was unraveled by applying the DFT calculation, indicating that the excited electrons in the GQDs/BWO composites have an extra transfer route from the Bi 6p and O 2p orbitals of BWO to GQDs instead of localization in the BWO crystal. Furthermore, GQDs with controllable size were synthesized by altering the parameters of reflux, and the size effect of GQDs on the visible light absorption capability and the charge separation property of GQDs/BWO was discussed.