Nitrogen doped carbon quantum dots promoted the construction of Z-scheme system with enhanced molecular oxygen activation ability

Abstract

Bismuth vanadate (BiVO4) as a visible-light photocatalyst is always restricted by rapid photoexcited electron-hole recombination. Hence, the construction of charge transfer path is an essential strategy to establish an efficient photocatalytic system. Notably, the nitrogen doped carbon quantum dots (N-CQDs) exhibit potential for application in photocatalysis due to its high charge transfer capability and molecular oxygen activation ability. In this work, a Z-scheme BiVO4/N-CQDs/Cu2O system with enhanced molecular oxygen activation ability was constructed. Under the optimum condition, the BiVO4/N-CQDs/Cu2O composite showed 99.1% tetracycline hydrochloride (TC) removal efficiency under visible light irradiation in 60 min. The N-CQDs provide a potential driving force to reestablish the local electric field and lead to the construction of the Z-scheme BiVO4/N-CQDs/Cu2O system. And the excellent photocatalytic performance of this system was ascribed to the greatly enhanced molecular oxygen activation by contacting N-CQDs and the construction of Z-scheme system. Furthermore, the visible light absorption capability was obviously improved due to the fact that Cu2O provided multiple reflection of visible light and the N-CQDs act as a photosensitizer. Noteworthily, this study may help to further understand the function of N-CQDs in heterojunction and it could be expanded to design other photocatalysts.