Highly efficient degradation of dyes by carbon quantum dots/N-doped zinc oxide (CQD/N-ZnO) photocatalyst and its compatibility on three different commercial dyes under daylight

Eco-friendly carbon quantum dots/nitrogen-doped ZnO (CQD/N-ZnO) composites were successfully prepared by a facile one-step method. The various techniques were employed to characterize the phase structure, morphology and optical properties of CQD/N-ZnO composites. The nitrogen doping was confirmed by Raman and X-ray photoelectron spectroscopy. Three commercial dyes, such as malachite green, methylene blue and fluorescein dyes were chosen to investigate the photocatalytic performance of CQD/N-ZnO under daylight irradiation. It was found that the CQD/N-ZnO photocatalyst established a high compatibility to degrade all three commercial dyes within 30–45min, under daylight irradiation. Also, it remains capable of reusing the CQD/N-ZnO photocatalyst for repeated photocatalytic performance due to anti-photocorrosion offered by CQDs. The synergetic effect of N-doping and CQDs is key to design a new class of photocatalyst for environmental remediation under naturally available daylight source.