Enhanced photocatalytic activity of ZnO sensitized by carbon quantum dots and application in phenol wastewater

Abstract

This work reports on preparation of ZnO composites sensitized by carbon quantum dots (CQDs) and its photocatalytic degradation on phenol under visible-light illumination. With the help of tools such as transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS), UV–vis diffusive reflectance spectra (UV–Vis DRS) and gas chromatograph-mass spectrometer (GC-MS), successful synthesis of ZnO composites sensitized by CQDs has been confirmed, which extend the spectral response range of the procatalyst to the visible region enhancing the utilization of sunlight. Meanwhile, transient photocurrent response and Nyquist plot analysis were further proved the increase in carrier separation efficiency of the procatalyst. The photocatalytic ability of the composites was measured by XPA-7 photocatalytic instrument with using phenol as simulate pollutants. And the photocatalytic reaction mechanism was also revealed by the Mott-Schottky plot, band structure and trapping experiments of active species. The results exhibit that the photocatalytic performance of ZnO composites sensitized by CQDs is 60% higher than that of pure ZnO with good stability and reusability, whose utilization has almost no significant change after 10 cycles.