Enhanced activity of C3N4 with addition of ZnO for photocatalytic removal of phenol under visible light

Phenol is a stable and hazardous compound that is commonly found as an industrial effluent. Phenol can be treated by photocatalysis using zinc oxide (ZnO) as a photocatalyst. Unfortunately, the use of ZnO in photocatalysis is limited due to the poor response to the visible light. On the other hand, carbon nitride (C3N4) is able to absorb visible light. In the present study, a series of ZnO-C3N4 was prepared by impregnation method. The effect of zinc to carbon mol ratio (Zn/C) on the properties and photocatalytic activity was examined. X-ray Diffraction (XRD) patterns of the samples revealed that as the Zn mol ratio increased, the intensity of diffraction peaks for ZnO also increased but the intensity for C3N4 decreased. All prepared composite materials have an extended absorption band in the visible light region due to the presence of C3N4, as supported by DR UV-Vis spectra. The prepared ZnO-C3N4 composites were further investigated in the photocatalytic removal of phenol under visible light for 5 hours. All ZnO-C3N4 samples showed higher activity than the bare ZnO with Zn/C mol ratio of 1% showed the highest photocatalytic activity for removal of phenol among all the samples. The high activity observed on the ZnO-C3N4 would be due to role of ZnO to suppress electron-hole recombination and C3N4 to extend the absorption of ZnO in the visible light region