NiO/g-C3N4 composite for enhanced photocatalytic properties in the wastewater treatment

The massive discharge of colored wastewater has seriously harmed the environment and people's health. Photocatalysis technology is an effective method to purify colored wastewater and has been widely concerned in colored wastewater treatment. In this study, based on the obtained nickel oxide (NiO) nanospheres by solvothermal method and graphite phase carbon nitride (g-C3N4) nanosheets by thermal polymerization method, the p-n heterojunction composed of NiO nanospheres and g-C3N4 nanosheets was successfully constructed by heat treatment for the photocatalytic degradation of methyl orange (MO). The morphology, crystallinity, surface features, and optical properties of the NiO/g-C3N4 composites were investigated by various characterization methods such as scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR), X-ray photoelectron spectroscopy (XPS), UV-vis spectrophotometer, and fluorescence spectrometer (PL), which provided the evidence for the formation of the heterojunction between NiO and g-C3N4. Compared with the g-C3N4 nanosheets and NiO nanospheres, the NiO/g-C3N4 composites showed the improved photocatalytic activity for the degradation of MO under visible light irradiation. And the NiO/g-C3N4 composite with the mole ratio of NiO and g-C3N4 of 2:8 displayed the best photocatalytic activity of MO, and more than 90% of MO can be degraded under the illumination of 100 min. The high photocatalytic properties over the NiO/g-C3N4 composite may be due to high specific surface area, the perfect band matching, and the formation of the p-n heterojunction, which helps to promote interfacial charge transfer and hinder the recombination of photo-generated electrons and holes. Moreover, the NiO/g-C3N4 composite exhibits the universality and cyclic stability, which is expected to have broad application prospects in the treatment of colored wastewater.

Automated summary

In this study, the photocatalytic degradation of methyl orange (MO) in colored wastewater was achieved by constructing NiO/g-C3N4 composites. The composite exhibited improved photocatalytic activity and cyclic stability, making it a promising material for the treatment of colored wastewater.