Synthesis and characterization of a ZrO2/g-C3N4 composite with enhanced visible-light photoactivity for rhodamine degradation†
Abstract
The visible-light-driven ZrO2/g-C3N4 hybrid photocatalysts were prepared by direct heating of ZrO2 and melamine. Compared to pure g-C3N4 or ZrO2, the synthesized ZrO2/g-C3N4 exhibited much higher photocatalytic activity for rhodamine (RhB) degradation under visible light irradiation. In order to reveal the origin of the high photoactivity, the ZrO2/g-C3N4 composites were characterized by various techniques including N2 adsorption, thermogravimetric analysis (TG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and electrochemical methods. The characterization results demonstrated that ZrO2 nanoparticles were well distributed on the surface of g-C3N4. Although the anchoring of ZrO2 on g-C3N4 increased the surface area and light absorption ability, the hetero-junctions formed between the two semiconductors which retarded the recombination of electrons and holes were believed to result in the enhanced photoactivity of the ZrO2/g-C3N4 composite. In addition, it was found that holes and ˙O2− generated in the photocatalytic process played a key role in RhB degradation over the ZrO2/g-C3N4 hybrids.