Graphitic carbon nitride (g-C3N4) was prepared by high-temperature calcination of urea. A mixture of g-C3N4 and nano-ZrO2 precursor was directly calcined to prepare g-C3N4/ZrO2 hybrid photocatalysts. The photocatalytic properties of the sample were characterized by degradation of rhodamine B (RhB) under visible light. The g-C3N4/ZrO2 hybrid photocatalysts have better degradation performance than the pure g-C3N4 and ZrO2. The prepared catalysts were characterized by various techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence spectroscopy (PL) and electrochemical tests. The reasons for the improvement of catalytic activity were investigated from the aspects of crystal structure, surface morphology and photoelectric properties, and the catalytic mechanism were studied. The results show that the ZrO2 nanoparticles were coated with g-C3N4 to form a heterostructure. Compared with the pure g-C3N4 and ZrO2, the g-C3N4/ZrO2 hybrids reduce the charge transfer resistance and inhibit the recombination of electron-holes well. In addition, it affects the band structure and improves the absorption of visible-light. At the same time, the study found that the main active species in the catalytic process were h+ and ·O2 -.
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