Nano-zirconia supported by graphitic carbon nitride for enhanced visible light photocatalytic activity

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 ^-.