Preparation and characterization of novel CuBi2O4/SnO2 p–n heterojunction with enhanced photocatalytic performance under UVA light irradiation

A novel p-CuBi2O4/n-SnO2 heterostructure photocatalyst with different mass ratios was synthesized by the solid state technique, and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–Vis diffuse reflectance spectroscopy (DRS). The photocatalytic activities of p-CuBi2O4/n-SnO2 photocatalysts were assessed based on the photodegradation of Congo red (CR) dye as a probe reaction under UVA (365 nm) light irradiation. Experimental results showed that the phase composition, surface morphology of particles, and optical absorption of the sample were found to vary significantly with the mass ratios and pH medium. The p-CuBi2O4/n-SnO2 photocatalyst exhibited higher photocatalytic performance as compared with CuBi2O4 and SnO2. The photodegradation reactions were satisfactory correlated with the pseudo-first-order kinetic model. The optimum amount of doped CuBi2O4 was 5 wt% as a result of 58.06% of photoactivity of CR within 100 min under UVA light at pH = 8 and 25 °C, which is about 2 times higher than that of pure SnO2. On the basis of the calculated energy band positions and the active species during photocatalytic process, the mechanism of the enhanced photocatalytic activity was discussed by solid state z-scheme photocatalysis system.