Efficient photocatalytic degradation of acid orange 7 on metal oxide p-n junction composites under visible light

MO(=CuO, Co ₃O ₄, NiO)/BiVO ₄ p-n junction composites were synthesized by urea-precipitation and wet impregnation method. The physicochemical and optical properties of the as-prepared materials were investigated by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and UV-visible diffuse reflectance spectra. The photocatalytic performance of the as-prepared materials was investigated for decomposition of azo dye, acid orange 7. The CuO/BiVO ₄ and Co ₃O ₄/BiVO ₄ p-n junction composite photocatalysts exhibited the higher photocatalytic degradation of acid orange 7 than those of BiVO ₄ and NiO/BiVO ₄ as-prepared samples under visible light irradiation. We also discussed the mechanism of enhanced photocatalytic activity of p-n junctioned composites based on their energy band structures.