Superior photocatalytic efficiency of visible-light-driven metal oxide–BiVO₄ heterostructure on degradation for nitroaromatic pollutants

BiVO 4 was synthesized via the hydrothermal method at different temperatures. Metal oxide (CuO, NiO, Fe 2 O 3 ) modified BiVO 4 nanocomposites were prepared using the impregnation method and then X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), photoluminescence spectroscopy (PL) and other techniques. The photocatalytic degradation mechanism for nitroaromatic pollutants was analyzed by Liquid Chromatography-Mass/Mass Spectrometry (LC-MS/MS) technique. The results show that metal oxides successfully entered the BiVO 4 lattice structure; the composites exhibit strong interactions, narrow band gaps, and small particle sizes, which improve visible-light absorption. Due to the synergistic effect between metal oxide and BiVO 4 , which causes weak recombination of electron-hole pairs and high photon efficiency. The nanocomposites exhibited significantly enhanced photocatalytic properties under light irradiation. The highest degradation efficiency was obtained with the BiVO 4 (pH 2-100 ℃) at 100 °C. The addition of CuO to the BiVO 4 structure improved the photocatalytic degradation performance of nitroaromatic compounds. Complete degradation of 4-nitrophenol (4-NP) was achieved in 30 min, and 4-nitroaniline (4-NA) was completely degraded in 60 min with BiVO 4 -5CuO. BiVO 4 -5CuO nanocomposite exhibits the highest photodegradation rate for 4-NP (1.30 min –1 ) and 4-NA (1.41 min –1 ). This work presents the synthesis of a novel nanocomposite, which has a spherical-like morphology, that exceptionally enhances the charge-carrying ability and thereby accelerates the photocatalytic degradation of nitrophenols.