Flower like Ni doped BiVO4 composite with efficient visible light photocatalytic performance for the removal of Naproxen: A detailed mechanism and DFT study

Abstract

BiVO4 and Ni doped BiVO4 (Ni-BiVO4) photocatalysts were synthesised by the co-precipitation method. BiVO4 and Ni-BiVO4 photocatalysts were characterized by various analytical techniques. PXRD studies of the BiVO4 and Ni-BiVO4 catalysts shows monoclinic-scheelite structure. Density functional theory calculations were carried out to predict the density of states and band gaps. The flower bunch is arrayed in a rod-like pattern on the HRTEM images, and the particle size was estimated using d-spacing and found to be in the range of 98-415 nm. Furthermore, the charge separation mechanism of photogenerated charge carriers of BiVO4 and Ni-BiVO4 photocatalysts were studied by photoelectrochemical response and impendence spectroscopy. The result shows that the Ni-BiVO4 photocatalyst possess the higher photocatalytic performance, and this can be attributed to the enhanced absorption of visible light, and lower recombination of electron and holes. Further, enhanced photocatalytic activity of Ni-BiVO4 photocatalyst was observed by addition of hydrogen peroxide (H2O2). The order of photocatalytic activity for the degradation of Naproxen under visible light: Ni-BiVO4 +H2O2 > Ni-BiVO4 > BiVO4 > Ni-BiVO4 + IPA. The investigation of degradation products was carried out utilising liquid chromatography mass spectroscopy coupled UV-visible absorption spectrum technique. Radical quenching is studied to reveal the substantial contribution of hydroxyl free radicals in the Ni-BiVO4 with H2O2 system.