Facile construction of heterostructured BiVO₄-ZnO and its dual application of greater solar photocatalytic activity and self-cleaning property

Development of coupled semiconductor oxides makes a significant advancement in catalytic functional materials. In this article, we report the preparation of nanobundle-shaped BiVO₄-ZnO photocatalyst by a simple hydrothermal process followed by thermal decomposition. The photocatalyst was characterized by X-ray powder diffraction (XRD), high-resolution scanning electron microscopy (HR-SEM), field emission scanning electron microscopy (FE-SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL), and UV-vis diffuse reflectance spectroscopy (DRS). The XRD pattern confirmed formation of monoclinic scheelite BiVO₄ and the hexagonal wurtzite structure of ZnO. HR-SEM images show nanobundle-like structure, and the size of the nanospheres ranges from 20 to 40 nm. BiVO₄-ZnO has increased absorption in the UV and visible region when compared to ZnO. The catalytic activity of BiVO₄-ZnO was evaluated by the photodegradation of Acid Violet 7 (AV 7), Evens Blue (EB), and Reactive Red 120 (RR 120). The results revealed that the photocatalytic activity of BiVO₄-ZnO was much higher than that of ZnO, BiVO₄, and TiO₂-P25 under natural sunlight. BiVO₄-ZnO is more advantageous than ZnO and BiVO ₄ in the degradation of AV 7, EB, and RR 120 because it has maximum efficiency at neutral pH 7. BiVO₄-ZnO was found to be stable and reusable without appreciable loss of catalytic activity up to four consecutive cycles. The self-cleaning property of BiVO₄-ZnO has been evaluated using contact angle measurements. Our results provide some new insights on the performance of solar active photocatalysts on environmental remediation.