Degradation of antibiotics using BiVO₄/ZnO photocatalysts: effect of composition on photocatalytic performance

Heterogeneous photocatalysis has demonstrated efficacy for the removal of toxic organic pollutants using semiconductor oxides. Microwave-assisted synthesis is a very attractive method for the fabrication of photocatalysts since microwave irradiation interacts directly with the solvent molecules due to its dielectric properties, and a uniform and rapid heating can be achieved. IIn this work, BiVO_₄, ZnO, and BiVO_₄/ZnO heterojunctions with different BiVO_₄ loadings (20BVZO, 50BVZO, and 80BVZO, corresponding to 20%, 50%, and 80% BiVO_₄, respectively) were synthesized via a microwave-assisted method without any subsequent high-temperature calcination. It was confirmed by X-ray diffraction (XRD) analysis that the crystal structures obtained were monoclinic scheelite for BiVO₄ and hexagonal wurtzite for ZnO. Ultraviolet–visible spectroscopy technique was performed to determine the bandgap of the materials: 2.29–3.16 eV. Surface area analysis of the samples was performed to determine the surface measurements of the materials. The specific surface area of the ZnO, BiVO₄, 20BVZO, 50BVZO, and 80BVZO samples was found to be 8.53, 0.72, 7.99, 5.91, and 3.59 m²/g, respectively. To complement the structural information, a Raman spectroscopy analysis was performed. The morphological analysis was carried out to determine the particle size and the distribution of particles. The photocatalytic activity of BiVO₄/ZnO compounds in comparison with bare BiVO₄ and pristine ZnO was tested for the degradation of methylene blue (MB), tetracycline hydrochloride (TC), and ciprofloxacin (CIP). The 20BVZO sample revealed enhanced photocatalytic performance (64.43%) among other compounds for tetracycline hydrochloride (TC) photodegradation with a photocatalyst dosage of 0.3 g/L.