Fabrication of visible-light photoactive $ \ce{TiO2/BiVO4} $ composite for photocatalytic degradation of ciprofloxacin

Pure \ce{BiVO4} and three \ce{TiO2/BiVO4} composite photocatalysts with \ce{Bi^{3+}:Ti^{4+}} mole ratios of 1:1, 2:1 and 4:1 were readily synthesized, for the first time, using a one-pot hydrothermal procedure for the photodegradation of ciprofloxacin. Conducting the hydrothermal reaction in a basic medium yielded single-phase scheelite monoclinic polymorphic \ce{BiVO4} (ms- \ce{BiVO4} ) in the composite samples. Microstructural analysis showed spherical \ce{TiO2} nanoparticles with an average grain size of 120 nm embedded on the surface of \ce{BiVO4} nanoplates. The optimized composite exhibited a ciprofloxacin photodegradation reaction rate constant about 3.8 times higher than that of the pure \ce{BiVO4} sample. This significant enhancement is attributed to the formation of a \ce{TiO2/BiVO4} heterojunction, which promotes efficient charge separation. This research expands the knowledge on designing of \ce{BiVO4} -rich composites (with \ce{Bi^{3+}:Ti^{4+}} mole ratio ≥1:1) via heterogeneous junction engineering to enhance photocatalytic activity beyond that of pure \ce{BiVO4} . The research also provided a perspective on using the \ce{BiVO4} -rich composites as effective photocatalysts for degradation of antibiotics in aqueous media under visible-light irradiation.