The preparation, characterization of TiO2-X/Ag3PO4 heterojunctions with enhanced photocatalytic visible-light performance

Highlights:• TiO_2-X/Ag₃PO₄ were fabricated by hydrothermal technology combined with the coprecipitation method for the first time.• The reduction of antimicrobial activity for the byproducts of gatifloxacin under visible-light irradiation were investigated.• The pathway and mechanism over TiO_2-X/Ag₃PO₄ heterojunctions for photocatalytic decomposition of gatifloxacin were proposed. -- Abstract: A critical issue in the removal of fluoroquinolone antibiotics, which were frequently detected in drinking water sources and water treatment plants, is the design of highly efficient photocatalysts. In order to utilize visible-light, improve the electrons transfer and reduce the recombination of photogenerated carriers, TiO_2-X/Ag₃PO₄ heterojunctions were fabricated by hydrothermal technology combined with the coprecipitation method for the first time. The morphological, structural, and optical properties of as-prepared catalysts were extensively characterized. In comparison with single-phase TiO_2-X and Ag₃PO₄, TiO_2-X/Ag₃PO₄ composite exhibited enhanced photocatalytic efficiency for the degradation of methyl orange (MO) and gatifloxacin (GAT). Especially for the composite with the mole ratio of TiO_2-X and Ag₃PO₄ was 1:1, the reduction of antimicrobial activity of the GAT byproducts reached 82.4% after 5 min visible-light irradiation. Furthermore, the pathway in photocatalytic decomposition of GAT was proposed by HPLC-MS and the electron transfer mechanism over TiO_2-X/Ag₃PO₄ heterojunctions was suggested by the radical capture experiments, transient photocurrent responses, and electrochemical impedance spectroscopy tests.