Jianxin Liu,Fangxia Xie,Rui Li,Tan Li,Zehui Jia,Yunfang Wang,Yawen Wang,Xiaochao Zhang,Caimei Fan
A novel TiO 2-x /Ag 3 PO 4 composite photocatalyst with controllable oxygen vacancies (V o ·) amount was designedly prepared to avoid the photocorrosion and promote reduction capacity of Ag 3 PO 4 photocatalyst. The V o · on TiO 2-x work as molecular oxygen activation center trapping electron and O 2 to form ·O 2 - , and then avoided the electrons combine with h + and/or Ag + . Compared with Ag 3 PO 4 , TiO 2-x , and TiO 2 /Ag 3 PO 4 , TiO 2-x /Ag 3 PO 4 showed obviously efficient visible light and natural indoor weak light photocatalytic activity and stability for the photodegradation of Bisphenol A (BPA). The photoelectric conversion spectra, Ag 3d XPS narrow scan spectra, ESR DMPO-·O 2 - species spectra revealed that the TiO 2-x /Ag 3 PO 4 had a higher photocurrent density, lower photocorrosion and more generation of superoxide radical than those of Ag 3 PO 4 . Interestingly, compare with single h + degradation pathway over Ag 3 PO 4 , the h + and ·O 2 - synergistic degradation pathway over TiO 2-x /Ag 3 PO 4 is more beneficial to the BPA degradation. This work highlights the relations between the photocatalyst structure, active species and pollutant degradation pathway.
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 /Ag 3 PO 4 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 Ag 3 PO 4 , TiO 2-X /Ag 3 PO 4 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 Ag 3 PO 4 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 /Ag 3 PO 4 heterojunctions was suggested by the radical capture experiments, transient photocurrent responses, and electrochemical impedance spectroscopy tests.
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