Synthesis of La2Ti2O7/Bi5O7I photocatalysts with improved photocatalytic activity for degradation of CIP under visible light

Abstract The La2Ti2O7/Bi5O7I (LB) composite photocatalyst was synthesized by an in-situ growth method. The microstructure, optical properties, and energy band structure of the prepared photocatalysts were studied by a series of characterization methods. The photocatalytic activity was studied by degrading ciprofloxacin (CIP) under visible light. The effects of hybrid ratio (La2Ti2O7/Bi5O7I) on photocatalytic activity were investigated. The results showed that the composite photocatalyst exhibited better photocatalytic activity than the corresponding single component (La2Ti2O7 or Bi5O7I). Among them, the LB-2 composite photocatalyst showed the optimal photocatalytic efficiency (reaction rate constant of 0.09403 min-1), which was 57.7 times and 12.3 times as that of La2Ti2O7 and Bi5O7I, respectively. The enhanced activity of the composite photocatalyst was mainly ascribed to the formed heterojunction between La2Ti2O7 and Bi5O7I. Finally, according to the data analysis and energy band theory, the possible charge transfer mechanism of La2Ti2O7/Bi5O7I composite photocatalyst was proposed. The degradation mechanism of CIP was also proposed based on the intermediates detected by LC-MS.