Construction of 2D/0D direct Z-scheme Bi4O5I2/Bi3TaO7 heterojunction photocatalysts with enhanced activity for levofloxacin degradation under visible light irradiation

Constructing a Z-scheme heterojunction with excellent oxidation–reduction ability is an effective way to develop high-efficiency photocatalysts for environmental pollution control. Herein, the synthesis and characterization of a novel Z-scheme Bi4O5I2/Bi3TaO7 heterojunction photocatalyst are reported, and the photocatalytic performance of samples is evaluated by the degradation of levofloxacin (LVFX) under visible light. The optimal composite photocatalyst (BIT-3) showed the highest photocatalytic activity, and its apparent rate constants were 4.09 and 14.13 times as that of Bi4O5I2 and Bi3TaO7, respectively. The improvement of photocatalytic activity can be attributed to the formation of 2D/0D heterojunction (conformed by TEM) between Bi4O5I2 and Bi3TaO7, which effectively promotes the separation and migration of photogenerated electron-hole pairs (conformed by PL and photocurrent), and retains photogenerated carriers with strong redox ability. According to the results of radical capture and energy band theory, the photocatalytic reaction mechanism of direct Z-scheme Bi4O5I2/Bi3TaO7 was proposed. The intermediate products in the degradation process of LVFX were determined by liquid chromatography-mass spectrometry (LC-MS), and the possible degradation pathway was put forward.