Insights into the Mechanism of the Bi/BiVO4 Composites for Improved Photocatalytic Activity

The increasing concentration of residual ciprofloxacin (CIP) can cause potential harm to the environment. Photocatalysis has been regarded as an effective method for the degradation of CIP. Bi/BiVO4 with excellent photocatalytic performance was synthesized partial reduction with NaBH4. The structure, morphology, composition, and optical performance of BiVO4 and Bi/BiVO4 were characterized by a variety of techniques. The results showed that the Bi/BiVO4 exhibits high photocatalytic activity in the degradation of CIP. Comparison of BiVO4 and Bi/BiVO4 has lower photoluminescence intensity and higher photocurrent responses intensity. The introduction of Bi made Bi/BiVO4 have a higher charge separation efficiency and generate more active free radicals. In addition, the radical trapping experiments revealed that superoxide free radicals and holes were the main active free radicals during the degradation of CIP. The pathway of CIP degradation was investigated through high performance liquid chromatography-mass spectrometry, and a possible degradation mechanism was proposed.