Fabrication of CuS/BiVO4 (040) binary heterojunction photocatalysts with enhanced photocatalytic activity for Ciprofloxacin degradation and mechanism insight

The photocatalytic performance of BiVO4 is restricted via the fast recombination of photogenerated carriers and low visible light absorption. Fabricating of CuS/BiVO4 (0 4 0) binary heterogeneous photocatalysts by in suit growing of CuS on the surface of BiVO4 can enhance the absorption range of visible light and the separation of photogenerated carriers. Simultaneously, CuS/BiVO4 heterogeneous can provide large surface area and more active sites. The photocatalytic activity of CuS/BiVO4 composites for Ciprofloxacin (CIP) removal was examined under visible light irradiation. The optimal mass ratio of CuS to BiVO4 was determined to be 7%, and the first-order kinetic constant of CIP degradation over 7% CuS/BiVO4 (0.02151 min(-1)) was 2.59 and 16.54 times of pristine BiVO4 and CuS, respectively. The improved photodegradation efficiency is attributed to the effective separation of photogenerated carriers via formation of p-n heterojunction. The high photostability of as-prepared CuS/BiVO4 heterojunction photocatalysts was explored by four successive cycling experiments. The detailed mechanism for improved photocatalytic performance was discussed and the possible degradation pathway of CIP was measured by Liquid Chromatography-Mass/Mass Spectrometry. The trapping experiments and electron spin resonance (ESR) spin-trapping tests confirm that holes are main active species in photocatalytic degradation of CIP.