Fabrication of BiVO4 photoanode loaded with Zn-doped Co9S8 for enhanced photoelectrochemical performance

The Zn-Co9S8/BiVO4 composite photoanodes were fabricated by loading Zn-doped Co9S8 nanoparticles to the electrodeposited BiVO4 photoelectrode. The composite photoanodes showed enhanced photoelectrocatalytic performance for the degradation of tetracycline. The improved separation of photogenerated carriers were evidenced by photocurrent measurement, electrochemical impedance spectroscopy, photoluminescence spectroscopy, and applied bias photon-to-current efficiency. Electron spin resonance spectroscopy and free radical scavenging experiments confirmed that OH, h+ andO2− played dominant roles. The optimized Zn-Co9S8/BiVO4 composite photoanode showed 2.5 times higher photocurrent density than BiVO4 photoanode. The Zn-Co9S8/BiVO4 photoanode presented an incident photon-to-current conversion efficiency of 56 %, higher than BiVO4 (25 %). According to the density functional theory results, a heterojunction between Zn-Co9S8 to BiVO4 was formed, prompting the separation of photogenerated pairs. The Zn-Co9S8/BiVO4 photoanode maintained good photoelectrocatalytic activity after five reuse cycles, confirming its good stability.