Architecting Z-scheme Bi2S3@CoO with 3D chrysanthemums-like architecture for both photoeletro-oxidization and -reduction performance under visible light

A large-area Z-scheme Bi2S3@CoO three dimensional(3D) hierarchical chrysanthemums-like array with a appropriate redoxpotential is synthesized via solvothermal self-assembly process. Many secondary Bi2S3 nanosheets are epitaxially grown on thready micropetals of flower-like CoO. By virtue of this special architecture, the composite used as photoanode shows highly improved photoeletro-oxidization activities towards single and binary mixed tetracycline (TC) and chlortetracycline (CTC), while as a photocathode the photoeletro-reduction activities of n-nitrophenyl (n-NP) and Cr(VI) are also increased. The enhanced photoelectrocatalytic activity of Bi2S3@CoO is ascribed to the hierarchical chrysanthemums-like structure and the synergistic effect between Bi2S3 and CoO. The unique structure endows Bi2S3@CoO with high specific surface area, multiple light reflection/scattering channels and improved molecular diffusion kinetics, providing more exposed active edges and greater light utilization efficiency. The introduction of Bi2S3 further optimizes the band structure of CoO with a narrower band gap, resulting in high removal capacity to pollutants as well as higher separation efficiency of photogenerated charges and holes. The present study provides a new photoelectrocatalytic material, which will have potential application in the fields of high-efficiency light-energy conversion.