Fabrication of Cu₂O/Bi₂S₃ heterojunction photocatalysts with enhanced visible light photocatalytic mechanism and degradation pathways of tetracycline

A novel efficient and visible light-driven p-n heterojunction photocatalyst, cuprous oxide/bismuth sulfide (Cu2O/Bi2S3) was prepared by a simple hydrothermal method. In this study, the photodegradation of tetracycline (TC) by Cu2O/Bi2S3 photocatalyst under visible light was considered. Compared with pure Cu2O and Bi2S3, the photocatalytic Cu2O/Bi2S3 composite has higher catalytic activity for the degradation of TC, and the degradation rate is highest at 95% when the Cu2O content is 10%. The effects of TC concentration and catalyst amount on degradation efficiency were also studied. SEM, XRD and XPS were used to study the morphology, crystal structure and chemical state of the composites and analyze the principle of photocatalytic enhancement. The ultraviolet-visible diffuse reflection (UV-vis DRS) and electrochemical workstation were used to study the photoelectrochemical performance, and the experimental data basis was created for the mechanism analysis. Free radical capture experiments show that superoxide radicals (center dot O-2(-)) and holes (h(+)) are the main active species. The improvement in the photocatalytic activity of composites can be attributed to the formation of heterojunctions that expand visible light absorption and effective electron-hole separation. At the same time, we also proposed a possible degradation pathway of tetracycline. This research provides new insights into the development of efficient photocatalysts for treating organic pollutants. (C) 2020 Elsevier B.V. All rights reserved.