Study on highly efficient p-n heterojunction Bi2MoO6/Cu2O: Synthesis, characterization and visible-light photocatalytic activity toward antibiotics degradation

Water pollution has reached alarming levels due to the overuse of antibiotics, and photocatalysis is considered to be a green and efficient degradation technology for the treatment of water pollution caused by antibiotics. In this paper, a series of p-n heterojunction Bi2MoO6/Cu2O composite photocatalysts were synthesized by hydrothermal method. The samples were characterized by XRD, SEM, XPS, UV-Vis-DRS, PL, and EIS. The photocatalytic ac-tivities of the photocatalysts were analyzed based on the degradation of two antibiotics under visible light illumination. Results showed a removal rate of 88% and 94% for chlortetracycline (CTC) and tetracycline (TC), respectively. The corresponding first-order kinetic curves indicated that the reaction rates were 4.2 and 7.9 times higher than those of the Bi2MoO6 and Cu2O monomers. The enhanced removal efficiency of antibiotics is ascribed to the improved light absorption and electron-hole pair transport channels, facilitated by the formation of p-n heterojunction within the catalyst. Further, a possible degradation mechanism was proposed. Finally, the intermediate products were analyzed using liquid chromatography-mass spectrometry (LC-MS), and a possible photocatalytic degradation pathway of CTC was proposed. Based on the present study and experimental ob-servations, Bi2MoO6/Cu2O as a visible-light-driven photocatalyst is suggested to be a promising candidate for the removal of antibiotics.