Activation of Z-scheme heterojunction of peroxymonosulfate for augmented visible-light-induced photocatalytic decomposition of tetracycline and enhanced antimicrobial efficacy with O-doped g-C3N4@Co3O4

Abstract

The widespread use of graphitic carbon nitride (CN) for environmental pollutant removal has been hampered by intrinsic limitations, notably facile electron-hole recombination and a limited surface area. This work successfully synthesized OCN/Co3O4 composite materials. Furthermore, the implementation of a peroxymonosulfate (PMS) reaction system remarkably enhanced the material’s capability to degrade Escherichia coli (E. coli) and tetracycline hydrochloride (TC). Compared with CN, the composite material possessed a notably larger specific surface area, affording it a profusion of reactive sites. Additionally, the replacement of carbon atoms with oxygen atoms in the original CN structure profoundly altered its electronic configuration. The characterization through UV–Vis diffuse reflectance spectra, photoluminescence, transient photocurrent responses, and electrochemical impedance spectroscopy also confirmed the excellent optical and electrochemical attributes of OCN/Co3O4. Experimental results illustrated OCN/Co3O4/Vis/PMS completely degraded E. coli at an initial concentration of 1 × 107 CFU mL−1 within 1 h and reduced TC with the adding concentration of 10 mg/L by 99.2% in only 20 min. An analysis was conducted on reactive oxygen species (ROS) using electron paramagnetic resonance spectroscopy and radical quenching experiments. The test results demonstrated the generation of ROS including •O2−, •OH, h+, and SO4•− within the reaction system. This work explored the degradation mechanism in the OCN/Co3O4/Vis/PMS system, providing innovative insights for the design of eco-friendly, efficient catalysts as well as the enhancement of TC and E. coli degradation through the synergistic activation of photocatalytic PMS.