Synthesis of the Type II Heterojunction of CeO₂/CuMoO₄ for Improving the Antibacterial Activity of Photocatalysis

The CeO2/CuMoO4 type II heterojunction with varying CeO2 contents was synthesized by the hydrothermal method. These heterojunction catalysts exhibit superior antibacterial activity against both Escherichia coli and Staphylococcus aureus under visible light irradiation compared to CuMoO4 alone. The evaluations of bacterial morphology, intracellular content concentration of bacteria, and reactive oxygen species (ROS) during the photocatalytic process indicated that the ROS oxidize phospholipids in the bacterial cell membrane, which leads to the damage of the cell structure and leakage of cell contents, ultimately resulting in bacterial inactivation. Both EPR (Electron Paramagnetic Resonance) and ROS scavenging experiments confirmed that superoxide radicals (·O2-) and e- play an important role in the photocatalytic antibacterial activity. The introduction of CeO2 into CuMoO4 enhances the heterojunction's photoelectric performance and promotes the efficient separation of photogenerated carriers, which benefits the production of ·O2-. Furthermore, the Ce3+/Ce4+ redox couple that exists in CeO2 may act as a trap to capture the electron, which inhibits the recombination of electrons and holes, and further reacts with the adsorbed oxygen on the catalyst surface to generate·O2-. This approach of introducing Ce3+/Ce4+ redox pairs as defect centrals to improve superoxide radicals offers an avenue for modifying photocatalytic materials and provides an alternative way to traditional antibiotic strategies in antibacterial applications.