Construction of Ce-OFDC/PCN heterostructure with superior antibacterial performance: synergistic effects and mechanism insights

In this study, a novel Ce-based metal–organic framework (Ce–OFDC) was synthesized via the hydrothermal method. To enhance its photocatalytic antimicrobial properties, polymeric carbon nitride (PCN) was incorporated into the Ce-OFDC matrix, forming a Ce-OFDC/PCN composite material. Antibacterial assays demonstrated that Ce-OFDC/PCN had significant inhibitory effects on both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), achieving inhibition rates of 99.5% and 94.3%, respectively. Notably, the antibacterial performance of Ce-OFDC/PCN was superior to that of Ce-OFDC or PCN alone. Furthermore, photocurrent and electrical impedance scanning measurements demonstrated that the Ce-OFDC/PCN composites showed improved photocurrent response and superior efficiency in separating photogenerated electrons and holes. The photocurrent density of Ce-OFDC/PCN reached 120 μA cm⁻², which was 1.5 times higher than that of PCN (80 μA cm⁻²) and 12 times higher than that of Ce-OFDC (10 μA cm⁻²). Electron paramagnetic resonance analysis indicated that reactive oxygen species played a crucial role in the antimicrobial process, with superoxide radicals (·O₂⁻) and hydroxyl radical (·OH) showing the most prominent influence. We conducted reactive oxygen species (ROS) scavenging experiments to further confirm this view. After adding glutathione (GSH) to remove all ROS, the antibacterial efficiency of Ce-OFDC/PCN decreased by about 40%. Adding D-mannitol to remove ·OH reduced the inhibition rate to 54.7%, and adding superoxide dismutase (SOD) to remove ·O₂⁻ reduced the inhibition rate to 65.4%. The Ce-OFDC/PCN heterostructure increased the separation efficiency of photogenerated electrons and holes, producing increased reactive oxygen species. That, in turn, contributed to the observed superior photocatalytic antibacterial performance. This research significantly advanced the development of metal–organic framework (MOF)-based materials and provided valuable insights into the design of antimicrobial photocatalysts.

Graphic abstract