ZIF‐8 modified by isocyanate as a photocatalytic antibacterial agent

Abstract Zeolite imidazole skeleton (ZIF‐8) is a promising option for self‐cleaning of building exterior walls due to its large specific surface area, high antibacterial activity and low biotoxicity. However, it suffers from low antibacterial efficiency and yield under visible light irradiation. To address the issues, we developed the photocatalytic materials T‐ZIF‐8‐TDI (thermally treated‐ZIF‐8‐toluene 2,4‐diisocyanate) by modifying ZIF‐8 with thermal oxygen sensitization and chemical bonding. The results show that the yield of T‐ZIF‐8‐TDI photocatalytic antibacterial agent is increased to 11.5 times of that of T‐ZIF‐8, while maintaining the crystal structure of T‐ZIF‐8 and thermal stability up to 60 °C. Furthermore, T‐ZIF‐8‐TDI exhibits extended optical response range to the near‐infrared region, significantly narrowed band gap, improved photogenerated electron–hole separation efficiency, reduced recombination rate, and excellent photocatalytic performance. When the concentration of antibacterial agent is 600 mg·L −1 , the antibacterial rate of Escherichia coli ( E. coli ) reaches 99.99% irradiated by visible light for 30 min, and when the concentration of antibacterial agent is 200 mg·L −1 , the antibacterial rate of Staphylococcus aureus ( S. aureus ) reaches 99.99% irradiated by visible light for 25 min. We also analyzed the reasons in detail from the aspects of bacterial species and antibacterial mechanism, and proposed the antibacterial mechanism of ·O 2 − and h + as the main active species. These findings suggest that T‐ZIF‐8‐TDI photocatalytic antibacterial agent has potential for use in self‐cleaning of building exterior walls.