Doping and defects in carbon nitride cause efficient in situ HO synthesis to allow efficient photocatalytic sterilization.

In situ photocatalytic synthesis of HO for disinfection has attracted widespread attention because it is a clean and environmentally friendly sterilization method. Graphitic carbon nitride has been used as a very selective photocatalyst for HO generation but has some limitations (e.g., insufficient light absorption, rapid electron-hole recombination, and slow direct two-electron reduction processes) that prevent efficient HO production. In this study, potassium-doped graphite carbon nitride with nitrogen vacancies (NDKCN) was prepared using a simple method involving a thermal fusion salt and N calcination, which possessed an ultrathin nanosheet structure (1.265 nm) providing abundant active sites. Synergistic effects caused by nitrogen vacancies and K and I doping in the NDKCN photocatalyst gave the NDKCN a good ability to absorb light, undergo fast charge transfer, and give a high photoelectric current response. The optimized photocatalytic HO yield of the NDKCN was 780.1 μM·g·min, which was 10 times the yield of the pristine g-CN. Tests involving quenching reactive species, electron spin resonance, and rotating disk electrodes indicated that one-step two-electron direct reduction on the NDKCN caused excellent HO generation performance. The ability to efficiently generate HO in situ gave NDKCN an excellent bactericidal performance, and 7.3 log (colony-forming units·mL) of Escherichia coli were completely eliminated within 80 min. Scanning electron microscopy images before and after sterilization indicated the changes in bacteria caused by the catalytic activity. The new g-CN-based photocatalyst and similar rationally designed photocatalysts with doping and defects offer efficient and simple in situ HO sterilization.