Urea-derived graphitic carbon nitride (u-g-C₃N₄) films with highly enhanced antimicrobial and sporicidal activity

In this manuscript, we describe the fabrication of photoactive biocidal or sporicidal films from urea-derived graphitic carbon nitride (u-g-C₃N₄). Co-deposited films of u-g-C₃N₄ and Escherichia coli O157:H7 (IC₅₀=14.1±0.2mJ) or Staphylococcus aureus (methicillin resistant IC₅₀=33.5±0.2mJ, methicillin sensitive IC₅₀=42.7±0.5mJ) demonstrated significantly enhanced bactericidal behavior upon administration of visible radiation (400nm≤λ≤426nm). In all cases, complete eradication of the microbial sample was realized upon administration of 100mJ of visible radiation, while no antimicrobial activity was observed for non-irradiated samples. In contrast, Bacillus anthracis endospores were more resistant to u-g-C₃N₄ mediated killing with only a ca. 25% reduction in spore viability when treated with a 200mJ dose of visible radiation. Characterization of u-g-C₃N₄ reveals that the improved activity results from enhancements of both the surface area and reduction potential of the material's conduction band edge, coupled with fast injection of charge carriers into localized states and a decline in radiative recombination events. The results of this study demonstrate that g-C₃N₄-based materials offer a viable scaffold for the development of new, visible light driven technologies for controlling potentially pathogenic microorganisms.