A photocatalytic weapon designed to combat the occurrence of waterborne pathogens has been developed and demonstrated by an international research team. The method boosts the bactericidal power of graphitic carbon nitride by addition of the polymer polyethylenimine (PEI), which results in production of long-lifespan reactive oxygen species.

Modification of graphitic carbon nitride with PEI promotes bacteria-photocatalyst contact via electrostatic adhesion and increases inactivation Escherichia coli and Enterococcus faecalis under simulated solar irradiation. The polymer changes the surface charge of the composite photocatalyst to be positive, enabling immobilization of negatively charged bacterial cells and their photocatalytic destruction by the generated reactive oxygen species.

The system removed 99.99% of E.coli from water in 45 minutes as well as 99.99% of E. faecalis within 60 minutes. The metal-free disinfection process might be combined with solar water disinfection schemes to ensure the sustainable and rapid disinfection of potable water supplies.

Researchers from Monash University (Australia), The Melbourne Centre for Nanofabrication (Australia), Sun Yat-sen University (China), University of New South Wales (Australia) and the Wuhan University of Technology (China) contributed to this study.

Schematic of the photocatalytic disinfection process. Source: Xiangkang Zeng et al.