Filtration-based water treatment system embedded with black phosphorus for NIR-triggered disinfection

Facile, efficient, and safe techniques for water disinfection are urgently needed, especially for people who cannot access pathogen-free drinking water. Here, a sandwich-structured filter system (CSBPP) is designed and constructed by layer-by-layer sequential stacking in the order of a chitosan hydrogel, black phosphorus (BP) nanosheets, and chitosan hydrogel for near-infrared (NIR)-triggered point-of-use (POU) water disinfection. Above 99% of bacterial cells can be captured by CSBPP during filtration, which is attributed to pore interception and electrostatic adsorption by the chitosan hydrogel. Almost 100% of entrapped bacterial cells can be inactivated under 808 nm illumination due to the photothermal bactericidal function of BP nanosheets, which can suppress the membrane fouling induced by the undesirable growth of bacteria. The operation is convenient, with no need for high energy input, which is superior to cryogels and conventional filtration membranes. The BP nanosheets can also improve the safety by avoiding the release of toxic metal ions that occurs in conventional POU water disinfection systems. Notably, the removal-disinfection process can be repeated at least 10 times without compromising the effectiveness. Thus, CSBPP has great potential as an alternative POU approach for potent, practical, and safe water disinfection.