Rapid inactivation of droplet-transmitted microorganisms using silver-single-atom photocatalysts impregnated masks under weak solar irradiation

Pathogenic microorganisms in the droplets/aerosols pose serious threats to human health, whereas existing masks can only separate but not inactivate them. Incorporating single-atom photocatalysts (SAPCs) into masks is a viable solution, but reported SAPCs with low single-atom loadings are inadequate for rapid solar disinfection. Here, up to 11.7 wt% Ag was loaded as the single atom on metal-organic frameworks (ZIF-8-NH2) substrate (Ag-1/ZIF) via a spatial confinement strategy-assisted photochemical reduction method. The bactericidal performance of Ag-1/ZIF in water is over 2500 times higher than that of the Ag nanoparticle counterpart, which is attributed to the fact that the high-loading Ag-1 facilitates light harvesting, electron-hole pairs separation, lifetime prolongation of photogenerated charge carriers, and enhancement of the (OH)-O-center dot generation concentration. We reveal that reduced metabolism and cellular damage by (OH)-O-center dot and e(-) are responsible for disinfection through transcriptomic analysis. Ag-1/ZIF incorporated new masks rapidly inactivate 99.98 % of Escherichia coli, 99.56 % of Staphylococcus aureus and over 99.99 % of virus MS2 within 5 min under only 0.11 sun (low light intensity at 4:00 pm in winter), conferring excellent self-sterilization capability to the mask. Moreover, an aerosols disinfection device with Ag-1/ZIF nonwoven as the core demonstrates nearly 100 % bactericidal efficiency. This work provides a feasible methodology towards high-loading SAPCs for scalable antimicrobial applications in air/water.