Photocatalytic Nanowires‐Based Air Filter: Towards Reusable Protective Masks

In the last couple decades, several viral outbreaks resulting in epidemics and pandemics with thousands of human causalities have been witnessed. The current Covid‐19 outbreak represents an unprecedented crisis. In stopping the virus’ spread, it is fundamental to have personal protective equipment and disinfected surfaces. Here, the development of a TiO2 nanowires (TiO2NWs) based filter is reported, which it is believed will work extremely well for personal protective equipment (PPE), as well as for a new generation of air conditioners and air purifiers. Its efficiency relies on the photocatalytic generation of high levels of reactive oxygen species (ROS) upon UV illumination, and on a particularly high dielectric constant of TiO2, which is of paramount importance for enhanced wettability by the water droplets carrying the germs. The filter pore sizes can be tuned by processing TiO2NWs into filter paper. The kilogram‐scale production capability of TiO2NWs gives credibility to its massive application potentials. In TiO2 nanowire‐based filters, the high dielectric constant of TiO2 enhances the wettability by the water droplets carrying the bacteria or viruses. Upon UV illumination, reactive oxygen species (e.g., OH., O2−., H2O2) are created, which destroy the germs. Such a filter is suitable for reusable personal protective mask, for a new generation of air conditioners and air purifiers.