Electric field activated ON/OFF surface charge polarization of transparent filter media for high-efficiency PM2.5 filtration

It is a cruel reality that the air we breathe has become an invisible but leading danger in terms of public health and the environment. Exposure to fine particulate matter (PM), and indoor volatile organic compounds (VOCs) is particularly harmful to urban residents among the different airborne pollutants. So far, different types of polymers has been widely used to fabricate filter media for clean air. Most of the developed filter are non-transparent not suitable for window. Moreover, the PMs concentration depends on different factors and fluctuates day-to-week and seasonally. Most present development air filter are non-transparent not suitable for window and single functional by their construction, high fiber diameter and large thickness. Therefore, to meet demands, we introduced a transparent advanced air filters with multi-functionality, such as in situ switch based tuning filtration efficiency, VOC adsorption capability and antibacterial properties. We have rationally designed an electric field activated ON/OFF surface charge polarization air filter composed of nanofiber/nets nanoarchitectured networks with 80% optical transparency. The electric field activated nanofiber/nets filter enhanced PM2.5 filtering efficiency from 61% to more than 95% at a low poling voltage of 0.2 kV. More importantly, here the low voltage is adequate to cause a high electric field (MV m(-1)) and surface charges can form on the fiber surface. In addition, due to the presence of chitosan in nanofiber/nanonet structure the filter can effectively adsorb gases such as ammonia, triethylamine, and formaldehyde and possessed anti-bacterial behaviour for P. aeruginosa and S.aureus. The approach introduced in this work has the potential to filter PMs under extremely hazardous air conditions and can reduce power consumption by turning off the power during low hazardous conditions.