Hybrid Nanofibrous Membrane with Durable Electret for Anti-Wetting Air Filtration

Electrospun fibrous materials with fine fibers and small pores are fundamental for particulate matter (PM) filtration, addressing its harmful environmental and health impacts. However, the existing electrospun fibers are still limited to their sub-micron diameters and unstable surface electrostatic effect, leading to deteriorated filtration performance after prolonged storage or wetting. Herein, the study creates nanofibrous membranes with long-time stable electrostatics by electret-enhanced electrospinning. The phase separation and polarization of the charged jet are manipulated to achieve rapid stretch and strong electret. The obtained membrane exhibits nanosized structures with fiber diameters of ≈220 nm, pore size <1 µm, as well as robust surface potential of 0.4 kV. By virtue of the synergistic effects of sieving and adsorption, the nanofibrous membrane showed a remarkable PM_0.3 filtration efficiency of 96.6% and pressure drop of 140 Pa, even reaching the N90 standard after five wetting cycles. The design of such durable membranes will offer a new sight in the functional filtration materials.