A Fluffy Dual-Network Structured Nanofiber/Net Filter Enables High-Efficiency Air Filtration

Particulate matter (PM) pollution has posed a huge health and economic burden worldwide. Most existing air filters used to remove PMs are structurally monotonous, cumbersome, and inevitably suffer from the compromise between removal efficiency and air permeability; developing an advanced air filter that can overcome these limitations is of significance but highly challenging. Herein, a novel strategy to create ultrathin, high-performance air filters based on fluffy dual-network structured polyacrylonitrile nanofiber/nets, via a humidity-induced electrospinning/netting technique, is reported. By tailoring the ejection and phase separation of the charged liquids, this approach causes 2D ultrafine (approximate to 20 nm) nanonets tightly bonded with fluffy pseudo-3D nanofiber scaffolds to form dual-network structures, with controllable pore size and stacking density on a large scale. The resultant nanofiber/net filters possess the integrated features of small pore size (<300 nm), high porosity (93.9%), low packing density, combined with desirable surface chemistry (4.3-D dipole moment), resulting in high-efficiency PM0.3 removal (>99.99%), low air resistance (only <0.11% of atmosphere pressure), and promising long-term PM2.5 purification. The synthesis of such materials may provide new insights into the design and development of high-performance filtration and separation materials for various applications.