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

Abstract 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 (≈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 PM 0.3 removal (>99.99%), low air resistance (only <0.11% of atmosphere pressure), and promising long‐term PM 2.5 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.