Two-Dimensional Piezoelectric Nanofibrous Webs by Self-Polarized Assembly for High-Performance PM 0.3 Filtration.

Particulate matter (PM) pollution has posed a serious threat to public health, especially the global spread of infectious diseases. Most existing air filtration materials are still subjected to a compromise between removal efficiency and air permeability on account of their stacking bulk structures. Here, we proposed a self-polarized assembly technique to create two-dimensional piezoelectric nanofibrous webs (PNWs) directly from polymer solutions. The strategy involves droplets deforming into ultrathin liquid films by inertial flow, liquid films evolving into web-like architectures by instantaneous phase inversion, and enhanced dipole alignment by cluster electrostatics. The assembled continuous webs exhibit integrated structural superiorities of nanoscale diameters (∼20 nm) of the internal fibers and through pores (∼100 nm). Combined with the wind-driven electrostatic property derived from the enhanced piezoelectricity, the PNW filter shows high efficiency (99.48%) and low air resistance (34 Pa) against PM _0.3 as well as high transparency (84%), superlight weight (0.7 g m ^-2 ), and long-term stable service life. This creation of such versatile nanomaterials may offer insight into the design and upgrading of high-performance filters.