High-performance electrospun particulate matter (PM) filters embedded with self-polarizable tetragonal BaTiO₃ nanoparticles

This study developed a novel transparent filter with a high particulate matter (PM) removal efficiency and low airflow resistance for use in windows. The main idea of this filter is to combine the ability of electrospun nanofiber (NF) structures to minimize airflow resistance with the unique self-polarizability of tetragonal BaTiO₃ (t-BTO) nanoparticles, which enables the capture of PM through electrostatic interactions. Density functional theory (DFT) calculation predicted the self-polarization of t-BTO, and the presence of static electricity on the NF filters with t-BTO was confirmed by Kelvin probe force microscopy and electrostatic force measurement. Their PM removal efficiency and airflow resistance were dependent on the t-BTO loading and filter transparency. The filter with 20% t-BTO and 90% transparency exhibited a high PM removal efficiency (∼99.1% for PM_10–2.5 and ∼98.9% for PM_2.5) and a pressure drop of <70 Pa, indicating an extremely low airflow resistance. Moreover, its quality factor value reached ∼0.79 Pa⁻¹, which far exceeds those of previously reported air filters (∼0.2 Pa⁻¹). Further, accelerated long-term experiments for verifying the filter's durability revealed that it exhibited a high PM removal performance and maintained a low airflow resistance despite a slight reduction in its performance. To enable the commercialization of our filter, the filter's properties will be optimized based on the results of a field test under actual environments.