Direct Spraying of Large-Scale Nanofiber Air Filters for Highly Efficient Particulate Matter Removal

Particulate matter (PM), as a major source of air pollutants, poses a substantial threat to public health and the environment. Nanofiber air filters, fabricated by electrospinning, are widely recognized for the effectiveness in capturing haze particles. However, achieving the production of large-scale transparent filters in a time-efficient and cost-effective manner remains a challenge. Besides, the inability to recharge the electret nanofibers efficiently hinders the achievement of reusability, long-term reliability, and high-efficiency filtration. Here, a direct spraying method is developed, enabling the rapid construction of large-scale transparent air filters with polyvinylidene fluoride (PVDF) modified by graphene oxide nanosheets (GOn). The filter (PGn) with a meter-scale dimension can be produced in just a few minutes. Coupling with pyroelectric and piezoelectric properties, the filter achieves high removal efficiencies, exceeding 99% for particles ranging from PM_0.3 to PM₁₀. Electrostatic charges can be regenerated in real time under moderate temperature variations or gentle mechanical stresses. The PGn filter maintains removal efficiencies of around 90% even after working for 76 h or undergoing four washes. The proposed direct spraying strategy opens up promising pathways to produce large-scale nanofibers, holding significant potential in industrial air purification system manufacturing.