Electrospinning with a spindle-knot structure for effective PM2.5 capture

Long-term air contamination and pollution challenges in particulate matter (PM) have raised fervent concerns for public health, e.g., the PM physical damage or the bacteria and virus carried by the PM. The desired air filter, seeking both high filtration efficiency and low pressure drop remains challenging. Here, we report a bio-inspired spindle-knot halloysite nanotube microsphere-incorporated nanofiber (HNM-NF) filter with the assembly and shape structures of the spider silk. The resulting HNM-NFs exhibit integrated properties of high surface energy, hydrophilicity and strong PM capture. The spindle-knot structures could shrink the outer pore size on two-dimensional (2D) surface and construct the fluffy 3D reticular architecture, facilitating high-efficiency air pollutant capture (>85.0%) while maintaining low resistance to airflow (~39 Pa). The spindle-knot construction method was applicable to various materials (i.e., Al2O3, ZnO and TiO2) and volume production of the microsphere-incorporated NF cartridge. The diversified spindleknot construction will be valuable for adapting to meet different filtration requirements.