<i>In Situ</i> Active Poling of Nanofiber Networks for Gigantically Enhanced Particulate Filtration

Enhancing the filtration efficiency of air filtering material without increasing its airflow resistance is a major challenge and of great significance. In this work, we report a type of active-poled nanofiber onto which <i>in situ</i> active poling is applied. It results in significantly enhanced filtration efficiency as well as dust holding capacity while keeping the airflow resistance constant. Owing to the <i>in situ</i> applied electric field, the nanofibers as well as the particulates are polarized. As a result, at a poling voltage of 2 kV, the removal efficiency and the quality factor for PM_2.5 are enhanced by 17% and 130%, respectively. More importantly, the dust holding capacity represents a 3.5-fold enhancement over normal nanofibers. The approach reported in this work has the potential of being practically utilized in air purification purposes because it can bring about not only promoted filtration performance but also lowered noise and reduced power consumption

Triboelectrification-Induced Self-Assembly of Macro-Sized Polymer Beads on a Nanostructured Surface for Self-Powered Patterning

Here we report an electrostatic-templated self-assembly (ETSA) method for arbitrarily patterning millimeter-sized polymer beads on a nanostructured surface without using an extra voltage source. A patterned electrode underneath an electrification layer generates “potential wells” of the corresponding pattern at predefined window sites, which capture and anchor the beads within the window sites by electrostatic force. Analytical calculation is combined with numerical modeling to derive the electrostatic force acting on the beads, which is in great agreement with experimentally measured values. The generated pattern is solely determined by the predefined underlying electrode, making it arbitrarily switchable by using different electrode patterns. By transferring the assembled beads into an elastomer matrix, possible applications of the ETSA in fabricating optical and flexible displays are demonstrated