Multilevel polarization-fields enhanced capture and photocatalytic conversion of particulate matter over flexible schottky-junction nanofiber membranes

Atmospheric Particulate matter (PM) with small sizes has caused a serious air-pollution problem calling for high-performance PM-capture materials and promising remediation strategies. In this contribution, we propose a new idea to proactively capture PM and simultaneously in-situ convert the captured PM pollution over the flexible schottky-junctions nanofiber membrane (NFM) consisting of ruffle TiO2 nanoparticles (NPs)-decorated electrospun carbon NFs. We also demonstrate that both the interfacial electron-transfer process at the TiO2/carbon schottky-junctions and the photo-excitation process at the surface of TiO2 NPs can induce polarization fields in the TiO2/carbon NFM due to the difference of the space-charge distribution. These multilevel polarization fields can drive the long-range electrostatic force to enhance the proactive PM-capture ability of the NFM. As such, the TiO2/carbon NFM exhibited a satisfactory quality factor (0.11 Pa-1) for balancing the PM2.5-filtration efficiency (99.92 %) and the pressure drop (only 63 Pa). More importantly, upon UV-vis-light irradiation, 92.98 % of the ultrafine PM0.3 was removed over this TiO2/carbon NFM. Furthermore, the as-captured PM on the NFM could be photocatalytically decomposed by the photoactive-component of TiO2 NPs, during which some of the carbonaceous PM was converted into the fuels of such CO and CH4 through a multi-step photoreaction.