Particulate matter (PM) air pollution has been established as a significant threat to public health and a destructive factor to the climate and eco-systems. In order to eliminate the effects of PM air pollution, various air filtering strategies based on electrospun nanofibers have recently been developed. However, to date, almost none of the existing nanofibers based air filters can meet the requirements of high-performance air PM filtering, including high PM removal efficiency, low resistance to airflow, and long service life, etc. For the first time, we report a fabrication process using the electrospinning method for air filters based on thermoplastic polyurethane (TPU) nanofibers. The average diameters of TPU nanofibers are tunable from 0.14 ± 0.06 μm to 0.82 ± 0.22 μm by changing the TPU concentrations in polymeric solutions. The optimized TPU nanofibers based air filters demonstrate the attractive attributes of high PM2.5 removal efficiency up to 98.92%, good optical transparency of ∼60%, low pressure drop of ∼10 Pa, high quality factor of 0.45 Pa−1, and long service life under the flow rate of 200 ml min−1, which is ground-breaking compared with the existing nanofibers based air filters. These TPU nanofibers based air filters, with the excellent filtration performance and light transmittance, will shed light on the future research of nanofibers for various filtration applications and greatly benefit the public health by reducing the effects of PM air pollution.

Nowadays, carbon dioxide (CO 2 ) produced by global energy consumption far exceeds what the environment can absorb. So, the world is seeking a way to control and reduce CO 2 emissions. The electrocatalytic CO 2 reduction reaction (CRR) can effectively convert this greenhouse gas into energy sources, thus providing a method to solve CO 2 emission and energy crisis issues. However, only quite limited catalysts are capable of converting CO 2 into high-value C1 products. Herein, four structures of single Ni atom-modified phosphorene, as an electrocatalyst for the CRR, have been studied by first-principles calculations based on density functional theory (DFT). The results show that a single Ni atom adsorbed on monoatomic defective phosphorene (Ni-D-BP) has higher long-term activity and stability, and better CRR selectivity against the hydrogen evolution reaction (HER). In particular, Ni-D-BP shows good selectivity for HCOOH with a limiting potential of −0.31 V. The production of CH 3 OH and CH 4 has the same limiting potential of −0.98 V, indicating that Ni-D-BP also has good catalytic properties for CH 3 OH or CH 4 production. This study can reveal the mechanism of the CRR for single Ni atom-modified phosphorene-based catalysts and provide a way to design electrocatalysts for the CRR on the atomic scale.

The recent pandemic of COVID-19 makes personal protective facial masks in high demand. Melt-blown or electrospun nanofibers are considered to be ideal air filter materials for resisting virus-containing fine aerosol particle, eliminating particulate matter (PM) air pollution, and protecting public health. For the commercial micro/nanofiber membranes, the general strategy for improving filtration efficiency is to simply increase the base weight. However, the influence of the base weight on overall filtration performance of air filters is usually ignored, which always leads to large pressure drop and poor breathing comfort. Here, a fabrication process using the electrospinning method with phase separation of charged droplets is reported for the thermoplastic polyurethane (TPU) nanofiber/net membranes based air filters. The average pore areas of TPU nanofiber/nets can be tunable from 0.6504 μm 2 to 0.0083 μm 2 via the incorporation of different Li + ion concentrations. The optimized TPU nanofiber/net membranes based air filter demonstrates the attributes of high PM 0.1 removal efficiency up to 97.08%, ∼58 Pa pressure drop, 0.061 Pa −1 quality factor, and good optical transparency with the only 6 g•m −2 base weight, which is ground-breaking compared with the existing micro/nanofiber membrane based air filters for ultrafine particle filtration.

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