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Carbon nanotubes (CNTs) individually exhibit exceptional physical properties, surpassing state-of-the-art bulk materials, but are used commercially primarily as additives rather than as a standalone macroscopic product. This limited use of bulk CNT materials results from the inability to harness the superb nanoscale properties of individual CNTs into macroscopic materials. CNT alignment within a textile has been proven as a critical contributor to narrow this gap. Here, we report the development of an altered direct CNT spinning method based on the floating catalyst chemical vapor deposition process, which directly interacts with the self-assembly of the CNT bundles in the gas phase. The setup is designed to apply an AC electric field to continuously align the CNTs in situ during the formation of CNT bundles and subsequent aerogel. A mesoscale CNT model developed to simulate the alignment process has shed light on the need to employ AC rather than DC fields based on a CNT stiffening effect (z-pinch) induced by a Lorentz force. The AC-aligned synthesis enables a means to control CNT bundle diameters, which broadened from 16 to 25 nm. The resulting bulk CNT textiles demonstrated an increase in the specific electrical and tensile properties (up to 90 and 460%, respectively) without modifying the quantity or quality of the CNTs, as verified by thermogravimetric analysis and Raman spectroscopy, respectively. The enhanced properties were correlated to the degree of CNT alignment within the textile as quantified by small-angle X-ray scattering and scanning electron microscopy image analysis. Clear alignment (orientational order parameter = 0.5) was achieved relative to the pristine material (orientational order parameter = 0.19) at applied field intensities in the range of 0.5-1 kV cm-1 at a frequency of 13.56 MHz.

Exposure to expired particles and droplets carrying infectious viruses is a primary transmission pathway for respiratory diseases. Removal of particles and droplets via filtration from a volume can drastically reduce the exposure to viruses, but viruses may remain active on filtration surfaces as potential resuspension or fomite risks. Here, we report the development of macroscopic carbon nanotube air filters synthesized using ultra-thin carbon nanotube electrically conductive membranes, mechanically supported by a porous polyester backing. Filtration efficiencies were measured up to 99.999%, while ultra-thin materials with low areal density (0.1 g m─2) exhibited pressure drops comparable to commercial High-Efficiency Particulate Air (HEPA) filters. These electrically conductive filters are actively self-sanitized by thermal flashes via resistive heating to temperatures above 80 °C within seconds or less. Such temperatures were proven to achieve full deactivation of a betacoronavirus and an adeno-associated virus retained on filter surfaces. A filtration unit prototype equipped with a CNT filter module (∼1.2 m2) was shown to achieve air purification of 99% of a room within 10 min at 26 air changes per hour.

Oil-contaminated effluents are widespread, yet purifying them of finely dispersed residual oil presents a significant challenge. Here we report on reactively spun carbon nanotube (CNT) mats, whose high electric conductivity is employed to irreversibly render them highly hydrophilic through electrooxidation (EO), while retaining the morphology, mesh size, conductivity, and mechanical strength of the pristine CNT material. EO treatment converts natively hydrophobic CNT mats to efficient filtration membranes, whose 30 nm mesh size favorably compromises between the hydraulic permeability and oil breakthrough pressure and allows complete and robust removal of dispersed oil (including surfactant-stabilized) down to its solubility in water.