Mechanical and functional enhancement of carbon nanofiber membranes via dual-scale defect control strategy for air purification

Abstract

Carbon nanofiber membranes (CNFMs) have significant applications in lithium batteries, flexible electronics, sensing, and wave absorption, etc. Their high electrical conductivity, good thermal stability and high specific surface area also render them promising for multifunctional air purification. However, the poor mechanical strength of carbon nanofiber membranes seriously restricts their large-scale application. In this work, a dual-scale defect control strategy is proposed to enhance the mechanical properties and air purification performance of CNFM, which refers to repairing graphite carbon defects on the molecular scale and constructing more micropore defects on the nano scale of the carbon nanofibers. Polyvinylpyrrolidone (PVP) increases the ratio of graphitic carbon and graphitic nitrogen, and the repair of graphite carbon defects results in a higher tensile strength of CNFM. The tensile strength increases from 0.42 to 8.44 MPa, with an increase of 1910 %. Terephthalic acid (TPA) constructs more microporous structures through sublimation to increase micropore defects, thus increasing the elongation at break and flexibility. The Young's modulus decreases from 389 MPa to 89 MPa with a decrease of 81.4 %. The prepared CNFM has a specific surface area of 630 m² g⁻¹. The PM_0.3 filtration efficiency, pressure drop, and quality factor are 99.53 %, 33.3 Pa, and 0.161 Pa^-1, respectively. The static adsorption capacity for toluene and formaldehyde is 228.0 mg g⁻¹ and 390.9 mg g⁻¹, respectively. This work provides clear insights into improving the mechanical properties of CNFM and its multifunctional air purification application.