Hierarchical Porous Carbon Nanofibers with Tunable Geometries and Porous Structures Fabricated by a Scalable Electrospinning Technique
Shuhui Xia, Yuanyuan Zhang, Yun Zhao, Xiao Wang, Jianhua Yan
Abstract
Porous carbon nanofibers (PCNFs) have rich channels for transporting ions, molecules, and nanoparticles, but the control over their porous structures is a challenge. Here, we report a scalable electrospinning technique by using poly(tetrafluoroethylene) as a pore template, boric acid as a cross-linking agent, and polyvinyl alcohol and polyurethane as dual carbon precursors to fabricate flexible PCNFs with tunable geometries and macro/meso/microporous structures. In the water solvent, the negatively charged template cross-links with the positively charged carbon precursors to form a stable sol for electrospinning. By varying the mass ratios of these precursors, the electrospun hybrid nanofibers are directly transformed into B–F–N–O doped PCNFs with tunable macro-, meso-, and micropores after carbonization. The porosity of an individual PCNF is as high as ∼85%, and the pore volume can be tuned from 0.23 to 0.58 cm3·g–1. When constructing high-sulfur-content (86 wt %) electrodes with the freestanding PCNF films, the porous structures with rich electroactive sites provide rapid pathways for poly-anions and have strong chemisorption of poly-sulfides, leading to a great electrochemical performance. The reported strategy offers a new perspective for synthesizing hierarchical PCNFs with appealing applications.