Facile Synthesis of Multichannel Lignin‐Based Carbon Nanofibers Decorated With Iron Oxide for Supercapacitor Electrodes

ABSTRACT Multichannel lignin‐based carbon nanofibers decorated with iron oxide (MCNFs@Fe) were first prepared using crude lignin with a low molecular weight of approximately 500 as the sole raw material. Using acetic acid as the electrospinning solvent and polyvinylpyrrolidone as a pore‐former, the optimized viscosity of the spinning solution (lignin: polyethylene oxide 95:5) ensured an average diameter of the as‐spun lignin fibers reaching 652 nm at a flow rate of 0.6 mL h −1 , a collector speed of 300 rpm, a spinning voltage of 25 kV, and a tip‐to‐collector distance of 15 cm. After stabilization at 250°C and carbonization at 600°C, the Raman spectral results of MCNFs@Fe demonstrated the degree of graphitization with I D /I G achieving 0.69. Using MCNFs@Fe to fabricate supercapacitors, the specific capacitance could achieve 67.3 F g −1 at a current density of 0.5 A g −1 in a three‐electrode system and capacitance retention of 102% after 1000 charge–discharge cycles, which was comparable to those from lignin with a molecular weight of approximately 10,000. This work provided a promising method for fabricating fully bio‐based carbon fibers as an alternative to petroleum‐based fibers and provided a competitive way for the high‐value utilization of low‐molecular waste biomass.