Nitrogen configurational modulation in polyacrylonitrile-based carbon nanofibers via melamine-assisted carbonization...

Three-dimensional carbon materials, such as Polyacrylonitrile (PAN)-based carbon fibers, play crucial roles in energy storage, electrocatalysis, and electromagnetic shielding etc.. However, their performance is limited by micron-scale fiber dimensions, restricted porosity and mass transport, and the detachment of active components, and all compounded by energy-consuming carbonization. Herein, we report a scalable strategy that combines needleless electrospinning with melamine-mediated chemical tuning to fabricate self-supported, nitrogen-doped porous carbon nanofibers from PAN. Melamine serves as a precise nitrogen configurational modulator to preferentially form pyridinic and pyrrolic nitrogen, which establish strong electronic interactions with the carbon support. This chemical tuning is combined with a stress-assisted pre-oxidation step to optimize fiber microstructure. The resulting membranes are self-supporting, with a uniform fiber diameter of ∼70 nm and a highly porous network. The material shows a large surface area of 612.1 m²/g and an ultra-high electrical conductivity of 9.38 × 10⁴ S/m. Electrochemical testing demonstrates accelerated reaction kinetics and near-unity bromine extraction efficiency from challenging low-grade brine at a low energy cost (1.75 kJ/g). In summary, this work provides a new design paradigm by integrating melamine templating with needleless electrospinning to achieve carbon fibers dominated by pyridinic and pyrrolic nitrogen, with ultra-high intrinsic conductivity and superior performance in environmental electrocatalysis, energy storage, and related applications.