Development of graphene-enhanced activated carbon nanofibers via multi-nozzle electrospinning: structural and electrochemical characterization

This study reports a scalable approach for fabricating graphene-enhanced activated carbon nanofibers (ACNFs) by integrating multi-nozzle electrospinning with controlled carbonization and activation processes. Polyacrylonitrile (PAN) solutions containing graphene nanoparticles at concentrations of 0.5, 1, and 1.5 wt% were electrospun using a five-nozzle system to enhance fabrication throughput while maintaining fiber uniformity. Morphological analysis revealed that graphene incorporation significantly influenced fiber diameter, with the average PAN nanofiber diameter increasing from 133 nm (0 wt%) to 203 nm (1 wt%) and subsequently decreasing to 153 nm at 1.5 wt% graphene; the corresponding ACNFs exhibited reduced diameters of 117, 146, 177, and 127 nm, respectively, after thermal treatment. This structural evolution was accompanied by a non-monotonic variation in specific surface area and inter-fiber pore size. Electrochemical characterization using cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy demonstrated enhanced capacitive behavior upon graphene incorporation. The ACNFs containing 1 wt% graphene exhibited the highest areal capacitance of 33.9 mF cm−2 at 0.25 mA cm−2, compared to 8.2 mF cm−2 for pristine ACNFs, indicating an optimal balance between surface accessibility and ion transport. At higher graphene loading (1.5 wt%), partial agglomeration led to a slight reduction in electrochemical performance. These findings establish a clear structure–property–performance relationship and demonstrate the potential of graphene-modified ACNFs produced via scalable electrospinning routes for electrochemical energy storage applications.