Remote plasma polymers of iron(ii) phthalocyanine in polyacrylonitrile-derived carbon electrospun fibres as electrodes for supercapacitors

Abstract

Remote plasma-assisted vapour deposition under nitrogen (RPAVD-N₂) is introduced as a single-step, solvent-free, room-temperature strategy to integrate iron(II) phthalocyanine (FePc) into carbon nanofibre (CNF) scaffolds for high-performance pseudocapacitive electrodes. In this process, CNFs are activated by low-energy N₂ remote plasma and subsequently exposed to sublimated FePc, which undergoes controlled plasma polymerization to form conformal, nitrogen-rich FePc-derived coatings while preserving Fe–N coordination. By tuning the plasma power, the degree of crosslinking, defect generation and molecular fragmentation are precisely controlled. Structural and spectroscopic analyses reveal progressive incorporation of amine, nitrile and oxygenated functionalities while maintaining the Fe–N coordination environment, with 30 W power providing the optimal balance between structural integrity and defect density. Plasma processing enhances the capacitance by nearly one order of magnitude compared to sublimated FePc films, underscoring the critical role of plasma-induced molecular integration. The FePc30W@CNFs electrode delivers 80.9 F g⁻¹ at 0.25 A g⁻¹ (areal capacitance of 0.79 F cm⁻² at 4.9 mA cm⁻²), achieves 7.42 Wh kg⁻¹ at 225 W kg⁻¹, and retains 86.5% of its initial capacitance after 6000 cycles. These results demonstrate that remote plasma polymerization enables robust, high-rate and durable phthalocyanine-based electrodes, establishing RPAVD as a scalable platform for next-generation energy-storage materials.