Novel melamine-ANF-MXene/Co modified multifunctional carbon paper: toward high‑performance PEMFCs and supercapacitors

This study presents a fabrication strategy for multifunctional carbon paper (CP) through the combined modification of phenolic resin (PF) carbon with melamine (MEL), aramid nanofibers (ANF), MXene, and cobalt nitrate. The effects of the modification on the structural stability and electrochemical performance of the electrode were evaluated, together with its application in proton exchange membrane fuel cells (PEMFCs) and supercapacitors (SCs). The modified CP showed increases of 151% and 125% in tensile and flexural strength, respectively. Its oxygen reduction reaction (ORR) half-wave potential shifted to 0.73 V. MEL contributed to the regulation of PF pyrolysis and the formation of N-containing carbon species, ANF-derived three-dimensional reinforcing framework, the conductive network formed by MXene, and Co-induced graphitization and active sites were associated with changes in electron/ion transport, carbon corrosion, and structural degradation. In PEMFCs tests, the limiting current density and peak power density increased by 42% and 43%, respectively; the corrosion potential reached 0.28 V, and the corrosion current density decreased to 0.42 μA·cm⁻². In SC tests, the electrode reached an areal specific capacitance of 1659.1 mF·cm⁻² and retained 91.42% of its initial capacitance after 3000 charge-discharge cycles. These results describe the effects of MXene-ANF/Co modification on CP-based multifunctional carbon paper and provide experimental data for their use in PEMFCs and SCs.