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Abstract

Carbon nanofibers (CNFs) have gained significant attention for applications in composites, supercapacitors, and catalysis, but their commercial viability is limited by the high cost of traditional precursors like polyacrylonitrile (PAN). Asphaltene, a byproduct of petroleum refining, has been considered as an appealing precursor of CNFs due to its high carbon content and low cost. This study explores the fabrication of CNFs from Alberta Oilsands Asphaltene (AOA) via electrospinning. In the first stage, this study aimed to identify viable routes for producing CNFs with as-received AOA. Based on previous studies, the effects of electrospinning parameters, polymer type, AOA/polymer ratio, dimethylformamide (DMF) and tetrahydrofuran (THF) solvent ratio, and solution concentration were systematically investigated. While PAN-AOA mixtures showed severe flocculation and poor spinnability, blends with polyethylene oxide (PEO) enabled successful fiber formation. Optimal conditions (concentration = 15 wt%, AOA: PEO = 9:1, DMF/THF = 1:1, 17 kV) yielded uniform electrospun nanofibers (ESNFs), but carbonization led to severe fiber fusion. Further thermogravimetric analysis (TGA) confirmed a loss of AOA content during electrospinning. In the next stage, nitric acid treatment was applied to AOA, producing nitric-acid-treated AOA (NT-AOA). Characterization by elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR ), and nuclear magnetic resonance (NMR) confirmed chemical modifications. The addition of sodium dodecyl sulfate (SDS) further enhanced ESNF morphology by reducing surface tension. The best results were achieved with ~27 wt% solution, NT-AOA: PEO = 95:5, and 2 wt% SDS, yielding bead-free ESNFs. Carbonization produced CNFs with average diameters of ~172 nm, characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Subsequent KOH activation resulted in activated CNFs (ACNFs) with a high surface area (984 m²/g) and enhanced porosity. Electrochemical testing showed a specific capacitance of 189 F/g and 84.8% retention after 5000 cycles, demonstrating the potential of NT-AOA-derived CNFs as low-cost, free-standing electrodes for supercapacitors.