Experimental and DFT evaluation of nitrogen-doped nanoporous carbon from run-of-mine coal as electrode material for supercapacitors

Abstract Global pressure to achieve net-zero emissions is driving major shifts in how fossil fuels are used and perceived. With the global push toward renewable energy, demand for coal as a fuel source is expected to decline, enhancing its appeal as a feedstock for advanced carbon materials. This study investigated nitrogen (N) functionalised nanoporous carbon material derived from run-of-mine coal as an electrode material for supercapacitors. Experimental findings and density functional theory (DFT) calculations revealed that N-doping causes a rearrangement of the carbon skeleton structure and improves the surface properties. Scanning electron microscopy (SEM) reveals that the structure is porous. X-ray diffraction analysis (XRD) confirms the material’s amorphous nature. Raman spectroscopy reveals defects in the material’s structure. Brunauer-Emmett-Teller (BET) analysis reveals that doping with nitrogen results in a higher surface area. The N-doped material showed a higher specific capacitance of 169 F/g, energy density of 23.5 Wh/kg, and power density of 600 W/kg. Notably, after 5000 cycles at 1 Ag − 1 , the capacitance retention remained at 78.2%, and coulombic efficiency was 99.9%. These improvements are attributed to enhanced conductivity and increased surface area for the electrolyte ions. This study highlights the potential of using run-of-mine coal as a viable feedstock for high-performance carbon materials in sustainable energy applications.