Methods and compositions of carbonaceous nanoparticle fabrication and their use for electrode materials in supercapacitors are provided. The method includes a first step of reacting a first carbon source with a second carbon source in the presence of a nitrogen source in a DC arc furnace to form a composite nanoparticle. The second carbon source includes a dopant. The composite nanoparticle includes a crystalline carbon phase having an amorphous phase comprising dopant or carbide. The method includes a second step of removing the amorphous second layer to form the carbonaceous nanoparticle.