Synthesis of graphitic carbon spheres for enhanced supercapacitor performance

Graphitic carbon spheres (GCS) with uniform particle diameter have been synthesized by K₃[Fe(CN)₆] catalytic graphitization of resorcinol/formaldehyde (RF) precursors. XRD and Raman spectra reveal that highly graphitic structure is developed by catalytic graphitization at 1000 °C successfully. The catalytic graphitization by K₃[Fe(CN)₆] maintains the spherical morphology of the RF resins, resulting in GCS-1000 (1000 = catalytic graphitization temperature of 1000 °C) with graphitic spherical morphology (625 nm in diameter). Besides conventionally microporous structure of carbonized RF resins, macropores with the diameter about 100 nm are yielded from the removal of iron particles, leading to hierarchical micro/macroporous structure and high surface area (381 m² g⁻¹). With a high degree of graphitization and prominent hierarchical porous structure, GCS exhibit a high capacitance of 155 F g⁻¹ and a good electrochemical stability, which make this type of GCS promising candidates as electrode materials for supercapacitors.