Synthesis of graphitic carbon spheres for enhanced supercapacitor performance

Abstract

Graphitic carbon spheres (GCS) with uniform particle diameter have been synthesized by K 3 [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 K 3 [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 m 2 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.

RhCu Bimetallic Nanoparticles in Hollow Carbon Spheres for Catalytic Halonitrobenzene Chemoselective Hydrogenation

“…As shown in Figure 3a, all of them exhibited a broad shoulder at ∼29.6°, which is a feature of amorphous carbon. 39,40 Rh@HCS exhibits a weak (111) diffraction peak at 41.1°without higher angle diffraction peaks, indicating the small size of the Rh crystals (PDF no. 05-0685).…”

Large‐scale production of nitrogen‐ and oxygen‐containing activated carbon microspheres for supercapacitors

“…Figure d shows the EIS results of the ACM electrodes, displaying semicircle in the high‐frequency area . The radius of the semicircle is in the order ACM‐700 > ACM‐900 > ACM‐800, indicating that the ACM‐800 electrode has the lowest interface resistance.…”

Geometrical effects on ionic diffusion in carbon‐carbon symmetric supercapacitors

“…27 Zhou and Yang 24 pointed out that "sheet-like structures, such as multilayer graphene, are preferable for EDLCs" in the analysis of dimensional effect on integral capacitance of rectangular structures, which can be attributed to the large amount of active sites available for electrolyte ions and the pathways presented for rapid migration/diffusion of electrolyte ions. 14,28,29 However, AC of spherical shape (ACSs) with considerable surface area can provide mechanical strength likely to maintain structural integrity during electrochemical cycling, 30,31 and the supercapacitors with ACSs as electrode material can exhibit favorable long-term cycling stability and low contact resistance. Also, carbon spheres can be readily produced through hydrothermal synthesis (HTS) at low cost in contrast to the production of graphene, and the size of carbon spheres can be simply controlled as well.…”