Oxygen-doped porous silicon carbide spheres as electrode materials for supercapacitors

Oxygen-containing functional groups were introduced onto the surface of the micro- and meso-porous silicon carbide sphere (MMPSiC) in order to investigate the relationship between the electric double layer properties and pseudo-capacitive properties; the degree of oxidation of MMPSiC was also optimized. Although the oxygenated surface functionalities can lead to a decrease in the surface area of MMPSiC, the oxygen functional groups attached to the external surface can participate in the redox reaction, resulting in the enhancement of the total super-capacitive performance. The MMPSiC electrode oxidized for 24 h exhibits a high charge storage capacity with a specific capacitance of 301.1 F g^-1 at a scan rate of 5 mV s^-1, with 86.8% rate performance from 5 to 500 mV s^-1 in 1 M KCl aqueous electrolyte. This outstanding capacitive performance of the MMPSiC electrode oxidized for 24 h can be attributed to the harmonious synergistic effect between the electric double layer capacitive contribution of MMPSiC and the pseudo-capacitive contribution of the oxygen-containing functional groups. These encouraging results demonstrate that the MMPSiC electrode oxidized for 24 h is a promising candidate for high performance electrode materials for supercapacitors.