Porous CaC₂-derived carbon (CCDC) was synthesized by one-step route from CaC₂ in a freshly prepared chlorine environment at low temperature. CCDC was oxidized by HNO₃ and treated with urea or melamine by carbonization at 950 ℃ in an inert atmosphere, then nitrogen-enriched CCDC was obtained. The samples were characterized by Fourier infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and elemental analysis. It found that the surface texture and chemistry activation of CCDC are improved by the containing nitrogen or oxygen functional groups preexisting on the surface. Electrochemical performances of supercapacitors using modified CCDC as electrodes were studied by cyclic voltammery, galvanostatic charge/discharge and cycle life measurements. The results showed that the HNO₃, urea and melamine modified CCDC revealed enhanced capacitances of 181.5, 210.8 and 225.4 F•g^－1 in 1 mol/L H₂SO₄, which increase by 17.3%, 36.3% and 45.7% compared with the initial carbon, respectively. Furthermore, the capacitance of supercapacitors are nearly no change after 5000 cycles.

Key words: carbide-derived carbon, functionalization, surface functional group, supercapacitor