Carbide-derived Carbon by electrochemical etching of vanadium carbides

Carbide-derived Carbon (CDC) has been demonstrated to be an excellent electrode material for electrochemical devices including supercapacitors duetoits chemical and electrochemical stability, large specific surface area and controllable pore size and morphology. Currently, CDC is prepared from metal carbides by chlorination in a chlorine gas atmosphere at temperatures of 350°C or higher. In this paper, conversion using electrochemical methods is reported, which can be achieved by oxidizing vanadium carbides (VC or V₂C) in aqueous solutions at room temperature and a mild electrode potential to prepare CDC thin film as electrode materials for "on-chip" supercapacitiors. It was found that VC and V₂C can both be oxidized at a potential of about 0.4 V vs. Ag/AgCl or higher in neutral, acidic, or basic solutions. After the oxidation, vanadium is readily detected in the electrolyte solutions by ICP-MS (Inductively Coupled Plasma - Mass Spectrometry). The so-produced CDC thin film electrode (ca. 2.0-2.6 μm thick) has a porous morphology and bears specific double layer capacitance values as high as 0.026 F. cm^-2 (or 130 F. cm^-3) with some dependence on the oxidation potential, time, and electrolyte solutions.