Electrochemical characterization of nanoporous honeycomb diamond electrodes in non-aqueous electrolytes

Oxygen plasma-etched nano-honeycomb diamond thin film electrodes were exami ned for electrochemical capacitor applications in non-aqueous electrolytes. As-deposited and nano-honeycomb diamond electrodes in 0.5 M TEABF(4)/PC bo th exhibited a wide potential window (approx. 7.3 V), similar to that of gl assy carbon electrodes. For as-deposited diamond, the impedance behavior wa s found to be similar for non-aqueous and aqueous electrolytes, and the dou ble-layer capacitance was found to be 21.8 muF cm(-2), almost the same as t hat obtained in aqueous electrolytes. For the honeycomb diamond electrodes, however, the impedance behavior observed in non-aqueous electrolytes was s ignificantly different from that in aqueous electrolyte and indicated that the ac signal cannot penetrate to the bottom of the honeycomb pores in the non-aqueous electrolytes due to low conductivity, and that not all the surf ace may contribute to the double-layer capacitance. This result was verifie d by mathematical simulation. (C) 2001 Elsevier Science B.V. All rights res erved.