Relationships between surface character and electrochemical processes on diamond electrodes: dual roles of surface termination and near-surface hydrogen

The electrochemical behavior of as-deposited, electrochemically oxidized and oxygen plasma-treated semiconducting polycrystalline diamond films was examined. The AD surface was much more active than the oxidized surfaces for solvent discharge reactions (H-2 and O-2 evolution) as well as for electron transfer involving the ferro/ferricyanide couple. The capacitance as a function of potential was used to calculate acceptor concentration profiles, which showed an enriched layer of approximately 15 nm in depth for the as-deposited surface, possibly due to loosely bound hydrogen. These additional carriers appear to enhance electron transfer rates. (C) 2001 Elsevier Science B.V. All rights reserved.