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 an d oxygen plasma-treated semiconducting polycrystalline diamond films was ex amined. 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 fun ction of potential was used to calculate acceptor concentration profiles, w hich showed an enriched layer of approximately 15 nm in depth for the as-de posited surface, possibly due to loosely bound hydrogen. These additional c arriers appear to enhance electron transfer rates. (C) 2001 Elsevier Scienc e B.V. All rights reserved.