Chemical surface characterization of electrochemically and thermally oxidized boron-doped diamond film electrodes

In-situ Cyclic Voltammetric analysis and ex-situ X-ray Photoelectron Spectroscopy investigations have been carried out on highly boron-doped diamond film electrodes subjected to different oxidative treatments. Both the electrochemical and thermal oxidation modify, at different extent, the qualitative and quantitative chemical surface composition of the as prepared samples by partially converting the non diamond carbon species, for instance graphitic-like and hydrogenated carbon forms, to oxygenated ones. These modifications are relatively stable: less oxidized (e.g., alcoholic) groups can be converted into more oxidized ones (e.g., carboxyls, ethers, esthers) under extreme polarization conditions, resulting in a loss of electrochemical activity for the surface species. Surface silicon enrichment has been observed after a thermal treatment at 400 °C, as a result of the silicon diffusion, along the columnar structure of the diamond layers, from the substrate.