The compacts of boron-doped synthetic diamond: Methods for the increasing of their electrochemical activity

Conducting diamond-compact electrode materials are obtained by graphite transformation to diamond at high pressure and high temperature (8 -9 GPa, similar to 2500 kappa) in two- and three-component B4C-C (graphite), Pt-C, and Pt-C-B growth systems; their physical and electrochemical properties are studied. Results of voltametric studies are in good agreement with the electrochemical impedance spectroscopy data obtained in f-sweep and E-sweep modes. The compacts' electroactivity can be improved in two ways: either extremely heavy doping with boron or adding with catalytically active metal, platinum. The boron content reached in the diamond compacts is as high as 4 at %. The obtained compacts showed the highest electroactivity of all diamond, diamond-based, and diamond-like materials we have studied (by example of the reaction of anodic chlorine evolution from KCl solution). In compliance with the earlier found general trend for all studied diamond, diamond-based, and diamond-like materials, the increase in the material's electroactivity occurs with the increasing of the compact doping level. The diamond electrode added with Pt in the Pt-C growth system behaves in the chloride-ion anodic oxidation reaction like a purely platinum one, with due allowance for the platinum actual amount at the electrode surface. The combined platinum and boron adding to the diamond grown in the Pt-C-B system produced electrodes electroactive with respect to the chloride-ion anodic oxidation reaction; the electroactivity increased with the increasing of the platinum content at the electrode surface.