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

Abstract

Conducting diamond-compact electrode materials are obtained by graphite transformation to diamond at high pressure and high temperature (8–9 GPa, ~ 2500 К) 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.