Tailored design of boron-doped diamond electrodes for various electrochemical applications with boron-doping level and sp2-bonded carbon impurities

The effects of sp2-bonded carbon impurities on the electrochemical properties of boron-doped diamond were investigated in moderately ([B] < 1020 cm−3) and heavily ([B] > 1021 cm−3) boron doping levels. Significant influences of sp2-bonded carbon impurities, which show glassy carbon-like electrochemical properties after anodic oxidation, were observed in heavily boron-doped diamond. This indicated that the significant effects of enhanced adsorption properties were possibly caused by surface relaxation of the strains induced by heavy boron doping and sp2-bonded carbon impurities. On the other hand, their durability was still similar to diamond electrodes rather than glassy-carbon electrodes because of the low fraction of sp2-bonded carbon impurities. Such "active" diamond electrodes are much less suitable for wastewater treatment than ordinary diamond electrodes due to a different oxygen-evolution mechanism. On the other hand, "active" BDD electrodes have a much higher efficiency for electrochemical ozone production than other BDD electrodes. The electrode properties of BDD can be designed by controlling the boron doping level and introducing the sp2-bonded carbon impurities. The guidelines proposed in this study can be used effectively to design electrodes according to their individual application, such as for use as electrochemical sensors, in wastewater treatment or electrochemical ozone production.