Increasing the electric double-layer capacitance in boron-doped diamond electrodes

Highly boron-doped diamond (BDD) electrodes containing sp² carbon impurities exhibit an increase in the electric doublelayer capacitance (C_dl) after anodic oxidation. Although it is known that the electrochemical properties of BDD electrodes are affected by several factors, including the boron concentration, the amount of sp² carbon impurity, and the surface termination and orientation, clarification of the mechanism for the increase in C_dl needs to be done. To this end, we prepared several BDD samples under various conditions and the properties of these samples, including C_dl, were systematically investigated. The mechanism for the increase in C_dl in particular, including the effect of the surface termination, is discussed.