Electrochemical characteristics of boron doped polycrystalline diamond electrode sintered by high pressure and high temperature

The bulk B-doped polycrystalline diamond (PCD) electrode in this study was prepared by high-pressure, high-temperature (HPHT) technology. The PCD was sintered under HPHT conditions, using B-doped diamond powders and a metal catalyst as raw materials, then the metal solvent phase was dissolved by aqua regia. The morphology and composition of the PCD were investigated with a scanning electron microscope (SEM), X-ray diffraction (XRD), and energy dispersion spectrum (EDS). The results show that the sintered body possesses a polycrystalline structure with direct diamond–diamond bond and irregularly shaped pores of 1–10 μm distributed on the grain boundaries after the metal solvent phase was removed. The cyclic voltammogram and electrochemical impedance spectroscopy of this B-doped electrode have been investigated. The B-doped PCD electrode exhibits stable electrochemistry in a KCl support solution over a wide potential range. The quasi-reversible reaction occurs on the electrode for the [Fe(CN)₆]^3−/4− couples. The electrode process combines the diffusion-controlled mass transport plus the kinetic process. The electrochemical impedance spectroscopy (EIS) analysis shows the porous structure characteristic of the PCD electrode.