Chem-mechanical polishing influenced morphology, spectral and electrochemical characteristics of boron doped diamond

Abstract

In this study complex characterization and comparison of as-grown and chemical-mechanical (CM) polished ultra-thin (≤500 nm) boron doped diamond (BDD) electrodes with various boron content (0.58–4.4 × 1021 cm−3, deposited with B/C 500–8000 ppm) was performed. Atomic force and scanning electron microscopy were used to compare morphological changes and confirm the reduction in roughness down to ≤2 nm. High-quality CM polishing enabled electron backscatter diffraction leading to the evaluation of grain size distribution (mean 0.3 μm) and preferred grain texture, {011}. X-ray photoelectron spectroscopy confirmed an increase in the B content on the surface of CM polished electrodes as a result of exposure of boron atoms incorporated into the bulk for highly doped BDD4000 and BDD8000 electrodes. Additionally, CM polished BDD electrodes are shown to possess uniform distribution of conductivity as proved by scanning electrochemical microscopy. This was reflected in faster heterogenous electron transfer kinetics for inner-sphere redox markers ([Fe(CN)6]3–/4– and dopamine) and higher values of double layer capacitance in comparison with as-grown electrodes. These changes were more pronounced for low doped electrodes. Finally, the improvement in electrochemical characteristics was demonstrated by superior electroanalytical performance of CM polished BDD electrodes for dopamine detection.