Electrochemical and in situ Raman spectroscopic measurements were made on boron-doped diamond powder (8-12 m diam., 0.63 m2g, 2 Scm) to assess the dimensional stability and corrosion resistance during potentiostatic polarization in acid. The powder was prepared by overcoating diamond abrasive with a layer of boron-doped microcrystalline diamond. The polarizations were performed at room temperature or 80C in either 0.1 M HClO4 or 0.1 M H2SO4 from 1.0-1.4 V vs. AgAgCl. Cyclic voltammetric measurements were made on the powders before and after polarization to probe for microstructural damage and ohmic resistance changes. Comparison measurements were made with the sp2 carbon, acetylene black (68 m2g, 2 Scm). Electrodes were prepared by casting a powder slurry on a glass slide with Nafion serving as the binder. No microstructural damage, alteration of the electrical conductivity or corrosion of the diamond powder was detected during polarization under the severest test conditions (ca. 1.4 V in 0.1 M H 2SO4 at 80C). In the Raman spectra, the diamond phonon line position, intensity and line width were unaffected by the polarization, consistent with excellent dimensional stability and corrosion resistance. In contrast, microstructural changes were seen for acetylene black during identical testing. Polarization at 1.4 V in 0.1 M H2SO4 at 80C produced increases in the surface area of the acetylene black due to surface oxidation and the associated microstructural damage. In situ Raman spectra confirmed the microstructural damage as the DG (I1350I 1580) peak intensity ratio increased from 1.03 to 1.09 during a 120-min room temperature polarization in 0.1 M HClO4 at 1.4 V.
|Journal||Journal of the Electrochemical Society|
|State||Published - 2011|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry