Publisher's Note: Oxidation Resistance of Bare and Pt-Coated Electrically Conducting Diamond Powder as Assessed by Thermogravimetric Analysis [J. Electrochem. Soc., 157, A19 (2010)]

Abstract

A corrosion-resistant electrocatalyst support was prepared by overcoatinghigh surface-area diamond powder (3-6 nm diameter, 250 m(2)/g) witha thin layer of boron-doped ultrananocrystalline diamond (B-UNCD)by microwave plasma-assisted chemical vapor deposition. This core-shellapproach produces electrically conducting (0.4-0.5 S/cm) and highsurface-area (150-170 m(2)/g) diamond powder (B-UNCD-D). Accelerateddegradation testing was performed by thermogravimetric analysis (TGA)to assess the oxidation resistance (i.e., corrosion resistance) ofpowder in the absence and presence of nanoscale Pt. The oxidationonset temperature for B-UNCD-D powder decreased with the Pt loadingfrom 0 to 30 wt % (Pt/C). However, compared with the bare powder,the rate of carbon consumption was significantly greater for Pt-(XC-72)as compared to the platinized diamond powder. For example, the temperatureof the maximum carbon consumption rate, T-d, occurred at 426 degreesC for Pt-(XC-72) (20% Pt/C), which was 295 degrees C lower than theT-d for bare XC-72. In contrast, T-d for Pt-(B-UNCD-D, 20% Pt/C)was 558 degrees C; a temperature that was only 62 degrees C lowerthan that for bare diamond. Isothermal oxidation at 300 degrees Cfor 5 h produced negligible weight loss for Pt-UNCD-D (20% Pt/C)while a 75% weight loss was observed for Pt-(XC-72) (20% Pt/C). Theresults clearly demonstrate that platinized diamond is more resistantto gas phase oxidation than is platinized Vulcan at elevated temperatures.(C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3246410] Allrights reserved.