A coulometric normalization procedure for comparing high surface area methanol anode catalysts by rotating disk electrode voltammetry
- Illinois Inst. of Tech., Chicago, IL (United States). Dept. of Chemical Engineering
A new method that allows one to normalize the current observed at electrocatalytic rotating disk electrodes (RDEs), based on coulometric analysis of hydrogen desorption waves, is presented. Current-voltage curves for methanol oxidation, using various platinum alloy compositions and application methods, were analyzed by this method. Mass-normalized I-V curves showed considerable scatter among similar alloys (Pt, Pt-Ru, and Pt-Ru-Os) applied by different methods and in different degrees of dispersion. The same curves normalized coulometrically are grouped more closely with respect to composition. Since the coulometric normalization procedure takes into account the electrochemically active surface area rather than the total mass of electrocatalyst, it provides a more precise correlation of catalytic activity with composition than does mass normalization. Combined with mass normalization, the procedure gives a useful estimate of catalyst utilization for different compositions and electrode preparations, under electrochemical conditions that are mimetic of direct methanol fuel cell operation. Comparison of normalized RDE currents at 25 and 50 C clearly shows that a ternary Pt-Ru-Os (65:25:10) composition is a more active anode catalyst than Pt-Ru (50:50) when both are prepared by borohydride reduction.
- Sponsoring Organization:
- Department of the Army, Washington, DC (United States); Advanced Research Projects Agency, Washington, DC (United States)
- OSTI ID:
- 516886
- Journal Information:
- Journal of the Electrochemical Society, Vol. 144, Issue 6; Other Information: PBD: Jun 1997
- Country of Publication:
- United States
- Language:
- English
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