Novel method for the estimation of the electro-active Pt area

The (COOH)(2) oxidation reaction was studied at potentials below which the oxygen evolution reaction (oer) takes place. Pt was found to catalyze the (COOH)(2) oxidation reaction more strongly than An, while Ru did not display any activity towards the (COOH)(2) oxidation reaction. Furthermore, under rapid stirring conditions, the (COOH)(2) oxidation reaction using Pt electrodes was shown to be purely activation controlled. Therefore, the (COOH)(2) oxidation currents can be related to the electroactive Pt area, as shown for a range of polycrystalline, bulk metal Pt and Pt powder electrodes. The Pt surface area for multi-component catalyst systems can also be estimated by combining (COOH)(2) oxidation data with the charge needed to oxidize adsorbed CO to CO2 (COads charge), as shown for a range of Pt and Ru containing powder electrodes. In fact, the combination of the two methods ((COOH)(2) oxidation current and COads charge) can be used as an in-situ probe to estimate the fraction of Ru in the metallic state in the potential region where CO is adsorbed provided that the surface ratio of Pt vs. Ru is known.