Evaluation of the Performance of Ru/C Electrocatalysts for the ORR in the Absence and Presence Of C2H5OH: Application in Direct Fuel Cells

摘要

The performance of Ru/C cathode electrocatalysts for the oxygen reduction reaction (orr) was evaluated Tests were performed in the absence and presence of ethanol (C2H5OH) in acid solution in a rotating disc electrode and in a Direct Alcohol Fuel Cell (DAFC). It was found that in ethanol-free solutions, the performance of Ru/C cathodes for the orr was lower compared to that of a Pt/C cathode. However, the Ru/C electrocatalysts showed a high selectivity and tolerance to increasing ethanol concentrations, with no significant cant shifting of the onset polentials for the orr (E-onset(ORR)) towards more negative potentials. On average, the shift in E-onset(ORR) from its value in the absence to its value in the presence of C2H5OH on the Ru/C electrocatalysts was 15 times smaller than the shift in E-onset(ORR) on Pt/C. The polarization curves of the orr with ethanol on Ru/C materials showed no current density peaks associated to an oxidation reaction, suggesting a negligible rate of adsorption of the alcohol on the electrocatalyst surface. Additionally, the performance of the DAFC based on a 20% Ru/C cathode was lower than the performance with a 20% Pt/C cathode. However, relevant electrochemical characteristics were obtained from the Ru-based cell.