Application In Direct Ethanol Fuel Cells Research Articles

Catalytic Activity of Carbon-Supported Electrocatalysts for Direct Ethanol Fuel Cell Applications

The catalytic activity of some carbon-supported electrocatalysts toward the ethanol oxidation reaction (EOR) and the oxygen reduction reaction (ORR) in the presence of ethanol was investigated. It was found that anodes based on PtSn alloys possess a higher catalytic activity for the EOR, compared to other anode catalysts such as Pt, PtRu, and Pt oxide. For example, when tested in a direct ethanol fuel cell, a twofold increase was observed in the current density obtained from a PtSn–Pt membrane electrode assembly (MEA) configuration at 0.4 V, compared to the current density obtained from a PtRu–Pt MEA. Furthermore, it was found that cathode catalysts based on Ru/C exhibit a good catalytic activity for the ORR and a high selectivity for this reaction in the presence of ethanol. The results showed that in the presence of 0.125, 0.25, or 0.5 M ethanol concentrations, a decrease in the onset potential of about 60, 62, and 68 mV emerged, respectively. These values were about ten times lower than those measured for some Pt-based cathode catalysts tested in this study in the presence of 0.125 M EtOH. Accordingly, an ethanol fuel cell based on a PtSn/C anode and a Ru/C cathode showed important current density vs cell voltage characteristics.

Palladium-Alloy Catalysts as Ethanol Tolerant Cathodes for Direct Alcohol Fuel Cell (DEFC) Applications

Palladium and palladium-alloy catalysts cathode have shown a high degree of tolerance to ethanol during the ORR in an acid medium. In particular, it was shown that the onset potential for the ORR in the presence of 0.5M C2H5OH decreases by only 33 mV and 18 mV on palladium and palladium-cobalt catalysts, respectively. This decrease in the onset potential due to the presence of ethanol on the Pd-based catalysts is more than ten times lower than those observed on Pt electrodes (513 mV). On the other hand, the palladium-based catalysts do not show any peak current attributed to the electro-oxidation of ethanol, whereas the Pt-based catalyst exhibited a high peak current related to the oxidation of ethanol. The high activity of Pd and Pd-Co catalysts for the ORR, as well as their high level of tolerance to the ethanol make them suitable candidates for Direct Ethanol Fuel Cell applications.