Performance of novel bimetallic carbonyl clusters as PEM fuel cell anodes,a comparative study

This work describes the performance of novel bimetallic catalysts, prepared from ruthenium, rhodium and iridium carbonyl clusters by a thermolysis procedure in o-dichlorobenzene. The electrochemical characterization by the rotating disk electrode technique in 0.5 mol L⁻¹ H₂SO₄ showed that the Ru_xIr_y(CO)_n, Ru_xRh_y(CO)_n and Rh_xIr_y(CO)_n clusters are able to perform both the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR), even in the presence of fuel cell contaminants such as CO and methanol, respectively. These promising results led us to evaluate the new materials as electrodes in a single fuel cell, using a Fuel Cell Test System designed and built in our group. The performance results of the three bimetallic clusters as anodes in a hydrogen PEM fuel cell are presented in this work. In the tests different H₂ and O₂ gas flows were fed into the cell to determine the most adequate ratio for maximum power. In the absence of CO, the results showed that although the three bimetallic materials had a similar performance to that of platinum with low flows of both reactants, Ru_xIr_y(CO)_n showed the best electrocatalytic parameters. When the hydrogen fuel feed was contaminated with 100 ppm and 0.5% CO, the commercial platinum activity decreased considerably or was completely lost. However, while the current density of the novel materials also decreased in the presence of CO, it was significantly above that of platinum nanoparticles, the Rh_xIr_y(CO)_n and Ru_xIr_y(CO)_n catalysts showing the best performance in the presence of 100 ppm CO and 0.5% CO respectively. These results are promising in the context of PEM fuel cells using reforming hydrogen.