From Half-Cells to Membrane-Electrode Assemblies: a Comparison of Oxygen Reduction Reaction Catalyst Performance Characteristics

Several studies relying on the improvements to the important oxygen reduction reaction (ORR) activity for increasing the performance of fuel cells have been reported. However, the application of catalyst conditions used for realizing the excellent activity in a half-cell to a single-cell does not guarantee the translation of the excellent performance. Therefore, we investigated the performance characteristics of various types of commercially available catalysts, including alloy catalysts, and compared the trends between the half-cells and single-cells using linear scan voltammetry (LSV), polarization curves (IVP), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements. Furthermore, regression analysis was performed to identify the influential factors for examining the complex relationship between the half-cell and single-cell performance parameters. The study reveals, that it is highly challenging to express the performances of the catalyst and single-cell using isolated factors. Additionally, even though the measured activity of the catalyst in a half-cell is higher than that in the other half-cells, the difference does not manifest significantly in the single-cell when the conditions required for its activity are not optimized, indicating that the overall performance of the fuel cell membrane electrode assembly (MEA) is not determined solely by the catalyst.