Influence of diffusion on the reaction in fuel cells unfolded

Fig.: Cross-section through the fuel cell with platinum thin film electrodes and the electrolyte (CsH2PO4) with an illustration of the reaction pathways of the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR). The gases hydrogen (dark blue) and oxygen (light blue) as well as the reaction product, water (violet), are marked. The green and red marked areas indicate the contribution of the double-phase and triple-phase boundary, respectively.

Fuel cell technology is particularly low-emission and efficient and is therefore considered the technology of the future. To improve the performance of this system, the electrodes at which the chemical reactions take place must be advanced. A main research focus is the investigation of the reaction path at the electrodes, which describes the reaction steps and areas that take place. Scientists at the IOM have now succeeded to unfold the reaction path. For this purpose, the influence of the diffusion of reaction intermediates was determined by varying the layer thickness of a tailored platinum thin-film electrode. The two sides of the electrode - oxygen and hydrogen - show a strongly differentiated behavior. Among other things, it was demonstrated that on the oxygen side the diffusion range is below 15 nm, whereas on the hydrogen side diffusion is rapid over a length of 60 nm (see Fig.). The results of the study were published in the renowned journal "Catalysts" and form the basis for further research into improving the electrodes in fuel cells.

More information in the publication:

Role of Reaction Intermediate Diffusion on the Performance of Platinum Electrodes in Solid Acid Fuel Cells
O. Lorenz, A. Kühne, M. Rudolph, W. Diyatmika, A. Prager, J. W. Gerlach, J. Griebel, S. Winkler, A. Lotnyk, A. Anders, B. Abel
Catalysts  2021, 11 (9), 1065
https://doi.org/10.3390/catal11091065

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