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Enhancing the quality of the tomography of nanoporous materials for better understanding of polymer electrolyte fuel cell materials

Enhancing the quality of the tomography of nanoporous materials for better understanding of polymer electrolyte fuel cell materials

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VIERRATH, Severin, Firat GÜDER, Andreas MENZEL, Matthias HAGNER, Roland ZENGERLE, Margit ZACHARIAS, Simon THIELE, 2015. Enhancing the quality of the tomography of nanoporous materials for better understanding of polymer electrolyte fuel cell materials. In: Journal of Power Sources. 285, pp. 413-417. ISSN 0378-7753. eISSN 1873-2755

@article{Vierrath2015Enhan-31171, title={Enhancing the quality of the tomography of nanoporous materials for better understanding of polymer electrolyte fuel cell materials}, year={2015}, doi={10.1016/j.jpowsour.2015.03.110}, volume={285}, issn={0378-7753}, journal={Journal of Power Sources}, pages={413--417}, author={Vierrath, Severin and Güder, Firat and Menzel, Andreas and Hagner, Matthias and Zengerle, Roland and Zacharias, Margit and Thiele, Simon} }

Hagner, Matthias Vierrath, Severin Vierrath, Severin To investigate the nanostructure of polymer electrolyte fuel cell catalyst layers, focused ion beam – scanning electron microscopy (FIB-SEM) tomography is a common technique. However, as FIB-SEM tomography lacks of image contrast between the catalyst layer and its pores, state-of-the-art reconstruction methods by threshold cannot accurately distinguish between these two phases. We show that this inability leads to an underestimation of the porosity by a factor of nearly two, a reconstruction with channel-like artifacts and that these artifacts make it impossible to calculate reliable diffusivities. To overcome this problem, we fill the pores of the catalyst layer with ZnO via atomic layer deposition prior to tomography. By using atomic layer deposition, even smallest pores can be filled with ZnO, which exhibits a good contrast to the catalyst layer in SEM images. As a result, we present the porosity of the catalyst layer (65%) and its three-dimensional representation without typical reconstruction artifacts. Calculated O<sub>2</sub> diffusivities (23.05–25.40 × 10<sup>−7</sup> m<sup>2</sup> s<sup>−1</sup>) inside the catalyst layer are in good agreement with experimental values from the literature. Furthermore, filling with ZnO permits the identification of large Pt clusters inside the catalyst layer, which were estimated to reduce the catalyst surface area by 9%. Zacharias, Margit Güder, Firat Menzel, Andreas Menzel, Andreas Zacharias, Margit 2015-06-17T12:03:48Z eng Thiele, Simon Zengerle, Roland Güder, Firat Thiele, Simon Hagner, Matthias 2015 2015-06-17T12:03:48Z Enhancing the quality of the tomography of nanoporous materials for better understanding of polymer electrolyte fuel cell materials Zengerle, Roland

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