1. German Aerospace Center (DLR) Institute of Engineering Thermodynamics Pfaffenwaldring 38–40 70569 Stuttgart Germany
2. Zentrum für Sonnenenergie‐ und Wasserstoff‐Forschung Baden‐Württemberg (ZSW) Helmholtzstraße 8 89081 Ulm Germany
3. Gdansk University of Technology Department of Electrochemistry, Corrosion and Materials Engineering, Chemical Faculty 11/12 Narutowicza 80‐233 Gdansk Poland