1. Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Republic of Korea
2. Institute of Engineering Thermodynamics, HTSP, German Aerospace Center (DLR), Pfaffenwaldring 38-40, 70569 Stuttgart, Germany
3. Center for Hydrogen and Fuel Cell Research, KIST, Seoul 02792, Republic of Korea
4. Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan