1. Hydrogen Research Department, Korea Institute of Energy Research (KIER), 152 Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea
2. Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
3. Current address: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
4. Current address: New Energy Technology Laboratory, Korea Electric Power Corp. Research Institute, Daejeon 34056, Republic of Korea
5. Current address: Department of Chemical Engineering, Hongik University, Wausan-ro 94, Mapo-gu, Seoul 04066, Republic of Korea
6. Materials Science and Engineering, Hanbat National University, 125 Dongseo-daero, Yuseong-gu, Daejeon 34158, Republic of Korea