1. Department of Materials Science and Engineering, National Fuel Cell Research Center (NFCRC), University of California-Irvine, Irvine, California 92697, USA
2. Department of Chemical and Biomolecular Engineering, National Fuel Cell Research Center (NFCRC), University of California-Irvine, Irvine, California 92697, USA
3. Institute of Chemistry and Processes for Energy, Environment and Health (ICPEES), UMR 7515 CNRS-Université de Strasbourg, 25 rue Becquerel, Strasbourg Cedex 02 67087, France