AUTHOR=Marques Fernando M. TITLE=Grand Challenges in Fuel Cells: Materials Issues at all Length Scales JOURNAL=Frontiers in Energy Research VOLUME=1 YEAR=2013 URL=https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2013.00005 DOI=10.3389/fenrg.2013.00005 ISSN=2296-598X