1. Energy & Environment Research Division, Korea Institute of Science and Technology (KIST), 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791, Korea; Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905; and Chemical Science Division, U.S Army Research Office, Research Triangle Park, North Carolina 27709-2211