1. University of Rome “La Sapienza,” Department of Chemistry, Ple A. Moro 5, 00185, Rome, Italy (A.F., M.V.R., G.P.); Institute of Gas Technology, Chicago, Illinois U.S.A. (K.M.); and Chemistry/Materials Science Divisions, Argonne National Laboratory, Argonne, Illinois 60439 U.S.A. (H.H.W., J.R.F.)