title: Energy efficiency enhancement of ethanol electrooxidation on Pd-CeO(2)/C in passive and active polymer electrolyte-membrane fuel cells.
abstract: Pd nanoparticles have been generated by performing an electroless procedure on a mixed ceria (CeO(2))/carbon black (Vulcan XC-72) support. The resulting material, Pd-CeO(2)/C, has been characterized by means of transmission electron microscopy (TEM), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and X-ray diffraction (XRD) techniques. Electrodes coated with Pd-CeO(2)/C have been scrutinized for the oxidation of ethanol in alkaline media in half cells as well as in passive and active direct ethanol fuel cells (DEFCs). Membrane electrode assemblies have been fabricated using Pd-CeO(2)/C anodes, proprietary Fe-Co cathodes, and Tokuyama anion-exchange membranes. The monoplanar passive and active DEFCs have been fed with aqueous solutions of 10 wt% ethanol and 2 M KOH, supplying power densities as high as 66 mW cm(-2) at 25 °C and 140 mW cm(-2) at 80 °C. A comparison with a standard anode electrocatalyst containing Pd nanoparticles (Pd/C) has shown that, at even metal loading and experimental conditions, the energy released by the cells with the Pd-CeO(2)/C electrocatalyst is twice as much as that supplied by the cells with the Pd/C electrocatalyst. A cyclic voltammetry study has shown that the co-support ceria contributes to the remarkable decrease of the onset oxidation potential of ethanol. It is proposed that ceria promotes the formation at low potentials of species adsorbed on Pd, Pd(I)-OH(ads), that are responsible for ethanol oxidation.
authors.affiliation: Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Bambagioni
authors.forename: Claudio
authors.initials: C
authors.lastname: Bianchini
authors.forename: Yanxin
authors.initials: Y
authors.lastname: Chen
authors.forename: Jonathan
authors.initials: J
authors.lastname: Filippi
authors.forename: Paolo
authors.initials: P
authors.lastname: Fornasiero
authors.forename: Massimo
authors.initials: M
authors.lastname: Innocenti
authors.forename: Alessandro
authors.initials: A
authors.lastname: Lavacchi
authors.forename: Andrea
authors.initials: A
authors.lastname: Marchionni
authors.forename: Werner
authors.initials: W
authors.lastname: Oberhauser
authors.forename: Francesco
authors.initials: F
authors.lastname: Vizza
mesh_terms: D002563:Cerium / Q000737:chemistry*; D011211:Electric Power Supplies; D004563:Electrochemistry / Q000379:methods*; D000431:Ethanol / Q000737:chemistry*; D008567:Membranes, Artificial; D053768:Metal Nanoparticles / Q000737:chemistry; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D011108:Polymers; D002563:Cerium; D000431:Ethanol; D010165:Palladium; C030583:ceric oxide