Oxidation of CO and Methanol on Pd-Ni Catalysts Supported on Different Chemically-Treated Carbon Nanofibers.
In this work, palladium-nickel nanoparticles supported on carbon nanofibers were synthesized, with metal contents close to 25 wt % and Pd:Ni atomic ratios near to 1:2. These catalysts were previously studied in order to determine their activity toward the oxygen reduction reaction. Before the deposition of metals, the carbon nanofibers were chemically treated in order to generate oxygen and nitrogen groups on their surface. Transmission electron microscopy analysis (TEM) images revealed particle diameters between 3 and 4 nm, overcoming the sizes observed for the nanoparticles supported on carbon black (catalyst Pd-Ni CB 1:2). From the CO oxidation at different temperatures, the activation energy Eactfor this reaction was determined. These values indicated a high tolerance of the catalysts toward the CO poisoning, especially in the case of the catalysts supported on the non-chemically treated carbon nanofibers. On the other hand, apparent activation energy Eapfor the methanol oxidation was also determined finding-as a rate determining step-the COadsdiffusion to the OHadsfor the catalysts supported on carbon nanofibers. The results here presented showed that the surface functional groups only play a role in the obtaining of lower particle sizes, which is an important factor in the obtaining of low CO oxidation activation energies.
Instituto de Carboquímica (CSIC), Miguel Luesma Castán 4, 50018 Zaragoza, Spain. jccalderon@icb.csic.es.
Juan Carlos
JC
Calderón
Instituto de Carboquímica (CSIC), Miguel Luesma Castán 4, 50018 Zaragoza, Spain. zoser1991@gmail.com.
Miguel
M
Rios Ráfales
Instituto de Carboquímica (CSIC), Miguel Luesma Castán 4, 50018 Zaragoza, Spain. mjnieto@icb.csic.es.
María Jesús
MJ
Nieto-Monge
Instituto Universitario de Investigación de Ingeniería de Aragón (I3A), Mariano Esquillor s/n, 50018 Zaragoza, Spain. jupardo@unizar.es.
Juan Ignacio
JI
Pardo
Instituto de Carboquímica (CSIC), Miguel Luesma Castán 4, 50018 Zaragoza, Spain. rmoliner@icb.csic.es.
Rafael
R
Moliner
Instituto de Carboquímica (CSIC), Miguel Luesma Castán 4, 50018 Zaragoza, Spain. mlazaro@icb.csic.es.
María Jesús
MJ
Lázaro
CO oxidation; Pd-Ni catalysts; alkaline medium; carbon nanofibers; direct methanol fuel cells; methanol oxidation