FRLP - I+D+i - CENTROS - CITEMA - TRABAJOS DE INVESTIGACIÓN

Permanent URI for this collectionhttp://48.217.138.120/handle/20.500.12272/1750

Browse

Author: search.filters.author.Cespedes, GermanSubject: search.filters.subject.ORR

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Research on methanol tolerant catalysts for the oxygen reduction reaction
    (Springer, 2015) Asteazaran, Mariano; Cespedes, German; Bengio, Silvina; Moreno, Mario; Triaca, Walter; Castro Luna, Ana
    Direct methanol fuel cells (DMFCs) generate electricity in a clean and efficient way, so they are a valuable alternative to traditional environmentally harmful technologies. Portable power sources are one of the applications of passive DMFCs. One of the requirements in these devices is the use of high alcohol concentration. Methanol permeation across the polymer electrolyte membrane (methanol crossover) causes a loss of fuel cell efficiency as the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) occur simultaneously at the cathode. To develop methanol-tolerant catalysts with suitable activity, different PtM/C and PtMRu/C combinations with M = Co or Fe were prepared by a modified impregnation method. The synthesized catalysts were studied to determine the role of the components in enhancing the ORR and simultaneously discouraging the MOR. The materials were characterized by TEM, XPS and EDS. Well-distributed particles for all the catalysts were shown by TEM. XPS spectra revealed that the method produces a great amount of metallic Pt. The electrochemical characterization was carried out by linear sweep voltammetry and cyclic voltammetry, in a three-electrode electrochemical cell with a glassy carbon rotating disk electrode covered with a thin catalytic layer and a Nafion film as the working electrode. Binary and ternary catalysts have a good activity for the ORR. However, the enhanced activity of binary catalysts is lost when the ORR is studied in the presence of methanol. Ternary catalysts containing Ru showed higher methanol-tolerance, regardless of the composition.
  • Thumbnail Image
    Item
    Searching for suitable catalysts for a passive direct methanol fuel cell cathode
    (Elsevier, 2015) Asteazaran, Mariano; Cespedes, German; Moreno, Mario; Bengio, Silvina; Castro Luna, Ana
    Trimetallic PtMRu/C cathode catalysts with M ¼ Co or Fe obtained by an impregnation procedure using ethylene glycol and NaBH4 as reducing agent, with suitable activity for the oxygen reduction reaction (ORR) and improved tolerance to methanol, have been physically characterized by HRTEM, EDS and XPS. The examined nanoparticles have a small particle size and are well spread on the carbon support. Pt is mainly found as Pt(0) and Co, Fe and Ru are mostly oxidized. To study their durability and performance for ORR and methanol tolerance over time, the catalysts were subjected to an electrochemical accelerated stress test (AST), consisting in cycling the potential 2000 times. Polarization curves for ORR with and without methanol were recorded. After the AST the trimetallic PtMRu/C catalysts are able to keep their performance for ORR in the presence of methanol.