Enhancement of oxidation of dimethyl ether through application of zirconia matrix for immobilization of noble metal cata
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ORIGINAL PAPER
Enhancement of oxidation of dimethyl ether through application of zirconia matrix for immobilization of noble metal catalytic nanoparticles Iwona A. Rutkowska 1 & Jakub P. Sek 1 & Piotr Zelenay 1,2 & Pawel J. Kulesza 1 Received: 5 June 2020 / Revised: 25 July 2020 / Accepted: 26 July 2020 # The Author(s) 2020
Abstract Electrocatalytic activity of Pt and bimetallic PtRu nanoparticles (both Vulcan supported and unsupported) toward electrooxidation of dimethyl ether (DME), a potential small organic molecule fuel, in an acid medium (0.5 mol dm−3 H2SO4) has been significantly enhanced by dispersing them over a thin film of zirconia (ZrO2). The enhancement effects concern increases of the DME electrocatalytic current densities recorded under both cyclic voltammetric and chronoamperometric conditions. Similar effects have been observed for the oxidation of methanol. Regarding the dissimilar DME electrooxidation mechanisms at Pt and PtRu catalytic centers, the activating capabilities of zirconia seem to originate from the high population of reactive –OH groups favoring mobility of protons and the capability of inducing the oxidative removal of poisoning (CO-type) intermediates both at platinum and ruthenium catalytic sites. In the presence of the zirconia matrix, the onset potential for the oxidation of DME (particularly at PtRu) is shifted more than 50 mV toward less positive potentials. Mutual metal-support interactions are also postulated. Keywords Dimethyl ether . Methanol . Catalytic electrooxidation . Pt and PtRu nanoparticles . Zirconia support
Introduction There has been growing interest in low-temperature fuel cells [1–7] during recent years, and the hydrogen-oxygen fuel cell is technologically the most advanced and the most commonly considered for practical purposes. In addition to hydrogen energy carrier, simple (small) organic molecules are also considered as potential fuels [8]. On scientific grounds, the limitations of fuel cells concern low efficiencies of electrocatalytic systems during oxidations of fuels in addition to limited stability of conventional electrocatalysts, the poisoning effects Dedicated to Prof. Dr. Fritz Scholz on occasion on His 65th Birthday * Iwona A. Rutkowska [email protected] * Pawel J. Kulesza [email protected] 1
2
Faculty of Chemistry, University of Warsaw, Pasteura 1, PL-02-093 Warsaw, Poland Los Alamos National Laboratory, Materials Physics and Applications, Los Alamos, NM 87545, USA
originating from strong adsorption of the undesirable reaction intermediates, as well as the fuel crossover through the membrane, which tends to depolarize the cathode and decreases its activity [1–3, 8–12]. Methanol, the simplest alcohol, is often considered as an alternative fuel to hydrogen in certain applications [8]. However, practical performance of the methanol-based systems is limited by several factors, which include the slow electrode kinetics of methanol oxidation, the alcohol crossover from the anode to the cathode side of the cell, and toxic features of th
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