Fabrication and testing of a H2–O2 fuel cell using MoxRuySez

Romero, Tatiana; Rivera, Ruben; Solorza, O.; Sebastian, P.J.

doi:10.1016/s0360-3199(98)00016-0

Cited by 7 publications

(3 citation statements)

References 3 publications

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“…Compared to that of Pt/Vulcan, the overpotential in the potential range between 0.8 and 0.6 V (equivalent to current densities up to ϳ2.5 mA/cm 2 ) is roughly 100 to 200 mV larger on the Ru/Vulcan electrode. A similarly lower catalytic activity of Ru compared to Pt in 0.5 M H 2 SO 4 was observed by Romero et al 25 This can be rationalized by the blocking of surface sites strongly adsorbed oxygenated species (OH ad ) at lower potentials than on Pt electrodes, 26 which is reducing the ORR activity. This can also be seen in the increasing amount of peroxide formed on the Ru/Vulcan electrode at E > 0.5 V which we attribute to the site blocking effects as discussed above for H upd on Pt/Vulcan, but in this case by strongly adsorbed oxygenated species (from H 2 O decomposition).…”

Section: Resultsmentioning

confidence: 59%

Oxygen Reduction on Ru[sub 1.92]Mo[sub 0.08]SeO[sub 4], Ru/Carbon, and Pt/Carbon in Pure and Methanol-Containing Electrolytes

Schmidt

Paulus

Gasteiger

et al. 2000

J. Electrochem. Soc.

227

163

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The oxygen reduction reaction (ORR) activity of a Ru 1.92 Mo 0.08 SeO 4 catalyst, a Vulcan XC72-supported Ru catalyst and, for comparison, a Vulcan XC72-supported Pt catalyst was studied with a rotating ring-disk electrode. The very similar reaction characteristics of the two Ru catalysts in pure and CH 3 OH-containing H 2 SO 4 electrolyte, which differ markedly from those of the Pt catalyst, indicate that the reactive centers in both Ru catalysts must be identical. They are highly selective (>95%) toward reduction to H 2 O (four electron pathway), independent of the presence of methanol. In the latter case, they are 100% selective toward the ORR, i.e., completely methanol tolerant, while the ORR on Pt catalysts is accompanied by significant CH 3 OH oxidation. Based on mass specific current densities, however, the Ru catalysts are significantly less active than the standard Pt catalysts. Only at methanol concentrations above 10-30 mM does their methanol tolerance make them more active than Pt/Vulcan. Implications for their use as cathode catalysts in a direct methanol fuel cell are discussed.

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Section: Resultsmentioning

confidence: 59%

Oxygen Reduction on Ru[sub 1.92]Mo[sub 0.08]SeO[sub 4], Ru/Carbon, and Pt/Carbon in Pure and Methanol-Containing Electrolytes

Schmidt

Paulus

Gasteiger

et al. 2000

J. Electrochem. Soc.

227

163

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“…Using the flow chart schematized in Figure 7.22 as a synthesis basis, other groups report chalcogenide materials in which CO is still involved as a ligand in, for example, Ru x Fe y Se z (CO) n , Mo x Ru y Se z (CO) n , W-Se-Os(CO) n , Mo x S y (CO) n , Mo x Se y (CO) n or W(CO) n [121][122][123][124][125][126][127][128][129][130][131][132][133][134][135][136]. These descriptive stoichiometries are most probably the result of an incomplete reaction of pyrolysis of the reactants, and make the understanding of the role of the catalytic sites of cathode materials rather difficult.…”

Section: Synthesis Of Metal Chalcogenidesmentioning

confidence: 99%

Methanol‐Tolerant Cathode Catalysts for DMFC

Lamy

Coutanceau

Alonso‐Vante

2009

Electrocatalysis of Direct Methanol Fuel Cells

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In this chapter, we will summarize the kinetic behavior of the oxygen reduction reaction (ORR), mainly on platinum electrodes since this metal is the most active electrocatalyst for the ORR in an acidic medium. The discussion will, however, be restricted to the characteristics of this reaction in direct methanol fuel cells (DMFCs) because the possible presence in the cathode compartment of methanol, which can crossover the proton exchange membrane and react with oxygen. IntroductionThe oxygen electrode has been the subject of many extensive investigations over the past century. The pronounced irreversibility of the cathodic and anodic reactions in aqueous solutions has imposed severe limitations on the information that can be obtained concerning the pathways from electrochemical kinetic studies. In most instances at current densities practical for fuel cell applications, the current-voltage data are not sensitive to the back reaction and hence yield information only up to the rate-determining step (r.d.s.), which usually occurs early in a multiple-step reaction sequence. Further the reduction and oxidation processes are usually studied only at widely separated potentials and thus the surface conditions differ sufficiently, so that the reduction and oxidation pathways are probably not complementary. The situation is still more complicated by the large number of possible pathways and intermediate states for the O 2 electrode reactions.The surface states of the anodic films play a key role in the reaction mechanisms. They usually depend strongly on potential and also on the time history of the electrode. Thus complex kinetic behavior of the ORR at a Pt electrode has been observed as a function of potential.

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“…Another route concerns the preparation of carbon supported transition-metal nanoparticles (mainly ruthenium), the surface of which is modified by chalcogen (for example, selenium) or cluster-like structures [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Studying the electrochemical behaviour of Ru/Se/C and Ru/C catalysts, it was found that carbon supported ruthenium nanoparticles without chalcogen also catalyse the electro-reduction of oxygen [33][34][35], however, with an activity, which is undersized to be considered as alternative for technical applications.…”

Section: Introductionmentioning

confidence: 99%