A Comparative Study of Carbon-Supported Pt-Mo and Pt-Ru Catalysts for the Anodic Oxidation of Methanol

Reyes, Orlando Ugalde; Roquero, Pedro; Maya, Roberto Hernández; Ocampo, Ana Lilia; Hernández, Eliceo Sosa

doi:10.1149/1.3660595

Cited by 2 publications

(1 citation statement)

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“…The Pt hexacarbonyl was obtained by bubbling CO, at 25 cm 3 min −1 , during 24 h in aqueous H 2 PtCl 6 solution. 10,18,19 In the thr method, the Mo(CO) 6 and Pt carbonyl species were added to 1,2-dichlorobenzene and subsequently, the Vulcan XC-72R carbon was added to the solution. In order to impregnate the Mo and Pt carbonyl species onto the carbon surface, the temperature of the system was increased up to 110 • C and maintained during 4 h with vigorous stirring.…”

Section: Methodsmentioning

confidence: 99%

Study of the Electrochemical Activities of Mo-Modified Pt Catalysts, for Application as Anodes in Direct Methanol Fuel Cells: Effect of the Aggregation Route

Reyes

Hernandez-Maya

Ocampo

et al. 2014

J. Electrochem. Soc.

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Electrocatalysts with constant metallic composition, consisting of carbon-supported platinum and molybdenum phases, were synthesized following the thermolysis (thr) and borohydride (bhr) reduction methods and using different metallic precursors. The obtained electrocatalysts were characterized by X-ray energy-dispersive spectrometry, X-ray diffraction and high resolution transmission electron microscopy. Their activities were studied by cyclic voltammetry. Different surface structures were obtained and the electrochemical activities toward methanol oxidation were compared. Pt, MoO 2 and MoO 3 phases were well identified with the characterization techniques used. However, the electrochemical responses obtained from both sample series were considerably different, suggesting that the arrangement and relationships between active phases strongly depend on the synthesis method and aggregation sequence of the metallic precursors, and being the cause of different catalytic activities and stabilities of molybdenum oxide phases. The bhr method offered higher activity than the thr method. Among the sample series obtained by bhr method, the catalyst obtained by platinum deposition on the previously synthesized molybdenum on carbon, led to the highest overall activity. Fuel Cells represent one of the most promising options for generating electricity with high efficiency and low environmental impact. The Direct-Methanol Fuel Cell (DMFC) is a low-temperature cell where methanol is directly supplied as fuel to the anode compartment, without any previous reforming. Furthermore, methanol can be stored and transported in liquid phase, it can be obtained from biomass, and its complete oxidation can yield a high energy density.1 Platinum has been recognized as the most active catalyst for the methanol oxidation reaction and it has been employed in the formulation of such materials. However, the formation of different organic intermediates, adsorbed on Pt surfaces during methanol electrooxidation, causes the poisoning of active sites and decreases the catalyst efficiency. Several studies indicate that the modification of the Pt catalyst with other transition metal can lead to good results in oxidizing methanol at a low potential (lower than in pure Pt). 2On the other hand, it is well known that bimetallic materials show increased activity toward the CO electro-oxidation reaction, yielding CO 2 . Studies on catalytic effects that take place on bimetallic surfaces, obtained from pure metals and modified by the deposition of a second metal, are closely related to the technological development of low temperature fuel cells. Some researchers have emphasized the use of CO as a test molecule to show the electronic effect associated with this reaction. The CO desorption energy is apparently related to strong intermetallic bonds and mixed orbitals of the active phases. Hence, a catalyst with high activity toward methanol oxidation must also have high activity for CO oxidation.3 This activity is explained by some authors in terms of the so-cal...

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Section: Methodsmentioning

confidence: 99%