Electrooxidation of small organic molecules on mesoporous precious metal catalysts

Jiang, Junhua; Kucernak, Anthony

doi:10.1016/s0022-0728(03)00046-9

Cited by 186 publications

(105 citation statements)

References 62 publications

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“…The observed current decay is not uncommon in chronoamperometry studies of methanol oxidation at Pt-and PtRubased electrocatalysts and could be ascribed to catalyst poisoning, due, in turn, to chemisorbed methanol dehydrogenation fragments ͑mainly CO͒ 12,13 or to formation of Ru oxides. 14 The presence of surface active impurities 15 or anions 13 in the electrolyte solution that may slowly adsorb onto the catalyst surface during long-term experiments, thereby determining loss of activity, has also been adduced as a possible further reason for the current decay. In agreement with cyclic voltammetry results, the Pt-Ru-Ir/2 catalyst displays the highest current density ͑i.e., apparent activity͒ in Fig.…”

Section: A168mentioning

confidence: 94%

Pt-Ru-Ir Nanoparticles Prepared by Vapor Deposition as a Very Efficient Anode Catalyst for Methanol Fuel Cells

Pasupathi

Tricoli

2006

Electrochem. Solid-State Lett.

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Preparation of Pt-Ru-Ir nanoparticle catalysts on carbon black by a novel vapor deposition method is reported. Particle size as assessed by transmission electron microscopy is ca. 2.5 nm with narrow distribution. Moreover, they are homogeneously dispersed on the substrate. The electrocatalytic activity of the particles toward methanol electro-oxidation was investigated by cyclic voltammetry, chronoamperometry at constant potential, and adsorbed CO-stripping voltammetry. It was found that these catalysts possess outstanding activity for methanol electro-oxidation. This is over one order of magnitude higher than in state of the art catalysts. The novel catalysts have the potential to bear significant performance improvement of direct methanol fuel cells. Fuel cells bring the promise of clean electrical energy generation with high efficiency. The polymer electrolyte fuel cell operating at relatively low temperature ͑typically from 25 to 130°C͒ with liquid methanol feed ͑direct methanol fuel cell, DMFC͒ is particularly promising for mobile applications, such as cars and mobile telephones. One major technical problem affecting up-to-date DMFCs is the low activity of the anode catalyst. Thus, in order to attain adequate power density and efficiency, a burdensome amount of catalyst is required. The latter is made out of metals such as platinum and ruthenium that are also very costly. Methanol electro-oxidation at Pt-Ru catalysts proceeds through several elementary steps. At first, methanol molecules are dehydrogenated, thereby producing organic fragments, mainly carbon monoxide ͑CO͒, that chemisorb and build up at the catalyst surface. CO fragments are subsequently oxidized to CO 2 by adjacent hydroxyl groups ͑-OH͒ that also form at the catalyst surface in the presence of water.1 Finally, CO 2 is liberated, thereby allowing turnover of the catalytic sites. To some extent, depending on the anodic potential, methanol may not be fully dehydrogenated to CO. In this case, further oxidation of the resulting dehydrogenation fragments generates formic acid or methylformate in place of CO 2 .2,3 Many investigators believe that methanol electro-oxidation occurs through a bi-functional mechanism: methanol molecules are adsorbed and dehydrogenated at Pt sites, whereas surface bonded-OH groups are preferentially formed at the Ru sites by water dissociation ͗PtCO ads + Ru − OH → Pt + Ru + CO 2 ↑ + H + + 1e − ͘ A good review on the bifunctional mechanism can be found in Ref. 1. Other investigations, however, suggest that the main role of ruthenium in the alloyed catalyst is a modification in the platinum electronic structure, which causes significant weakening of the CO chemisorption bond at Pt sites thereby enhancing the turnover rate. 4 Whether the promoting effect of Ru can be ascribable to a bifunctional mechanism or to weakening of the Pt-CO chemisorption bond, it is clear that the most effective catalysts for methanol electro-oxidation must be based on Pt-Ru combinations. Despite considerable advance in development of these ele...

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Section: A168mentioning

confidence: 94%

Pt-Ru-Ir Nanoparticles Prepared by Vapor Deposition as a Very Efficient Anode Catalyst for Methanol Fuel Cells

Pasupathi

Tricoli

2006

Electrochem. Solid-State Lett.

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“…But, if the linear decay of the current density variation is studied at longer times, the tri-catalytic electrode shows the smaller slope compared to results obtained for the bi-catalytic electrode. The linear decay of the currents at long periods of time may be characterized by the poisoning rate [15]:…”

Section: Co Electro-oxidationmentioning

confidence: 99%

Co‐catalytic effect of Rh and Ru for the ethanol electro‐oxidation in amorphous microparticulated alloys

Blanco

Pierna

Barroso

2011

Phys. Status Solidi C

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The ethanol electro‐oxidation on platinum catalyst in acid media leads to the formation of acetaldehyde and acetic acid as main products. Another problem is the poisoning of the electro‐catalyst surface with CO formed during the fuel oxidation reaction. To increase the performance of Direct Ethanol Fuel Cells (DEFCs) it is necessary to develop new electrode materials or modification of the existing Pt catalysts. This work presents the electrochemical response to ethanol and CO oxidation of different compositional amorphous alloys obtained by ball milling technique, used as electrodes. Alloys with Ni59Nb40Pt0.6Rh0.4 and Ni59Nb40Pt0.6Rh0.2Ru0.2 composi‐tions were studied. The current density towards ethanol oxidation decreases with the presence of ruthenium; however, this electrode shows the best tolerance to CO, with lower surface coverage (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…All remaining factors in Equation (10.1) should, therefore, be maximal. The factor 2Á10 3 is the ideal Pt surface area that corresponds to spreading 1 mg of Pt as a monoatomic layer in Pt (111) configuration; this value is a theoretical baseline for total active surface area at the atomistic scale. The intrinsic exchange current density of the catalyst, j 0* (mA/cm 2 ), is the target of fundamental studies in electrocatalysis [6][7][8][9].…”

Section: Challenges and Opportunities In Catalyst-layer Researchmentioning

confidence: 99%

“…Equation (10.2) is represented by the dotted lines in Figure 10.2. The tetrahedral structure, enclosed by four Pt (111) facets, corresponds to the largest e S=V . Maximum (tetrahedral) and minimum (cubocahedral) e S=V values from the particle shapes explored differ by 15-20%.…”

Section: Size Effects In Nanoparticle Electrocatalysismentioning

confidence: 99%

“…The variation in e S=V with particle shape suggests that shape control could be a suitable means of enhancing the mass activity of Pt [76,77]. The nanocrystalline particles in Figure 10.1 are enclosed by (111) and (100) facets. Surface atoms on distinct facets, corner atoms, and edge atoms possess varying coordination numbers.…”

Section: Size Effects In Nanoparticle Electrocatalysismentioning

confidence: 99%

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Nanoscale Phenomena in Catalyst Layers for PEM Fuel Cells: From Fundamental Physics to Benign Design

et al. 2010

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Electrooxidation of small organic molecules on mesoporous precious metal catalysts

Cited by 186 publications

References 62 publications

Pt-Ru-Ir Nanoparticles Prepared by Vapor Deposition as a Very Efficient Anode Catalyst for Methanol Fuel Cells

Pt-Ru-Ir Nanoparticles Prepared by Vapor Deposition as a Very Efficient Anode Catalyst for Methanol Fuel Cells

Co‐catalytic effect of Rh and Ru for the ethanol electro‐oxidation in amorphous microparticulated alloys

Nanoscale Phenomena in Catalyst Layers for PEM Fuel Cells: From Fundamental Physics to Benign Design

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