Low-Temperature Synthesis of a PtRu∕Nb[sub 0.1]Ti[sub 0.9]O[sub 2] Electrocatalyst for Methanol Oxidation

García, Benito Mendoza; Fuentes, Roderick E.; Weidner, John W.

doi:10.1149/1.2732074

Cited by 91 publications

(71 citation statements)

References 7 publications

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“…It is known that rutile (TiO 2 ) can be doped with other cations to prepare Ti 1−x M x O 2 , where M = Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ru, Os, Ir and Sn, and some of these oxides have been evaluated in electrochemical environments (Chang 1968;Sakata et al 1969;Horkans & Shafer 1977;Pejryd 1986;Smith et al 1998;Murata et al 2000;Roy et al 2000;Chen et al 2003;Colomer & Velasco 2007;Garcia et al 2007;Sasaki et al 2008). In this paper, we discuss the preparation and properties of W-doped TiO 2 (rutile phase: Ti 1−x W x O 2 ) and explore the preparation and use of 50 nm nanoparticles suitable for catalyst supports.…”

confidence: 99%

Catalyst supports for polymer electrolyte fuel cells

Subban

Zhou

Leonard

et al. 2010

Phil. Trans. R. Soc. A.

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A major challenge in obtaining long-term durability in fuel cells is to discover catalyst supports that do not corrode, or corrode much more slowly than the current carbon blacks used in today's polymer electrolyte membrane fuel cells. Such materials must be sufficiently stable at low pH (acidic conditions) and high potential, in contact with the polymer membrane and under exposure to hydrogen gas and oxygen at temperatures up to perhaps 120• C. Here, we report the initial discovery of a promising class of doped oxide materials for this purpose: Ti 1−x M x O 2 , where M = a variety of transition metals. Specifically, we show that Ti 0.7 W 0.3 O 2 is electrochemically inert over the appropriate potential range. Although the process is not yet optimized, when Pt nanoparticles are deposited on this oxide, electrochemical experiments show that hydrogen is oxidized and oxygen reduced at rates comparable to those seen using a commercial Pt on carbon black support.

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confidence: 99%

Catalyst supports for polymer electrolyte fuel cells

Subban

Zhou

Leonard

et al. 2010

Phil. Trans. R. Soc. A.

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“…[2][3][4][5][6] 15,[18][19][20] To fundamentally solve this technological issue and improve electrocatalyst durability, alternative carbon-free electrocatalyst support materials such as tin oxide (SnO 2 ) 21-29 and titanium oxide (TiO x ) [30][31][32][33][34] have also been proposed. It has been shown that SnO 2 is a promising alternative platinum support, since it has good electronic conductivity and thermochemical stability under the strongly acidic cathode conditions in a PEFC.…”

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confidence: 99%

Platinum-Decorated Tin Oxide and Niobium-Doped Tin Oxide PEFC Electrocatalysts: Oxygen Reduction Reaction Activity

Tsukatsune¹,

Takabatake²,

Noda³

et al. 2014

J. Electrochem. Soc.

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Using tin oxide (SnO 2 ) and niobium-doped tin oxide (Nb-SnO 2 ) as alternative electrocatalyst support materials can effectively solve the issue of carbon corrosion in polymer electrolyte fuel cell (PEFC) cathodes. Here, we systematically explore the effect of support surface area, Pt loading, and Pt nanoparticle size on the electrochemistry of these carbon-free electrocatalysts. Reducing the Pt loading leads to an increase in electrochemical surface area, but the specific activity decreases as previously observed in conventional carbon based electrocatalysts. Removing residual chlorine impurities by replacing the H 2 PtCl 6 nanoparticle precursor with Pt(acac) 2 increases the specific activity. Niobium-doping of the SnO 2 support also results in an increase in specific activity, due to the increased electronic conductivity. Consequently, the oxygen reduction reaction activity of optimized Pt-decorated Nb-SnO 2 is approaching to that of Pt-decorated carbon black, the current state-of-the-art PEFC electrocatalyst. The polymer electrolyte membrane fuel cell (PEFC) is one of the most promising energy conversion technologies for e.g. residential and automotive applications. Pt nanoparticles supported on carbon black are widely used as electrocatalysts.1-6 However, carbon corrosion is an issue under high cathode potential, resulting in detachment of Pt catalyst particles from the carbon support, and leading to a decrease in electrochemical surface area (ECSA) and oxygen reduction reaction (ORR) activity over time. [2][3][4][5][6] 15,[18][19][20] To fundamentally solve this technological issue and improve electrocatalyst durability, alternative carbon-free electrocatalyst support materials such as tin oxide (SnO 2 ) 21-29 and titanium oxide (TiO x ) [30][31][32][33][34] have also been proposed. It has been shown that SnO 2 is a promising alternative platinum support, since it has good electronic conductivity and thermochemical stability under the strongly acidic cathode conditions in a PEFC. 28,[35][36][37] Remarkable retention of ESCA in Pt-decorated SnO 2 electrocatalysts has been demonstrated compared to Pt-decorated Vulcan carbon black, by severe voltage cycling (up to 60,000 cycles) between 0.9 and 1.3 V versus the reversible hydrogen electrode (V RHE ) in electrochemical half-cell durability tests. 28 Recently, the high durability has been confirmed in membrane electrode assemblies (MEAs), during more severe voltage cycling between 1.0 and 1.5 V RHE . 29 These studies have demonstrated the stability of Pt-decorated SnO 2 against the start-stop cycles typical in fuel cell vehicles. However, high ORR activity is also required for PEFC cathode electrocatalyst applications and this has not yet been demonstrated. Relatively low ORR activity has been reported to date compared with state-of-the-art Pt supported on carbon black. 28,36 Most of the ORR values have been measured below 0.9 V RHE for oxide-supported electrocatalysts, while the ORR of conventional Pt-decorated carbon black is usually evaluated at * Electroch...

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“…Some of these doped titania supports have been catalyzed and evaluated for electrochemical stability and activity in a PEFC. Most of the doped titania materials have electronic conductivities in the interval 0.1-1 S · cm −1 (substantially lower than carbon catalyst supports), but showed activities for the oxygen reduction reaction that were comparable to commercial Pt/C catalysts when evaluated in a rotating disk electrode (RDE) (25)(26)(27)(28)(29)(30)(31)(32)(33).…”

Section: Significancementioning

confidence: 99%

Platinum supported on titanium–ruthenium oxide is a remarkably stable electrocatayst for hydrogen fuel cell vehicles

Parrondo

Han

Niangar

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

131

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We report a unique and highly stable electrocatalyst-platinum (Pt) supported on titanium-ruthenium oxide (TRO)-for hydrogen fuel cell vehicles. The Pt/TRO electrocatalyst was exposed to stringent accelerated test protocols designed to induce degradation and failure mechanisms identical to those seen during extended normal operation of a fuel cell automobile-namely, support corrosion during vehicle startup and shutdown, and platinum dissolution during vehicle acceleration and deceleration. These experiments were performed both ex situ (on supports and catalysts deposited onto a glassy carbon rotating disk electrode) and in situ (in a membrane electrode assembly). The Pt/TRO was compared against a state-of-the-art benchmark catalyst-Pt supported on high surfacearea carbon (Pt/HSAC). In ex situ tests, Pt/TRO lost only 18% of its initial oxygen reduction reaction mass activity and 3% of its oxygen reduction reaction-specific activity, whereas the corresponding losses for Pt/HSAC were 52% and 22%. In in situ-accelerated degradation tests performed on membrane electrode assemblies, the loss in cell voltage at 1 A · cm −2 at 100% RH was a negligible 15 mV for Pt/TRO, whereas the loss was too high to permit operation at 1 A · cm −2 for Pt/HSAC. We clearly show that electrocatalyst support corrosion induced during fuel cell startup and shutdown is a far more potent failure mode than platinum dissolution during fuel cell operation. Hence, we posit that the need for a highly stable support (such as TRO) is paramount. Finally, we demonstrate that the corrosion of carbon present in the gas diffusion layer of the fuel cell is only of minor concern.noncarbon catalyst supports | PEFC | start-stop protocol | TiO 2 -RuO 2 | carbon corrosion C arbon has traditionally been the most common material of choice for polymer electrolyte fuel cell (PEFC) electrocatalyst supports (1) due to its low cost, high abundance, high electronic conductivity (30 S · cm −1 ), and high Brunauer, Emmett, and Teller (BET) surface area (200-300 m 2 · g −1 ), which permits good dispersion of the platinum (Pt) catalyst (2-4). The (in) stability of the carbon-supported platinum electrocatalyst is a key issue that currently precludes widespread commercialization of PEFCs for automotive applications. Carbon is known to undergo electrochemical oxidation to carbon dioxide, as shown in Eq. 1. The standard electrode potential for this reaction is 0.207 V vs. standard hydrogen potential (SHE; all potentials henceforth reported vs. SHE, unless otherwise stated). Under normal PEFC operating conditions, the electrode potential is <0.1 V at the anode and between 0.6 V and 0.8 V at the cathode. Despite the fact that the cathode potential is usually significantly higher than the standard potential for carbon oxidation (with an effective overpotential of 0.4-0.6 V), the actual rate of carbon oxidation is very slow due to intrinsic kinetic limitations; in other words, a very low standard heterogeneous rate constant (5).During operation of automotive PEFC stacks, fuel/air ...

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Low-Temperature Synthesis of a PtRu∕Nb[sub 0.1]Ti[sub 0.9]O[sub 2] Electrocatalyst for Methanol Oxidation

Cited by 91 publications

References 7 publications

Catalyst supports for polymer electrolyte fuel cells

Catalyst supports for polymer electrolyte fuel cells

Platinum-Decorated Tin Oxide and Niobium-Doped Tin Oxide PEFC Electrocatalysts: Oxygen Reduction Reaction Activity

Platinum supported on titanium–ruthenium oxide is a remarkably stable electrocatayst for hydrogen fuel cell vehicles

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