Cathodic performance and high potential durability of Ta-SnO2−δ-supported Pt catalysts for PEFC cathodes

Senoo, Yuichi; Taniguchi, Koji; Kakinuma, Katsuyoshi; Uchida, Makoto; Uchida, Hiroyuki; Deki, Shigehito; Watanabe, Masahiro

doi:10.1016/j.elecom.2014.12.005

Cited by 58 publications

(88 citation statements)

References 16 publications

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“…The value of jk of Pt/TiC-600 °C at 0.85 V was 0.70 mA cm −2 , which was approximately 1.4 times higher than that of cPt/CB. Similar enhancement factors of the jk were also reported for Pt/Nb-SnO2−δ and Pt/Ta-SnO2−δ [29,30]. The value of MA of Pt/TiC-600 °C at 0.85 V (507 A g ), since the ECA of Pt/TiC-600 °C was smaller than that of c-Pt/CB.…”

Section: Electrochemical Characterization Of Pt/tic Catalystssupporting

confidence: 65%

“…By TEM observation, we have clearly demonstrated that the major reason for such a high durability of Pt/TiC-600 °C was suppression of the detachment of Pt particles from the support, unlike c-Pt/CB. Hence, based on our systematic work using various ceramic supports (TiN [26], doped SnO2 [27][28][29][30], and TiC in the present work), the essential factors for the highly active and highly durable cathode catalysts are the use of a chemically and electro chemically stable support with high electrical conductivity, uniform dispersion of Pt nanocrystals on the support, and the removal of an oxide layer, if any, on the Pt surface and/or Pt-ceramic support interface.…”

Section: Discussionmentioning

confidence: 99%

“…The support materials used are typically in the form of nanoparticles with HSA to disperse Pt catalyst particles uniformly, but the use of HSA supports often leads to a high contact resistance between the particles. Recently, Kakinuma et al have developed Sb-, Nb-and Ta-doped SnO2−δ nanoparticle supports with a fused aggregated structure having both HSA and low contact resistance [27][28][29][30]. They reported that Pt-dispersed Nb-SnO2−δ and Ta-SnO2−δ exhibited both higher ORR activity and higher durability at high potentials than those for commercial Pt/CB (c-Pt/CB) catalysts.…”

Section: Introductionmentioning

confidence: 99%

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Oxygen Reduction Reaction Activity and Durability of Pt Catalysts Supported on Titanium Carbide

et al. 2015

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Abstract:We have prepared Pt nanoparticles supported on titanium carbide (TiC) (Pt/TiC) as an alternative cathode catalyst with high durability at high potentials for polymer electrolyte fuel cells. The Pt/TiC catalysts with and without heat treatment were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). Hemispherical Pt nanocrystals were found to be dispersed uniformly on the TiC support after heat treatment at 600 °C in 1% H2/N2 (Pt/TiC-600 °C). The electrochemical properties (cyclic voltammetry, electrochemically active area (ECA), and oxygen reduction reaction (ORR) activity) of Pt/TiC-600 °C and a commercial Pt/carbon black (c-Pt/CB) were evaluated by the rotating disk electrode (RDE) technique in 0.1 M HClO4 solution at 25 °C. It was found that the kinetically controlled mass activity for the ORR on Pt/TiC-600 °C at 0.85 V (507 A g ). Moreover, the durability of Pt/TiC-600 °C examined by a standard potential step protocol (E = 0.9 V↔1.3 V vs. RHE, holding 30 s at each E) was much higher than that for c-Pt/CB. OPEN ACCESSCatalysts 2015, 5 967

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Section: Electrochemical Characterization Of Pt/tic Catalystssupporting

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oxygen Reduction Reaction Activity and Durability of Pt Catalysts Supported on Titanium Carbide

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“…The characterization of the catalysts was reported in a previous paper. 33 Briefly, the Ta-SnO 2 support obtained was detected to be a single-phase rutile oxide from the X-ray diffaction profiles, without any impurity. The Ta dopant content in the support was determined to be 2.5 at% by use of ICP-MS.…”

Section: F236mentioning

confidence: 99%

Improvement of Cell Performance in Low-Pt-Loading PEFC Cathode Catalyst Layers with Pt/Ta-SnO₂Prepared by the Electrospray Method

Takahashi

Koda

Kakinuma

et al. 2017

J. Electrochem. Soc.

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To reduce the Pt loadings in cathode catalysts for polymer electrolyte fuel cells, we focused on the catalyst material and catalyst-layer (CL) fabrication method, and prepared low Pt loading CLs with Pt/Ta-SnO 2 by the electrospray (ES) method. Two CLs were prepared by the ES method with different mass ratios of ionomer binder to support material (I/S), I/S = 0.7 and 0.2, and are compared to that prepared by the pulse-swirl-spray (PSS) method. Both ES CLs have higher porosity than that for the PSS CL, and have improved ionomer coverage and increased electrochemically active surface area (ECA) and mass activity at 0.85 V. In particular, that for the ES with I/S = 0.2 has high porosity and remarkably increased cell performance. The improvement obtained by use of the ES method can be explained on the basis that the coverage and uniformity of ionomer are increased due to the small droplet size. The performance of the ES cells is high, particularly under high backpressure conditions, because of the improved transport of both O 2 and protons. ES is an attractive method for the reduction of the Pt loading while improving cell performance. Polymer electrolyte fuel cells (PEFCs) have the potential to reduce the emission of greenhouse gases and air pollutants in comparison to the use of fossil fuels. [1][2][3][4][5][6] There has been a strong effort to reduce the cost of PEFC components, with attempts being made to decrease catalyst loadings while maintaining similar or improved cell performance. In order to address these challenges, several different approaches have been proposed, including the synthesis of Pt alloy catalysts and the optimization of Pt particle size or Pt interparticle distance.7-9 Our group evaluated the practical utilization of Pt under operating conditions, finding that the effectiveness of Pt was only on the order of 7.5% in air at 65• C and 0.1 MPa. 10 In order to increase the effectiveness of Pt, we examined its relationship with catalyst layer (CL) thickness and use of a Pt alloy catalyst. 11,12 In particular, the mass activity of a CL was increased by reducing the Pt loading to about 0.05 mg cm −2 . However, we also found that a new preparation method, which can construct a highly uniform layer, is necessary to improve performance of thin CLs with micrometer-order thickness. CLs are usually fabricated from a catalyst ink, which includes the Pt catalyst, an ionomer binder and a dispersing solvent. Researchers have reported the use of inkjets, 13 electrospinning 14 and electrospray (ES) 15,16 to fabricate CLs with low Pt loadings. In case of the ES method, micrometer-sized droplets of the catalyst ink can be synthesized. The ES method essentially makes use of a nozzle, which is connected to an ink reservoir, and the substrate to be coated (Fig. 1). When the ink is ejected by the influence of a strong electric field, the resulting spray can take on several different forms, according to the ink meniscus formation at the tip of the nozzle. One of these modes is the cone-jet, 17,18 involving a Taylor c...

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“…28 The support has much higher electrical conductivity than that of the previous Nb-SnO 2 support and is expected to have improved anodic activity and cell performance.…”

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confidence: 99%

Electrochemical Oxidation of Hydrolyzed Poly-Oxymethylene-Dimethylether by Pt and PtRu Catalysts on Ta-Doped SnO₂Supports for Direct Oxidation Fuel Cells

Kakinuma

Hirayama

Iiyama

et al. 2017

J. Electrochem. Soc.

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We synthesized Pt and PtRu catalysts supported on Ta-doped SnO 2 (Pt/Ta-SnO 2 , PtRu/Ta-SnO 2 ) for the anodes of direct oxidation fuel cells fueled with poly-oxymethylene-dimethylether (POMM n , n = 3∼8). The onset potential for the oxidation of the hydrolyzed fuel of POMM 3 (h-POMM 3 ; methanol-formaldehyde mixtures with the composition equivalent to 100% hydrolyzed POMM 3 ) on Pt/Ta-SnO 2 and PtRu/Ta-SnO 2 was at least 0.2 V lower than that on a commercial Pt 2 Ru 3 /carbon black (c-Pt 2 Ru 3 /CB). The Pt-based mass activities at 0.50 V (MA 0.50V ) of PtRu/Ta-SnO 2 for the h-POMM 3 and formaldehyde oxidations were more than four times larger than those of the c-Pt 2 Ru 3 /CB. Elemental tin was found to exist on the top surface, brought by the diffusion from the Ta-SnO 2 support. The elemental tin may contribute to enhancing the anodic reaction via an acceleration of carbon monoxide oxidation by a bifunctional mechanism or ligand effect. Single cells using Pt/Ta-SnO 2 and PtRu/Ta-SnO 2 as anodes exhibited higher current densities in all voltage regions when supplied with the h-POMM 3 fuels dissolved in water. We deduced that both the elemental tin diffusion from the Ta-SnO 2 support to the catalyst nanoparticles and the unique fused-aggregate network structure of the Ta Polymer electrolyte fuel cells (PEFCs) supplied directly with liquid fuels are suitable as power sources for various portable applications with extended operating time. Liquid alcohol fuels such as methanol and ethanol are attractive energy carriers with environmental compatibility, good energy density and low cost. 1-6The liquid oligomers of poly-oxymethylene-dimethylethers (POMM n : CH 3 -O-(CH 2 -O) n -CH 3 , n = 3∼8) have also been proposed as an alternative class of liquid fuels for the future, 7 but they have several hurdles to clear before they can enjoy widespread use. Fortunately, the POMM n preparation from methane has already been established as an industrial process, with the methane feedstock existing on a massive scale as natural gas and even as a by-product from oil wells.8 The POMM n compounds have been applied as raw materials of the polyacetal resins used in vehicle parts and medical devices. [8][9][10] A project on the application of POMM n has been conducted in Germany. 8 The POMM n compounds have no corrosive properties for steels used containers of various sizes, including tankers. Other attractive properties are non-toxicity, high flash points (>64• C) and high boiling temperatures (ca. 100• C), unlike methanol. In addition, the POMM n compounds can easily and immediately hydrolyze under acidic conditions to form methanol and formaldehyde (Eq. 1):7,11-13Thus, the POMM n class of compounds is becoming one of the more promising candidates for new energy carriers for use in fuel cells, and the essential properties described above have the potential to lower the hurdle of cost, to improve the safety, and to maintain a stable supply, in comparison with other energy carriers such as methanol, even with increasing demand for POM...

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Cathodic performance and high potential durability of Ta-SnO2−δ-supported Pt catalysts for PEFC cathodes

Cited by 58 publications

References 16 publications

Oxygen Reduction Reaction Activity and Durability of Pt Catalysts Supported on Titanium Carbide

Oxygen Reduction Reaction Activity and Durability of Pt Catalysts Supported on Titanium Carbide

Improvement of Cell Performance in Low-Pt-Loading PEFC Cathode Catalyst Layers with Pt/Ta-SnO₂Prepared by the Electrospray Method

Electrochemical Oxidation of Hydrolyzed Poly-Oxymethylene-Dimethylether by Pt and PtRu Catalysts on Ta-Doped SnO₂Supports for Direct Oxidation Fuel Cells

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Cathodic performance and high potential durability of Ta-SnO2−δ-supported Pt catalysts for PEFC cathodes

Cited by 58 publications

References 16 publications

Oxygen Reduction Reaction Activity and Durability of Pt Catalysts Supported on Titanium Carbide

Oxygen Reduction Reaction Activity and Durability of Pt Catalysts Supported on Titanium Carbide

Improvement of Cell Performance in Low-Pt-Loading PEFC Cathode Catalyst Layers with Pt/Ta-SnO2Prepared by the Electrospray Method

Electrochemical Oxidation of Hydrolyzed Poly-Oxymethylene-Dimethylether by Pt and PtRu Catalysts on Ta-Doped SnO2Supports for Direct Oxidation Fuel Cells

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Product

Resources

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Improvement of Cell Performance in Low-Pt-Loading PEFC Cathode Catalyst Layers with Pt/Ta-SnO₂Prepared by the Electrospray Method

Electrochemical Oxidation of Hydrolyzed Poly-Oxymethylene-Dimethylether by Pt and PtRu Catalysts on Ta-Doped SnO₂Supports for Direct Oxidation Fuel Cells