Electrochemical and Raman spectroscopic evaluation of Pt/graphitized carbon black catalyst durability for the start/stop operating condition of polymer electrolyte fuel cells

Hara, Masanori; Lee, Myoungseok; Liu, Cheng‐Hong; Chen, Bing‐Hung; Yamashita, Yuya; Uchida, Makoto; Uchida, Hiroyuki; Watanabe, Masahiro

doi:10.1016/j.electacta.2012.03.043

Cited by 115 publications

(102 citation statements)

References 43 publications

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“…Figure 9 shows the TEM images of Pt/TiC-600 °C and c-Pt/CB before and after the durability test (N = 5000). As is well known, the CB support of c-Pt/CB corrodes severely at high potentials [17,39]. Many Pt particles were found to be detached from the CB support, in addition to the agglomeration of Pt particles.…”

Section: Durability Of Pt/tic-600 °C In the Potential Step Cycle Testmentioning

confidence: 79%

“…It is known that the corrosion rate of carbon itself is low even under PEFC operating conditions, but the rate is accelerated by Pt catalyst loading with increasing temperature and potential [2,[7][8][9]. The corrosion of the carbon support leads to agglomeration (sintering) and/or a detachment of Pt nanoparticles from the surface, together with a reduction of the electronic conductance in the CL [1,[10][11][12][13][14][15][16][17]. Thus, the ECA for the ORR decreases significantly.…”

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: Durability Of Pt/tic-600 °C In the Potential Step Cycle Testmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

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

et al. 2015

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“…At the materials level, researchers have been investigating new catalyst supports that are not susceptible to corrosion, including metal oxides and thermally treated carbon supported catalysts. [10][11][12][13] Another approach is the complete removal of all Pt support material from the cathode layer, as is the case with 3M Company's nanostructure thin film structured Pt whisker electrodes. 14 The limited wettability of the catalyst carbon surface is critically important for increasing its corrosion resistance in an MEA, since water is directly involved in the electrochemical oxidation of the carbon support material of a fuel cell cathode 14,15 (via Equation 1).…”

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confidence: 99%

Power Output and Durability of Electrospun Fuel Cell Fiber Cathodes with PVDF and Nafion/PVDF Binders

Brodt

Dale

Pintauro

2016

J. Electrochem. Soc.

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Membrane-electrode-assemblies (MEAs) with electrospun nanofiber mat electrodes (0.10 mg/cm 2 Pt loading) and a Nafion 211 membrane were prepared and tested in a H 2 /air fuel cell at 100% and 40% relative humidity. The cathode binder was either neat poly(vinylidene fluoride) (PVDF) or a Nafion/PVDF blend (20 to 80 wt% Nafion) and the anode binder was Nafion with poly(acrylic acid). Polarization curves were recorded at 80 • C and ambient pressure before, intermittently, and after a carbon corrosion voltage cycling experiment. The Nafion/PVDF cathode MEA with the smallest amount of PVDF (80/20 Nafion/PVDF weight ratio) produced the highest maximum power at beginning-of-life (BoL), 545 mW/cm 2 at 100% RH, which was 35% greater than that for a conventional MEA with a neat Nafion binder. Carbon corrosion scaled inversely with cathode PVDF content, with a 33/67 Nafion/PVDF cathode binder MEA producing the highest end-of-life (EoL) power (330 mW/cm 2 ). MEAs with < 50 wt% PVDF in the cathode binder exhibited a power density decline during carbon corrosion, whereas the power increased during/after carbon corrosion for nanofiber cathodes with binders containing > 50 wt% PVDF due to favorable increases in the hydrophilicity of the carbon support and Pt mass activity, coupled with a lower carbon loss. The hydrogen/air proton-exchange membrane fuel cell is a promising candidate for emission-free automotive power plants, but issues remain regarding the high cost and durability of membrane-electrodeassemblies (MEAs).1 For commercialization, the Pt loading of fuel cell MEAs (particularly the cathode) must be reduced while maintaining high power output and the catalytic activity of the cathode for electrochemical oxygen reduction must be maintained during long-term operation with various power cycles and numerous stack start-ups and shut-down events. 2In a series of recent papers, Pintauro and coworkers have shown that an electrospun nanofiber cathode, composed of Pt/C particles and a binder of Nafion + poly(acrylic acid) (abbreviated as PAA) performs remarkably well in a hydrogen/air proton exchange membrane fuel cell.3-5 For example, a nanofiber electrode MEA with 0.055 mg Pt /cm 2 at the cathode and 0.059 mg Pt /cm 2 at the anode (Johnson Matthey Pt/C catalyst) produced more than 900 mW/cm 2 at maximum power in a H 2 /air fuel cell at 80• C, 100% RH, and high feed gas flow rates at 2 atm backpressure. 4 In a recent collaborative study between Vanderbilt University and Nissan Technical Center North America, Brodt et al. 5 showed that MEAs with an electrospun particle/polymer cathode generated high beginning-of-life power and also exhibited excellent durability, as determined from end-of-life polarization curves after an accelerated start-stop voltage cycling (carbon corrosion) test. Thus, after 1,000 simulated start-stop cycles, a nanofiber MEA with Johnson Matthey Pt/C catalyst and a binder of Nafion + PAA maintained 53% of its initial power at 0.65 V and 85% of its maximum power, as compared to a 28% power retention at 0.65...

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“…4,5,10 Carbon supports with a high degree of graphitization (e.g. steam etched carbon blacks, 23,24 graphitic carbon blacks, 13,25,26 graphitized multiwall carbon nanotubes (MWCNTs), 27,28 graphitic carbon nanocages (CNCs), 29,30 nanographite, 31 and graphitized mesoporous carbon (MC) 32 ) show improved stability in relation to non-graphitized carbon supports when subjected to accelerated stress tests (ASTs). Besides these studies that employed high-temperature (>2500…”

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confidence: 99%

Polybenzimidazole (PBI) Functionalized Nanographene as Highly Stable Catalyst Support for Polymer Electrolyte Membrane Fuel Cells (PEMFCs)

Xin

Yang

Qiu

et al. 2016

J. Electrochem. Soc.

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Nanoscale graphenes were used as cathode catalyst supports in proton exchange membrane fuel cells (PEMFCs). Surface-initiated polymerization that covalently bonds polybenzimidazole (PBI) polymer on the surface of graphene supports enables the uniform distribution of the Pt nanoparticles, as well as allows the sealing of the unterminated carbon bonds usually present on the edge of graphene from the chemical reduction of graphene oxide. The nanographene effectively shortens the length of channels and pores for O 2 diffusion/water dissipation and significantly increases the primary pore volume. Further addition of p-phenyl sulfonic functional graphitic carbon particles as spacers, increases the specific volume of the secondary pores and greatly improves O 2 mass transport within the catalyst layers. The developed composite cathode catalyst of Pt/PBI-nanographene (50 wt%) + SO 3 H-graphitic carbon black demonstrates a higher beginning of life (BOL) PEMFC performance as compared to both Pt/PBI-nanographene (50 wt%) and Pt/PBI-graphene (50 wt%) + SO 3 H-graphitic carbon black (GCB). Accelerated stress tests show excellent support durability compared to that of traditional Pt/Vulcan XC72 catalysts, when subjected to 10,000 cycles from 1.0 V to 1.5 V. This study suggests the promise of using PBI-nanographene + SO 3 H-GCB hybrid supports in fuel cells to achieve the 2020 DOE targets for transportation applications. High stability is required for polymer electrolyte membrane fuel cells (PEMFCs) catalyst supports because they play a critical role in determining the overall durability of PEMFC systems.1 Carbon-based supports have been widely used to support Pt or Pt alloy catalysts in PEMFCs.2 High-surface-area carbon (HSAC) supports minimize the aggregation of the catalyst nanoparticles as HSAC provides more sites for catalyst to nucleate than low-surface-area-carbon (LSAC), thereby avoiding forming big aggregates. Thus, it increases the Pt utilization that leads to more active electro-catalysts with low platinum loadings (< 0.1 mg-Pt/cm 2 ), 2 yet HSAC is vulnerable for corrosion due to the increased surface area. Good electrical conductivity of the carbon materials provides good electron transport.3 In addition, the random aggregates of the primary carbon particles help the distribution of ionomer to access the active sites during the fabrication of membrane electrode assemblies (MEA), and also allow the construction of a highly porous catalyst layer that enables O 2 diffusion and the water dissipation in PEMFCs. The most commonly used carbon blacks in low temperature PEMFCs include Vulcan XC72 (Cabot Corp., USA), Black Pearls 2000 (Cabot Corp., USA) Ketjen Black EC300j (AkzoNobel Corp., the Netherlands), Ketjen Black EC600 (AkzoNobel Corp., the Netherlands), etc. These carbon blacks consist of inhomogeneous graphitic structures and amorphous carbons. 4 The small size of the graphitic domains cause a high density of edge sites, (particularly in the case of high BET (Brunauer-Emmett-Teller) surface area carbon supports), ...

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Electrochemical and Raman spectroscopic evaluation of Pt/graphitized carbon black catalyst durability for the start/stop operating condition of polymer electrolyte fuel cells

Cited by 115 publications

References 43 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

Power Output and Durability of Electrospun Fuel Cell Fiber Cathodes with PVDF and Nafion/PVDF Binders

Polybenzimidazole (PBI) Functionalized Nanographene as Highly Stable Catalyst Support for Polymer Electrolyte Membrane Fuel Cells (PEMFCs)

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