Analytical TEM study of Pt particle deposition in the proton-exchange membrane of a membrane-electrode-assembly

Akita, Tomoki; Taniguchi, Atsushi; Maekawa, Junko; Siroma, Zyun; Tanaka, Koji; Kohyama, Masanori; Yasuda, Kazuaki

doi:10.1016/j.jpowsour.2005.10.111

Cited by 132 publications

(112 citation statements)

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“…Pt migration occurs when the dissolved Pt species diffuse into the ionomer phase and subsequently precipitate in the membrane through the reduction of Pt ions by crossover hydrogen from the anode side [13][14][15]. Pt migration into the membrane dramatically decreases its stability and conductivity.…”

Section: Catalyst Layer Degradationmentioning

confidence: 99%

A review of polymer electrolyte membrane fuel cell durability test protocols

Yuan

Zhang

et al. 2011

Journal of Power Sources

291

121

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a b s t r a c tDurability is one of the major barriers to polymer electrolyte membrane fuel cells (PEMFCs) being accepted as a commercially viable product. It is therefore important to understand their degradation phenomena and analyze degradation mechanisms from the component level to the cell and stack level so that novel component materials can be developed and novel designs for cells/stacks can be achieved to mitigate insufficient fuel cell durability. It is generally impractical and costly to operate a fuel cell under its normal conditions for several thousand hours, so accelerated test methods are preferred to facilitate rapid learning about key durability issues. Based on the US Department of Energy (DOE) and US Fuel Cell Council (USFCC) accelerated test protocols, as well as degradation tests performed by researchers and published in the literature, we review degradation test protocols at both component and cell/stack levels (driving cycles), aiming to gather the available information on accelerated test methods and degradation test protocols for PEMFCs, and thereby provide practitioners with a useful toolbox to study durability issues. These protocols help prevent the prolonged test periods and high costs associated with real lifetime tests, assess the performance and durability of PEMFC components, and ensure that the generated data can be compared.Crown

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Section: Catalyst Layer Degradationmentioning

confidence: 99%

A review of polymer electrolyte membrane fuel cell durability test protocols

Yuan

Zhang

et al. 2011

Journal of Power Sources

291

121

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“…[2]- [4] From the measurement of the particle size distribution under TEM observation, it was found that the size of the electrode catalyst particle increased, the composition of the Pt-Ru fine particle changed [2] as the Ru eluted from the anode Pt-Ru/C catalyst as seen by energy dispersive X-ray spectroscopy (EDS), and the phenomenon occurred where the metal particles of the electrode catalyst precipitated into the electrolyte membrane depending on the test condition, as shown in Fig. 5.…”

Section: Degradation Observation Of the Real Cellmentioning

confidence: 99%

“…For the particles that precipitated into the electrolyte membrane, it was found that the particle size distribution and the spatial distribution and precipitated particles changed by the influence of the type of gas supplied to the anode and cathode and by the thickness of the electrolyte membrane. [4] Figures 5a and 5b are the TEM images of the surrounding area of the cathode when the cathode potential was retained at 1.0 V, nitrogen gas was supplied, and the electrolyte membranes with thickness 50 m (Fig. 5a) and 175 m (Fig.…”

Section: Degradation Observation Of the Real Cellmentioning

confidence: 99%

Durable polymer electrolyte fuel cells (PEFC) for residential co-generation application

Tanimoto

Yasuda

Siroma

et al. 2012

Synthesiology English edition

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The fuel cell researches using the molten salts, oxides, and others as electrolytes were conducted in the early 20th century. In 1921, the high-temperature fuel cell of 1.5 kW was demonstrated using molten carbonate as the electrolyte.The basic configuration of the current fuel cell in which the porous structures of the cathode and anode are sandwiched between electrolytes was established in 1933 in the Bacon cell that used alkaline water solution as the electrolyte and nickel sintered compact as the electrode. The Bacon cell was significant in presenting a practical fuel cell configuration where the efficient electrode reactions were obtained at the Introduction (Background of research)The fuel cell power generation, in which the energy generated in the production of water in the electrochemical reaction of hydrogen and oxygen is used as electricity, is a technology where the chemical energy of a substance is directly converted into electric energy. It is not limited by the Carnot efficiency because it does not involve heat energy as in the heat engine, and high energy conversion efficency can be expected. Therefore, many researches have been conducted for its practical application. Since the fuel cell converts the energy of the chemical reaction between hydrogen and oxygen to electricity, the reaction progresses faster at higher reaction temperature, and this enables improvement in efficiency. Since the produced emission is water, it is clean and is highly environment friendly.The fuel cell started from the gas reaction experiment conducted by Sir William Robert Grove of Britain in 1839. As shown in Fig. 1, this experiment probably involved two platinum electrodes in dilute sulfuric acid solutions, where one electrode was filled with hydrogen gas and the other with oxygen gas. The electrodes were connected in series, and electrolysis was conducted by the generated electricity. The power generation using the electrochemical process did not advance far compared to the dramatic leap of the generation using the heat engines. However, the basic researches for the high-temperature fuel cell were conducted as one application of this technology to the generation method using coals combustion technology, the major fuel course of that time. -Elucidation of degradation mechanism to establish an accelerated aging test method of PEFC-Co-generation system using clean and compact PEFC which makes highly efficient power generation possible, promotes considerable energy savings at home since it provides both heat and electricity together. Therefore, its commercialization has been expected. The goal of 40000-hour-operation has been set as a practical target. In order to realize it, the durability of PEFC has been technologically prospected and the accelerated aging test protocol of PEFC has been developed within the frame of the consortium of PEFC makers, energy companies, academia and AIST. AIST has shown the rationality of the accelerated aging test protocol of PEFC through the experimental verification of hypothetical degrad...

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“…In addition, TEM also helps investigating the change of catalyst microstructure during electrochemical test. Akita et al have studied Pt nanoparticle distribution before and after membrane electrode assembly (MEA) test and an aggregation process during MEA testing was found under high resolution TEM [7].Herein we apply a novel depositing method, the Reactive Spray Deposition Technique (RSDT) for catalyst layer fabrication from vapor phase [8]. RSDT, a one-step, open-atmosphere dry deposition, is 1614…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Transmission Electron Microscopy Study on Platinum Nanoparticle Distribution in PEMFC Catalyst Layers under Different Ionomer/Carbon Ratios Fabricated by Direct Dry Deposition

Yu¹,

Roller²,

Jain³

et al. 2013

Microsc Microanal

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Proton exchange membrane fuel cells (PEMFC) are poised for market penetration in the automobile, portable and back-up power markets. Cost and durability issues are crucial to the performance of PEMFC, which primarily depends on the design of catalyst layers [1]. Current catalysts layers use platinum (Pt) supported on high-surface-area carbons (e.g., Ketjen Black® and Vulcan®) with perfluorosulfonic acid (PFSA) ionomer as a binding agent. It is widely believed that incorporation of ionomer can extend the reaction zone, increasing the proton conductivity and catalyst utilization [2]. The catalyst layers are predominately comprised of primary carbon particles, 20-50 nm in diameter. Stacking of primary carbon aggregates creates a unique 3D structure between the fractal structured carbon branches [3]. Depositing the carbon with Pt nanoparticles can block these micropores since the size of the Pt particles ranges between 2-4 nm. The PFSA ionomer is distributed on the surface of carbon agglomerates and covers intra-agglomerate pores (<20nm) at lower ionomer content, e.g., below 30 wt.% ionomer. Significant blocking of the pores is observed with higher ionomer content (>50% wt.) [4].Although researches have been focused on influence of ionomer/carbon ratio in catalyst layer microstructure, few have truly revealed the mechanism of how Pt nanoparticles are incorporated into the carbon matrix and the reason for certain ionomer/carbon ratio exhibit better electrochemical performance and higher catalyst utilization [4]. Transmission electron microscopy (TEM) is an advantageous tool for investigating the spatial distributions of components even for complicated functional materials, and can be used to analyze the composition of a local area at a nano-or atomicscale. For example, using TEM combined with electron energy loss spectroscopy (EELs) and energydispersive X-ray spectroscopy (EDS), researchers characterized Pt binary alloys for fuel cell catalysts and investigated the interaction with catalyst support materials. Oezaslan et al. discovered the existence of different morphology regimes in dealloyed Pt-Co and Pt-Cu particle ensembles, a core-shell structure of nanoparticles with 10-30nm in diameter [5]. The interaction of Pd 3 Pt 2 alloy nanoparticles with the carbon support was studied by Slanac et al. [6]. Aberration corrected STEM revealed a corrugated crystalline alloy core surrounded by a disordered alloy shell that created strong electronic binding of Pd to the 20-50 nm carbon particles, facilitate strong wetting on the carbon at the particle-support interface, which significantly enhanced the mass activity for oxygen reduction reaction (ORR) [6]. In addition, TEM also helps investigating the change of catalyst microstructure during electrochemical test. Akita et al. have studied Pt nanoparticle distribution before and after membrane electrode assembly (MEA) test and an aggregation process during MEA testing was found under high resolution TEM [7].Herein we apply a novel depositing method, the Reactive Spray Depositi...

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Analytical TEM study of Pt particle deposition in the proton-exchange membrane of a membrane-electrode-assembly

Cited by 132 publications

References 13 publications

A review of polymer electrolyte membrane fuel cell durability test protocols

A review of polymer electrolyte membrane fuel cell durability test protocols

Durable polymer electrolyte fuel cells (PEFC) for residential co-generation application

Transmission Electron Microscopy Study on Platinum Nanoparticle Distribution in PEMFC Catalyst Layers under Different Ionomer/Carbon Ratios Fabricated by Direct Dry Deposition

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