Investigation of the Microstructure in the Catalyst Layer and Effects of Both Perfluorosulfonate Ionomer and PTFE‐Loaded Carbon on the Catalyst Layer of Polymer Electrolyte Fuel Cells

Uchida, Makoto; Aoyama, Yuko; Eda, Nobuo; Ohta, Akira

doi:10.1149/1.2048477

Cited by 400 publications

(240 citation statements)

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“…0, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]However, the optimum N/C ratios are found to be lower, namely 0.7 and 0.5 for the VC and HG supports, respectively. The optimum N/C value using VC as catalyst support is essentially the same as reported by Liu and Song et al [19,20] i.e.…”

Section: Original Research Papermentioning

confidence: 99%

“…The catalyst support material should have high electronic conductivity, high stability against corrosion, and preferably a mesoporous structure to allow for effective catalyst deposition, fuel access and water management [8]. Uchida [9,10] reported the effects of the microstructure of the catalyst layer on the performance of polymer electrolyte fuel cells (PEFCs) and reported that the pore-size distribution of the carbon support influences the performance of the fuel cell.…”

mentioning

confidence: 99%

“…Solutions of Nafion are impregnated into the electrode catalyst layer to increase the contact area between the Pt catalyst and the Nafion ionomer. In this way, the Pt utilization can be increased, resulting in higher FC performances if an optimum amount of ionomer is used [9][10][11][12][13][14].…”

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confidence: 99%

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The Influence of Pt Loading, Support and Nafion Content on the Performance of Direct Methanol Fuel Cells: Examined on the Example of the Cathode

et al. 2011

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Nano‐sized Pt colloids were prepared using the polyol method and supported on Ketjen black EC 600J (KB), Vulcan XC‐72 (VC) and high surface area graphite 300 (HG). The effects of the Nafion ionomer content, and the Pt loading of the cathode catalyst layer as well as the Pt loading on the support on the performance of direct methanol fuel cells (DMFCs), were studied. The membrane electrode assemblies (MEAs) were analysed using current–voltage curves, cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and adsorbed CO stripping voltammetry. Optimum Nafion to carbon (N/C) ratios (N/C being defined as the weight ratio of the Nafion ionomer to the carbon) were determined. The optimum N/C ratios were found to depend on the support as follows, 1.4, 0.7 and 0.5 for Pt/KB, Pt/VC and Pt/HG, respectively and to be independent of the Pt/C loading range of 20–80 wt% tested in this work. The highest DMFC performances, as well as the highest electrochemical active surface areas, and improved gas diffusivities, were achieved using these ratios. For the catalysts prepared in this work, the average Pt crystallite size was found to decrease with increasing surface area of the support for a particular Pt loading. MEAs made using KB as support and the optimal N/C ratio of 1.4 showed the best performances, i.e. higher than the VC and HG supports for any N/C ratio. The highest DMFC performance was observed using 60 wt% Pt on KB cathode electrodes of 1 mg Pt cm–2 loading and an N/C value of 1.4. For all three supports studied, the 60 wt% Pt on carbon loading resulted in the best DMFC performance. This may be linked to the Pt particle size and catalyst preparation method used in this work. In comparison to literature results, high DMFC performances were achieved using relatively ‘low' Pt and Ru loadings. For example, a maximum power density of >100 mW cm–2 at 60 °C was observed using a 1 mg Pt cm–2 cathode loading and a 2 mg PtRu cm–2 anode loading.

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Section: Original Research Papermentioning

confidence: 99%

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The Influence of Pt Loading, Support and Nafion Content on the Performance of Direct Methanol Fuel Cells: Examined on the Example of the Cathode

et al. 2011

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“…The three-phase boundary (TPB), comprising a carbon support with the Pt particles (electron conductor), the ionomer (ion conductor) and the voids (mass transfer), is a key parameter in fuel cell reactions and performance. The pores in the thin film layer can be divided into the primary pores, which exist between catalyst particles (0.02-0.04 μm), and secondary pores, which exist between the agglomerates of catalyst particles and the ionomer (0.04 μm to several μm) [78]. In order to investigate the electrode layer structure, characterization of MEA of the anode materials was done before and after the fuel cell tests.…”

Section: Fuel Cell Performance Of Ptru-cnmsmentioning

confidence: 99%

Nitrogen-doped graphene with enhanced oxygen reduction activity produced by pyrolysis of graphene functionalized with imidazole derivatives

Borghei

Azcune

Carrasco

et al. 2014

International Journal of Hydrogen Energy

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Direct methanol fuel cells (DMFC) are great candidates for portable power source applications. However, the sluggish reaction kinetics are key challenges in DMFC technology. The state-of-the-art electrocatalysts are Pt-based catalysts supported on carbon black. However, the high price of Pt, corrosion of carbon support and Pt degradation are the main problems.In this thesis, carbon nanomaterials, namely few-walled carbon nanotubes (FWCNTs) and graphitized nanofibers (GNFs) were used as catalyst supports in the search for stable and durable catalysts. PtRu nanocatalysts with similar particle size and composition were synthesized and deposited on FWCNTs and GNFs. The electrochemical activities for methanol oxidation were compared with that of PtRu-carbon black in acidic conditions. The half-cell electrochemical measurements revealed higher activity with PtRu-GNFs and PtRu-FWCNTs. Later, the electrocatalysts were tested in macro-and micro-DMFC. The results revealed the significant influence of the catalyst support, inomer contect, electrode structure, preparation method, as well as the fuel cell architecture on the performance of a specific electrode material. The results also highlighted the necessity of electrode composition optimization when applying new materials at the electrodes, in order to achieve the best activity and durability for a certain electrocatalyst.A special effort was also done to achieve Pt-free electrocatalysts with high activity for the oxygen reduction reaction (ORR) by introducing nitrogen heteroatoms in carbon nanomaterials, namely FWCNTs and graphite nanoplatelets (GNPs). N-FWCNTs exhibited remarkable electrocatalytic activity for ORR in alkaline media, despite their very low nitrogen content (~0.5 at.%). N-FWCNTs performed on par or better than a commercial Pt-C at the cathode of an alkaline DMFC. The N-GNPs exhibited enhanced electrocatalytic activity for ORR compared to pristine GNPs in alkaline media. The results indicated that N-doped carbon nanomaterials could be promising alternatives to their Pt counterparts to reduce fuel cell costs. However, further investigations are necessary to ascertain the real active sites in order to design more efficient and durable ORR electrocatalysts.Keywords Carbon nanomaterials, PtRu catalysts, nitrogen-doping, direct methanol fuel cell ISBN (printed) 978-952-60-6140-5 ISBN (pdf) 978-952-60-6141-2

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“…CLs fabricated this way consist only of useful parts for 3-phase boundary: the catalyst, the electron conductor, the ion conductor and pores. The pores in the thin film layer can be defined as primary pores, which exist between catalyst particles (0.02-0.04 μm), and secondary pores, which exist between the agglomerates of catalyst particles and the ionomer (0.04 μm to micrometers) [173].…”

Section: Membrane-electrode Assembly Fabrication Historymentioning

confidence: 99%

Silicon nanograss as micro fuel cell gas diffusion layer

et al. 2010

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Direct methanol fuel cells (DMFC) produce electrical energy directly from chemical energy. They are a promising candidate for power sources of portable devices due to the high energy density of methanol and the quick recharging procedure by fuel insertion. However, the problem areas of the DMFC are the slow electro-oxidation of methanol and the permeated methanol reacting at the cathode. New catalysts are constantly searched but they are often tested only for catalytic activity and the DMFC testing is omitted even though the catalyst layer (CL) structure has a large impact on the performance. Miniaturization of the system is also necessary for portable applications. Silicon etching can be used to fabricate small structures for fuel cells replacing or enhancing the functions of laboratory-scale components.In the first part of this thesis, new catalysts for the DMFC are studied with the emphasis on the CL structure. Different carbon supports for the anode were studied: standard carbon black and alternative few-walled carbon nanotubes (FWCNT) and graphitized carbon nanofiber (GNF). The alternative supports showed better DMFC performance but their stability was lower than with carbon black. However, the CL formed with GNF showed a very porous structure enhancing the mass transfer, so that higher binder content could be used improving the stability to the level of carbon black and the performance by 30%. The FWCNTs were also investigated as a platform for enzymatic methanol oxidation by studying the electrochemical properties of an immobilized cofactor pyrroloquinoline quinone (PQQ). A large amount of PQQ was adsorbed having a strong redox response and good stability in a wide pH window. For the cathode, a methanol-tolerant, Pt-free nitrogen-doped FWCNTs were tested in an alkaline DMFC as such testing is not often made. Its performance was remarkably 4 times better than with Pt when synthetic air was used as the oxidant.In the second part of thesis, an integrated gas diffusion layer (GDL) consisting of Si nanoneedles (nanograss) was tested in a micro fuel cell (MFC). The layer functioned properly at low current densities. For high power applications, a standard carbon cloth GDL was tested with the nanograss as a contact surface reducing the resistance between the GDL and the flow field. The use of the nanograss improved the MFC performance and stability. Finally, the MFCs were used as a catalyst testing platform and the results were compared with a similar test in a laboratory-scale DMFC. The results varied showing that the DMFC components also have a large impact on catalyst testing.Keywords direct methanol fuel cell, carbon nanomaterials, micro fuel cells, catalyst layer Tiivistelmä Suorametanolipolttokennot (SMPK) tuottavat sähköenergiaa suoraan kemiallisesta energiasta. Ne ovat lupaava vaihtoehto kannettavien laitteiden voimanlähteeksi, koska metanolilla on korkea energiatiheys ja lataaminen tapahtuu nopeasti polttoainelisäyksellä. SMPK:lla on kuitenkin rajoitteina metanolin hidas hapetusreaktio ja katodi...

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Investigation of the Microstructure in the Catalyst Layer and Effects of Both Perfluorosulfonate Ionomer and PTFE‐Loaded Carbon on the Catalyst Layer of Polymer Electrolyte Fuel Cells

Cited by 400 publications

References 5 publications

The Influence of Pt Loading, Support and Nafion Content on the Performance of Direct Methanol Fuel Cells: Examined on the Example of the Cathode

The Influence of Pt Loading, Support and Nafion Content on the Performance of Direct Methanol Fuel Cells: Examined on the Example of the Cathode

Nitrogen-doped graphene with enhanced oxygen reduction activity produced by pyrolysis of graphene functionalized with imidazole derivatives

Silicon nanograss as micro fuel cell gas diffusion layer

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