Alternative Support Materials for Fuel Cell Catalysts

Ettingshausen, Frank; Weidner, André; Zils, Susanne; Wolz, André; Suffner, J.; Michel, M. F.; Roth, Christina

doi:10.1149/1.3210743

Cited by 18 publications

(5 citation statements)

References 19 publications

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“…A wide range of non-carbon supports based on metal oxides and metal carbides have been explored and many have shown good electrochemical stability. [113][114][115][116] (a) (b) . Reproduced with permission.…”

Section: Experimental Spectroscopy Analysismentioning

confidence: 99%

Iron‐Free Cathode Catalysts for Proton‐Exchange‐Membrane Fuel Cells: Cobalt Catalysts and the Peroxide Mitigation Approach

et al. 2019

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High‐performance and inexpensive platinum‐group‐metal (PGM)‐free catalysts for the oxygen reduction reaction (ORR) in challenging acidic media are crucial for proton‐exchange‐membrane fuel cells (PEMFCs). Catalysts based on Fe and N codoped carbon (Fe–N–C) have demonstrated promising activity and stability. However, a serious concern is the Fenton reactions between Fe2+ and H2O2 generating active free radicals, which likely cause degradation of the catalysts, organic ionomers within electrodes, and polymer membranes used in PEMFCs. Alternatively, Co–N–C catalysts with mitigated Fenton reactions have been explored as a promising replacement for Fe and PGM catalysts. Therefore, herein, the focus is on Co–N–C catalysts for the ORR relevant to PEMFC applications. Catalyst synthesis, structure/morphology, activity and stability improvement, and reaction mechanisms are discussed in detail. Combining experimental and theoretical understanding, the aim is to elucidate the structure–property correlations and provide guidance for rational design of advanced Co catalysts with a special emphasis on atomically dispersed single‐metal‐site catalysts. In the meantime, to reduce H2O2 generation during the ORR on the Co catalysts, potential strategies are outlined to minimize the detrimental effect on fuel cell durability.

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Section: Experimental Spectroscopy Analysismentioning

confidence: 99%

Iron‐Free Cathode Catalysts for Proton‐Exchange‐Membrane Fuel Cells: Cobalt Catalysts and the Peroxide Mitigation Approach

et al. 2019

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“…6 Pt loaded Nb-doped TiO 2 electrospun nanofibres. 89 Much effort is being devoted to developing novel catalyst supports or secondary supports, including conductive or semiconductive oxides such as TiO x , [124][125][126] SiO 2 , 127 MnO x , 128 WO x , 129 SnO 2 130 as well as carbides 91,131 and nitrides, 132 to modify the catalyst support for PEM fuel cells and enhance the catalytic performance of the system. Metal oxides represent a very attractive alternative to conventional catalyst supports, because of their exceptional chemical stability and corrosion resistance at the potentials and pH of use in PEM fuel cells.…”

Section: A Electrospun Nanofibres For Fuel Cellsmentioning

confidence: 99%

Electrospinning: designed architectures for energy conversion and storage devices

Cavaliere

Subianto

Savych

et al. 2011

Energy Environ. Sci.

657

423

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International audienceElectrospinning is attracting close interest as a versatile fabrication method for one dimensional mesostructured organic, inorganic and hybrid nanomaterials of controlled dimensions prepared as randomly oriented or oriented continuous nanofibres that can present internal compositional organisation such as core-sheath, hollow or porous fibre, or even multichannel microtube arrangements. The dimensionality, directionality and compositional flexibility of electrospun nanofibres and mats are increasing being investigated for the targeted development of electrode and electrolyte materials. Specific properties associated with the nano-scale features such high surface to volume and aspect ratios, low density and high pore volume allow performance improvements in energy conversion and storage devices. We review here the application of electrospinning for designing architectured nanofibre materials for dye sensitised solar cells, fuel cells, lithium ion batteries and supercapacitors, with particular emphasis on improved energy and power density imparted by performance improvement to, inter alia, ionic conductivity, cyclability, reversibility, interfacial resistance and electrochemical stability, as well as mechanical strength, of electrospun electrode and electrolyte components

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“…A wide range of non-carbon supports based on metal oxides and metal carbides have been explored with several of them exhibiting good electrochemical stability. 32,[38][39][40][41][42][43][44][45] However, these oxides and carbide-based supports do not usually have the necessary electron conductivities to obtain electrodes with acceptable performance. Our group has synthesized high-surface-area mixed-metal oxide and doped metal oxide supports that are highly corrosion resistant and possess more than adequate electron conductivity (> ∼5 Scm -1 ) 32,36 and BET surface area (30-300 m 2 g -1 ) to be used in PEFC electrodes.…”

mentioning

confidence: 99%

Contribution of Electrocatalyst Support to PEM Oxidative Degradation in an Operating PEFC

Prabhakaran

Wang

Parrondo

et al. 2016

J. Electrochem. Soc.

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The contribution of the electrocatalyst support to polymer electrolyte membrane (PEM) oxidative degradation in an operating polymer electrolyte fuel cell was investigated. A corrosion-resistant non-carbon catalyst support based on mixed ruthenium and silicon oxides (RuO 2 -SiO 2 ; RSO) was compared against a benchmark carbon-based support (Vulcan XC 72; C). The rates of in-situ reactive oxygen species (ROS) generation (Pt/C: 9.0 ± 0.20 × 10 −5 s −1 ; Pt/RSO: 5.9 ± 0.19 × 10 −5 s −1 ) and macroscopic PEM degradation measured ex-situ as the fluoride emission rate (FER; Pt/C: 2.7 ± 0.32 × 10 −5 ppm cm -2 s -1 ; Pt/RSO: 2.5 ± 0.31 × 10 −5 ppm cm -2 s -1 ) were significantly lower for platinum supported on RSO than for platinum supported on carbon. There was an excellent correlation between the in-situ ROS generation rate and the FER, thereby confirming the causal relationship between ROS generation and PEM degradation. The lower rate of ROS generation over RSO and Pt/RSO was attributed to a lower net rate of electrochemical H 2 O 2 generation during the oxygen reduction reaction (ORR). Rotating ring-disk electrode experiments confirmed that the net electrochemical H 2 O 2 generation rate on Pt/RSO was about twice lower than that on Pt/C. Kinetic parameters estimated for the ORR supported a direct 4e -pathway on both Pt/RSO (with i k of 4.5 mAcm -2 , n = 3.97 and a Tafel slope of 64 mVdec -1 ) and Pt/ C (with i k of 4.1 mAcm -2 , n = 3.93 and a Tafel slope of 68 mVdec -1 ). In conjunction with its high corrosion-resistance, this finding further illustrates the viability of RSO (and analogs such as ruthenium-titanium oxide) as outstanding PEFC electrocatalyst supports. Polymer electrolyte fuel cells (PEFCs) have attracted a lot of interest as electrochemical energy conversion sources for multiple applications in the automotive, stationary power, portable power, and military sectors due to their high efficiency, modularity and environmental benefits.1-3 The commercialization of PEFCs, particularly for the automobile sector, has been hindered by high cost and insufficient component durability. 2,4 The high cost of component materials, such as platinum (Pt) electrocatalyst 5,6 and Nafion electrolyte membranes are among the main factors influencing the cost of PEFCs.4,7-9 Recent advances in the design of PEFCs enable high performance with very low total Pt loadings (ca. 0.15 mg Pt cm -2 ) and using very thin polymer electrolyte membranes (PEMs; e.g. Nafion 211, ca. 25 μm, or even lower thickness variants). 4,10,11 However, the long-term durability of PEFC components still remains a major concern. The key issues affecting PEFC durability include electrode degradation via carbon corrosion, 1,12-15 Pt dissolution, 5,16-19 catalyst sintering 20,21 and electrolyte degradation via PEM oxidative degradation.2,3,22 Carbon corrosion and PEM degradation are key degradation modes that need to be mitigated. Carbon corrosion is primarily caused by oxidation of carbon at higher electrode potentials that are encountered during transient...

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Alternative Support Materials for Fuel Cell Catalysts

Cited by 18 publications

References 19 publications

Iron‐Free Cathode Catalysts for Proton‐Exchange‐Membrane Fuel Cells: Cobalt Catalysts and the Peroxide Mitigation Approach

Iron‐Free Cathode Catalysts for Proton‐Exchange‐Membrane Fuel Cells: Cobalt Catalysts and the Peroxide Mitigation Approach

Electrospinning: designed architectures for energy conversion and storage devices

Contribution of Electrocatalyst Support to PEM Oxidative Degradation in an Operating PEFC

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