Platinum-Based Anode Catalysts for Polymer Electrolyte Fuel Cells

Rodríguez, Paramaconi; Schmidt, Thomas

doi:10.1007/978-1-4419-6996-5_209

Cited by 1 publication

(3 citation statements)

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“…18 Motivated by the promising initial performance of Pt 3 Ni anodes, this MEA and the ones from carbon-supported catalysts were subjected to an inhouse-developed accelerated stress test that simulates gross fuel starvation events, in which the anode potential increases from the ≈0 V RHE at which the HOR typically takes place to ≥ 1.5 V RHE . 8,9,[22][23][24][25] To be precise, the AST consisted of 250 square wave voltammogram (SWV) cycles on the anode between 0 and 1.5 V RHE with holding times of 10 s at each potential, as illustrated by the inset in Figure 1B. As discernable from the end-of-life (EOL) I/E curves, significant performance deterioration is observed for the MEAs with commercial Pt/CB and Pt/GCB anodes (whereby the overpotential at 1.5 A/cm 2 geom increased by ≈300 and ≈100 mV, respectively), whereas no losses occur for the MEA implementing the Pt 3 Ni aerogel as the anode catalyst.…”

Section: Resultsmentioning

confidence: 99%

“…The accelerated stress tests used to mimic PEFC anode degradation upon H 2 starvation (whereby the anode potential transitions from an HOR-operative value of ≈0 V RHE to ≥ 1.5 V RHE ) 8,9,[22][23][24][25] were performed at 80 • C, 100% RH, ambient pressure, cathode H 2 flow of 100 ml/min and anode N 2 flow of 100 ml/min. More specifically, the inhouse-developed AST protocol consisted of 250 potential cycles in a square wave voltammetry pattern between 0 and 1.5 V RHE with a holding time of 10 s at upper and lower potential limit, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…8 Most importantly, unlike in the start-up/shut-down degradation discussed above, these hydrogen starvation issues are difficult to overcome by engineering solutions. 9 Alternatively, material-based mitigation strategies include composite anode electrodes exhibiting high HOR and oxygen evolution reaction (OER) activity, as well as corrosion-resistant, non-carbon supported or even completely support-free catalysts. 9 Inspired by the latter approach, and motivated by our recent results with PEFC cathodes from unsupported Pt 3 Ni aerogel catalysts that demonstrate excellent stability during start-up/shut-down accelerated stress tests (ASTs), 10,11 this work investigates the applicability of the = These authors contributed equally to this work.…”

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Unsupported Pt₃Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions

Henning

Shimizu

Herranz

et al. 2018

J. Electrochem. Soc.

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Mitigating catalyst corrosion is crucial for the commercial success of polymer electrolyte fuel cells (PEFCs). Novel catalysts that can withstand the harsh conditions in case of gross fuel (i.e. H 2 ) starvation events at the PEFC anode are needed to increase the fuel cell stack's service life and to meet the durability targets set for automotive applications. To make progress in this respect, we have tested an unsupported, bimetallic Pt 3 Ni alloy (aerogel) catalyst at the PEFC anode and subjected it to a stress test that mimics the high potentials (≥ 1.5 V vs. the reversible hydrogen electrode) encountered upon fuel starvation. In contrast to commercial carbon-supported platinum catalysts (Pt/C), the Pt 3 Ni aerogel displays excellent durability and performance retention in end-oflife fuel cell polarization curves. Additionally, the aerogel catalyst shows ≈35% higher surface-specific activity for the hydrogen oxidation/evolution reaction than Pt/C. These results highlight the great potential of using novel unsupported catalysts at the anode of PEFCs. Polymer electrolyte fuel cells (PEFCs) customarily rely on platinum nanoparticles supported on carbon (Pt/C) to catalyze the anodic hydrogen oxidation and the cathodic oxygen reduction reactions (HOR and ORR, respectively, leading to anode and cathode sometimes being referred to as hydrogen-and oxygen-electrodes).1,2 Among the latter, the ORR is catalytically more demanding, and thus higher Pt loadings are implemented in PEFC cathodes vs. anodes (up to ≈0.4 vs. ≈0.05 mg Pt /cm 2 geom ).3 Irrespectively of this activity difference, both anodic and cathodic Pt/C catalysts suffer from significant corrosion of the carbon support during the high potential excursions (> 1 V vs. the reversible hydrogen electrode, V RHE ) concomitant to PEFC operation, which limits the device's service life.4 Potentials ≥ 1.5 V RHE on the cathode side can for instance be caused by PEFC start-up/shut-down and local fuel starvation. 5,6 To minimize the damage of these start-up/shut-down events, technical solutions like a highflow air purge of the anode compartment that minimizes the residence time of the H 2 /air anode front have been developed. 7 On the other hand, complete absence of fuel in the anode compartment under load leads to the so called gross hydrogen starvation. This is typically triggered by the blockage of hydrogen gas inlets in an individual anode flow field by liquid water which, in order to sustain the cell current, leads to an anode potential increase up to a value at which water oxidation and carbon support corrosion can occur.8 Most importantly, unlike in the start-up/shut-down degradation discussed above, these hydrogen starvation issues are difficult to overcome by engineering solutions. Alternatively, material-based mitigation strategies include composite anode electrodes exhibiting high HOR and oxygen evolution reaction (OER) activity, as well as corrosion-resistant, non-carbon supported or even completely support-free catalysts. 9Inspired by the latter approach, an...

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Unsupported Pt₃Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions

Henning

Shimizu

Herranz

et al. 2018

J. Electrochem. Soc.

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Platinum-Based Anode Catalysts for Polymer Electrolyte Fuel Cells

Cited by 1 publication

References 87 publications

Unsupported Pt₃Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions

Unsupported Pt₃Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions

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Platinum-Based Anode Catalysts for Polymer Electrolyte Fuel Cells

Cited by 1 publication

References 87 publications

Unsupported Pt3Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions

Unsupported Pt3Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions

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Unsupported Pt₃Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions

Unsupported Pt₃Ni Aerogels as Corrosion Resistant PEFC Anode Catalysts under Gross Fuel Starvation Conditions