Measurement of Ionomer Coverage on Carbon and Pt in Catalyst Layer of Polymer Electrolyte Fuel Cells by Electrochemical Impedance Spectroscopy

Minami, Saori; Kajiya, Shuji; Yamada, Haruhiko; Shinozaki, Kazuma; Jinnouchi, Ryosuke

doi:10.1007/s12678-023-00809-y

Cited by 5 publications

(2 citation statements)

References 41 publications

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“…[ 38 ] Figure 6b shows the current–time diagram of CO displacement, and the different amounts of electricity on the Pt surface can be observed, indicating that the total amount of sulfonic acid groups adsorbed on the Pt surface varied depending on the nanostructure of carbon support. [ 39 ] The CO oxidative stripping CV curves are shown in Figure 6c and the coverage of the sulfonic acid groups on the surface of Pt is presented in Figure 6d. It should be noted that the coverage of sulfonic acid groups on Pt/GMC1300‐1800 is the lowest, further demonstrating a relatively high percentage of active Pt NPs.…”

Section: Resultsmentioning

confidence: 99%

Structurally Tunable Graphitized Mesoporous Carbon for Enhancing the Accessibility and Durability of Cathode Pt‐Based Catalysts for Proton Exchange Membrane Fuel Cells

Wu,

Meng,

Xiong

et al. 2024

Small Science

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Low Pt utilization and intense carbon corrosion of cathode catalysts is a crucial issue for high‐efficiency proton exchange membrane fuel cells due to the highly demanded long‐term durability and less acquisition/application cost. Herein, structurally tunable graphitized mesoporous carbon (GMC) is obtained by direct high‐temperature pyrolysis and in situ‐controlled mesopore formation; the structure‐optimized GMC1300‐1800 exhibits a mesopore size of 7.54 nm and enhanced corrosion resistance. Functionalized GMC1300‐1800 is loaded with small‐sized Pt nanoparticles (NPs) (1.5 nm) uniformly by impregnation method to obtain Pt/GMC1300‐1800 and form an “internal platinum structure” to avoid sulfonic acid groups poisoning as well as ensure O2/proton accessibility. Hence, the electrochemically active surface area (ECSA) of Pt/GMC1300‐1800 reaches 106.1 m2 g−1Pt, while mass activity and specific activity at 0.9 V are 2.1 and 1.4 times those of commercial Pt/C, respectively. Notably, the ECSA decay is less than 17% for both 30 000 cycles’ accelerated durability tests (ADTs) of Pt attenuation and carbon attenuation. Accordingly, the optimized mesoporous structure of GMC1300‐1800 significantly decreases the coverage of sulfonic acid groups on Pt NPs, leading to the highest peak power density in the single‐cell test. Density functional theory calculations demonstrate the synergistic effect between graphitization and mesoporosity on enhancing the accessibility and durability of the catalysts.

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Section: Resultsmentioning

confidence: 99%

Structurally Tunable Graphitized Mesoporous Carbon for Enhancing the Accessibility and Durability of Cathode Pt‐Based Catalysts for Proton Exchange Membrane Fuel Cells

Wu,

Meng,

Xiong

et al. 2024

Small Science

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“…In contrast to measuring the HAD charge to determine the ECSA, the CO oxidation charge is quantified from CV measurements. As CO oxidation occurs at higher potentials in the presence of water, 16 the measured charges do not interfere with H 2 evolution at low potentials and can lead to more accurate determination of the ECSA. Garrick et al 17 investigated the difference in measured ECSA from HAD and CO stripping for Pt and Pt alloy catalysts at varying temperatures.…”

mentioning

confidence: 99%

The Effect of Ionomer to Carbon Ratio and Relative Humidity on Cathode Catalyst Degradation in PEM Fuel Cells

Schneider,

Scherzer,

Storey

et al. 2023

J. Electrochem. Soc.

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The effect of ionomer to carbon (I/C) weight ratio and relative humidity (RH) on cathode catalyst degradation was investigated by comprehensive in situ characterization. Membrane electrode assemblies (MEA) with I/C ratios of 0.5, 0.8 and 1.2 were subjected to an accelerated stress test performed at 40, 70 and 100% RH. The results show an increasing loss in electrochemical active surface area (ECSA) for both higher I/C ratios and RH during voltage cycling. To differentiate between ionomer and water connected ECSA, carbon monoxide stripping measurements were performed at varying RH. Before degradation, all MEAs show comparable total ECSA values, while higher I/C ratios lead to a larger fraction of ionomer connected ECSA. After degradation, ECSA measurements of the lowest I/C ratio showed a relatively higher loss of Pt in contact with ionomer than Pt in contact with water, while an opposite trend was observed for higher I/C ratios. H2/N2 impedance measurements showed drastically increasing protonic catalyst layer resistances for decreasing RH especially at low I/C ratios, which might hinder Pt2+ ion diffusion towards the membrane, hence decreasing the ECSA loss. Limiting current measurements show increasing molecular O2 diffusion resistances at end of test for samples with higher I/C ratios and higher ECSA loss.

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Modeling of local mass transport in cathode catalyst layer of proton exchange membrane fuel cell: Catalyst partially covered by ionomer

Li¹,

Tang²,

Wang³

et al. 2024

International Journal of Hydrogen Energy

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Measurement of Ionomer Coverage on Carbon and Pt in Catalyst Layer of Polymer Electrolyte Fuel Cells by Electrochemical Impedance Spectroscopy

Cited by 5 publications

References 41 publications

Structurally Tunable Graphitized Mesoporous Carbon for Enhancing the Accessibility and Durability of Cathode Pt‐Based Catalysts for Proton Exchange Membrane Fuel Cells

Structurally Tunable Graphitized Mesoporous Carbon for Enhancing the Accessibility and Durability of Cathode Pt‐Based Catalysts for Proton Exchange Membrane Fuel Cells

The Effect of Ionomer to Carbon Ratio and Relative Humidity on Cathode Catalyst Degradation in PEM Fuel Cells

Modeling of local mass transport in cathode catalyst layer of proton exchange membrane fuel cell: Catalyst partially covered by ionomer

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