Atomic force microscopy and infrared analysis of aging processes of polymer electrolyte membrane fuel cell components

Hiesgen, Renate; Wehl, Ines; Helmly, Stefan; Haug, Andrea; Schulze, Mathias; Bauder, Alexander; Wang, Haijiang; Yuan, Xiao‐Zi; Friedrich, K. Andreas

doi:10.1016/j.jelechem.2011.07.014

Cited by 13 publications

(9 citation statements)

References 26 publications

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“…8b, the formation of differently adhesive structures, hydrophobic/PTFE-rich and hydrophilic/waterrich, both orientated parallel to the interface, is visible. Higher adhesion values typically indicates a higher PTFE-like content [46], which in this case, is associated with a backbone-rich phase; low adhesion indicates a water-rich phase, as discussed above. Close to the interface, more of the higher adhesive water-poor phase is present, which agrees with measurements at membranes [21].…”

Section: Interface Formation Of Ionomer Layer To Hydrophobic and Hydrmentioning

confidence: 83%

Atomic Force Microscopy on Cross Sections of Fuel Cell Membranes, Electrodes, and Membrane Electrode Assemblies

Hiesgen

Morawietz

Handl

et al. 2015

Electrochimica Acta

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Dedicated to Prof. Jacek Lipkowski, in recognition of his achievements and on the occasion of his 70th birthday.Keywords: AFM PFSA conductive ionic network fuel cell catalytic layer ionomer content A B S T R A C T Using material-sensitive and conductive atomic force microscopy (AFM) on cross sections of perfluorinated and sulfonated membranes at low humidity, crystalline polymer lamellae were imaged and their thickness determined to approximately 6 nm. In the capacitive current, water-rich and waterpoor areas with different phase structures were investigated. The formation of a local electrochemical double layer within the water-rich ionically conductive areas at the contact of the AFM tip with the electrolyte enabled their visibility. The large water-filled ionically conductive areas include numerous ionic domains. Under equilibrium conditions, these areas are spherical (appearing circular in the images) and with distinct size distribution. Forcing a current through the membranes (current-induced activation) led to merging of the water-filled ionically conductive areas in the voltage direction and resulted in an anisotropic ionically conducting network with flat channels. The distribution of the current in the membrane and catalytic layers of a pristine membrane electrode assembly (MEA) was analyzed. From the adhesion force mappings, an inhomogeneous distribution of ionomer in the catalytic layer was detected. Cross currents between Pt/C particles through large ionomer particles within the catalytic layer were detected and the ionomer content across an electrode was evaluated.

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Section: Interface Formation Of Ionomer Layer To Hydrophobic and Hydrmentioning

confidence: 83%

Atomic Force Microscopy on Cross Sections of Fuel Cell Membranes, Electrodes, and Membrane Electrode Assemblies

Hiesgen

Morawietz

Handl

et al. 2015

Electrochimica Acta

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“…With respect to controlling the residual energy of the sputtered particle, the deposition parameters of substrate temperature, gas pressure and sputter power are commonly varied, while the substrate mechanical properties are not considered. In the context of this study, the relative dissipation energy was mapped for the different hard‐coat samples using an AFM using PeakForce mode. Figure illustrates the difference in dissipation energy measured by the AFM tip as it scans across the respective surfaces.…”

Section: Resultsmentioning

confidence: 99%

Growth of Sputtered Nanocomposite Alloys on Polymeric Substrates: The Role of the Substrate's Mechanical Hardness

et al. 2013

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Thin multilayer structures consisting of a nanocomposite CrZr x alloy on SiO 2 are grown by magnetron sputtering onto hard-coated polymeric substrates at 350 K. The grain structure and electrical, optical, and mechanical properties of the nanocomposite alloy were investigated using atomic force microscopy, dc conductivity, spectrophotometry, and nano-scratch testing. Despite the sputtered films being grown in the same deposition run, the grain structure and properties of the thin films were observed to change depending on the siloxane-based hard-coat employed. These studies indicate that in addition to the substrate's roughness, the hardness of the siloxane-based hard-coat correlates well with the changing properties of the sputtered thin films. To rationalize the influence of the substrate hardness, a hypothesis is proposed where the substrate hardness dissipates a portion of the sputtered material's energy upon impact, leading to changes in its residual energy, thus influencing the material's ability to laterally diffuse on the substrate.

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“…The indentation test was conducted with scanning probe microscopy (SPM, AFM5100N, Hitachi High-Technologies Corp., Japan) in force curve mode to determine the indentation stiffness of the sample surface. Sample surface stiffness (modulus of the sample surface) is given by the slope ΔF, the reaction force that a cantilever receives by tapping on the sample surface/ΔD, displacement of a cantilever by bending, of the reaction curve [16]. The lower the ΔF/ΔD, the softer is the sample surface [17].…”

Section: Characterizationmentioning

confidence: 99%

Resistance of wood coated with oriental lacquer (urushi) against damage caused by subterranean termite

2019

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The sap of urushi tree (Toxicodendron vernicifluum (Stokes) F.A. Barkley) has been used for coating materials and is known as urushi or oriental lacquer in East Asia. The potential of termite attacks against wood samples coated with four types of urushi: Ki-urushi, Sugurome-urushi, Kuro-Sugurome-urushi, and Bengara-urushi, in correlation with their chemical and mechanical properties was investigated in this study. Mortalities of the subterranean Formosan termite (Coptotermes formosanus Shiraki) after a 3-week no-choice feeding tests in samples coated with all types of urushi showed no significant difference from those of control samples. However, mass loss of the sample coated with urushi was lower than that of the control sample especially for Sugurome-urushi (Tukey's test: p < 0.05). Results of Fourier transform infrared spectra analysis suggested that the degree of crosslinking reaction of Sugurome-urushi was higher than that of other urushi. The highest indentation stiffness was detected in the sample surface coated with Sugurome-urushi and Sugurome-urushi film, which have better ductile properties when compared with others. Moreover, the tangential section of Sugurome-urushi was smoother than that of the others. Increasing the hardness and smoothness of wood samples by coating with urushi could be effective in preventing termite penetration. which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

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Atomic force microscopy and infrared analysis of aging processes of polymer electrolyte membrane fuel cell components

Cited by 13 publications

References 26 publications

Atomic Force Microscopy on Cross Sections of Fuel Cell Membranes, Electrodes, and Membrane Electrode Assemblies

Atomic Force Microscopy on Cross Sections of Fuel Cell Membranes, Electrodes, and Membrane Electrode Assemblies

Growth of Sputtered Nanocomposite Alloys on Polymeric Substrates: The Role of the Substrate's Mechanical Hardness

Resistance of wood coated with oriental lacquer (urushi) against damage caused by subterranean termite

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