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Please use this identifier to cite or link to this item: http://hdl.handle.net/10119/17075

Title: Cross-Correlated Humidity Dependent Structural Evolution of Nafion Thin Film Confined on Platinum Substrate
Authors: Shrivastava, Udit N.
Suetsugu, Kota
Nagano, Shusaku
Fritzsche, Helmut
Nagao, Yuki
Karan, Kunal
Issue Date: 2019-12-16
Publisher: Royal Society of Chemistry
Magazine name: Soft Matter
Volume: 16
Number: 5
Start page: 1190
End page: 1200
DOI: http://dx.doi.org/10.1039/C9SM01731C
Abstract: Nanometer thin films of Nafion ionomer interfacing with platinum form the functional electrode in many electrochemical devices including fuel cells and electrolyzers. To impart facile proton conduction in Nafion ionomer, sufficient hydration of Nafion ionomer is necessary to create a percolating network of water-filled nanometer sized hydrophilic domains that manifests as macroscopic swelling. This hydration behavior of ionomer thin films is poorly understood especially for films confined on electrochemically relevant Pt substrates. In this work, we present the evolution of hydration-dependent microscopic hydrophilic domains and macroscopic expansion of 55 nm thin Nafion film on a Pt substrate. The cross-correlation among the film macro-expansion from ellipsometry, the micro-expansion from GISAXS, and the water distribution from neutron reflectometry (NR), explains the observed non-affine behavior of the film which can be attributed to the randomly and spatially non-uniform distribution of water domains. A correlation between macroscopic factor (ε/τ) for protonic conductivity, and the domain size and swelling is presented for the first time. In addition, interfacial water between Pt and the ionomer interface estimated at 75% and 84% RH, and increase in domain size with RH, are discussed to explain increased activity and oxygen diffusivity with RH.
Rights: Copyright (C) 2019 Royal Society of Chemistry. Udit N. Shrivastava, Kota Suetsugu, Shusaku Nagano, Helmut Fritzsche, Yuki Nagao, Kunal Karan, Soft Matter, 16(5), 2019, 1190-1200. http://dx.doi.org/http://dx.doi.org/10.1039/C9SM01731C.
URI: http://hdl.handle.net/10119/17075
Material Type: author
Appears in Collections:c10-1. 雑誌掲載論文 (Journal Articles)

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