TY - JOUR
T1 - Sublayered Thin Films of Hydrated Anion Exchange Ionomer for Fuel Cells Formed on SiO2 and Pt Substrates Analyzed by Neutron Reflectometry under Controlled Temperature and Humidity Conditions
AU - Kimura, Taro
AU - Kawamoto, Teppei
AU - Aoki, Makoto
AU - Mizusawa, Takako
AU - Yamada, Norifumi L.
AU - Miyatake, Kenji
AU - Inukai, Junji
N1 - Funding Information:
This work was partly supported by the New Energy and Industrial Technology Development Organization (NEDO) of Japan through funds for the “Advanced Research Program for Energy and Environmental Technologies”, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, through Grant-in-Aids for Scientific Research (18H02030, 18H05515, 18K19111), Japan Science and Technology (JST) through SICORP, and by the Iwatani Naoki Foundation. The NR experiments were performed as a project approved by the Japan Proton Accelerator Research Complex under User Program No. 2019A0257. The authors thank Prof. Donald A. Tryk of the University of Yamanashi for his valuable comments.
Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/5/12
Y1 - 2020/5/12
N2 - Anion-conductive ionomers are used for electrolyte membranes in membrane-electrode assemblies and for binders in catalyst layers in anion exchange membrane fuel cells (AEMFCs). The conformations of these ionomers as well as their water distribution are important for designing new efficient/durable anion-conductive ionomers for AEMFCs. For a deeper understanding of the distribution of deuterium oxide (D2O) as a function of depth, neutron reflectometry (NR) was carried out on thin films of an anion exchange ionomer, BAF-QAF, with a thickness of approximately 60 nm formed on a thermally formed SiO2 film on Si(100) and on a 20 nm Pt layer deposited on the SiO2 film at a temperature of 60 °C and relative humidities of 0, 50, 70, and 90%. Clear NR modulation was obtained under each condition. The NR data were fit very well with a three-sublayered model parallel to the substrate with different densities of BAF-QAF and D2O. The influence of the SiO2 and Pt substrates was observed not only at the BAF-QAF/substrate interface but also on the entire thin film. The D2O absorption/desorption behavior in each sublayer differed in the BAF-QAF films cast on SiO2 and Pt. The BAF-QAF/SiO2 interface was rather hydrophilic, while the BAF-QAF/Pt interface was very hydrophobic.
AB - Anion-conductive ionomers are used for electrolyte membranes in membrane-electrode assemblies and for binders in catalyst layers in anion exchange membrane fuel cells (AEMFCs). The conformations of these ionomers as well as their water distribution are important for designing new efficient/durable anion-conductive ionomers for AEMFCs. For a deeper understanding of the distribution of deuterium oxide (D2O) as a function of depth, neutron reflectometry (NR) was carried out on thin films of an anion exchange ionomer, BAF-QAF, with a thickness of approximately 60 nm formed on a thermally formed SiO2 film on Si(100) and on a 20 nm Pt layer deposited on the SiO2 film at a temperature of 60 °C and relative humidities of 0, 50, 70, and 90%. Clear NR modulation was obtained under each condition. The NR data were fit very well with a three-sublayered model parallel to the substrate with different densities of BAF-QAF and D2O. The influence of the SiO2 and Pt substrates was observed not only at the BAF-QAF/substrate interface but also on the entire thin film. The D2O absorption/desorption behavior in each sublayer differed in the BAF-QAF films cast on SiO2 and Pt. The BAF-QAF/SiO2 interface was rather hydrophilic, while the BAF-QAF/Pt interface was very hydrophobic.
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U2 - 10.1021/acs.langmuir.0c00440
DO - 10.1021/acs.langmuir.0c00440
M3 - Article
C2 - 32310665
AN - SCOPUS:85084693581
SN - 0743-7463
VL - 36
SP - 4955
EP - 4963
JO - Langmuir
JF - Langmuir
IS - 18
ER -