Coherent anti-Stokes Raman scattering spectroscopy system for observation of water molecules in anion exchange membrane

Solomon Wekesa Wakolo; Atsushi Syouji; Masaru Sakai; Hiromichi Nishiyama; Junji Inukai

doi:10.1016/j.saa.2024.123875

Coherent anti-Stokes Raman scattering spectroscopy system for observation of water molecules in anion exchange membrane

Spectrochim Acta A Mol Biomol Spectrosc. 2024 Mar 15:309:123875. doi: 10.1016/j.saa.2024.123875. Epub 2024 Jan 9.

Authors

Solomon Wekesa Wakolo¹, Atsushi Syouji², Masaru Sakai³, Hiromichi Nishiyama⁴, Junji Inukai⁵

Affiliations

¹ Integrated Graduate School of Medicine, Engineering, and Agricultural Sciences, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan.
² Center for Basic Education in Faculty of Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan.
³ Faculty of Engineering, Graduate Faculty of Interdisciplinary Research, University of Yamanashi, 4-4-37 Kofu, Yamanashi 400-8510, Japan.
⁴ Hydrogen and Fuel Cell Nanomaterials Center, University of Yamanashi, 6-43 Miyamae, Kofu, Yamanashi 400-0021, Japan. Electronic address: hiromichi.nishiyama@jp.gs-yuasa.com.
⁵ Hydrogen and Fuel Cell Nanomaterials Center, University of Yamanashi, 6-43 Miyamae, Kofu, Yamanashi 400-0021, Japan; Clean Energy Research Center, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8510, Japan. Electronic address: jinukai@yamanashi.ac.jp.

PMID: 38217988
DOI: 10.1016/j.saa.2024.123875

Abstract

Anion exchange membrane fuel cells (AEMFCs) provide one of the most feasible remedies to fuel cells' dependency on the dwindling Pt group catalysts. Nevertheless, AEMFCs still suffer reduced durability, which requires an in-depth understanding of their membranes. The low thermal endurance of the anion exchange membranes (AEMs) usually limits the direct application of powerful techniques, such as Raman spectroscopy. We sought to establish a system for coherent anti-Stokes Raman scattering (CARS) spectroscopy capable of taking measurements inside an AEM rapidly and accurately without photodamage. A 785 nm CARS system was newly developed to study the water species in an AEM (QPAF-4) located vertically in a fuel cell. From the results of water measurement in a QPAF-4 membrane, the OH-related region was deconvoluted into nine Gaussian peaks: Five H-bonded OH peaks, non-H-bonded OH, OH^-, and two CH peaks. The H-bonded species increased with increasing relative humidity, but the other species remained constant. These results open unlimited possibilities for studying and comparing different AEMFCs, enabling more rapid technology optimization.

Keywords: Anion Exchange Membrane Fuel Cell; Coherent anti-Stokes Raman; OH Species of Water; Vertically Oriented Fuel Cell.