ISIS Neutron and Muon Source Data Journal

Probing Proton Dynamics in Phosphoric Acid-Doped PIM-based Composite Membranes Using Quasi-Elastic Neutron Scattering

Abstract: Proton transport in polymer electrolyte membranes depends on the coupled dynamics of the polymer matrix, absorbed molecules, and ionic carriers. In low-temperature PEMs water dominates, while high-temperature systems rely on phosphoric acid, improving tolerance but leaving open questions on conduction mechanisms. To address these, we will apply quasi-elastic neutron scattering (QENS), which offers micro-electronvolt resolution and sensitivity to hydrogen, to phosphoric acid-doped PVP/PIM composite membranes developed for HT-PEMFCs. These microporous membranes show excellent conductivity and stability, yet the roles of polymer, confined water, and acid remain unclear. Experiments will be performed on IRIS (ISIS), a mid-resolution spectrometer with a 30 100 ps dynamic window suited to proton and molecular motions. Membranes will be studied in dry, hydrated (H O, D O), and acid-doped (H PO , D PO ) states, both at room temperature and at elevated conditions (60 C for water, 150 C for acid) to reflect operation. Isotopic substitution will disentangle polymer, water, and acid contributions. Combined with molecular dynamics simulations, the results will yield relaxation times and diffusion coefficients, providing molecular-level insight into ion transport and guiding the design of durable membranes for fuel cell applications.

Principal Investigator: Dr Zhiming Feng
Experimenter: Professor Stuart Holmes
Experimenter: Dr Heng Zhai
Experimenter: Dr Marta Falkowska
Local Contact: Dr Ian Silverwood
Experimenter: Mr Xiaochen Yang
Experimenter: Dr Maria Perez-Page
Experimenter: Mr Rukang Guo

DOI: 10.5286/ISIS.E.RB2610482

ISIS Experiment Number: RB2610482

Publisher: STFC ISIS Neutron and Muon Source

Data format: RAW/Nexus
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Data Citation

The recommended format for citing this dataset in a research publication is as:
[author], [date], [title], [publisher], [doi]

For Example:
Dr Zhiming Feng et al; (2026): Probing Proton Dynamics in Phosphoric Acid-Doped PIM-based Composite Membranes Using Quasi-Elastic Neutron Scattering, STFC ISIS Neutron and Muon Source, https://doi.org/10.5286/ISIS.E.RB2610482

Data is released under the CC-BY-4.0 license.