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Investigation of proton dynamics and the proton transport pathway in choline dihydrogen phosphate using solid-state NMR
journal contribution
posted on 2010-01-01, 00:00 authored by L Cahill, U Rana, Maria ForsythMaria Forsyth, M SmithCholine dihydrogen phosphate has previously been shown to be a good ionic conductor as well as an excellent host for acid doping, leading to high proton conductivities required for e.g., electrochemical devices including proton membrane fuel cells and sensors. A combination of variable-temperature 1H solid-state NMR and 2D NMR pulse sequences, including 31P and 13C CODEX and 1H BaBa, show that the proton conduction mechanism primarily involves assisted transport via a restricted three-site motion of the phosphate unit around the P–O bond that is hydrogen bonded to the choline and exchange of protons between these anions. In other words, proton transport at ambient temperatures appears to occur most favorably along the crystallographic b axis, from phosphate dimer to dimer. At elevated temperatures exchange between the protons of the hydroxyl group on the choline cation and the hydrogen-bonded dihydrogen phosphate groups also contributes to the structural diffusion of the protons in this solid state conductor.
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Journal
Physical chemistry chemical physicsVolume
12Issue
20Pagination
5431 - 5438Publisher
Royal Society of ChemistryLocation
Cambridge, EnglandPublisher DOI
ISSN
1463-9076eISSN
1463-9084Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2010, Owner SocietiesUsage metrics
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