Ionic Diode Current Rectification in High Salt Media with Sulfonated Poly(oxy‐1,4‐phenylene‐oxy‐1,4‐phenylenecarbonyl‐1,4‐phenylene)

Sulfonated poly(oxy‐1,4‐phenylene‐oxy‐1,4‐phenylenecarbonyl‐1,4‐phenylene) also known as SPEEK is a chemically robust cation conductor with good solution processability. A thin film (approx. 0.7 μm) coated asymmetrically over a 10 μm diameter microhole in a Teflon substrate film (5 μm thickness) pro...

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Bibliographic Details
Published in:ChemElectroChem 2024-10, Vol.11 (19), p.n/a
Main Authors: Sharma, Chhavi, Dale, Sara E. C., Mathwig, Klaus, Zevenbergen, Marcel A. G., Li, Zhongkai, E., Bhuvanesh, Parida, Kaushik, Negi, Yuvraj Singh, Marken, Frank
Format: Article
Language:English
Subjects:
Aqueous electrolytes
Cationic polymerization
Desalination
Ionic circuits
Ionic logic
Ionic strength
Ionomers
Lithium chloride
Low currents
Magnesium chloride
Nanofluidic diode
Polarization
Polytetrafluoroethylene
Sodium chloride
Substrates
Thickness
Thin films
Voltammetry
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Summary:Sulfonated poly(oxy‐1,4‐phenylene‐oxy‐1,4‐phenylenecarbonyl‐1,4‐phenylene) also known as SPEEK is a chemically robust cation conductor with good solution processability. A thin film (approx. 0.7 μm) coated asymmetrically over a 10 μm diameter microhole in a Teflon substrate film (5 μm thickness) produces ionic diode effects in aqueous electrolyte media even at high ionic strengths up to 2 M NaCl. The enhancement in the ionic diode performance under high salt conditions is tentatively attributed to a (partial) switch from a concentration polarisation effect (dominant for high diode currents) to interfacial polarisation (dominant at low current; proposed for molecularly rigid ionomers). Ionic strength effects on the diode performance seem relatively low further indicative of a mechanism for the diode effect caused by interfacial polarisation without significant concentration polarisation. Preliminary comparison of diode phenomena in aqueous HCl, LiCl, NaCl, and MgCl2 reveals cation specific effects due to interaction with the polymer. High‐salt conditions are challenging for desalination and selective ion removal via ionic diode mechanisms. Here, current rectification with ionic diodes based on SPEEK ionomer is demonstrated up to aqueous 2 M NaCl and attributed to a change in mechanism form concentration polarisation to interfacial polarisation effects.
ISSN:2196-0216
2196-0216
DOI:10.1002/celc.202400411