Wain, A J; Smith, G (2025) Monitoring Carbonate and Bicarbonate within an Anion Exchange Membrane during Self-Purge Using Infrared Spectroelectrochemistry. ACS Electrochemistry, 1 (9). pp. 1794-1802. ISSN 2997-0571

Full text not available from this repository.

Abstract

The carbonation of anion exchange membranes (AEMs) upon exposure to atmospheric CO2 can have a significant impact on their performance in electrochemical energy technologies since the replacement of OH- anion charge carriers with less mobile HCO3- and CO32- results in a loss of ionic conductivity. In the case of AEM fuel cells (AEMFCs) this is in part mitigated against by the self-purge mechanism, in which oxygen reduction at the cathode replenishes the lost OH-. While this process is reasonably well-understood, it is not clear what the speciation of HCO3- and CO32- is within and AEM under operating conditions and how this is correlated with membrane ion conductivity. In this work we developed a spectroelectrochemical method based on attenuated total reflection – infrared (ATR-IR) spectroscopy enabling estimation of the relative concentration of HCO3- and CO32- anions within an AEM during the self-purge reaction alongside periodic measurement of ionic conductivity. We show that for the AEM PiperION (HCO3- form), the self-purging behaviour is qualitatively similar to that observed during chemical anion exchange with 1 M KOH, in which HCO3- anions are rapidly converted to CO32- followed by the much slower displacement of CO32- by OH-. The equilibrated in-plane membrane conductivity measured at currents of 20 µm – 100 µm is shown to correlate well with the relative CO32- concentration. The method presented offers insights into the transient behaviour of AEMs in the context of anion exchange and self-purging, thus offering a route to a more complete understanding of AEM performance.

Item Type:	Article
Subjects:	Advanced Materials > Electrochemistry
Divisions:	Electromagnetic & Electrochemical Technologies
Identification number/DOI:	10.1021/acselectrochem.5c00163
Last Modified:	16 Sep 2026 13:57
URI:	https://eprintspublications.npl.co.uk/id/eprint/10532