Imidazolium-Quaternized Poly(2,6-Dimethyl-1,4-Phenylene Oxide)/Zeolitic Imidazole Framework-8 Composite Membrane as Polymer Electrolyte for Fuel-Cell Application

Thabakgolo T Letsau; Penny P Govender; Phumlani F Msomi

doi:10.3390/polym14030595

Imidazolium-Quaternized Poly(2,6-Dimethyl-1,4-Phenylene Oxide)/Zeolitic Imidazole Framework-8 Composite Membrane as Polymer Electrolyte for Fuel-Cell Application

Polymers (Basel). 2022 Feb 1;14(3):595. doi: 10.3390/polym14030595.

Authors

Thabakgolo T Letsau^{1

2

3}, Penny P Govender¹, Phumlani F Msomi^{1

2

3}

Affiliations

¹ Department of Chemical Science, University of Johannesburg, Johannesburg 2028, South Africa.
² Research Centre for Synthesis and Catalysis, Department of Chemical Sciences, University of Johannesburg, Johannesburg 2028, South Africa.
³ Centre for Nanomaterials Science Research, University of Johannesburg, Johannesburg 2028, South Africa.

Abstract

Anion exchange membrane fuel cells (AEMFCs) are considered superior to their counterpart proton exchange fuel cells due to their many advantages. Both fuel cells use membranes as polymer electrolytes to improve fuel-cell properties and power output. This work evaluates a series of imidazolium-quaternized poly(2,6-dimethyl-1,4-phenylene oxide) (ImPPO) functionalized zeolitic imidazole framework-8 (ZIF-8) (ImPPO/ZIF-8) as anion exchange membrane (AEM) electrolytes in a direct methanol alkaline fuel cell. FTIR and ¹H NMR were used to confirm the successful membrane fabrication. SEM and TGA were used to study the morphological and thermal stability properties of the ImPPO/ZIF-8 membranes. The AEMs obtained in this work had contact angles ranging from 55.27-106.73°, water uptake from 9-83%, ion exchange capacity (IEC) from 1.93-3.15 mmol/g, and ion conductivity (IC) from 1.02-2.43 mS/cm. The best-performing membrane, ImPPO/3%ZIF-8, showed a water uptake of up to 35% at 80 °C, a swelling ratio of 15.1% after 72 h, IEC of 4.06 mmol/g, and IC of 1.96 mS/cm. A power density of 158.10 mW/cm² was obtained. This makes ZIF-8 a good prospect as a filler for enhancing membrane properties.

Keywords: anion exchange membrane; direct methanol alkaline fuel cell; imidazolium quaternized; inorganic-organic hybrid membrane; poly(2,6-dimethyl-1,4-phenylene oxide); zeolitic imidazole framework-8 (ZIF-8).