University of Oulu

Basso Peressut A, Di Virgilio M, Bombino A, Latorrata S, Muurinen E, Keiski RL, Dotelli G. Investigation of Sulfonated Graphene Oxide as the Base Material for Novel Proton Exchange Membranes. Molecules. 2022; 27(5):1507.

Investigation of sulfonated graphene oxide as the base material for novel proton exchange membranes

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Author: Peressut, Andrea Basso1; Di Virgilio, Matteo1; Bombino, Antonella1;
Organizations: 1Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano, Italy
2Environmental and Chemical Engineering Research Unit, Faculty of Technology, University of Oulu, Pentti Kaiteran katu 1, FI-90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 20.8 MB)
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Language: English
Published: Multidisciplinary Digital Publishing Institute, 2022
Publish Date: 2022-04-27


This work deals with the development of graphene oxide (GO)-based self-assembling membranes as possible innovative proton conductors to be used in polymer electrolyte membrane fuel cells (PEMFCs). Nowadays, the most adopted electrolyte is Chemours’ Nafion; however, it reveals significant deficiencies such as strong dehydration at high temperature and low humidity, which drastically reduces its proton conductivity. The presence of oxygenated moieties in the GO framework makes it suitable for functionalization, which is required to enhance the promising, but insufficient, proton-carrying features of GO. In this study, sulfonic acid groups (–SO₃H) that should favor proton transport were introduced in the membrane structure via a reaction between GO and concentrated sulfuric acid. Six acid-to-GO molar ratios were adopted in the synthesis procedure, giving rise to final products with different sulfonation degrees. All the prepared samples were characterized by means of TGA, ATR-FTIR and Raman spectroscopy, temperature-dependent XRD, SEM and EDX, which pointed out morphological and microstructural changes resulting from the functionalization stage, confirming its effectiveness. Regarding functional features, electrochemical impedance spectroscopy (EIS) as well as measurements of ion exchange capacity (IEC) were carried out to describe the behavior of the various samples, with pristine GO and commercial Nafion® 212 used as reference. EIS tests were performed at five different temperatures (20, 40, 60, 80 and 100 °C) under high (95%) and medium (42%) relative humidity conditions. Compared to both GO and Nafion® 212, the sulfonated specimens demonstrate an increase in the number of ion-carrying groups, as proved by both IEC and EIS tests, which reveal the enhanced proton conductivity of these novel membranes. Specifically, an acid-to-GO molar ratio of 10 produces a six-fold improvement of IEC (4.23 meq g⁻¹) with respect to pure GO (0.76 meq g⁻¹), while a maximum eight-fold improvement (5.72 meq g⁻¹) is achieved in SGO-15.

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Series: Molecules
ISSN: 1420-3049
ISSN-E: 1420-3049
ISSN-L: 1420-3049
Volume: 27
Issue: 5
Article number: 1507
DOI: 10.3390/molecules27051507
Type of Publication: A1 Journal article – refereed
Field of Science: 216 Materials engineering
Funding: This work was funded by the European Institute of Innovation and Technology (EIT) RawMaterials (Berlin, Germany), project ADMA2—practical training between academia and the industry during doctoral studies, grant number 18252.
Copyright information: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (