Proton exchange membrane fuel cells (PEMFCs) are an attractive technology for the green energy production. However, their use is limited due to the instability under working conditions of the materials commonly used as electrolyte (e.g.: the commercially used Nafion). Metal-Organic Frameworks (MOFs) has been recently proposed as a promising alternative. Their huge structural and chemical variety and their outstanding permanent porosity, make them excellent candidates as electrolyte for PEMFCs and for many other industrial applications.
In order to improve the properties of the electrolyte, in this work, we propose the insertion of natural proton carrier species into a MOF. Specifically, the lysine (Lys) amino acid was encapsulated for the first time in the porosity of the zirconium phosphonate UPG-1, resulting in the composite material denominated Lys@UPG-1. Both materials have been evaluated as proton conductors to use them as electrolytes in PEMFCs, presenting a moderate proton conductivity (10-4 S·cm-1). It is interesting to note that the Lys@UPG-1 composite shows an increased cyclability when compared with the pristine UPG-1 material, due to the stabilizing effect of the lysine.
(*) Vilela, S.M.F., Salcedo-Abraira, P., Gómez-Peña, A., Trens, P., Várez, A., Salles, F., Horcajada, P. Proton conductive Zr-phosphonate UPG-1-Aminoacid insertion as proton carrier stabilizer (2020) Molecules, 25 (15), art. no. 3519. DOI: 10.3390/molecules25153519.
More information: Patricia Horcajada, Senior researcher and head of the Advanced Porous Materials Unit, email@example.com
UPG-1 structure (a) and Lysine aminoacid (b)