Phase Transformation Dynamics in Sulfate-Loaded Lanthanide Triphosphonates. Proton Conductivity and Application as Fillers in PEMFCs

Phase transformation dynamics and proton conduction properties are reported for cationic layer-featured coordination polymers derived from the combination of lanthanide ions (Ln3+) with nitrilo-tris(methylenephosphonic acid) (H6NMP) in presence sulfate ions. Two families materials isolated structurally characterized, i.e., [Ln2(H4NMP)2(H2O)4](HSO4)2·nH2O (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Er, Yb; n 4-5, Series I) [Ln(H5NMP)]SO4·2H2O Tb; II). Eu/Tb bimetallic solid solutions also prepared photoluminescence studies. Members I II display high conductivity (10-3 10-2 S·cm-1 at 80 °C 95% relative humidity) studied as fillers Nafion-based composite membranes PEMFCs, under operating conditions. Composite exhibit higher power current densities than pristine Nafion membrane working range 70-90 100% humidity similar conductivity.