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

      Salcedo, Inés R.; Colodrero, Rosario MP; Bazaga-García, Montse; López-González, M; Del Río, Carmen; Xanthopoulos, Konstantinos; Demadis, Konstantinos D.; Hix, Gary B.; Furasova, Aleksandra D; Choquesillo-Lazarte, Duane; et al. (American Chemical Society (ACS), 2021-03-25)
      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 the presence of sulfate ions. Two families of materials are isolated and 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) and [Ln(H5NMP)]SO4·2H2O (Ln = Pr, Nd, Eu, Gd, Tb; Series II). Eu/Tb bimetallic solid solutions are also prepared for photoluminescence studies. Members of families I and II display high proton conductivity (10–3 and 10–2 S·cm–1 at 80 °C and 95% relative humidity) and are studied as fillers for Nafion-based composite membranes in PEMFCs, under operating conditions. Composite membranes exhibit higher power and current densities than the pristine Nafion membrane working in the range of 70–90 °C and 100% relative humidity and with similar proton conductivity.