Proton conductive watery channels constructed by in situ generated 3D lanthanide connected monolacunary polyoxometalate

Recently, research on lanthanide based polyoxometalates serving as a new type of proton conducting material holds tremendous promise for electrochemical devices. Herein, we have designed and characterized a new type 3D lanthanide silicotungstic acid proton conductor, namely La0.67(H2O)La(H2O)6 [{La(H2O)3(SiW11O39)}]·7H2O (1) under hydrothermal conditions. Compound 1 is a three-dimensional structure built from lanthanide-substituted polyoxoanion [{La(H2O)3(SiW11O39)}]5− building blocks with large number of channels filled with free water molecules. It shows a high proton conductivity of 1.26 × 10−3 S cm−1 at 90 °C under 98% RH. The activation energy of compound 1 calculated from the Arrhenius plots of the proton conductivity is 0.57 eV, which indicated the vehicle mechanism of proton transfer.