Controllable Synthesis and Ultrahigh Proton Conduction of a Hydrogen-Bond Network

The functionalization of polyoxometalates with organic ligands provides a new-style strategy to accurately incorporate polyoxometalates with advanced functional organic moieties on their surfaces, the development of which has attracted increasing research interest due to the potential applications. A germanium tungstate Na2(H3O)6[{RuIV(bpy)}2{WO2(C2O4)}2(GeW11O39)2]·27H2O (bpy = 2,2′-bipyridine) with two ligands covalently modified was triumphantly synthesized, using the conventional one-pot hydrothermal method. It was systematically characterized by thermogravimetric analysis (TGA), elemental analysis, infrared (IR) spectroscopy, single-crystal X-ray diffraction, X-ray photoelectron spectroscopy (XPS), powder diffraction (PXRD), scanning electronic microscopy (SEM), and ultraviolet–visible (UV–vis) spectroscopy. The two-dimensional (2D) layered structure was established through hydrogen bonding and Na+ bridges. Impedance measurements indicate that it displays outstanding proton conduction properties, with a splendid conductivity up to 1.24 × 10–2 S·cm–1 under 353 K and 90% relative humidity (RH), owing to the rich interlayer hydrogen-bond network formed by the organic ligands ({RuC10H8N2}4+ and {WC2O4}4+), hydrated protons (H3O+), and crystal waters.