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 Na 2 (H 3 O) 6 [{Ru IV (bpy)} 2 {WO 2 (C 2 O 4 )} 2 (GeW 11 O 39 ) 2 ]·27H 2 O (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 ({RuC 10 H 8 N 2 } 4+ and {WC 2 O 4 } 4+ ), hydrated protons (H 3 O + ), and crystal waters.