| Heteropoly acids (HPAs) are a fascinating kind of inorganic metal-oxygen cluster compounds. They play very important roles in catalysis, biology, electrochemistry and materials science as a consequence of their variety of physicochemical properties. The design and synthesis of HP As and their derivatives have widely attracted researchers’ attention.Two ternary heteropoly acids H7ZnW11VO40·8H2O (ZnW11V) and H5[In(H2O)SiW11O39]·8H2O (SiW11In) were firstly synthesized by the stepwise acidification, stepwise addition of solutions of the component elements as well as ion exchanging method. They were characterized by the IR, UV, XRD, TG-DTA and EIS. The results of EIS show that ZnW11V and SiW11In exhibit proton conductivities more than 10-4 S·cm-1 at 18 ℃, so they are new kind of solid proton conductor. Their proton conduction proceeds by Vehicle mechanism.Moreover, a series of reversible phase transformation tungstovanadosilicate-based ionic liquids, [MIMPS]5SiW11VO40, [MIMPS]7SiW9V3O40, [PyPS]5SiW11VO40, [PyPS]7SiW9V3040, [TEAPS]5SiW11V040, [TEAPS]7SiW9V3O40 and [TBTP]5SiW11VO40 were synthesized from 1-(3-sulfonic group) propyl-3-methyl imidazolium (MIMPS), 1-(3-sulfonic group) propyl-pyridine (PyPS), 1-(3-sulfonic group) propyl-triethylammonium (TEAPS), tributyltetradecylphosphonium chloride (TBTPC) and H5SiW11VO40, H7SiW9V3O40. Their structure, thermostability and electrochemical properties were investigated. More vanadium atoms in the molecule will bring about greater oxidability and lower thermostability, besides, SO3-based ionic liquids show higher conductivity than the phosphonium-based ionic liquid. The products can undergo a reversible phase transformation from quasi-solid state to liquid state below 100 ℃, and above the phase transition temperature the conductivities of the products increased apparently. Ionic conductivity up to 10-4-10-3 S·cm-1 was observed at high temperature for these ionic liquid compounds. |
PDF Full Text Request