Water assisted high proton conductance in a pure-inorganic framework vanadoborate

Abstract

A new pure-inorganic framework vanadoborate H₁₀[V₁₂B₁₈O₅₄(OH)₆]·20H₂O (1) was hydrothermally synthesized and structurally characterized. Its inorganic framework was constructed by discrete [V₁₂B₁₈O₅₄(OH)₆]¹⁰⁻ polyanion clusters decorated with H⁺ as a counterion. For 1, the abundant water molecules in its one-dimensional (1D) channels, together with pure H⁺ and –OH groups from its framework, cooperate to create a continuous hydrogen bond network. Pure H⁺ and extensive H-bonds in the framework facilitate fast proton conduction, and endow this compound with a good proton conductivity of 2.36 × 10⁻³ S cm⁻¹ at 353 K and 100% RH, which is ultra-high for vanadoborate-based proton-conducting materials and also can compete with those of numerous state-of-the-art MOF-based proton conductors.