CsHSO4 — Proton conduction in a crystalline metal–organic framework

The approach, combining metal–organic frameworks and functional guests such as proton conductors of MmHn(XO4)p family has been proposed and successfully realized in the (1 − x)CsHSO4–xCr-MIL-101 nanocomposites. − x)CsHSO4–xCr-MIL-101 (x = 0–0.07) hybrid compounds with unusual transport, structural and thermodynamic properties have been synthesized and investigated by impedance, infrared spectroscopy and XRD methods. The addition of the nonconducting matrix to CsHSO4 results in decrease of the temperature of superionic phase transition and considerable increase (up to 2 orders of magnitude) of proton conductivity of CsHSO4 in low temperature phase due to its disordered state in cavities of Cr-MIL-101 with the maximum conductivity at x = 0.02–0.04. As a result (1 − x)CsHSO4–xCr-MIL-101 nanocomposites have proton conductivity 10− 7–10− 2 S/cm at temperatures 50–200 °C and thermal stability up to 190 °C. Nanocomposite effect is similar to known CsHSO4–SiO2 and CsHSO4–TiO2 systems, however is not so high. The used approach may be perspective for the other composite systems with proton conductivity.