A water-stable open-framework zirconium(IV) phosphate and its water-assisted high proton conductivity

A water stable proton-conducting material (NH4)5[Zr3(OH)3F6(PO4)2(HPO4)] (ZrP) was hydrothermally synthesized. The three-dimensional (3D) framework of ZrP is composed of ZrF2O4 octahedra and HxPO4 phosphate units forming 18-ring channels through sharing oxygen atoms. Ammonium cations charge balance the anionic framework. Alternating current (AC) impedance measurements on ZrP powder samples show that at 25–60 °C and 98% relative humidity (RH), the proton conductivity is around 10−2 S cm−1, and the activation energy (Ea) is 0.33 eV.