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

Abstract

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 H_xPO₄ 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 (E_a) is 0.33 eV.