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

A water stable proton-conducting material (NH 4 ) 5 [Zr 3 (OH) 3 F 6 (PO 4 ) 2 (HPO 4 )] ( ZrP ) was hydrothermally synthesized. The three-dimensional (3D) framework of ZrP is composed of ZrF 2 O 4 octahedra and H x PO 4 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. A water stable open-framework zirconium (iv) phosphate ( ZrP ) has a low anhydrous proton conductivity of 7.73 × 10 −7 S cm −1 at 220 °C, and a water assisted high proton conductivity of 4.41 × 10 −2 S cm −1 at 60 °C and 98% RH.