Crown-type tetranuclear Ag-POM exhibits excellent proton conductivity performance

A crown-type tetranuclear Ag-POM, Na24[Ag3.4Na0.6(As4W40O140)]·82H2O (1), was synthesized based on the structural features of {As4W40} using simple materials through the hydrothermal method. The polyanion of compound 1 consists of a tetranuclear silver cluster embedded in the cyclic ligand {As4W40} and the polyanions linked by Na+ to form a 3D framework. Moreover, compound 1 exhibits excellent proton conductivity, with an optimal conductivity of 2.24 × 10-2 S cm-1 at 90% RH, 358 K. Furthermore, it demonstrates outstanding cycling stability during heating-cooling cycles and durability over 68 h.