Efficient Proton Conductor Based on Bismuth Oxide Clusters and Polyoxometalates.

Developing new solid-state electrolyte materials for improving the proton conductivity remains an important challenge. Herein, a novel two-dimensional layered solid-state proton conductor Bi 2 O 2 -SiW 12 nanocomposite, based on silicotungstic acid (H 4 SiW 12 O 40 ) and Bi(NO 3 ) 3 ·5H 2 O, was synthesized and characterized. The composite consists of a layered cation framework [Bi 2 O 2 ] 2+ and interlayer-embedded counteranionic [SiW 12 O 40 ] 4- , which forms continuous hydrogen bond (O-H···O) networks through the interaction of adjacent oxygen atoms on the surface of the [Bi 2 O 2 ] 2+ and oxygen atoms of the H 4 SiW 12 O 40 . Facile proton transfer along these pathways endows the Bi 2 O 2 -SiW 12 (30:1) nanocomposite with an excellent proton conductivity of 3.61 mS cm -1 at 90 °C and 95% relative humidity, indicating that the nanocomposite has good prospects as a highly efficient proton conductor.