Construction of Strandberg‐Type Polyoxometalate‐Based Inorganic‐Organic Hybrid Material with Water‐Assisted Proton Conductivity

Polyoxometalates (POMs) were widely applied in the field of proton conduction due to their rapid charge transfer capability and large proton capacity. The Strandberg‐type POM has small size and large charge density, can form functional organometallic compounds with metal ions. In this study, by using [P2Mo5O23]6− coordinate with the cobalt ion with cytosine as the structure‐directing agent, a compound of Co1.5(C4H6N3O)3[P2Mo5O23]⋅8.5H2O was synthesized, which showed one‐dimensional chain structure and exhibits proton conductivity of 3.62 × 10−4 S cm−1 at 98 °C and 97% RH. The amino group and nitrogen atoms in the cytosine can form hydrogen bond with the coordination water molecules. Meanwhile, the hydrogen bond network can also be formed between the water molecules, which is one of the main factors for proton conduction performance. The compound Co1.5(C4H6N3O)3[P2Mo5O23]⋅8.5H2O exhibited the corresponding activation energies and conduction mechanisms at different temperature intervals, by analyzing the temperature‐dependent PXRD spectrum under high‐humidity conditions, which showed the hydrogen bond network of the crystal during the temperature changes affects its proton conduction performance. Inorganic‐organic hybrid material as a solid electrolyte. {P2Mo5}‐based coordination polymer with Co2+ exhibits good proton conductivity with 3.62 × 10−4 S cm−1. Rearrangement of the hydrogen bond network allows the sample to have different activation energies at different temperatures.