Proton conduction of DNA–imidazole composite material under anhydrous condition

Abstract

Materials with high anhydrous proton conduction at intermediate temperatures (100–200 °C) have attracted remarkable interest for applications in a polymer electrolyte membrane fuel cell (PEMFC). Especially, for the development of PEMFC technology, an anhydrous proton-conductive material, which is low cost and benign for the environment, has been desired. In this study, an anhydrous proton conductor was prepared by mixing double-stranded DNA (dsDNA), the most important genetic material of living organisms, and the imidazole (Im) molecule, a heterocyclic molecule. This DNA–Im composite material showed a thermal stability owing to electrostatic interaction between the phosphate group of DNA and −N= group of the Im molecule. In addition, DNA–Im showed an anhydrous proton conduction of 5.2 × 10−3 S cm−1 at intermediate temperature. On the other hand, the single-stranded DNA–Im composite material did not show high anhydrous proton conduction. Therefore, the high anhydrous proton conduction in dsDNA–Im composite material was due to the arrangement of phosphate groups along the one-dimensional molecular chain. These results suggested that the DNA–Im composite material possesses two proton-conducting pathways in the composite material. An anhydrous proton conductor was prepared by mixing with double-stranded DNA (dsDNA), the most important genetic material of living organisms, and the imidazole (Im) molecule, one of the heterocyclic molecules. This DNA–Im showed an anhydrous proton conduction of 5.2×10−3 S cm−1 at the intermediate temperature. On the other hand, the single-stranded DNA–Im composite material did not show the high anhydrous proton conduction. Therefore, the high anhydrous proton conduction in dsDNA–Im composite material was due to the arrangement of phosphate groups along the one-dimensional molecular chain.