Imidazole-doped nanocrystalline cellulose solid proton conductor: synthesis, thermal properties, and conductivity

A new proton conducting material with a possible application as a membrane in fuel cells is synthesized. It is formed by nanocrystalline cellulose (NCC) doped with a different concentration of the imidazole molecules (Im) used as "dry" conducting species. The nanocomposites (NCC-Im) are obtained in the form of films. Their chemical composition, thermal properties, and the electric conductivity are determined by elementary and thermogravimetric analysis, differential scanning calorimetry and impedance spectroscopy methods, respectively. The nanocomposite (1.7NCC-Im) with the highest concentration of imidazole i.e. one Im per 1.7 glucose unit shows the highest electrical conductivity equal to 2.7 × 10−2 S/m at 140 °C. This value is about five orders of magnitude higher than that of the pure NCC film at this same temperature. The important feature is that it is obtained for nanocomposite under anhydrous conditions.