Chitosan‑based electrolytes containing carbon nanotube‑titanium dioxide for energy conversion devices applications

Abstract

Polymer membranes based on natural polymer chitosan (CH) and variable content of carbon nanotube-titanium dioxide (CNT-TiO2) composites were prepared by solvent casting at room temperature. The interest in natural polymers is enormous due to the depletion of oil and natural gas resources. Furthermore, the use of biodegradable biopolymers reduces the environmental impact of the disposal and avoids the long-term degradation of synthetic polymers. The thermal, morphological and electrochemical properties of the membranes were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarized optical microscopy (POM) and complex impedance spectroscopy. The obtained results revealed a predominantly semi-crystalline morphology and a satisfactory ionic conductivity. The sample with the highest conductivity was CH-20CNT-TiO2-0.05, which attained 1.22 x 10(-4) S cm(-1) at 90 degrees C. The significant effect of glycerol as a plasticizer on the conductivity of the materials was studied. The combination of Pt-based catalysts with TiO2 led to a conductivity increase (90 x 10(-3) S cm(-1) at 90 degrees C). The conductivity measurements in the obtained composites allowed some evidence to be considered for the influence of CNT-TiO2 in the transfer of current through the CH matrix. The encouraging properties (conductivity, thermal behaviour, morphology) of the samples lead us to suggest the incorporation of these materials as electrolytes in solid electrochemical devices. Composite membranes that are environmentally friendly and have attractive properties are developed for energy conversion device applications.