Chitosan-based composite membranes containing chitosan-coated carbon nanotubes for polymer electrolyte membranes

Considering the poor dispersion and inert ionic conduction ability of carbon nanotubes (CNTs), functionalization of CNTs is a critical issue for their application in polymer electrolyte membranes. Herein, CNTs were functionalized by the polyelectrolyte, chitosan (CS), via a facile noncovalent surface-deposition method. The obtained CS-coated CNTs (CS@CNTs) were then incorporated into the CS matrix and fabricated composite membranes. The CS coating can enhance the compatibility between CNTs and the matrix, thus ensuring the homogenous dispersion of CS@CNTs and effectively improved the mechanical properties of the composites. Moreover, the CS coating can make CS@CNTs act as an additional proton-conducting pathway through the membranes. The CS/CS@CNTs-1 composite shows the highest proton conductivity of 3.46x10(-2)S cm(-1) at 80 degrees C, which is about 1.5-fold of the conductivity of pure CS membrane. Consequently, the single cell equipped with CS/CS@CNTs-1 membrane exhibits a peak power density of 47.5mWcm(-2), which is higher than that of pure CS (36.1 mWcm(-2)).