Carbon nanotubes based gas diffusion layers in direct methanol fuel cells

A carbon nanotube based gas diffusion layer (CNT-GDL) for direct methanol fuel cells (DMFCs) was prepared by sintering the wet carbon paper made of CNT, polyacrylonitrile-based carbon fibre (PCF) and PTFE, completely replacing the commercial carbon paper based GDL (Toray-GDL). The results of X-ray diffraction (XRD), scanning electron microscope (SEM) and mercury intrusion porosimeter (MIP) showed that CNT-GDL is of higher graphitization degree, more abundant pores in the pore diameter range of 1000–3000 nm and better mass transfer ability, compared with those of Toray-GDL. Electrochemical impedance spectroscopy (EIS) results display that the cell with CNT-GDL had better electrical conductivity and mass transfer ability than those of Toray-GDL. As a result, the limiting current density and peak power density of DMFC single cell with CNT-GDL are improved by 40% and 27%, respectively.