Gas diffusion layers for proton exchange membrane fuel cells using in situ modified carbon papers with multi-walled carbon nanotubes nanoforest

Gas diffusion layers (GDLs) in the proton exchange membrane fuel cells (PEMFCs) enable the distribution of reactant gases to the reaction zone in the catalyst layers by controlling the water in the pore channels apart from providing electrical and mechanical support to the membrane electrode assembly (MEA). In the present work, we report the in situ growth of carbon nanotubes nanoforest (CNN) directly onto macro-porous carbon paper substrates. The surface property as analysed by a Goniometer showed that the CNN/carbon paper surface is highly hydrophobic. CNN/carbon paper was employed as a GDL in an MEA using Nafion-212 membrane as an electrolyte and evaluated in single cell PEMFCs. While the GDLs prepared by wire-rod coating process have major performance losses at lower humidities, the in situ CNN/carbon paper, developed in this work, shows very stable performance at all humidity conditions demonstrating a significant improvement for fuel cell performance. The CNN/carbon-based MEAs showed very stable performance with power density values of-1,100 and 550 mW cm ^-2, respectively, both using O₂ and air as oxidants at ambient pressure.