Effect of surface modification for the growth of multi-walled carbon nanotubes on carbon paper for proton exchange membrane fuel cells

Gas Diffusion Layers (GDL) were fabricated with carbon paper substrate and multi-walled carbon nanotubes (MWCNTs) grown in situ as microporous layer by chemical vapor deposition (CVD) process. In order to nucleate, various nano-oxides viz., aerosil-380, hydrophilic silica, hydrophobic silica, Al ₂O ₃ and a mixed oxide (Al ₂O ₃ and SiO ₂) and TiO ₂ were evaluated for optimum growth of MWCNTs. The GDL samples with the MWCNTs were characterized by surface morphology, and wetting characteristics using a scanning electron microscope and goniometer, respectively. Pt nanocatalyst was deposited on the MWCNTs both for anode and cathode. The fuel cell performance of the Pt/MWCNTs/carbon paper cathodes was evaluated by using PEMFC with H ₂/O ₂ and H ₂/air, at 80°C and at different RH conditions using Nafion-212 electrolyte. Al ₂O ₃ led to homogenous growth of MWCNTs and the GDL exhibited the maximum performance. The in-situ Pt/CNT/carbon paper electrodes showed 1 and 0.5 W.cm ^-2 with H ₂/O ₂ and H ₂/air, respectively.