Vertically aligned carbon nanotubes as proton exchange membrane fuel cell catalyst support

The dependence of the morphology of metal-catalyzed vertically aligned carbon nanotube (VACNT) films on chemical vapor deposition (CVD) process procedures was examined. VACNT were synthesized using atmospheric pressure CVD of ethylene and ammonia at temperatures between 600°C and 900°C. The VACNT were grown on an iron film "wedge", ranging from 0 to 5 nm thickness over a 76 mm length, previously prepared on a SiO2/Si wafer substrate. Nanotube morphology as a function of position along the substrate was studied using SEM so that the impact of Fe thickness could be conveniently mapped in a single experiment with a particular growth condition. The VACNT forests were used as supports for sputtered Fe-C-N catalysts and the electrochemical characteristics of the annealed Fe-C-N catalysts on VACNT supports were measured by the Rotating Ring Disc Electrode (RRDE) technique.