Improvement of Heat-Treated Fe/N/C-Based Catalysts for Oxygen Reduction in PEM Fuel Cells By Using New Carbon Black Powders as Catalyst Supports

Abstract

Several new developmental carbon blacks were prepared at the Sid Richardson Carbon Black Corporation by injecting ammonia, methane or water vapor in the carbon black furnace during their fabrication. These new carbon powders were then used to obtain Fe/N/C catalysts for oxygen reduction reaction (ORR) in the acidic conditions prevailing in PEM fuel cells. The best catalysts were obtained when ammonia and methane were injected in the carbon black furnace during its production. The results are interpreted in terms of structural changes induced in the carbon blacks during their fabrication. These changes influence their subsequent reaction rate with NH3 when the structurally modified carbon black supports, loaded with 0.2 wt% Fe, are heat-treated at 950 degrees Celcius in pure ammonia to obtain the catalysts. This etching reaction produces up to ten times more catalytic sites with these modified carbon blacks than with their respective regular forms.