Carbon black functionalized by grafting of Azo-generated-radicals as electrocatalyst support for the oxygen reduction reaction

Abstract

Functionalization of the carbon support is a promising strategy for lowering platinum loadings at the cathode of proton exchange membrane fuel cells. Here, nitrogen-containing moieties are introduced directly onto carbon black by a simple and easily tunable grafting method initiated by the thermal decomposition of azo compounds in water. X-ray photoelectron spectroscopy (XPS) and elemental analysis confirm the successful functionalization. After deposition of Pt nanoparticles onto the carbon supports, the electrocatalysts are characterized in thin film rotating disk electrode (RDE) configuration towards the acidic oxygen reduction reaction (ORR). The grafting does not influence the Pt intrinsic ORR activity when the thin film does not include ionomer. However, the functionalization modifies the ionomer/carbon material interaction, leading to higher apparent ORR activity when the ionomer is included in the thin film. Moreover, accelerated stress testing shows durability enhancement as the result of grafting.