Nitrogen functionalized carbon black: A support for Pt nanoparticle catalysts with narrow size dispersion and high surface area

Abstract

Amorphous carbon is widely used as a support for Pt nanoparticle catalysts. We show here that catalytic performance can be greatly improved by functionalizing the carbon support with a nitrogen-containing molecule, in conjunction with a new method for the in situ synthesis of nanocrystalline Pt. Vulcan® carbon black is covalently functionalized with 4-aminomethylpyridine (4AMP) via formation of an acid chloride on the surface followed by amidation. The resulting 4AMP-functionalized Vulcan® (4AMP-VC) was thoroughly characterized and shown to contain N at the surface of the Vulcan® carbon support. Pt nanoparticles grown on the 4AMP-VC have a smaller average size and much narrower size distribution than Pt nanoparticles grown on bare Vulcan® (VC). In addition, the Pt/4AMP-VC catalysts show higher catalytic activity and are more durable than their Pt/VC counterparts. We infer through careful analysis of X-ray photoelectron spectra that the Pt nanoparticles bind preferentially to the pyridinic nitrogen of the 4AMP.