Graphene-Supported Pt, Ir, and Pt-Ir Nanoparticles as Electrocatalysts for the Oxidation of Ammonia

Graphene oxide nanosheets are used as a support to anchor metal ions and produce graphene-metal nanoparticle hybrids in a sol-gel method. The influence of experimental conditions on the features of graphene-supported Pt, Ir, and Pt-Ir alloy nanoparticles is studied using transmission electron microscopy. Good dispersion of metal nanoparticles on the graphene sheets are observed for the catalysts heat-treated under exposure to N-2 gas. The existence of metal species with zero oxidation state in the prepared catalysts is evident from the X-ray photoelectron spectroscopy. The characteristic X-ray diffraction peaks of Pt are observed for the graphene-supported Pt and Pt-Ir catalysts. Electrochemical activity of the finely dispersed catalysts toward ammonia oxidation is investigated using cyclic voltammetry. The performance increased in the order Ir < Pt a parts per thousand Pt-Ir.