Investigation of the Electrocatalytic Properties of Spherical Palladium Nanoparticles and Palladium(100)iridium Bimetallic Nanocomposites towards Ammonia Electrooxidation on Pt Electrodes

摘要

The electrocatalytic properties of cubic palladium-iridium {Pd(100)Ir} bimetallic nanocomposite andspherical nanoparticles {Pd NPs} towards the electrochemical oxidation of ammonia were investigatedin sodium hydroxide on platinum electrode. Interrogation of their electrocatalytic properties throughcyclic and square wave voltammetric techniques (CV and SWV)) revealed that the bimetallicnanocomposite {Pd(100)Ir} has better conductivity and higher catalytic activity as evidenced by the-4 maximum current density reached for NH3 oxidation at 1.9838 x 10 A with a decreased onset-4potential. The Pd NPs gave a maximum catalytic current value of 1.45 x 10 A. This was furthervalidated by the results from electrochemical impedance spectroscopy (EIS) where the bimetallicnanocomposite gave charge transfer and solution resistance values of 96.35 and 137.9 ,respectively with the nanoparticles exhibiting higher resistances at 670.6 and 189.5 . These resultsconfirm that facile interfacial electron transfer processes occur on the Pt/Pd(100)Ir electrode during theelectrocatalytic ammonia oxidation and were made possible by the synergistic effect of the bimetallicpalladium and iridium in the nanocomposite which causes a weakening of the adsorption strength ofpoisonous adsorbed nitrogen (Nads) during the electrooxidation process.