Investigation of the Electrocatalytic Properties of Spherical Palladium Nanoparticles and Palladium (100) Iridium Bimetallic Nanocomposites Towards Ammonia Electrooxidation on …

Abstract

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