Surface analysis and electrochemical characterization of palladium–cobalt nanoring formation from molecular precursor, [Et₃NH]₂[CoPd₂(μ‐4‐I‐3,5‐Me₂pz)₄Cl₄], on highly ordered pyrolytic graphite

Abstract

A Pd2Co precursor, [Et3NH]2[CoPd2(μ‐4‐I‐3,5‐Me2pz)4Cl4], was used to synthesize palladium–cobalt nanorings and nanoparticles on highly ordered pyrolytic graphite (HOPG) surface. Different types of nanostructures were formed on HOPG surfaces and were controlled by relative humidity (%RH). These structures included Pd2Co nanorings on HOPG surface by self‐assembly with humidity control. The %RH affects the size and dispersion of the self‐formation of the Pd2Co rings on HOPG surfaces. The modified HOPG surface with Pd2Co precursor at 80%RH has rings of similar sizes, while modification at 76%RH gives well‐formed rings and 70%RH with smaller diameters. After thermal reduction of the Pd2Co precursor on HOPG, bimetallic nanostructures were formed. X‐ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy with energy‐dispersive X‐ray fluorescence spectroscopy techniques were employed to study the composition and morphology of the nanostructures formations on the HOPG surface. Electrochemical characterization of the Pd2Co nanostructures was performed. Moreover, the bimetallic catalyst has electrocatalytic activity for the oxygen reduction reaction. Copyright © 2013 John Wiley & Sons, Ltd.