Electrochemical synthesis of flower-like Pd nanoparticles with high tolerance toward formic acid electrooxidation

Abstract

Flower-like nanoparticles exhibit unique properties due to the presence of edge and corner atoms, ad-atoms, pits and other collection of defects. In this work, flower-like Pd nanoparticles were obtained by surfactantless and additiveless square wave voltammetry as an electrochemical method of synthesis. Furthermore, other well-defined Pd shapes with dendritic growth such as spinous flower-like, cone and coral reef-like shapes were obtained by electrochemical methods using cyclic voltammetry, differential pulse amperometry and second harmonic AC voltammetry. Crystal sizes were calculated through the X-ray diffraction patterns for the spinous flower-like, cone, flower and coral reef-like palladium architectures resulting in sizes of 33, 56, 44 and 47 nm, respectively. SEM and cross-section TEM images confirmed that the architectures were composed of micro and nanostructures with dendritic growths. Cyclic voltammetry in acidic medium confirmed the presence of certain facets and terraces in both, flower-like Pd and the dendritic growths. The electrocatalytic properties of the palladium architectures were evaluated to the formic acid electrooxidation at 0.1, 0.5 and 1 M. The flower-like Pd architectures exhibited the highest tolerance to CO poisoning due to the process being carried out by a direct pathway and can be related to the effect of the unique flower-like shape which due to its nature exhibits a high presence of terraces and defects.