Iridium Surface Treatment by Glow Plasma Treatment and Its Application as Electrocatalyst for Methanol and CO Oxidation

The regulation of the electrocatalytic activity of an iridium surface using a plasma activation treatment process has been studied experimentally and using first-principles calculations. The microstructures and catalytic properties were investigated using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammetry and CO-stripping voltammograms. The results show that the plasma activation treatment process can promote the surface energy of iridium particles, thereby increasing their surface activity as a catalyst. Furthermore, the current density of Ir/C-Plasma is 1.46 times higher than that of Ir/C, indicating that the electrocatalytic activity is significantly increased upon increasing the number of surface-active sites. More importantly, the mechanism of the surface activity sites that improves the catalyst performance of the iridium surface was illustrated using first-principle calculations. We also find that CH3OH molecules form chemical bonds with the dangling bonds localized on the iridium atoms around the vacancies and that these sites have the lowest adsorption energy (–0.578 eV). Meanwhile, the TS results indicate that the dissociation of CH3OH on a non-vacancy surface was more difficult than on the one-vacancy surface. In addition, the charge transfer further confirms that the vacancies on the iridium surface can provide a large number of active sites for chemical adsorption/desorption, which can promote CO anti-poisoning processes. This study not only reveals the CH3OH adsorption/desorption reaction mechanism of Ir/C-Plasma, but also provides effective guidance toward improving the catalyst performance of noble metal catalysts.