The microscopic study was done by SEM and TEM micrographs that were obtained using a scanning electron microscope (Leo series VP1430, Germany) and a transmission electron microscope (Jeol JEM 2100, USA), after dispersing the catalyst sample in ethanol by sonication and deposited on an Al grid coated with gold using a Polaron Sputter Coater (for SEM) and on a Cu grid coated with carbon film (for TEM).