*2.3. Transmission Electron Microscopy (TEM)*

Transmission electron microscopy (TEM) and high resolution TEM (HRTEM) analysis were performed using a JEOL 3010 high resolution electron microscope (0.17 nm point-to-point resolution at Scherzer defocus), operating at 300 kV, equipped with a Gatan slow-scan CCD camera (model 794) and an Oxford Instrument EDS microanalysis detector Model 6636. Drops of colloidal solutions were deposited on holey-carbon copper grids and let dry at room temperature before analysis.
