For transmission electron microscope (TEM) imaging,a small drop of dispersed NCs in chloroform was placed on a gold TEM grid coated with a thin carbon support film. TEM images and Energy-Dispersive X-ray (EDX) spectra were acquired using a JEOL analytical transmission electron microscope (model JEM 2100F operated with a 200 kV acceleration voltage) equipped with an Oxford EDX energydispersive X-ray spectrometer.