Figure 1: SEM images of the ccNPs with CTAB surfactant concentration below the CMC. (a) The SEM images and further magnified (b and c) show homogeneous and nearly spherical structures with size around 600 nm. Image (c) shows more details in the interior and the surface of the sphere with the top cover removed. (d) FESEM images show details in the enlargement of the highlighted area (inset) with the interior of structures filled with ccNPs showing that copper is incorporated inside the ccNPs with a size around 15 nm.