Fig. 2. Micrographs show that NPs-ZnSe join to form micrometersized agglomerates. It is noted that the surface morphology of the agglomerates depends on the molar concentration. Fig. 3 presents micrographs of samples obtained with pH¼8. Fig. 3(a) shows sample obtained with 1:1 as molar concentration. This sample presents roughness surface a high amount of agglomerates. In some cases, particles with irregular shape and some rod-like structures are attributed to the elimination of Zn during the cleaning process. The mechanism is related with the formation of ZnCl2 from the erosion of NPs-ZnSe by HCl [13], therefore a high amount of selenium concentration is obtained, and the morphology is like nanorods even elemental selenium is also formed as nanorods. The surface morphology for the Zn:Se samples with 1:2