ZnSe nanoparticles growth by aqueous colloidal solution at room temperature

ZnSe nanoparticles (ZnSe-NPs) were obtained by aqueous colloidal solution at room temperature (25 °C) at different pH. A physicochemical study of the aqueous solution was proposed. The chemical reagents of the colloidal solution were zinc chloride, selenium elementary powder, Extran® as a surfactant, and sodium borohydride as a reducing agent. The species distribution diagrams (SDDs) and solubility curves (SCs) as pH functions were plotted as a result of the physicochemical analysis. The SDDs and SCs predicted the ZnSe-NPs formation and their growing process, therefore, a series of experiments according to these diagrams were performed at various pH of the colloidal solution through different Extran® content. The ZnSe-NPs were obtained without further purification. The ZnSe-NPs were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) techniques. The XRD results revealed that the ZnSe-NPs have mixed cubic and hexagonal crystalline structures, with crystal size at the nanoscale. The Raman spectra exhibited two peaks at 253 cm−1 of the longitudinal optical (LO) phonon mode, and 235 cm−1 of the surface phonon mode corresponding to the ZnSe bulk. The SEM images showed a variety of morphologies with different Zn/Se atomic ratios estimated from the EDS analysis.