Optimized synthesis of ZnSe nanocrystals by hydrothermal method

Zinc selenide (ZnSe) nanocrystals were prepared via a facile hydrothermal method in the presence of different surfactants from the solution of zinc salt, SeCl₄ and hydrazine. In this process, hydrazine was used as reductant. The size, morphology, chemical composition and purity of the nanocrystals depend on the type of surfactant, zinc source, reaction temperature and time. ZnSe nanospheres are synthesized at 180 °C for 18 h in the presence of cetyltrimethylammonium bromide (CTAB) and polyethylene glycol, whereas in the presence of sodium dodecyl sulfate and sodium dodecylbenzenesulfonate, the coalesced particles and bulk structures are formed. In the presence of CTAB at 180 °C, spherical assemblies of nanoparticles are formed after 6 h. With increasing the time to 12 h, the samples are found to be a mixture of nanospheres and nanorods. With longing the reaction time up to 24 h, nanorods disappear while there are still nanospheres. The pure ZnSe nanospheres are obtained at high temperatures (220 °C) and also when using from zinc nitrate.