General Two-Phase Routes to Synthesize Colloidal Metal Oxide Nanocrystals: Simple Synthesis and Ordered Self-Assembly Structures

Abstract

Different two-phase approaches have been developed for the synthesis of two classes of monodisperse colloidal metal oxide nanocrystals (NCs): rare earth oxide NCs and transition metal oxide NCs. These routes were simple and inexpensive, using metal salts instead of organometallic compounds, with mild reaction conditions, easily controlled size and shape, and multigram-scale products. The obtained products were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), Fourier transform infrared absorption spectroscopy (FTIR), and nitrogen adsorption−desorption isotherms (BET). The possible mechanisms for the formation and growth of nanocrystals were discussed. Accordingly, tert-butylamine (nucleophile agent) and ethanol (reduced agent) are the key factors for the formation of rare earth oxide NCs and transition metal oxide NCs, respectively. Different sizes and shapes of monodisperse nanoparticles such as ...