One-step synthesis of stoichiometrically defined metal oxide nanoparticles at room temperature

A great variety of metal oxide nanoparticles have been readily synthesized by using alkali metal oxides, M₂O (M is Na or Li) and soluble metal salts (metal chlorides) in polar organic solutions, for example, methanol and ethanol, at room temperature. The oxidation states of the metals in the resulting metal oxides (Cu₂O, CuO, ZnO, Al₂O₃. Fe₂O₁, Bi₂O₃, TiO₂, SnO₂, CeO₂, Nb₂O₅, WO₃, and CoFe₂O₄) range from 1 to 6 and remain invariable through the reactions where good control of stoichiometry is achieved. Metal oxide nanoparticles are 1-30 nm and have good monodis-persivity and displayed comparable optical spectra. These syntheses are based on a general ion reaction pathway during which the precipitate occurs when O^2- ions meet metal cations (Mⁿ⁺) in anhydrous solution and the reaction equation is Mⁿ⁺ + n/2 O^2- → MO_n/2 (n = 1-6).