Abstract
Superfine cobaltous oxide nanoparticles (CoONPs) of ∼2.5 nm diameter were synthesized at high rate via discharge plasma operated in an aqueous solution of Co(II) acetate. Two potential routes are proposed for the CoONP formation: one is the plasma-induced electrolysis of the aqueous solution of Co(II) acetate, and the other is the oxidization of neutral Co, which is formed by the plasma-induced reduction of Co(II). In addition, the resultant CoONPs are soluble in ethanol but insoluble in water, which is attributed to the surface conjugation of functional groups of CH3· produced by the plasma-induced electrolysis of an aqueous solution of Co(II) acetate.