Oxygen Content-Controllable Synthesis of Non-Stoichiometric Silicon Suboxide Nanoparticles by Electrochemical Anodization

A facile route to producing non-stoichiometric silicon suboxide nanoparticles (SiO(x) NPs, 0 < x < 1) with an adjustable oxygen content is proposed. The process is based on electrochemical anodization involving the application of a strong electric field near the surface of a Si electrode to directly convert the Si electrode into SiO(x) NPs. The difference in ion mobility between oxygen species (O(2−) and OH(−)), formed during anodization, causes the production of non-stoichiometric SiO(x) on the surface of the Si while, simultaneously, fluoride ions in the electrolyte solution etch the formed SiO(x) layer, generating NPs under the intense electric field. The adjustment of the applied voltage and anodization temperature alters the oxygen content and the size of the SiO(x) NPs, respectively, allowing the characteristics of the NPs to be readily controlled. The proposed approach can be applied for mass production of SiO(x) NPs and is highly promising in the field of batteries and optoelectronics.