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

Abstract

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.