Electrochemical synthesis of magnetite and maghemite nanoparticles using dissymmetric potential pulses

Magnetic iron oxide nanoparticles of controlled size distribution were electrochemically synthesized applying a dissymmetric pattern of potential pulses to iron-based electrodes in aqueous media. The best pattern was determined through a design of experiments based on a previous voltammetric study. The applied method conveys an optimization of previous methods which employed direct or symmetric alternate potentials. XRD results indicate that magnetite phase is favored to anodic potentials larger -0.2 V versus SSE. TEM images show quasi spherical particles with size ranging from 10 to 50 nm, depending on the synthesis conditions, which agrees with size estimated from diffractograms. EDS indicate that the electrolyte is not totally eliminated by washing although its content is lower than 1 %.