To enhance the purity and crystallinity of magnetite nanoparticles prepared by surfactant-free electrochemical method by imposing higher voltage

Magnetite (Fe₃O₄) nanoparticles has many important applications due to its reactivity, size, and magnetism. Many synthesis methods of the material, including electrochemical, have been developed in order to generate the desired particles. Electrochemical is one simple synthesis method in producing the nanoparticles. Characters of the particles synthesized, such as its size, crystallinity and magnetic property, depend on the electrochemical parameters like the kind and concentration of electrolyte, the kind of electrodes, the inter-electrodes distance, temperature, cell volume, current density or voltage applied. We have been succesfully synthesized monodispersed magnetite nanoparticles by electro-oxidation of iron in plain water without using any surfactant, although there are some impurities in the form of FeOOH, an intermediate species created during the formation of Fe₃O ₄. Nevertheless a high purity of magnetite nanoparticles were required in some special applications. By applying higher voltage in the range of 30-70 V with inter-electrodes distances between 2-4 cm, it was shown by XRD and FTIR analysis that a high purity and crystalinity material have been succesfully prepared. Higher voltage enhance the rate of magnetite formation indirectly, so the reaction will be complete without retaining FeOOH anymore. It was also found from XRD, BET and VSM analysis that the imposed voltage influenced unsignificantly to the properties of the particles, but the inter-electrodes distance influenced the crystalinity, size and saturation magnetization of the particles. This way appears to be an efficient route to produce surfactant free magnetite nanoparticles.