Magnetite nanoparticles: Electrochemical synthesis and characterization

Magnetite (Fe3O4) nanoparticles (NP) with sizes between 20 and 30 nm have been obtained by Fe electrooxidation in the presence of an amine surfactant, which acted as a supporting electrolyte and coating agent, controlling particle size and aggregation during the synthesis. The effect of different parameters on the nature and size of the particles as well as the mechanism of formation of the particles have been studied by different techniques. It was concluded that, under the electrochemical conditions used in this work, the NP mean size was found to be constant at around 20 nm when the electrooxidation current density is increased from 10 to 200 mA cm−2. However, when the potential is over 6 V, particle size decreases from 30 to 20 nm and metallic iron appears as an impurity. The mechanism of particles formation has being clarified and the critical effect of the distance between electrodes for obtaining magnetic iron oxide nanoparticles has been understood. Finally, the presence of an electrostatic adsorbed surfactant coating the particles allows the functionalization of the particles easily by exchange reaction with biomolecules of interest, which makes this material very promising for future application in biotechnology.