High-throughput production of magnetite nanoparticles prepared by the monopolar arrangement of iron electrodes in water

Magnetite nanoparticles have been successfully produced by the electro-oxidation of iron in water using a monopolar arrangement of iron electrodes. Two types of monopolar configurations were used: conventional monopolar (CM) and alternating monopolar (AM). The production rate of the magnetite nanoparticles could be increased significantly (∼30 times higher) by using the AM electrode arrangement compared to the production rate of one-pair of electrodes in the same system. The particle sizes ranged from 28 to 88 nm for the CM and from 20 to 25 nm for the AM arrangements. The performance of the AM arrangement was superior that of the CM arrangement in regard to production rate, particle size, and product purity. A numerical simulation showed distinguishable electric fields between the AM and CM arrangements. The magnetite particles produced using the CM arrangement contained impurities in the form of FeOOH and Fe₂O₃. On the other hand, only magnetite was identified in the particles prepared using the AM arrangement. In addition, particle morphologies other than spherical could also be produced using the AM arrangement by changing the operating condition. The magnetite nanoparticles exhibited ferromagnetic properties. They can be used as a promising catalyst for oxygen reduction reactions in alkaline media.