Facile Synthesis of Fe3O4@g-C Nanorods for Reversible Adsorption of Molecules and Absorption of Ions

It is an interesting but challenging task to design a facile and scalable procedure for the making of multifunctional materials for energy and environmental applications. Here, we developed a one-pot facile procedure for the preparation of disordered carbon (a-C) coated Fe 2 O 3 nanorods. By heating Fe 2 O 3 @a-C nanorods under argon, they were easily converted to graphite carbon (g-C) coated magnetic Fe 3 O 4, or Fe 3 O 4 @g-C, nanorods. We demonstrated that the as-prepared magnetic Fe 3 O 4 @g-C nanorods could reversibly store molecules, using dye as a model. This suggested that one of the possible applications would be as recyclable and reusable adsorbents for water remediation. At the same time, the magnetic Fe 3 O 4 @g-C nanorods are proposed as vehicles for the controlled release of drugs in an aqueous environment and, in particular, for the targeted treatment of infected regions through guided external magnetic forces. The Fe 3 O 4 @g-C nanorods were also investigated for their performances in the reversible storage of sodium ions, which is closely relevant to future sodium-ion batteries. We discovered that thin graphite carbon sheaths, which encapsulate the high-capacity Fe 3 O 4 cores, could actually prevent the cores from having full access to sodium ions. We suggested that carbon coating, commonly used in electrode materials for lithium-ion batteries, may not be generally suitable for electrode materials used in future sodium-ion batteries. This discovery is helpful in guiding future studies on the use and selection of carbon coating, a common strategy to overcome electrode pulverization in lithium-ion batteries, for electrodes in future sodium-ion batteries.