Carbon Nanocapsules as Nanoreactors for Controllable Synthesis of Encapsulated Iron and Iron Oxides: Magnetic Properties and Reversible Lithium Storage

This paper reports the synthesis of carbon-encapsulated Fe 3 O 4, γ-Fe 2 O 3, and Fe nanostructures using FeOOH as a precursor and carbon nanocapsules (CNCs) as nanoreactors via controllable thermal transformation processes. The magnetic property investigation reveals that the as-synthesized Fe 3 O 4 -CNCs, γ-Fe 2 O 3 -CNCs, and Fe-C nanostructures all exhibit ferromagnetic behavior with quite high saturation magnetizations. Moreover, the Fe 3 O 4 -CNCs with a controlled carbon coating are prepared and their comparative lithium storage properties are investigated. It is found that optimized Fe 3 O 4 -CNCs exhibit high capacity and good cycling performance.