Comprehensive design of carbon-encapsulated Fe3O4 nanocrystals and their lithium storage properties

Controlling the bulk and surface structure of metal oxide nanostructures is crucial to obtain superior electronic and electrochemical properties. However, the synthetic or post-treatment techniques for preparing such structures, especially those with complex configurations, still remains a challenge. Herein, we report a completely novel approach - an amorphous carbon coating on the surface coupled with a controlled metal oxidation state in the bulk - via a simple glucose treatment. The bulk and surface structures of iron oxides are controlled by the carbothermal reaction associated with the decomposition of glucose. These novel configurations of iron oxides possess an amorphous carbon layer and ferrous state with high electronic conductivity, which definitely enhances their electrochemical properties compared to pristine iron oxides. Our findings provide an effective solution for the synthesis of complex metal oxide nanostructures, which can pave the way to further expand the electronic or electrochemical applications of metal oxides.