Metal-organic framework derived α-Fe2O3 nano-octahedron with oxygen vacancies for realizing outstanding energy storage performance

Transition metal oxide, alpha-Fe2O3, has attracted great interest as a kind of potential battery-type electrode material due to its high theoretical specific capacity. However, alpha-Fe2O3 still suffers from poor conductivity and large volume expansion during charge and discharge process. Herein, for the first time, the oxygen vacancies-modifying alpha-Fe2O3 are prepared via a novel two-step calcination of MIL-88-Fe (Fe-MOF) template. Note that the incorporation of oxygen vacancies into alpha-Fe2O3 nano-octahedron will promote faster charge storage kinetics and enables the alpha-Fe2O3 structure to be retained during the Li-ions. The oxygen vacancies-modifying alpha-Fe2O3 nano-octahedron exhibits high specific capacity (250.2 mAh g(-1)), and an activated carbon (AC)//alpha-Fe2O3 hybrid supercapacitor is constructed, delivering a high energy density of 63 W h kg(-1) at a power density of 900 W kg(-1). This finding underlines the importance of incorporating oxygen vacancies into battery-type electrode materials for promoting the practical application.