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

Transition metal oxide , α-Fe 2 O 3 , has attracted great interest as a kind of potential battery-type electrode material due to its high theoretical specific capacity. However, α-Fe 2 O 3 still suffers from poor conductivity and large volume expansion during charge and discharge process. Herein, for the first time, the oxygen vacancies-modifying α-Fe 2 O 3 are prepared via a novel two-step calcination of MIL-88-Fe (Fe-MOF) template. Note that the incorporation of oxygen vacancies into α-Fe 2 O 3 nano-octahedron will promote faster charge storage kinetics and enables the α-Fe 2 O 3 structure to be retained during the Li-ions. The oxygen vacancies-modifying α-Fe 2 O 3 nano-octahedron exhibits high specific capacity (250.2 mAh g −1 ), and an activated carbon (AC)//α-Fe 2 O 3 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.