Fe2O3@FeSe2 heterostructure as high-performance supercapacitor negative electrode material

Electrode materials play an important role in determining the electrochemical performance of supercapacitors. As the negative electrode material for supercapacitors, Fe2O3 has been receiving a lot of attention. However, its low electrical conductivity and ion storage capacity have become urgent problems to be solved. In this paper, Fe2O3@FeSe2 heterostructures were prepared by a sequence of hydrothermal synthesis followed by template calcination. The SEM, XRD, TEM, and XPS characterizations show that the preparation of the heterostructure is successful. In addition, the electrode material exhibited 526.3 mF cm−2 in 1 M Na2SO4. Moreover, the retention rate was as high as 80.3 % after cycling for 4000 cycles at a high rate of 10 mA cm−2. Based on the first-principles calculations, it can be seen that the construction of the heterostructure effectively increases the total DOS of the electrode material and also generates a new built-in electric field. This facilitates the transfer of electrons, which results in the electrode material exhibiting good electrochemical properties. To further verify the practical application performance of the electrode material, it was matched and assembled with MnO2. The assembled hybrid supercapacitor has an operating voltage of 2.0 V and a specific capacitance of 155 mF cm−2. The energy density is up to 86 uWh cm−2 at a power density of 2 mWh cm−2. In addition, the device has good stability and shows good potential for application.