Selenium-doped Se-CoSe2@ZnSe heterojunction structure derived from ZIF-8 metal organic skeleton is used in high-performance asymmetric supercapacitors

Reasonable construction of multi-pore heterogeneous structures and enhancement of synergistic interaction between metal ions are important means to improve the performance of supercapacitors. This work selected metal organic frameworks (MOF) as the sacrificial template, and Se-doped needle-like nanosphere heterostructures Se-CoSe2@ZnSe were successfully prepared by in situ growth and selenization treatment. The specific capacity of the Se-CoSe2@ZnSe-5 (CZS-5) electrode is up to 2469.12 F g−1 at 1 A g−1, and the capacity retention rate of 3000 cycles at a current density of 10 A g−1 is 85.39 %. The CZS-5//AC hybrid supercapacitor has a high power density of 1280.00 W kg−1 at an energy density of 68.88 Wh kg−1. The excellent electrochemical properties are attributed to the construction of Se-CoSe2@ZnSe heterostructure of needle-shaped nanospheres enhances the synergy between Zn and Co ions; the doping of selenium effectively improves the conductivity of the electrode material; selenium vacancies produced during selenization increase the activity of the active site. In addition, the density functional theory (DFT) calculation shows that Se-CoSe2@ZnSe-5 has higher density of states (DOS) near the Fermi energy level, which provides additional theoretical support for the improvement of electrochemical performance.