A high-performance asymmetric supercapacitor based on morphologically tuned CoB anode and heterostructured graphitic carbon nitride/ MoSe2 cathode

Transition metal borides (TMBs) are among the fascinating electrode materials for supercapacitors. TMBs have high theoretical capacity, however the narrow potential window, structural deterioration during redox cycling, and fairly small surface area remains a major limitation. To resolve these, we synthesize cobalt boride (CoB) in different morphologies by initiating the reaction with different precursors namely, zeolitic imidazolic framework-67 (ZIF-67), Co layered hydroxide (SLH), and CoCl2. CoB synthesis from ZIF-67, SLH, and CoCl2 results in nanoflower, nanoplate, and nanowire morphology. CoB in nanowire morphology, shows highest charge storage of 273 F g-1 at 1 A g-1 due to 1D structure that endow plentiful surface area, high conductivity, ample electroactive sites and structural stability. We also engineer layer structure of molybdenum selenide (MoSe2) to favorably expand interlayer distance to enhance atomic surface exposure by successfully inserting graphitic carbon nitride (gCN) nanosheets into adjacent MoSe2 layers. Herein, asymmetric supercapacitor, CoB||gCN/ MoSe2 displays a wide potential window of 1.5 V, remarkable energy density of 97.44 Wh kg- 1 at 621.3 W kg- 1 along with 93 % capacitance retention after 10 k GCD cycles. The research reported here demonstrates the great application potential for the asymmetric devices based on CoB||gCN/MoSe2 for the future of electrochemical charge storage devices.