Three-dimensional flower-like MoS2-CoSe2 heterostructure for high performance superccapacitors

A novel three-dimensional (3D) flower-like MoS2-CoSe2 heterostructure has been designed and synthesized by a facile two-step hydrothermal process as the electrode materials for supercapacitors. The MoS2-CoSe2 heterostructure is demonstrated to deliver a high specific capacitance (2577 F g(-1) at 1 A g(-1)) and remarkable rate capability (896 F g(-1) at 20 A g(-1)). Besides, the MoS2-CoSe2 electrode also exhibits excellent cycling stability of 91.03% capacitance retention after 5000 cycles even at a relatively high current density of 20 A g(-1). A two-electrode configuration symmetric supercapacitor based MoS2-CoSe2 heterostructure delivers a maximum energy density of 60.5 W h kg(-1) at a power density of 800 W kg(-1) and the energy density remains at 35.6 W h kg(-1) at a power density of 8000 W kg(-1). Excellent cycling stability is also achieved with 83.62% retention after 2000 charge-discharge cycles, revealing its potential and viability for practical applications. The outstanding electrochemical performances of the fabricated electrode stem from the unique structure characteristic of the flower-like MoS2-CoSe2 heterostructure. The high-quality heterointerface facilitates electron conduction while the porosity not only allows fast ion transport but provides abundant active sites for Faradic reaction and the buffer for volume variety in repeat charge-discharge process. The design strategy offers a new idea for fabricating high-performance supercapacitor electrode materials. (C) 2017 Elsevier Inc. All rights reserved.