Decoration of NiCoP nanowires with interlayer-expanded few-layer MoSe2 nanosheets: A novel electrode material for asymmetric supercapacitors

Tailoring hybrid electrodes with rational microstructure and appropriate active components is crucial for developing high performance supercapacitors (SCs). Herein, we assemble highly conductive arrayed NiCoP nanowires on flexible carbon cloth substrate (CC) and subsequently decorate the nanowires with MoSe2 nanosheets to form a 3D NiCoP@MoSe2 heterostructure for high performance SCs. The interaction between tightly bound NiCoP and MoSe2 results in the reduction of the number of MoSe2 layers from more than 15 to 2-3, and expansion of the interplanar spacing from 0.65 nm to 0.76 nm. Such heterostructure integrates the advantages of more accessible active sites of the interlayerexpanded few-layer MoSe2 nanosheet, the high conductivity of the arrayed NiCoP nanowires, and the 3D open nanostructures, achieving the synergistic effects of the directionally efficient electron transfer and efficient utilization of active sites. Consequently, the CC supported binder-free electrode of NiCoP@MoSe2 exhibits a high specific areal (gravimetric) capacitance of 5613.5 mF cm(-2) (2245.4 F g(-1)) at a current density of 1 mA cm(-2) and outstanding longterm durability. A flexible asymmetric supercapacitor constituted of NiCoP@MoSe2 as positive electrode and active carbon (AC) as negative electrode achieves a high energy density of 55.1 Wh kg(-1) at the power density of 799.8 W kg(-1) and a remarkable cycling stability of 95.8% capacitance retention after 8000 cycles. This study provides a new route for the designing of novel nanoarchitecture with multi-components in energy storage applications.