Enhanced capacitive performance of CoO-modified NiMoO4 nanohybrid as advanced electrodes for asymmetric supercapacitor

A three-dimensional criss-crossed CoO-modified NiMoO4 (NiMoO4/CoO) nanohybrid was designed to enhance the capacitance performance of NiMoO4 via two-step hydrothermal strategies. The NiMoO4/CoO nanohybrid demonstrates a higher specific surface area (55 m(2)g(-1)) than that of simplex NiMoO4(25 m(2)g(-1)). The presence of CoO enhances the density of reaction active sites of NiMoO4 /CoO nanohybrid, which contributes to improving the electrochemical performance of NiMoO4/CoO nanohybrid. The specific capacitance is obviously improved from 1.99 F cm(-2) (1331 F g(-1)) of NiMoO4 to 5.36 F cm(-2) (2332 F g(-1)) of NiMoO4/CoO nanohybrid at 2 mA cm(-2) in 6 M KOH electrolyte. Furthermore, an asymmetric all-solid-state supercapacitor employing NiMoO4/CoO nanohybrid and exfoliated graphite carbon paper exhibits superior energy density of 71.4 W h kg(-1) at a power density of 750 W kg(-1) as well as a considerable cycling durability of 87.1% after 2000 cycles at 5 A g(-1). The NiMoO4/CoO supported on Ni foam could act as binder-free electrode to provide highly enhanced electrochemical performance and show promising energy storage application. (C) 2019 Elsevier B.V. All rights reserved.