Tuning the electrochemical performance of NiCo2O4@NiMoO4 core-shell heterostructure by controlling the thickness of the NiMoO4 shell

Core-shell heterostructure nanomaterials are promising candidate for supercapacitor electrodes owing to their effective electrolyte accessibility and rapid electrons transport rates. In this work, multi-dimensional core-shell NiCo2O4@NiMoO4 nanowires/nanosheets arrays are successfully grown on carbon cloth via a two-step hydro-thermal route coupled with post annealing process. The thickness of NiMoO4 shell can be easily controlled by using a alkali sources or not in the secondary hydrothermal process and the dependence of electrochemical performance on the NiMoO4 shell thickness is researched. Owing to a higher specific surface area, lower electrons transfer resistance and good strain accommodation, the heterostructure electrode with a thick NiMoO 4 shell exhibits the optimal electrochemical performance, showing a high areal capacitance of 2522 mF cm(-2) and superior cycle performance of 89.8% capacitance retention over 5000 cycles. Moreover, using it as positive electrode and activated carbon as negative electrode, the fabricated asymmetric supercapacitor delivers a maximum energy density of 53.3 Wh kg(-1) at 750 W kg(-1), indicating its promising applications as efficient electrode for supercapacitors.