Abstract:

NiMoO₄ nanosheets-based microspheres were successfully fabricated on nickel foam substrate through hydro-thermal method combined with an annealing post-treatment,using nickel nitrate and sodium molybdate as raw materials and polyvinyl pyrrolidone as structure directing agent.The structure and morphology of the obtained NiMoO₄ nanosheets-based microspheres were characterized by XRD,Raman,SEM and TEM.The test results showed that the β-NiMoO₄ nanosheets-based microspheres with three-dimensional micro/nano hierarchical structure and a diameter of 2.3~3.0 μm,was consisted of numerous interlaced nanosheets with thickness of about 16 nm.The growth mechanism of β-NiMoO₄ nanosheets-based mi-crospheres was studied.Electrochemical tests showed NiMoO₄ nanosheets-based microspheres electrode exhibited high spe-cific capacitance of 1 161.8 F/g at current density of 1 A/g in 6 mol/L KOH electrolyte,which was attributed to the unique features of three-dimensional micro/nano hierarchical structure that could provide more redox active sites during the charge storage process.Additionally,this hierarchical structure of NiMoO₄ nanosheets-based microspheres electrode could alleviate the volume variation during the charge/discharge cycling process and maintain the stability of the structure.Thus,NiMoO₄ na-nosheets-based microspheres electrode showed a capacitance retention of 82.2% after 2 000 cycles at a large current density of 20 A/g,indicating good cycling stability.

Key words: NiMoO₄ nanosheets-based microspheres, structure directing, supercapacitors, elctrochemical performance