Synergistic Regulation of Phase and Nanostructure of Nickel Molybdate for Enhanced Supercapacitor Performance

Nickel molybdate, which has a relatively high theoretical capacity, demonstrates potential for use in supercapacitors. However, its inferior electrical conductivity and cycling stability have led to poor electrochemical performance. Nanostructure engineering of NiMoO₄ is an efficient strategy to overcome its performance limitations as an electrode. Here, a facile approach is reported for the precise phase regulation and nanostructure of NiMoO₄ by manipulating the synthesis parameters, including duration, precursor selection, and urea concentration. The electrochemical properties of the electrode materials are also investigated. It is interesting to note that the β-NiMoO₄ nanosheets show a decent specific capacity of 332.8 C/g at 1 A/g, surpassing the 252.6 C/g of the α-NiMoO₄ nanorods. Furthermore, the supercapacitor device constructed with β-NiMoO₄ and reduced graphene oxide hydrogel (rGH) electrodes achieves an acceptable energy density of 36.1 Wh kg^-1, while retaining 70.2% after 5000 cycles.