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 beta-NiMoO4 nanosheets show a decent specific capacity of 332.8 C/g at 1 A/g, surpassing the 252.6 C/g of the alpha-NiMoO4 nanorods. Furthermore, the supercapacitor device constructed with beta-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.