Morphology-dependent NiMoO4/carbon composites for high performance supercapacitors

In order to improve the capacitive performance of supercapacitors, NiMoO4 electrode materials were successfully prepared by a simple and safe solvent-thermal method, and the morphology, microstructure and properties of the materials were successfully optimized by adding reduced graphene oxide (rGO) and multiwalled carbon nanotubes (MWCNTs). The morphology, structure and electrochemical properties of the as-prepared samples were investigated by SEM, XRD, laser particle size, cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results showed that the addition of rGO and MWCNTs could greatly affect the morphology and capacitance properties of NiMoO4. The mixed characteristics of pine needle-like and microspheres NiMoO4 gradually changes into honeycomb structure of NiMoO4/rGO after the addition of rGO, while the NiMoO4/MWCNTs shows the mixed characteristics of honeycomb and microrod-like. In addition, compared with pure NiMoO4 and NiMoO4/rGO, the NiMoO4/MWCNTs shows more uniform particle size distribution, more active sites, smaller charge transfer resistance and higher ionic diffusion coefficient, thus exhibiting better supercapacitance performance. Under the current density of 1, 4, 7 and 10 A g−1, the discharge specific capacitance is 805, 702, 643 and 584 F g−1, respectively. Moreover, the capacity retention of NiMoO4/MWCNTs still maintains 66.7% after 1000 cycles at the high rate current density of 1 A g−1, which shows good high current charging and discharging performance and application prospect, providing a new idea for designing high efficiency and low cost supercapacitors electrode materials.