Preparation And Application Of Nickel Molybdate And Its Composites

In this paper,we synthesized nitrogen–doped carbon NiMoO₄?NDC/NiMoO₄?nanospheres using cetyltrimethylammonium bromide?CTAB?–polyvinylpyrrolidone?PVP?–cyclohexane–water–ethanol microemulsion aggregates as soft template to prepare nitrogen–doped carbon NiMoO₄?NDC/NiMoO₄?nanospheres by solvent heat treatment.In the preparation process,an oil–in–water O/W microemulsion system was first formed,and then the morphology of the NDC/NiMoO₄ nanospheres was controlled by adjusting the solvothermal temperature?solvent temperature:100°C–200°C?.Finally,the calcination under a nitrogen atmosphere not only retains the carbon element contained in the surfactant,but also the nitrogen element is doped into the NiMoO₄nanosphere.At a solvothermal temperature of 130°C,NDC/NiMoO₄ nanospheres assembled into smaller size nanosheets and ultra–small nanoparticles.The composition of NiMoO₄ provides a high specific capacitance,while the doping of nitrogen and carbon helps accelerate the transport of electrons and ions,which further promotes rapid charge/discharge,cycle performance and rate performance of the synthesized active material.In addition,the NDC/NiMoO₄–130°C sample has the maximum specific capacitance at a current density of 1 A g^–1 is 1045 F g^–1,and the initial capacity is retained 60%after 10000 cycles.The energy density of the asymmetric two–electrode cell reached 107.3 Wh kg^–1 at a power density of 799.9 W kg^–1.These results can be attributed to the unique morphology of NDC/NiMoO₄ and the rich doping of N and C elements.This study provides an alternative to the synthesis of ternary metal oxide materials for high performance supercapacitors.In addition,we used a similar two–step method to prepare SiO₂/NiMoO₄nano–core shell composites.The first step was to synthesize an oil–in–water O/W SiO₂microemulsion system,then add a molybdenum source and a nickel source to solvent.Heat treatment,and finally the sample is calcined under an air atmosphere.The morphology of SiO₂/NiMoO₄ nano–core shell composites was controlled by adjusting the ratio of SiO₂ and molybdenum source and nickel source.It was found that the SiO₂/NiMoO₄ nanospheres with the hollow double–shell morphology and the particle size of the nanospheres were synthesized at a ratio of SiO₂?NiMoO₄=2?3.When the ratio of SiO₂?NiMoO₄ is 4?1,an yolk core structure appears in the nanospheres.The effect of different proportions of SiO₂:NiMoO₄ on the morphology is very large.Raman and XRD results show that the SiO₂/NiMoO₄ composites were successfully prepared.The results of EIS,CV and GCD confirmed the good electrochemical capacitance performance of SiO₂/NiMoO₄–3,and the maximum specific capacitance obtained at a current density of 1 A g^–1 was 833 F g^–1.In this paper,we have adopted a variety of methods to characterize NiMoO₄composites,such as TEM,XRD,Raman spectroscopy,N₂ adsorption/desorption analysis,etc.,confirmed that NiMoO₄ nanocomposites were successfully prepared and explored.The higher specific capacitance characteristics of NiMoO₄ nanomaterials also confirm that the synergistic effect of NiMoO₄ nanomaterials combined with other materials is beneficial to improve the cycle stability and other electrochemical properties of the materials.