水热法可控制备NiMoO_(4)纳米片微球及其超级电容器性能

Controllable preparation of NiMoO_(4)nanosheets-based microspheres by hydrothermal method and their supercapacitor properties

以硝酸镍和钼酸钠为原料,聚乙烯吡咯烷酮为结构导向剂,采用水热-热处理方法在镍网基底上制备了NiMoO_(4)纳米片微球。通过XRD、Raman、SEM以及TEM测试表征了所得NiMoO_(4)纳米片微球的结构与形貌。测试结果表明,三维微/纳分级结构的β-NiMoO_(4)纳米片微球的直径范围为2.3~3.0μm,且纳米片微球是由厚度约为16 nm的纳米片相互交错而成。研究分析了β-NiMoO_(4)纳米片微球的生长机理。电化学测试结果表明,NiMoO_(4)纳米片微球电极在6 mol/L KOH电解液中、1 A/g电流密度下的比电容高达1 161.8 F/g,这可归因于其独特的三维微/纳分级结构在电荷存储过程中可提供更多的氧化还原反应活性位点。另外,NiMoO_(4)纳米片微球电极的分级结构可减缓充放电循环过程中的体积变化,保持结构的稳定性,使其在20 A/g大电流密度下,循环2 000次后的电容保持率为82.2%,展现出良好的循环性能。

NiMoO_(4)nanosheets-based microspheres were successfully fabricated on nickel foam substrate through hydrothermal 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 NiMoO_(4)nanosheets-based microspheres were characterized by XRD,Raman,SEM and TEM.The test results showed that the β-NiMoO_(4)nanosheetsbased microspheres with three-dimensional micro/nano hierarchical structure and a diameter of 2.3~3.0μm,was consisted of numerous interlaced nanosheets with thickness of about 16 nm.The growth mechanism of β-NiMoO_(4)nanosheets-based microspheres was studied.Electrochemical tests showed NiMoO_(4)nanosheets-based microspheres electrode exhibited high specific 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 NiMoO_(4)nanosheets-based microspheres electrode could alleviate the volume variation during the charge/discharge cycling process and maintain the stability of the structure.Thus,NiMoO_(4)nanosheets-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.