Abstract

Monoclinic nickel molybdate (NiMoO₄) micro-crystals were synthesized via a conventional solid-state synthesis route with a prospective to investigate its conductivity response with high-temperature evolution and phenomenal electrochemical performance for supercapacitor application. The tenacious phase formation, Raman active phonon vibration and metal oxide (Ni–O, Mo–O) stretching vibration in octahedral and tetrahedral sites of as-synthesized NiMoO₄ were confirmed by X-ray diffraction techniques, Raman and FTIR spectra. The UV-DRS absorbance spectra of NiMoO₄ exhibits several effective absorption peaks in the UV–Visible wavelength range (200–800 nm). The optical band gap of NiMoO₄ was estimated at 2.50 eV experimentally with the famous Kubelka–Munk equation and theoretically correlated with the result obtained from the density of states (DOS) calculation. The saturation magnetization of NiMoO₄ diminished from 0.0026 to 0.0013 emu g⁻¹. significantly due to the embodiment of MWCNT but the coercivity maintain a minute change. Lessening of real (Z′) and imaginary impedance (Z″) with temperature was observed with high-temperature evolution (633–773 K) and the Nyquist plots were well fitted with equivalent circuit model (QR)(QR)(CR) network. The temperature-dependent frequency exponent (n) suggested the band-correlated barrier-hopping process in high temperature for the conduction mechanism of NiMoO₄. The maximum specific capacitance (C_sp) was estimated 518 F g⁻¹ for NiMoO₄ at current density 5 Ag⁻¹ and its value intensified up to 1050 A g⁻¹ at current density 5 Ag⁻¹ in MWCNT-integrated NiMoO₄. Imperatively, the upmost energy density 66.12 Wh Kg⁻¹ was detected at power density 1075 W Kg⁻¹ for MWCNT-blended NiMoO₄ which is significantly larger than pristine NiMoO₄ (energy density 42.28 Wh Kg⁻¹ at power density 612 W Kg⁻¹) at a current density 5 Ag⁻¹, which reveals their great potential application as a supercapacitor and energy storage technology.

中文翻译：

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α-NiMoO4微晶中的能带相关势垒跃迁传导及其与MWCNT集成复合物的储能性能比较

摘要

通过常规的固态合成路线合成了单斜晶的钼酸镍（NiMoO ₄）微晶体，以期研究其在高温演变过程中的电导率响应以及在超级电容器应用中的惊人电化学性能。X射线衍射技术，拉曼光谱和FTIR光谱证实了刚合成的NiMoO _4的八面体和四面体中的顽强相形成，拉曼活性声子振动和金属氧化物（Ni-O，Mo-O）拉伸振动。NiMoO ₄的UV-DRS吸收光谱在UV-可见波长范围（200-800 nm）内显示几个有效吸收峰。NiMoO ₄的光学带隙用著名的Kubelka-Munk方程在实验上以2.50 eV估算，并且理论上与从状态密度（DOS）计算获得的结果相关。NiMoO ₄的饱和磁化强度从0.0026降低至0.0013 emu g ^-1。由于MWCNT的具体体现，矫顽力保持了微小的变化。的实数（减轻Ž '）和虚部阻抗（Ž “）与温度，用高温演进（633-773 K）和Nyquist曲线观察到了良好装有等效电路模型（QR）（QR）（CR）网络。温度相关的频率指数（n）提出了NiMoO ₄的传导机理是高温下带相关的势垒跳跃过程。最大比电容（C ^ _SP）估计518 F G ^-1为NiMoO ₄在电流密度5的Ag ^-1和它的值强化高达1050 A G ^-1在电流密度5的Ag ^-1在MWCNT集成NiMoO ₄。势在必行，的最上方的能量密度66.12瓦千克^-1在功率密度1075W¯¯公斤检测^-1为MWCNT共混NiMoO ₄比原始NiMoO显著较大₄（能量密度42.28瓦公斤^-1在功率密度612W¯¯千克^-1处的电流密度5 Ag）的^-1，这揭示了它们的巨大潜力应用程序作为超级电容器和能量存储技术。