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This paper investigates the synthesis and enhanced electrochemical behaviors of ZnO and NiO/ZnO nanocomposites for electrode material of supercapacitors. ZnO and NiO/ZnO nanocomposites were produced via sol–gel technique. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) were used to determine the size and structure of as-synthesized nanomaterials, respectively. The capacitive behavior and charge–discharge characteristics of the electrode using ZnO and NiO/ZnO nanocomposites (as active material) were individually probed with the help of cyclic voltammetry (CV) and galvanostatic charge-discharge tests, respectively. The specific capacitance of nanocomposites-based electrode calculated from galvanostatic charge-discharge tests was 469F ${\text{g}}^{-1}$ at the scan rate of 1mA ${\text{g}}^{-1}$ in 1M Na₂SO₄ electrolyte. The power density and energy density at the current density of 1mA ${\text{g}}^{-1}$ were determined as 1458.33W ${\text{kg}}^{-1}$ and 91.14Wh${\text{kg}}^{-1}$, respectively. Hence, NiO/ZnO nanocomposites could be reckoned to be a promising electrode material for supercapacitor while comparing to ZnO-based electrode material.

In this study, two hydrogen sensors with Pd/SiO₂/Si and Ni/SiO₂/Si structures have been fabricated. Palladium nanoparticles are synthesized and then deposited on the oxide surface using spin coating. Capacitance–voltage curves for the Pd/SiO₂/Si sensor at room temperature and for the Ni/SiO₂/Si sensor at 140${}^{\circ }$C in pure nitrogen and 1% H₂–N₂ mixture are described. The time required for reaching 90% of the steady-state signal magnitude ($t_{90\%}$) for Pd/SiO₂/Si capacitor was 1.4s and for Ni/SiO₂/Si capacitor was 90 s. The time interval for recovery from 90% to 10% of steady-state signal magnitude ($t_{10\%})$ for Pd/SiO₂/Si capacitor was 14s and for Ni/SiO₂/Si capacitor was 40min. For the Pd/SiO₂/Si capacitor, the response is 88% and for Ni/SiO₂/Si capacitor the response is 29%. Comparison of Pd nanoparticles capacitive- and resistance-based sensors shows that the metal-oxide-semiconductor capacitive is faster and more sensitive than the resistance-based hydrogen gas sensors.

The influence of temperature on the dielectric properties of sol-gel routed spin-coated molybdenum trioxide (MoO${}_3)$ thin film has been investigated. Prepared films were annealed at temperatures 250${}^{\circ }$C, 350${}^{\circ }$C and 400${}^{\circ }$C. The phase transformation from amorphous to $\alpha$-orthorhombic phase with preferential orientation (0 2 2) has been found by XRD for the film annealed above 250${}^{\circ }$C. The vibration modes of $\alpha$-orthorhombic MoO₃ have been examined by Raman spectrum. The predominant Raman’s band of $\alpha$-orthorhombic MoO₃ thin film has been found at the frequency range 1000–600cm${}^{-1}$. Using the UV–Vis spectrum, the band gap of the film is found to be 3.3–3.8eV. The surface morphology of the MoO₃ films has been examined by scanning electron microscope. The AC conductivity measurement of the MoO₃ film has been carried out in the frequency range 10–10⁶ Hz. The frequency dependence of the impedance has been plotted in the complex plane. The variation of the capacitance and dielectric constant of MoO₃ film with respect to temperature and frequency has been analyzed. Tunability of capacitance and figure of merit of the film are also determined.

The measurements of SbSCl_xI_1-x(x = 0.2) temperature dependent capacitance were carried out. The temperature of ferroelectric phase transition T_C ≈340 K was measured experimentally. T_C of SbSCl_xI_1-x was calculated theoretically in anharmonic and harmonic approximations. T_C was calculated in anharmonic approximation using temperature dependence of mean potential energy of Sb atoms as a function of the soft B_1u symmetry normal coordinate along c(z)-axis. Moreover, T_C was calculated in harmonic approximation using temperature dependence of vibrational thermodynamic functions (Helmholc free energy). T_C dependence from unit cell parameters a, b and from mixture composition x was carried out.

Tailoring pore-creating method to fit the various demands of different researchers is the frontier issue in the research of electrode capacitance of boron-doped diamond (BDD). Two critical factors in achieving the desired capacitance are the pore size and shape. This work compares the characteristics and applicability of various pore-creating methods, and reveals the influence mechanism of factors such as surface area, size and shape of the pore, on the capacitance of BDD electrodes. Obtained results could facilitate researchers to develop a personalized pore-creating method to achieve the desired capacitance.

The copper oxide, CuO, and copper hydroxide, Cu(OH)₂ nanomaterials have been prepared by a simple copper salt aqueous solution reaction. The powder X-ray diffraction (XRD) analysis showed the successful formation of Cu(OH)₂ and CuO nanoparticles. The average crystallite size of these Cu(OH)₂ and CuO nanoparticles was estimated and found to be around 17nm (Cu(OH)₂) and 10nm (CuO). The surface morphology and size of the CuO particles were confirmed by Scanning Electron Microscope (SEM) and High-resolution transmission electron microscope (HRTEM). The Raman analysis, dielectric and conductivity of CuO nanoparticles have been performed. The frequency variation of the capacitance (real dielectric constant) and dielectric loss was studied. The capacitance of the CuO nanoparticles is high at low frequencies and decreases rapidly when the frequency is increased. The frequency dependent ac conductivity follows Johnscher’s power law.

This paper reviews the interpretation of impedance and capacitance spectra for different capacitor technologies and discusses how basic electrical characteristics can be inferred from them. The basis of the interpretation is the equivalent circuit for capacitors. It is demonstrated how the model parameters, such as capacitance and equivalent series resistance, can be extracted from the measured spectra. The aspects of measurement accuracy are exemplarily discussed on the measured spectra.

The capacitance between the origin and any other lattice site in an infinite square lattice of identical capacitors each of capacitance C is calculated. The method is generalized to infinite Simple Cubic (SC) lattice of identical capacitors each of capacitance C. We make use of the superposition principle and the symmetry of the infinite grid.