Electrical conductivity and supercapacitor properties of polyaniline/chitosan/nickel oxide honeycomb nanocomposite

Dielectric, AC Conductivity, and DC Conductivity Behaviours of Sr2CaTeO6 Double Perovskite

Relatively new double perovskite material, Sr₂CaTeO₆, has been prepared through conventional solid-state procedures. Structural, dielectric, and optical characteristics of this exquisite solid-state material were analysed in this study. The single-phase monoclinic P2₁/n structure of this prepared compound was well correlated with the literature review. Good distribution of grain sizes and shapes was observed in the morphological study of this compound. The discussions on its optical and dielectric properties are included in this manuscript. High dielectric real permittivity, low dielectric loss, and good capacitance over a range of temperatures possessed by this compound, as shown in dielectric and electrical modulus studies, indicated good potential values for capacitor applications. The R_o(R_gQ_g)(R_gbQ_gb) circuit fitted well with the impedance and electrical modulus plot of the compound. Its relatively high electrical DC conductivity in grain at high frequencies and its increasing value with the temperature are typical of a semiconductor behaviour. This behaviour might be attributed to the presence of minor oxygen vacancies within its lattice structure and provides a long-range conduction mechanism. A small difference between activation energy and E_a of DC conductivity indicates that the same charge carriers were involved in both grains and the grain boundaries’ long-range conduction. The electrical AC conductivity of this compound was found to contribute to the dielectric loss in grain structure and can be related to Jonscher’s power law. The presence of polarons in this compound was exhibited by non-overlapping small polaron tunnelling (NSPT) and overlapping large polaron tunnelling (OLPT) conduction mechanisms over a range of temperatures. Wide optical band gap and E_opt in the range of 2.6 eV to 3.6 eV were determined by using an indirect and direct allowed mechanism of electrons transitions. These values supported the efficient semiconducting behaviour of the grain in this material and are suitable for applications in the semiconductor industry.

Preparation of Hierarchic Porous Films of α-MnO2 Nanoparticles by Using the Breath Figure Technique and Application for Hybrid Capacitor Electrodes

The honeycomb-structured film has advantages such as high wettability and high surface area. This structure and properties are suitable for the capacitor electrode. In this study, the electrode structure is controlled by the synthesis of MnO₂ nanoparticles using the breath figure method. The electrode performance was calculated by electrochemical measurements. As a result, the capacitance value was 100.5 F/g at 1 mV s^-1, which was improved 2.7 times as compared with that without structure control.

Construction of Chitosan-Zn-Based Electrochemical Biosensing Platform for Rapid and Accurate Assay of Actin

This work reports a study on the development of a sensitive immunosensor for the assay of actin, which is fabricated using sensing material chitosan-Zn nanoparticles (NPs) and anti-actin modified on glassy carbon electrode respectively. The prepared materials were characterized using transmission electron microscope (TEM), fourier transform infrared spectra (FTIR), X-ray diffraction (XRD) spectra, and circular dichroism (CD) techniques. Meanwhile, the electrochemical properties were studied by linear sweep voltammetric (LSV), electrochemical impedance spectra (EIS), and differential pulse voltammetry (DPV). According to the experiments, under the optimum conditions, the linear fitting equation was I (μA) = −17.31 + 78.97c (R² = 0.9948). The linear range was from 0.0001 to 0.1 mg/mL and the detection limit (LOD, S/N = 3) was 21.52 ng/mL. The interference studies were also performed for checking the sensors’ selectivity to actin. With better properties of the chitosan-Zn NPs, the modified electrode is considered as a better candidate than Western blot or immunohistochemical method for real-time usability. The detection limit reported is the lowest till date and this method provides a new approach for quality evaluation.

Electrical Conduction Mechanism and Dielectric Properties of Spherical Shaped Fe₃O₄ Nanoparticles Synthesized by Co-Precipitation Method

On the basis of dielectric measurements performed in a wide temperature range (173⁻373 K), a comprehensive analysis of the dielectric and electrical properties of magnetite nanoparticles electrical conduction mechanism of compressed spherical shaped Fe₃O₄ nanoparticles was proposed. The electrical conductivity of Fe₃O₄ nanoparticles was related to two different mechanisms (correlated barrier hopping and non-overlapping small polaron tunneling mechanisms); the transition between them was smooth. Additionally, role of grains and grain boundaries with charge carrier mobility and with observed hopping mechanism was described in detail. It has been confirmed that conductivity dispersion (as a function of frequencies) is closely related to both the long-range mobility (conduction mechanism associated with grain boundaries) and to the short-range mobility (conduction mechanism associated with grains). Calculated electron mobility increases with temperature, which is related to the decreasing value of hopping energy for the tunneling of small polarons. The opposite scenario was observed for the value of electron hopping energy.