Fabrication and Excellent Dielectric Performance of Exfoliated Graphite Sheets

In the present investigation, exfoliated graphite sheets were obtained from the thermo-chemical treatment of natural graphite flakes. In this process, the graphite expands almost 300-350 times of its original volume and takes the shape of worms. These worms can be pressed or rolled into any desired shape without any binder. The exfoliated graphite sheets show excellent electrical properties i.e. high dielectric constant (ε = 6.374 ×107) and comparatively low dielectric loss (tanδ = 138) across the frequency in the range 50 Hz to 30 MHz and temperature in the range 40-300 °C. The products developed from exfoliated graphite can have very good sealing applications in industrial areas, especially for gaskets in the automobile industries

Fabrication and Excellent Dielectric Performance of Exfoliated Graphite Sheets

In the present investigation, exfoliated graphite sheets were obtained from the thermo-chemical treatment of natural graphite flakes. In this process, the graphite expands almost 300-350 times of its original volume and takes the shape of worms. These worms can be pressed or rolled into any desired shape without any binder. The exfoliated graphite sheets show excellent electrical properties i.e. high dielectric constant (ε = 6.374 ×107) and comparatively low dielectric loss (tanδ = 138) across the frequency in the range 50 Hz to 30 MHz and temperature in the range 40-300 °C. The products developed from exfoliated graphite can have very good sealing applications in industrial areas, especially for gaskets in the automobile industries

Recent Advances of MOF-Based Nanoarchitectonics for Chemiresistive Gas Sensors

It is sad but true that, as industrialization increases, a large number of hazardous gases are discharged into the environment, which can cause major health problems relating to respiratory disorders. Thus, to eliminate this pressing issue constant monitoring of air quality is mandatory, for this gas sensors play a huge role. There have been various gas sensors developed till now with respect to high sensitivity and selectivity. However, a sensor which having properties of high surface-to-volume ratio, good reactivity, long life cycles, and so on is difficult to produce. To remove this issue, a metal organic framework (MOF) can be utilized to measure various analytes as it has high sensitivity and selectivity. Further to upgrade the properties of a sensor in terms of optimum pore size, and high surface reactivity, which cannot only create a sensor with high efficiency, but also reduce energy consumption and maintenance, nanostructures have been incorporated into the MOFs. Furthermore, numerous reviews on gas sensing using MOF-based materials have been published. Only chemiresistive-based nanostructures embedded in MOF have yet to be described. In a nutshell, this review elicits thorough insightful details regarding advancements in MOF-derived nanostructure-based gas sensors for the measurement of various gas analytes, as well as the chemical mechanism, challenges associated with it, factors impacting the gas sensing process, and morphological data, which are also explained

Dielectric properties of graphene/nano-Fe2O3 filled poly (vinyl alcohol)/ Chitosan blends

Novel nanocomposites based on Poly (vinyl alcohol) (PVA), Chitosan (CS), Graphene quantum dots (GQDs) and iron oxide (Fe2O3) nanoparticles (NPs) have been synthesized by solution casting method. The structural mod-ifications and morphological studies were carried out by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and Scanning electron microscopy/Energy-dispersive X-ray (SEM/EDX) techniques. The results confirm the microscopic interactions and sphere-like morphology of the nanocomposites due to the presence of GQDs and Fe2O3 within the polymer blend. The thermal stability with almost 25% leftover residue for higher nanofillers loading in the nanocomposite was estimated by thermo-gravimetric analysis (TGA). Moreover, the frequency and temperature-dependent dielectric properties were investigated. The dielectric constant and loss tangent values are greatly influenced by reinforcement of GQDs/Fe2O3 and the obtained values were in the range of-104 and-101, respectively at 150 degrees C and 50 Hz. The rise in ac conductivity i.e., 9.8 x 10-4 (S/m) with increasing nanofiller loadings suggests the reduction in capacitive reactance and impedance. However, the semi-circular arcs are observed in the cole-cole plot where the fitted impedance data along with the equivalent circuit is also presented. The reduction of bulk resistance and impedance on increasing the nanofiller loadings with enhanced dielectric properties signifies the use of PVA/CS/GQDs/Fe2O3 nanocomposites as a potential material for energy storage applications.Novel nanocomposites based on Poly (vinyl alcohol) (PVA), Chitosan (CS), Graphene quantum dots (GQDs) and iron oxide (Fe2O3) nanoparticles (NPs) have been synthesized by solution casting method. The structural mod-ifications and morphological studies were carried out by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and Scanning electron microscopy/Energy-dispersive X-ray (SEM/EDX) techniques. The results confirm the microscopic interactions and sphere-like morphology of the nanocomposites due to the presence of GQDs and Fe2O3 within the polymer blend. The thermal stability with almost 25% leftover residue for higher nanofillers loading in the nanocomposite was estimated by thermo-gravimetric analysis (TGA). Moreover, the frequency and temperature-dependent dielectric properties were investigated. The dielectric constant and loss tangent values are greatly influenced by reinforcement of GQDs/Fe2O3 and the obtained values were in the range of-104 and-101, respectively at 150 degrees C and 50 Hz. The rise in ac conductivity i.e., 9.8 x 10-4 (S/m) with increasing nanofiller loadings suggests the reduction in capacitive reactance and impedance. However, the semi-circular arcs are observed in the cole-cole plot where the fitted impedance data along with the equivalent circuit is also presented. The reduction of bulk resistance and impedance on increasing the nanofiller loadings with enhanced dielectric properties signifies the use of PVA/CS/GQDs/Fe2O3 nanocomposites as a potential material for energy storage applications

A Magnetite Composite of Molecularly Imprinted Polymer and Reduced Graphene Oxide for Sensitive and Selective Electrochemical Detection of Catechol in Water and Milk Samples: An Artificial Neural Network (ANN) Application

In the present study, a stable and more selective electrochemical sensor for catechol (CC) detection at magnetic molecularly imprinted polymer modified with green reduced graphene oxide modified glassy carbon electrode (MIP/rGO@Fe3O4/GCE). Two steps have been applied to achieve the imprinting process: (1) adsorption of CC on the surface of the polypyrrole (Ppyr) during the polymerization of pyrrole and (2) the green extraction of the template (CC) from the mass produced. Hence, the present paper doesn't present the first use of MIP technology for CC identification but, it presents a new extraction process. The MIP/rGO@Fe3O4/GCE was characterized by voltammetry techniques and exhibited a wide linear range from1 50 mu M of CC while the detection limits were estimated to be around 4.18 nM CC and limit of quantification in the range of 12.69 nM CC. Furthermore, the prepared MIP-based sensor provided outstanding electroanalytical performances including high selectivity, stability, repeatability, and reproducibility. For the accurate estimation of CC concentrations, an artificial neural network (ANN) was developed based on the findings of the study. The MIP/rGO@Fe3O4/GCE exhibits excellent stability with a very important selectivity and sensitivity. The analytical testing of the modified electrode has been analyzed in water and commercial milk samples and provided adequate recoveries. (c) 2023 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/ by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited

Simple Thermal Annealing-Assisted Direct Synthesis and Optical Property Study of CuO Nanoparticles Incorporated Polyvinyl Alcohol Films

This article reports a simple thermal annealing-assisted direct synthesis method to prepare copper oxide (CuO) nanoparticles incorporated in polyvinyl alcohol (PVA) films and a systematic study of their optical properties. CuO-PVA nanocomposite films are prepared with a different weight percentage of CuO in the PVA matrix. Scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible spectroscopy, and photoluminescence spectroscopy are employed to study the prepared films. XRD confirms the formation of crystalline CuO nanoparticles in PVA, while the SEM analysis shows uniformly distributed spherical nanoparticles in PVA. The findings show that thermal annealing at a mild temperature plays a crucial role in improving the crystallinity and optical properties of the nanocomposite film. In comparison to PVA, CuO-PVA nanocomposite exhibits improved absorption with a new absorption band in the lower wavelength region. The nanocomposite samples excited with 300 nm show intense photoluminescence (PL) at 365 nm and an increase of PL intensity with CuO concentration in the PVA matrix. In contrast, samples excited with 425 nm show green emission at 550 nm in the visible region of the electromagnetic spectrum. The PL in CuO-PVA nanocomposites can be originated due to the transitions associated with acceptor and donor defects in the material. The study opens up a new route to fabricate CuO-PVA nanocomposites with superior optical properties

Evaluation of microstructural and thermal properties of sol-gel derived silica-titania based porous glasses

PING 2019 is organized with the support of funds for specific university research project SVK1-2019-002.In recent years, the synthesis of sol-gel derived porous glasses has drawn widespread attention owing to the convenience and versatility of the sol-gel method. The sol-gel synthesis process mainly involves hydrolysis and condensation of precursors followed by drying and stabilization. The characteristics such as pore structure, morphology and compositions of sol-gel derived glasses significantly affect their final properties. In the present study, silica-titania (Si-Ti) based porous glasses with different compositions were synthesized using the sol-gel method. Metal alkoxides such as tetraethoxysilane (TEOS) and titanium isopropoxide (TIP) were used as a source as the source for silica and titania respectively. Nitric acid (HNO3) was used as catalysts to trigger the hydrolysis reaction and polyethylene glycol (PEG) was used as a polymeric component to induce phase separation. The influence of different processing parameters on the microstructural and thermal properties was investigated. The microstructure of the synthesized Si-Ti based porous glasses was investigated using Scanning electron microscopy (SEM) and the thermal characteristics were evaluated using thermogravimetric analysis (TGA) and thermomechanical analysis (TMA). The main objective of this study is to ascertain the application of sol-gel derived Si-Ti porous glasses as a potential biomaterial for bone tissue regeneration. To understand this facet of Si-Ti porous glasses, the biological performance will be investigated and their porous architecture will be explored in relation to their interaction with the bioactive nanoparticles

Fabrication of flexible ternary polymer blends comprising polypyrrole, polyvinylalcohol, and poly(4-styrenesulfonic acid): Study of structural, morphological, and dielectric properties

A new ternary polymer blend was synthesized and characterized in the presentwork. A series of ternary polymer blends comprising water soluble polypyrrole, polyvinyl alcohol, and poly(4-styrenesulfonic acid) were prepared by solution casting method. The structural, electrical, and thermal properties of prepared ternary blends were investigated. X-ray diffraction studies indicated the semicrystalline nature of the polymer blends and chemically interacted polymer chain were revealed by Fourier transform infrared spectra. The morphological phase transformations were observed from scanning electron microscope and atomic force microscopy images. Thermogravimetric analysis explained the thermal degradation process. The ternary blends also possess excellent mechanical stability observed through force versus extension plot. The dielectric constant value of ternary blends was obtained in the range of 600–800 at low frequency range. The highest conductivity obtained was between 101 to 103 S cm1 for ternary blends at higher frequency range. The overall results explains the charge transportation and relaxation process in the ternary blends due to presence of an electric field. The excellent dielectric constant values of ternary blends will be efficient for various electronics application

Room temperature ammonia sensing based on graphene oxide integrated flexible polyvinylidenefluoride/cerium oxide nanocomposite films

In this work, novel room temperature (RT) ammonia (NH3) sensors comprising graphene oxide (GO) integrated polyvinylidenefluoride (PVDF)/cerium oxide (CeO2) nanocomposite films have been prepared via simple solution casting technique. The structural and morphological characteristics of flexible tertiary PVDF/CeO2/GO nanocomposite films have been investigated using various analytical techniques and their NH3 gas-sensing performance was evaluated at RT and the relevant sensing mechanism was established. The flexible PVDF/CeO2/GO nanocomposite films responded strongly to NH3 gas with enhanced gas sensing properties at RT as compared with various other volatile organic compounds (VOCs) such as acetone, ethanol, formaldehyde and toluene

Dielectric and electromagnetic interference shielding properties of zeolite 13X and carbon black nanoparticles based PVDF nanocomposites

In the present work, Zeolite 13X and carbon black nanoparticles (CBNPs) reinforced polyvinylidene fluoride (PVDF) nanocomposites were obtained by a simple solvent casting technique. The structural, morphological and thermal properties of PVDF/Zeolite 13X/CBNPs nanocomposites with various loadings of Zeolite 13X and CBNPs were investigated using Fourier-transform infrared spectroscopy, X-ray diffraction, Scanning electron microscopy and thermo-gravimetric analysis. The dielectric studies were carried out in the 50 Hz–10 MHz frequency range at room temperature. The electromagnetic interference (EMI) shielding effectiveness (SE) of PVDF/Zeolite 13X/CBNPs nanocomposite was investigated in the 8–18 GHz frequency region (X-band and Ku-band). The maximum EMI SE of approximately −11.1 dB (8–12 GHz) and −11.5 dB (12–18 GHz) was observed for PVDF/CBNPs nanocomposites with 10 wt% loading of CBNPs. These findings emphasize the application of PVDF/ Zeolite 13X/CBNPs nanocomposites as a potential EMI shielding material