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Nickel oxide (NiO) nanoparticles (NPs) and graphene quantum dots (GQDs) reinforced polyvinyl alcohol (PVA) nanocomposite films were prepared using a solution casting technique. The physicochemical characteristics of PVA/NiO/GQDs (PNG) nanocomposite films were studied using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). The obtained PNG nanocomposite films showed good mechanical flexibility and improved tensile strength. The influence of nanofiller concentrations on PNG nanocomposite film. The obtained results demonstrate an increase in the activation energy (Ea) up to PNG3 upon increasing the GQDs concentration and thereafter, its decreases. The fundamental interactions of the constituents of PNG nanocomposite film were investigated using density functional theory (DFT). This study on electronic structure reveals that the PVA model indirectly interacts with GQDs through the NiO model. This configuration is favoured in terms of interaction energy (-78 kJ/mol) compared to the one in which PVA interacts directly with the GQDs model., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Over the last few decades, various volatile organic compounds (VOCs) have been widely used in the processing of building materials and this practice adversely affected the environment i.e. both indoor and outdoor air quality. A cost-effective solution for detecting a wide range of VOCs by sensing approaches includes chemiresistive, optical and electrochemical techniques. Room temperature (RT) chemiresistive gas sensors are next-generation technologies desirable for self-powered or battery-powered instruments utilized in monitoring emissions that are associated with indoor/outdoor air pollution and industrial processes. In this review, a state-of-the-art overview of chemiresistive gas sensors is provided based on their attractive analytical characteristics such as high sensitivity, selectivity, reproducibility, rapid assay time and low fabrication cost. The review mainly discusses the recent advancement and advantages of graphene oxide (GO) nanocomposites-based chemiresistive gas sensors and various factors affecting their sensing performance at RT. Besides, the sensing mechanisms of GO nanocomposites-based chemiresistive gas sensors derived using metals, transition metal oxides (TMOs) and polymers were discussed. Finally, the challenges and future perspectives of GO nanocomposites-based RT chemiresistive gas sensors are addressed., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The present work reports the preparation of polyvinyl formal (PVF)/Titanium dioxide (TiO 2 ) nanocomposite films using a solution casting method followed by the characterization of the synthesized PVF/TiO 2 nanocomposite films using various analytical techniques namely FTIR, XRD, UV-vis, SEM and TGA analysis. The results obtained from different analyses confirmed that the TiO 2 NPs was fine dispersed within the PVF matrix and there exists well compatibility among the polymer matrix and the nanofiller. The pristine TiO 2 NPs based fabricated chemiresistive sensor exhibits the maximum sensitivity of 50.25% at 370 °C where as PVF/TiO 2 nanocomposite sensor showed the enhanced sensitivity of 83.75% at a relatively low operating temperature of 150 °C towards 600 ppm sulfur dioxide (SO 2 ) gas. The 25 wt% PVF/TiO 2 nanocomposite film sensor exhibited good sensitivity (∼83.75%), selectivity, rapid response time (66 s)/recovery time (107 s), and long-term stability of 60 days for SO 2 gas detection. The fabricated PVF/TiO 2 nanocomposite film sensors in our work possesses the advantages of low power consumption, cost-effective, and distinguished sensing abilities for SO 2 detection makes it possible for potential applications. Thus, the fabricated chemiresistive sensors based on TiO 2 NPs reinforced PVF nanocomposites films are evaluated and experimental results to show an excellent behavior towards SO 2 gas detection for industrial processes control and environmental monitoring applications., Competing Interests: Declaration of competing interest All the authors declare no conflict of interest., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Polymer composites have established an excellent position among the technologically essential materials because of their wide range of applications. An enormous research interest has been devoted to zinc oxide (ZnO) based polymer nanocomposites, due to their exceptional electrical, optical, thermal, mechanical, catalytic, and biomedical properties. This article provides a review of various polymer composites consisting of ZnO nanoparticles (NPs) as reinforcements, exhibiting excellent properties for applications such as the dielectric, sensing, piezoelectric, electromagnetic shielding, thermal conductivity and energy storage. The preparation methods of such composites including solution blending, in situ polymerization, and melt intercalation are also explained. The current challenges and potential applications of these composites are provided in order to guide future progress on the development of more promising materials. Finally, a detailed summary of the current trends in the field is presented to progressively show the future prospects for the development of ZnO containing polymer nanocomposite materials., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this work, zirconia (ZrO2) nanoparticles (NPs) incorporated poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanocomposites were fabricated at varying weight ratios through solution casting approach. The structural properties of PVDF-HFP/ZrO2 nanocomposites have been investigated by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. The strong interaction of ZrO2 with the PVDF-HFP matrix was observed revealing the structural modifications in the nanocomposites. The thermal degradation behavior of PVDF-HFP/ZrO2 nanocomposites was investigated by thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and differential thermal analysis (DTA). Addition of ZrO2 in the PVDF-HFP matrix has greatly improved the thermal stability of the PVDF-HFP/ZrO2 nanocomposites. The dielectric properties of the PVDF-HFP/ZrO2 nanocomposites were investigated as a function of frequency and temperature. The dielectric constant was observed to be higher at low frequency and decreased abruptly on increasing the frequency. Moreover, the impedance behavior of PVDF-HFP/ZrO2 nanocomposites with different loadings was studied by plotting Nyquist plots. These results revealed that PVDF-HFP/ZrO2 nanocomposites have shown enhanced thermal, dielectric and impedance properties as compared to neat PVDF-HFP film. These significant outcomes suggest that the PVDF-HFP/ZrO2 nanocomposites hold promise as viable options for energy storage applications. [ABSTRACT FROM AUTHOR]

Herein, Ti2CTx MXene‐Polyvinyl alcohol (PVA) nanocomposite films with different weight percent (wt%) of MXene loadings were successfully prepared using the facile solution casting method. The structural, morphological, optical, thermal, and tensile properties of the nanocomposite films were analyzed using FTIR, XRD, Raman, SEM, UV–Vis spectroscopy, TG‐DTA, mechanical tests, and so forth. The variation in dielectric constant, loss tangent, and AC conductivity of the nanocomposite films was analyzed in the range of 1 Hz to 10 MHz with the variation of temperature (30–150°C) and MXene concentrations (5–20 wt%) using impedance spectroscopy. The nanocomposite films showed a very high dielectric constant in the range of ~105 for lower frequency and very low dielectric loss in the range of 0–1 for higher frequency (100 kHz–10 MHz). The dielectric constant, loss tangent, and AC conductivity values increased at a certain temperature and further decreased with increase in temperature. The increase in filler concentration increased the values of these investigated electrical parameters but at a concentration of 20 wt%, the nanocomposite films reached the percolation limit, and hence a slight reduction in the dielectric properties was noticed. Moreover, the complex impedance spectroscopy studies of the nanocomposite films were also carried out and their corresponding circuit diagrams were fitted according to the obtained cole‐cole plots. [ABSTRACT FROM AUTHOR]