Search Results (4)

With the rapid development of new electronic products and sustainable energy systems, there is an increasing demand for electrical energy storage devices such as electrostatic capacitors. In order to comprehensively improve the dielectric, insulating, and energy storage properties of PVDF-based composites, sandwich-structured composites were prepared by layer-by-layer solution casting. The outer layers of the sandwich structure composite are both PVDF/boron nitride nanosheet composites, and the middle layer is a PVDF/Ba_0.6Sr_0.4TiO₃ nanoparticles composite. The structural and electrical properties of the sandwich-structured composites were characterized and analyzed. The results show that when the volume percentage of Ba_0.6Sr_0.4TiO₃ nanoparticles in the middle layer of the sandwich structure composite is 1 vol.%, the dielectric properties are significantly improved. Its dielectric constant is 8.99 at 10 kHz, the dielectric loss factor is 0.025, and it has better insulating properties and resistance to electrical breakdown. Benefiting from the high breakdown electric field strength and the large maximum electrical displacement, the sandwich-structured composites with 1 vol.% and Ba_0.6Sr_0.4TiO₃ nanoparticles in the middle layer show a superior discharge energy density of 8.9 J/cm³, and excellent charge and discharge energy efficiency of 76%. The sandwich structure composite achieves the goal of simultaneous improvement in breakdown electric field strength and dielectric constant. Full article

SrTiO₃ and BaTiO₃ nanoparticles (NPs) were activated using H₂O₂ or aqueous HNO₃, and pristine and activated NPs were functionalized with a 2,2′-bipyridine phosphonic acid anchoring ligand (1), followed by reaction with RuCl₃^.3H₂O and bpy, RhCl₃^.3H₂O and bpy, or RuCl₃^.3H₂O. The surface-bound metal complex functionalized NPs were used for the photogeneration of H₂ from water, and their activity was compared to related systems using TiO₂ NPs. The role of pH during surface complexation was found to be important. The NPs were characterized using Fourier transform infrared (FTIR) and solid-state absorption spectroscopies, thermogravimetric analysis mass spectrometry (TGA-MS), and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), and the dihydrogen generation was analyzed using gas chromatography–mass spectrometry (GC-MS). Our findings indicate that extensively functionalized SrTiO₃ or BaTiO₃ NPs may perform better than TiO₂ NPs for water reduction. Full article

The present work aims to follow the influence of TiO₂ nanoparticles (TiO₂ NPs) on bioactive compounds, the elemental content of wheat, and on wheat leaves’ ultrastructure. Synthesized nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and transmission electron microscopy (TEM). The concentration of phenolic compounds, assimilation pigments, antioxidant capacity, elemental content, as well as the ultrastructural changes that may occur in the wheat plants grown in the presence or absence of TiO₂ NPs were evaluated. In plants grown in the presence of TiO₂ NPs, the amount of assimilating pigments and total polyphenols decreased compared to the control sample, while the antioxidant activity of plants grown in amended soil was higher than those grown in control soil. Following ultrastructural analysis, no significant changes were observed in the leaves of TiO₂-treated plants. Application of TiO₂ NPs to soil caused a significant reaction of the plant to stress conditions. This was revealed by the increase of antioxidant capacity and the decrease of chlorophyll, total polyphenols, and carotenoids. Besides, the application of TiO₂ NPs led to significant positive (K, Zn, Br, and Mo) and negative (Na, Mn, Fe, As, Sr, Sb, and Ba) variation of content. Full article

Ceramic-polymer nanocomposites, consisting of surface hydroxylated cube-shaped Ba_0.6Sr_0.4TiO₃ nanoparticles (BST–NPs) as fillers and poly(vinylidenefluoride) (PVDF) as matrix, have been fabricated by using a solution casting method. The nanocomposites exhibited increased dielectric constant and improved breakdown strength. Dielectric constants of the nanocomposite with surface hydroxylated BST–NPs (BST–NPs–OH) were higher as compared with those of their untreated BST–NPs composites. The sample with 40 vol % BST–NPs–OH had a dielectric constant of 36 (1 kHz). Different theoretical models have been employed to predict the dielectric constants of the nanocomposites, in order to compare with the experimental data. The BST–NPs–OH/PVDF composites also exhibited higher breakdown strength than their BST–NP/PVDF counterparts. A maximal energy density of 3.9 J/cm³ was achieved in the composite with 5 vol % BST–NPs–OH. This hydroxylation strategy could be used as a reference to develop ceramic-polymer composite materials with enhanced dielectric properties and energy storage densities. Full article