ZnO/CuO nanocomposite-based carboxymethyl cellulose/polyethylene oxide polymer electrolytes for energy storage applications

As a part of this investigation, polymer nanocomposite films were obtained by the casting method whereby polyethylene oxide (PEO) was mixed with carboxymethyl cellulose (CMC) at a 70:30 wt ratio (PEO/CMC) as a base before adding different concentrations (0.0, 0.3, 0.8, 2, 4, and 6 wt%) of ZnO/CuO nanocomposite (ZC NC) as a dopant, prepared by the sol-gel method. Subsequent analyses revealed that, compared with the pure mixture, the dielectric parameters and conductivity of the polymer nanocomposite (CMC/PEO-ZC NC) films markedly improved with the increase of ZC NC up to 2 wt%, while a decrement was noted for 4 and 6 wt%. Thus, the optimal concentration (CMC/PEO-ZC NC 2 wt%) was used in the subsequent investigations focusing on dielectric properties, and the temperature dependence of the dielectric parameters and conductivity. As ZC NC addition yielded beneficial outcomes, the structural and morphological changes caused by the doping process were successfully counteracted, as confirmed by the x-ray diffraction (XRD) and scanning electron microscopy (SEM) results. The calculated relaxation time (τ), activation energy (Ea), and improved dielectric properties suggest that these nanocomposite films are promising candidates for the development of solid-state supercapacitors

Synthesis of Zn Intercalated Zn–V@Mo–V Nanorods-based Cathodes for Prolonged Cyclic Stability of Rechargeable Aqueous Zinc-Ion Batteries

Stationary rechargeable Zn-ion batteries (ZIBs) are attractive energy storages systems because of their natural abundance, safety, and low cost. High capacity, stable, and robust cathode materials play an important role in aqueous electrolyte systems in ZIBs, where metal oxide cathode dissolution is a problem that needs to be addressed. Herewith, we report an intercalation-type Zn-doped Zn–V@Mo–V (ZMV) cathode material affording prolonged cycle stability and high storage capacity. Porous, superfine nanostructures offer Zn2+ ion diffusion pathways, alleviating intercalation redox reactions without dissolution. Zn doping restructures the cathode expansion-like, resulting in increased electrical conductivity and faster electrochemical ion diffusion. A reversible and uniform Zn electroplating at the anode surface interface indicates improved cell reversibility. The ZMV cathode scales up to assemble a pouch cell of Zn//ZnSO4//ZMV, where the cathode enhances the rate performance and decreases the self-discharge rate. High efficiency and long cycle life can be endowed to the cathode material to construct a stable Zn-ion battery, accelerating the commercialization of the whole system

Photocatalytic Synthesis of Coumarin Derivatives Using Visible-Light-Responsive Strawberry Dye-Sensitized Titanium Dioxide Nanoparticles

This study presents a novel method for the photocatalytic synthesis of 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones (a coumarin derivative) using strawberry dye-sensitized TiO2 (SD-TiO2) under visible light. The synthesis of 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones was achieved through a three-component, one-pot condensation reaction involving 3-acetyl coumarin, aldehydes, and urea, utilizing SD-TiO2 as a reusable and innovative photocatalyst at room temperature. The resulting SD-TiO2 photocatalyst was thoroughly characterized using FT-IR, XPS, XRD, SEM, and BET. The efficacy of SD-TiO2 was evaluated by comparing it to pristine TiO2 in terms of photocatalytic activity, and the optimal conditions for the synthesis process were determined. Notably, the SD-TiO2 photocatalyst exhibited a maximum yield of the compound, reaching up to 96% in just 30 min with a catalyst concentration of 1 mg/mL. This yield surpasses traditional thermal procedures employing reflux conditions, where 1 mg/mL of SD-TiO2 is sufficient to complete the reaction. The resulting 4-aryl-6-(3-coumarinyl) pyrimidin-2 (1H)-ones were further characterized using 1H-NMR and 13C-NMR. Moreover, the stability of the SD-TiO2 photocatalyst was confirmed through recyclability experiments and spectroscopic characterization, demonstrating its practicality for up to three consecutive reaction cycles

Fabrication and Wettability Study of WO3 Coated Photocatalytic Membrane for Oil-Water Separation: A Comparative Study with ZnO Coated Membrane

Superhydrophilic and underwater superoleophobic surfaces were fabricated by facile spray coating of nanostructured WO3 on stainless steel meshes and compared its performance in oil–water separation with ZnO coated meshes. The gravity driven oil-water separation system was designed using these surfaces as the separation media and it was noticed that WO3 coated stainless steel mesh showed high separation efficiency (99%), with pore size as high as 150 µm, whereas ZnO coated surfaces failed in the process of oil-water separation when the pore exceeded 50 µm size. Since, nanostructured WO3 is a well known catalyst, the simultaneous photocatalytic degradation of organic pollutants present in the separated water from the oil water separation process were tested using WO3 coated surfaces under UV radiation and the efficiency of this degradation was found to be quite significant. These results assure that with little improvisation on the oil water separation system, these surfaces can be made multifunctional to work simultaneously for oil-water separation and demineralization of organic pollutants from the separated water. Fabrication of the separating surface, their morphological characteristics, wettability, oil water separation efficiency and photo-catalytic degradation efficiency are enunciated

Modeling the magnetocaloric effect of spinel ferrites for magnetic refrigeration technology using extreme learning machine and genetically hybridized support vector regression computational methods

AbstractSpinel ferrites are magnetic oxide materials with potentials to promote green technology in magnetic refrigeration which is known to be economically clean, energy saving and efficient. Maximum magnetic entropy change of spinel ferrites decides and controls the applicability as well as the strength of spinel ferrite magnetic oxide since it measures the hugeness of magnetocaloric effect. However, experimental determination of maximum magnetic entropy change requires intensive procedures, costly equipment and consumes appreciable time. Intelligent models are presented in this work using spinel-ferrite-molecular-based descriptors such as the ionic radii of spinel ferrites constituents, applied magnetic field and their concentrations. The developed intelligent models for prediction of spinel ferrite maximum magnetic entropy change include extreme learning machine (ELM) and hybrid genetic-algorithm-coupled support vector regression (GSVR). The developed ELM model has correlation coefficient (CC) and mean absolute error (MAE) of 98.45% and 0.117 J/kg/K, respectively, while the developed GSVR model has CC of 80.87% and MAE of 0.129 J/kg/J. The developed ELM model which is based on empirical risk minimization principle shows better performance over GSVR model that premises on structural minimization risk principle with improvement of 0.06%, 17.86% and 8.765% using root mean square error, CC and MAE yardsticks, respectively. Closeness of the estimates of the developed models with the experimental values is a strong indication of the potentials of the proposed intelligent methods in facilitating practical implementation of magnetic cooling refrigeration to solve energy crisis which promote efficiency and environmental friendliness

The Impact of Full-Scale Substitution of Ca2+ with Ni2+ Ions on Brushite’s Crystal Structure and Phase Composition

Because the impact of the full-scale substitution of Ca2+ in brushite (CaHPO4·2H2O) with Ni2+ ions has never been systematically explored, it is the focus of this investigation, as it holds potential for use in CaxNi1−xHPO4·nH2O production. These biomaterials have many beneficial characteristics that can be modified to suit diverse applications, including bone tissue regeneration and pharmaceutics. For the present study, NaH2PO4·2H2O, Ca(NO3)2·4H2O, and Ni(NO3)2·6H2O were used in various molar concentrations to obtain the required starting solutions. Previous studies have shown that adding Ni ions in the initial solution below 20% results in the precipitation of monophasic brushite with slight changes in the crystal structure. However, this study confirms that when the Ni ions substitution increases to 20%, a mixture of phases from both brushite and hexaaquanickel(II) hydrogenphosphate monohydrate HNiP (Ni(H2O)6·HPO4·H2O) is formed. The results confirm that the full replacement (100%) of Ca ions by Ni ions results in a monophasic compound solely comprising orthorhombic HNiP nanocrystals. Therefore, a novel technique of HNiP synthesis using the precipitation method is introduced in this research work. These materials are subsequently analyzed utilizing powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The obtained results confirm that the material microstructure is controlled by the Ni/Ca ratio in the starting solution and can be modified to obtain the desired characteristics of phases and crystals

Enhancing the Structural, Optical, Thermal, and Electrical Properties of PVA Filled with Mixed Nanoparticles (TiO₂/Cu)

In this work, new samples of PVA-TiO2/Cu nanocomposites were prepared via the casting method. The prepared samples were examined using different analytical methods. An XRD analysis showed the semi-crystalline nature of the PVA polymer, as well as showing a decrease in the degree of the crystallinity of the PVA structure as a result of the addition of the mixed nanoparticles. TEM images indicate the spherical shape of the Cu NPs, with a size ranging from 2 to 22 nm, and the rectangular shape of the TiO2 NPs, with a size ranging from 5 to 25 nm. It was evident via FTIR measurements that there were interactions between the functional groups of the PVA and the TiO2/Cu NPs. The optical properties of the PVA nanocomposites were improved with an increase in the content of the TiO2/Cu nanoparticles, as shown via a UV/Vis analysis. DSC curves showed an improvement in the thermal stability of the PVA-TiO2/Cu nanocomposites after the embedding of the TiO2/Cu nanoparticles. It was evident using impedance spectroscopy that the AC conductivity was improved by adding the TiO2 and Cu nanoparticles to the polymeric matrix. The maximum AC conductivity was found at 1.60 wt.% of TiO2/Cu nanoparticles in the PVA polymer, and this was 13.80 × 10−6 S/cm at room temperature. Relaxation occurred as a result of the charge carrier hopping between the localized state and the correlated barriers hopping model, describing the dominant mechanism, as presented in an electrical modulus analysis. These results indicate that the PVA-TiO2/Cu nanocomposite samples can be used in energy storage capacitor applications and in the alternative separator-rechargeable lithium-ion battery industry

Enhanced Structural, Optical Properties and Antibacterial Activity of PEO/CMC Doped TiO₂ NPs for Food Packaging Applications

In this article, the synthesis, optical, and electrical properties of composites consisting of polyethylene oxide (PEO), carboxymethyl cellulose (CMC), and titanium dioxide nanoparticles are examined. Flexible nanocomposite samples comprising PEO, CMC, and TiO2 nanoparticles were produced swiftly via using the cast synthesis method. In addition, XRD and FT-IR analysis were performed in order to analyze the structures of the prepared samples. Our results demonstrate the PEO/CMC blend’s effectiveness in interacting with TiO2 nanoparticles. The optical properties of the PEO/CMC and nanocomposite samples, such as the energy band gap, were studied using the UV/Vis optical absorbance. It was found that as TiO2 NP weight fraction increases, the energy gap narrows. Moreover, TiO2 nanoparticles with an average size of 16 nm were formed in spherical and rod shapes, according to a TEM image. The SEM images demonstrate how the distribution of TiO2 NPs increased upon the surfaces of the prepared films. The antibacterial activity in the nanocomposites was shown to be enhanced by the TiO2 NP concentrations. Finally, we proposed that PEO/CMC-0.8 wt. % TiO2 nanocomposites with enhanced optical, electrical, and dielectric properties should be used in electrochemical devices

Improving the polyethylene oxide/carboxymethyl cellulose blend's optical and electrical/dielectric performance by incorporating gold quantum dots and copper nanoparticles: nanocomposites for energy storage applications

Herein, nanocomposite polymer electrolyte films were prepared from the blend of two polymers, polyethylene oxide (PEO) and carboxymethyl cellulose (CMC), stuffed with various contents of gold quantum dots (AuQDs) and copper nanoparticles (CuNPs) as hybrid nanofiller via the solution casting method. AuQDs were prepared using laser ablation in liquid (LAL). TEM images showed that the average size of AuQDs is nearly 6.21 nm with a spherical shape. The effects of AuQDs and the hybrid nano-filler (AuQDs and CuNPs) on the PEO/CMC blend structural, optical, and electrical/dielectric characteristics have been investigated and discussed. XRD results revealed that the crystallinity degree of the nanocomposite samples decreased with increasing AuQDs/CuNPs content. Also, UV–Vis spectroscopy analysis uncovered that the optical energy gap reduced as the hybrid nanofillers' content increased. At room temperature, the electrical impedance spectroscopy (EIS) measurements showed that the hybrid nanofiller loading increases the electrolyte films’ electrical conductivity. In the dielectric properties, space charges polarization revealed higher values, where the dielectric constant (ε′) increased at lower frequency regions. The Nyquist diagram showed a semicircular shape at the lower frequencies part with a linear shape at the higher frequencies part with decreasing radius; two equivalent circuit models could be the best fit. These results suggest that these nanocomposite electrolyte films could be candidates for capacitors and flexible energy storage devices