Journal of Nano Research Vol. 80

Abstract: In this work we studied the effect of doping on heterogeneous photocatalysis application we used the samples CuO, 5% Ag:CuO, 15% Ag:CuO, 25% Ag:CuO and 50% Ag:CuO catalysts thin layers which were prepared by the sol gel method on a glass substrate. The structural, morphological, optical and electrical characteristics of these layers were studied by XRD, IR, SEM, UV-Vis spectrophotometry and four-point analysis. The results of the XRD, it is observed that the structure of the monoclinic phase develops, with preferential orientations following the plane (-111). This indicated that the thin films are polycrystalline, these results and confirmed by the IR spectra. In the case of Ag doping the SEM revealed the creation of pores on the surface of the samples, which enhanced the degradation of orange II under UV light. The gap energy decreases from 2.17 eV to 1.25 eV with increasing doping. These results show that thin films doped with Ag exhibit a higher degradation than that obtained by pure CuO. After 5 hours in the case of doping with 50% Ag the percentage of degradation is 43%, on the other hand in the pure case the percentage of degradation is 27%.With this, it can be said that 50% Ag:CuO is a good catalyst because the sample has pores, and therefore a larger catalytic area. Creating pores on the surface of the samples, obtaining a less energy gap enables the creation of a greater number of •Oand OH• that works to disintegrate the dye and give the white color to the solution.

Abstract: Tailoring diverse characteristics of nanostructured cellulose acetate (CA) membranes by incorporating nanocomposite-tubes ZFS composed of zinc ferrites decorated over single walled carbon nanotubes (SCNTs) for desalination application, is presented in the current research. In situ coprecipitated route is adopted to synthesize ZFS composite filler that imparts morphological, structural, and thermal modifications in CA membranes. Phase inversion via immersion precipitation route has been adopted to synthesis mixed matrix membranes. Microstructural analysis divulges pore size tuning from 1µm to 5nm by increasing loading content of infused filler (ZFS) from 0 to 4wt.%. XRD and FTIR examinations verified the existence and linkages of impregnated composite nanotubes in the modified membranes. Increasing ZFS contents 1-4wt.% enhanced the thermal stability of host membranes up to 17°C in comparison to pristine CA membranes as proclaimed by thermal degrative investigations. Membranes’ performance is evaluated by deionized water flux and sulphate salts (aluminum and copper) rejection capabilities. The prepared membranes are highly effective in salts removal application as evident from 98% of aluminum sulphate rejection that emanates from micro to nano porosity transformation after increasing filler composite into the membrane matrices.

Abstract: In this study, the use of boron nitride (BN) foam composites as adsorbents in wastewater treatment using polyvinyl alcohol (PVA), polyvinyl butyral (PVB) and polyester (PE) polymers has been investigated. BN powder has been functionalized by Hummer’s and sodium hydroxide (NaOH) methods to facilitate BN binding with the polymer. Fourier Transform Infrared (FT-IR) results show that hydroxyl (-OH) groups are effectively bounded to the BN structure. Scanning Electron Microscope (SEM) observation demonstrated the 3D interconnected porous structure of the obtained BN foams using different polymers. It is observed that BN and polymer interaction is better in foams formed with PVA and PVB compared to PE polymers. PVA and PVB structure shows a bridge property to link the layers so that a porous network structure is formed. It has been determined that the foam composite modified with Hummer’s method and using PVB as a polymer (h-BN-PVB-H) reaches an adsorption capacity of 8.843 mg/g in 44 hours and provides approximately 18% Crystal Violet (CV) dye removal. h-BN-PVB-H foam composite removes approximately 26% of Reactive Blue 49 (RB 49) dye with an adsorption capacity of 12.313 mg/g in the first 10 minutes. The 3D BN/Polymer foams showed reasonable absorption capacities for olive oil, cyclohexane and toluene from 200-980 wt% relative to the foam’s dry weight. It shows that the produced composite foams can absorb approximately 2-10 times their own weight.

Abstract: This article presents an analytical approach to explore the free vibration behaviour of new functionally graded carbon nanotube-reinforced composite beams (FG-CNTRC) based on a two-variable higher-order shear deformation theory and nonlocal strain gradient theory. The beams resting on the Pasternak elastic foundation, including a shear layer and Winkler spring, are considered. The kinematic relations of the shaft are proposed according to novel trigonometric functions. The vibrated nanobeam’s motion equations are obtained via the classical Hamilton’s principle and solved using Navier’s steps. A comparative evaluation of results against predictions from literature demonstrates the accuracy of the proposed analytical model. Moreover, a detailed parametric analysis checks for the sensitivity of the vibration response of FG nanobeams to nonlocal length scale, strain gradient microstructure scale, material distribution, constant spring factors, and geometry. The current work presents the free vibration problem of supported (FG-CNTRC) beams reinforced by different patterns of carbon nanotube (CNT) distributions in the polymeric matrix.

Abstract: A magnetic resonance imaging contrast agent is proposed using iron oxide nanoparticles (IONPs) synthesized by a pulsed laser ablation technique. Experimentally, an Nd: YAG laser (1064 nm, 7 ns, 30 mJ) was directed and focused on a high-purity iron plate immersed in a liquid solution of deionized water and polyvinylpyrrolidone (PVP). After a few minutes of laser bombardment, iron oxide nanoparticles dispersed in the liquid were homogeneously produced. A reddish yellow color-colloidal IONPs are produced in the water, while its color changes to dark brown for the PVP solution. The characterization results demonstrated that IONPs in the form of Fe₂O₃ and Fe₃O₄ made in the PVP have an excellent dispersibility with a spherical shape that is significantly smaller than that of IONPs made in the deionized water at the same laser repetition rate. The produced IONPs are further applied as a contrast agent for the magnetic resonance imaging (MRI) modality by varying concentrations from 0.05 mM to 2.31 mM. The results demonstrated that images of the IONPs sample with a concentration of 2.31 mM showed the highest contrast enhancement (Cenh), with an enhancement factor of 221.875 % for T₁-weighted images and 91.227 % for T₂-weighted images. IONPs with a concentration of 2.31 mM had the highest signal-to-noise ratio (SNR) for a T₁-weighted picture of 52.92, while IONPs with a concentration of 0.05 mM had the highest SNR for a T₂-weighted image of 179.117.

Abstract: Iron is a ubiquitous element found on Earth's crust, existing in various forms, such as Magnetite (Fe₃O₄) and Hematite (α-Fe₂O₃). Magnetic iron oxide nanoparticles (MIONPs) have become increasingly popular because they possess unique properties such as high surface area to volume ratio, super-paramagnetic properties, photocatalytic properties, and economical synthesis methods. This study produced MIONPs using the co-precipitation method, stabilized by a molybdenum magnet. Two soluble iron salts (FeCl₃.6H₂O and FeSO₄.7H₂O) were reacted with 5N NH₄OH solution at 80 °C in a nitrogen atmosphere. The MIONPs had a high saturation magnetization of 74.2emu/g, good crystallinity with crystalline spinel structured magnetite phase of iron oxide, high thermal stability depicted by 2.09 wt. % weight loss, and small particle sizes (6-25 nm). FTIR revealed a high-intensity peak at 546.28 cm^-1, attributed to the Fe-O stretching bond. Furthermore, the study showed that the co-precipitation method could be used to produce nanoparticles with a wide range of properties that could be used for various applications. It is a promising solution for producing stabilized magnetic nanoparticles since it uses non-toxic reagents and a straightforward, secure technique. Therefore, it may be used to synthesize nanoparticles for targeted treatment, magnetic resonance imaging, drug delivery, water treatment purposes and environmental remediation.

Abstract: Thin films of tungsten oxide were deposited on glass substrates by the radio frequency (RF) reactive sputtering from a high purity tungsten metal target (99.9%) with a diameter of 10 cm. The reactive sputtering was carried out in an argon-oxygen gas mixture containing 20% of O₂ and 80% of Ar. The used RF power is 200 W while fixing the deposition time at 120 min. Finally, the prepared films were annealed at different temperatures (350 °C, 400 °C, 450 °C, 500°C and 550 °C) for 1 hour under air and under vacuum. X-ray diffractograms showed that the deposited thin films crystallized in Hexagonal/Monoclinic WO₃ phase. It was found that the crystallite size varies with the annealing temperature and the lattice parameters is a= 7.3064Å, b = 7.5292Å, c = 7.6875Å and a=b= 7.3242Å, c= 7.6624 Å, for h-WO₃ and m-WO₃ structures, respectively. Scanning Electron Microscopy (SEM), Raman spectra confirmed the formation of WO₃ thin films. In addition, optical transmittance data revealed that the optical bandgap of the films decreases with increasing the annealing temperature. Electrical measurements revealed that annealing in air results in more resistive samples, which should be taken into account in future investigations, especially as buffer layers for efficient photovoltaic solar cells. Keywords: Vacuum, Tungsten oxide, Raman spectroscopy, RF Sputtering method, RF Power, Annealing temperature.

Abstract: The solar light radiation causes some of the heat to be trapped inside the solar cell that raises the solar cell’s temperature, then reduces the electrical efficiency of the overall system. The thermal radiation from solar light causes overheating on the solar cell surface and degrades its functionality. In this study, the thermal insulation coating has been proposed to prevent interior trapped heat. Different nanocoating systems have been developed using nano-Titanium Dioxide (TiO₂) namely T1B2 and T2B2, nano-Zinc Oxide (ZnO) namely Z1B2 and Z2B2 and nano-Tin Oxide (SnO) namely S1B2 and S2B2. All the nanoparticles have been synthesized at various weight percentages which are 20wt.% and 60wt.% in the B2 binder system, Methyltrimethoxysilane (MTMS) / nitric acid (HNO₃). The incorporation of nanoparticles increases the hydrophobicity of binder coating in which the Water Contact Angle (WCA) of coating improves up to 105°. The embedded nanoparticles increase the surface roughness, then reduce the contact of water to the substrate’s surface. Apart from that, the coating is also capable to halt the drastic increment in surface temperature. The result has shown that the B2 binder coating increases the surface temperature of solar cell by 2.54°C after 1hr of Xe 1000 W/m² irradiation. The raise in temperature is due to the strong oxidation of nitric acid. However, the incorporation of nano-ZnO and nano-SnO in B2 binder matrix capable to reduce the temperature of the solar cell. The wide bandgap of both nanoparticles induces good stability of coating at high operating temperature. The Z1B2 and S2B2 has reduced the temperature of solar cell by 7°C and 3°C, indicating their great thermal insulation property for solar cell application.

Abstract: In this paper, we have investigated the electronic, optical and thermoelectric properties of the puckered Si₂SeTe monolayer when subjected to various levels of biaxial strain ranging from −10% to +10%. The structural stability, as determined by the cohesive energy, shows that the puckered Si₂SeTe structure is energetically stable. The results reveal that the unstrained Si₂SeTe monolayer is an indirect band gap semiconductor with an energy gap of 0.5 eV, which can be effectively adjusted with biaxial strain. The semiconductor–metal phase transition occurs when the monolayer is compressed by −4% biaxial strain. Moreover, the optical properties, including the real ε₁(ω) and imaginary ε₂(ω) components of the dielectric function, extinction coefficient K(ω), reflectivity R(ω), refractive index n (ω), and absorption coefficient α (ω), were evaluated as a function of the energy of light and under biaxial strain. We discovered that the puckered Si₂SeTe monolayer is capable of absorbing light in the visible region of 64.7×10⁴ cm⁻¹, 73.8×10⁴ cm⁻¹ for equilibrium state and under the compression strain (−8%), respectively. Lastly, the influence of biaxial strain on thermoelectric properties such as electrical conductivity (σ/τ), electronic thermal conductivity (k_e/τ), Seebeck coefficients, and electronic figure of merit (ZT_e) was studied. The calculated electronic figure of merit ZT_e presents an improvement in the p-type doping (μ<0) under the tensile biaxial strain. Taking into account the optical and thermoelectric properties, the puckered Si₂SeTe monolayer is a promising material for use in optoelectronic devices and energy conversion technologies.