Crystalline Structure Properties Research Articles

Photocatalytic Degradation of Diazinon with a 2D/3D Nanocomposite of Black Phosphorus/Metal Organic Framework

Metal–organic frameworks (MOFs) are promising materials for the removal and photodegradation of pesticides in water. Characteristics such as large surface area, crystalline structure and catalytic properties give MOFs an advantage over other traditional adsorbents. The application of MOFs in environmental remediation is hindered by their ability to only absorb in the UV region. Therefore, combining them with an excellent charge carrier 2D material such as black phosphorus (BP) provides an attractive composite for visible-light-driven degradation of pesticides. In the study, a nanocomposite of black phosphorus and MIL-125(Ti), defined as BpMIL, was prepared using a two-stage hydrothermal and sonication route. The as-prepared composite was characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) spectroscopy. These techniques revealed that the circular and sheet-like morphology of the nanocomposites had minimum charge recombination, allowing them to be effective photocatalysts. Furthermore, the photocatalysts exhibited extended productive utilization of the solar spectrum with inhibited recombination rate and could be applied in visible-light-driven water treatment. The photodegradation of diazinon in water was studied using a series of BpMIL (4%, 6% and 12% by mass) nanocomposites as a photocatalyst. The optimal composite was determined to be 4%BpMIL. The degradation parameters were optimized and these included photocatalyst dosage, initial diazinon concentration and pH of the solution. The optimal conditions for the removal and degradation of diazinon were: neutral pH, [diazinon] = 20 mg/L, photocatalyst dosage = 0.5 g/L, achieving 96% removal of the pesticide after 30 min with 4%BpMIL, while MIL-125(Ti) showed 40% removal. The improved photodegradation efficiency of the 4%BpMIL composite was attributed to Ti3+-Ti4+ intervalence electron transfer and the synergistic effect between MIL-125(Ti) and BP. The photodegradation followed pseudo-first-order kinetics with a rate constant of 1.6 × 10−2 min−1.

Preparation of TiO2/Ag[BMIM]Cl Composites and Their Visible Light Photocatalytic Properties for the Degradation of Rhodamine B

In order to degrade toxic pollutants such as dyes during the process of sewage treatment, considerable attention has been paid to photocatalytic technologies. In this paper, TiO2/Ag[BMIM]Cl (1-butyl-3-methyl imidazolium chloride ([BMIM]Cl)) nanocomposites were prepared with TiO2 as the carrier, silver ions as dopants and ionic liquids (IL) as modifiers. The morphologies, microstructures, crystalline structure and optical properties of the TiO2/Ag[BMIM]Cl nanospheres are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), total organic carbon (TOC), and UV-vis diffuse reflectance spectrum (UV-vis DRS) techniques. The TiO2/Ag[BMIM]Cl nanocomposites can selectively degrade rhodamine B (Rh B) under visible light because of the unstable quaternary ammonium salt. The as-obtained nanocomposites exhibit better photocatalytic activity performance than pure TiO2, TiO2/IL, and TiO2/Ag+. The experimental results show that the Rh B degradation rate can reach 98.87% under optimized producing conditions by using the TiO2/Ag[BMIM]Cl composites as the catalyzer. It shows that simultaneous doping with silver ions and ionic liquids can significantly improve the photocatalytic activity of TiO2 in Rh B degradation, indicating the formation of photosensitive AgCl in the process of TiO2/Ag[BMIM]Cl preparation. Ag+ and IL addition exchange the band gap of TiO2 and lengthen the visible wavelength range of the composite. The material has the advantages of low cost, facile preparation and reusability with the excellent degradation effect of Rh B.

Effect of Mechanical Agitation on Cr-Al<sub>2</sub>O<sub>3</sub> Nanocomposite Coatings Fabricated from Trivalent Chromium Electrodeposition

In the present work, Cr-Al2O3 nanocomposite coatings were electrodeposited onto a copper substrate using a modified trivalent chromium electroplating bath with the addition of 80nm Al2O3 powder. The effects of mechanical agitation of electrodeposition bath on Al2O3 particles dispersion and particles embedment were studied. The Cr-Al2O3 nanocomposite samples were subjected to different tests to characterize their surface morphology, crystalline structure, and mechanical properties. The crystalline structure, composition and surface morphology of the deposits were studied by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FESEM). The corrosion resistance test was carried out by electrochemical polarization method. The microhardness was studied via Vickers Microhardness Test. The variation in the microhardness as a main property to achieve enhancement of Al2O3 incorporations with Cr matrix. From the EDX analysis, Cr-Al2O3 nanocomposite deposited at 200 rpm stirring speed showed the highest weight percentage (wt%) of alumina. The hardness results showed the Cr-Al2O3 composite coating has the best performance at 200 rpm stirring speed which the hardness increased 32.3 % compared to that of Cr coating. The corrosion current density (icorr) of Cr-Al2O3 coating achieved highest value at 200 rpm. This result revealed that the corrosion resistance of Cr-Al2O3 coating decreases with increasing Al2O3 particles content.

Structural, Magnetic, Optical Properties and Photocatalytic Activity of Nanocrystalline Cobalt Ferrite Prepared by Three Different Methods

Cobalt ferrite (CoFe2O4) is an interesting material due to its rich physical properties. In order to study the influence of synthetic methods on the crystalline and morphological structure, optical and magnetic properties of the CoFe2O4, we synthesized here the CoFe2O4 by three different methods, including the chemical co-precipitation method, sol-gel method, and ceramic method. The resulting powders were characterized by different analyses: XRD, SEM, TEM, BET, FTIR, UV-Vis, PL, XPS, and surface acidity. The characterization results showed a significant variation in the structural, particle size, surface area, and optical properties of pure cobalt ferrite with changing the synthetic method. Both XRD and FTIR analyses confirm the formation of the cubic spinel phase, where the crystallite size changes from 21 to 36 nm. XPS analyses demonstrated the effect of the synthetic method on the cation distribution at the tetrahedral and octahedral sites in the spinel ferrite lattice. The magnetic properties of the prepared samples were studied at room temperature using the vibrating sample magnetometer (VSM) and found to be strongly dependent on the synthetic method and showed either ferromagnetic or super-paramagnetic character. The cobalt ferrite samples showed high photocatalytic activity against Basic Red 18 (BR 18) dye under visible light irradiation. The effects of particle size, surface areas, and morphology on the photocatalytic activity were discussed and the positive holes are suggested to be the major active species of the dye dissociation.

Температурна стабільність кристалічної структури, електро- і магнетотранспортних властивостей функціональних наноструктур спін-клапанного типу Ni/Dy/Co

Температурна стабільність кристалічної структури, електро- і магнетотранспортних властивостей функціональних наноструктур спін-клапанного типу Ni/Dy/Co

Preparation and characterization gallic acid-titanium dioxide nanocomposites for biosensing application on voltammetric detection of DNA

Abstract The preparation and testing of Chitosan-[Gallic Acid-Titanium Dioxide] (CHIT-[GA-TiO2]) modified single-use electrodes was performed herein. TiO2 nanoparticles were firstly synthesized by alkoxide hydrolysis and solvothermal method. [GA-TiO2] samples were prepared by using gallic acid and TiO2 nanoparticles while being dissolved in chitosan solution. Crystalline structure and surface properties of the obtained Chitosan-[Gallic Acid-Titanium Dioxide] (CHIT-[GA-TiO2]) nanocomposite were characterized by using X-ray diffraction analysis and scanning electron microscopy (SEM). The CHIT-[GA-TiO2] modified single-use electrodes were developed for the first time in our present study and applied for electrochemical monitoring of nucleic acid interaction. For this purpose, the modification of nanocomposite was examined using pencil graphite electrodes (PGEs) in combination with differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. After fsDNA was immobilized onto the surface of CHIT-[GA-TiO2]/PGE, fsDNA concentration and immobilization time were optimized as 30 µg/mL and 15 min, respectively. The detection limit was calculated and found to be 0.95 µg/mL in the linear concentration range of fsDNA from 2 to 10 µg/mL with the sensitivity of 1.161 µA mL cm−2 µg−1.

CdS Nanostructured Thin Films Synthesized by Pulsed Laser Deposition for Solar Cell Technology

CdS thin films have been grown on glass substrate at 250o C employing pulsed laser deposition method. The effect of laser pulses number on the crystalline structure, surface morphology, optical properties, and films thickness have been studied. XRD analysis shows that the CdS films have polycrystalline and hexagonal nanostructure with three notable peaks along (100), (002), and (101) planes and preferentially orientated along (101). The crystallite size of the preferred orientation was in the range of (21.4 - 27.3 nm). With small pulses number, XRD pattern confirms the formation of CdO with three peaks (111), (200), and (220). Theses peaks gradually reduce with the increasing of the pulses. The absorbance of the films is in the visible part of the spectrum. The band gap of the synthesized films reduces by rising the number of laser pulses. AFM studies indicate that the grain size and surface roughness increase with the film thickness. Due to the good crystalline structure and optical properties of the film of the highest thickness, it has been grown on a wafer silicon substrate for solar cell applications measurements. Hall measurements indicate low resistivity of 0.3×10-2 (Ω.m) and high conductivity of 3.3×10+2 (Ω.m)-1. The efficiency of the n-CdS/ p-Si junction has been calculated to be 3.4 % using I-V characteristic measurement. Keywords: pulsed laser, thin films, structural, optical, morphology, solar cell measurements

Adsorptive removal of eriochrome black T (EBT) dye by using surface active low cost zinc oxide nanoparticles: A comparative overview

The ecological toxicity imparted by non-biodegradable organic dyes has been considered as a major risk to handle in front of mankind. In this view, the low-cost zinc oxide nanoparticles (ZnO-NPs) were facially synthesized by coating the surface with surfactant (CTAB) and ionic liquid (BMTF) molecules for the effective removal of Eriochrome Black T (EBT) from aqueous media. Various advanced characterization techniques have given insight into the morphological features, crystalline structure and physio-chemical properties of as-synthesized ZnO-NPs. The systematic analysis of the adsorption isotherms and kinetics models specifies that the adsorption of EBT follow Freundlich model and pseudo-second-order kinetics. The intraparticle diffusion model displayed a linear relationship (R2 = 0.98, 0.97 and 0.94 for BMTF@ZnO, CTAB@ZnO and bare ZnO-NPs), which shows that pore diffusion rate is affected by surface modification and effects the overall EBT adsorption process. Furthermore, after the removal of 87% and 84% of EBT dye by BMTF@ZnO-NPs and CTAB@ZnO-NPs, the fabricated nanoadsorbents of ZnO were successfully regenerated and reused after the treatments up to four times. The adsorption aptitude of ZnO-NPs towards EBT dye was systematically explored in real wastewater samples and interference study of inorganic metallic salts was also performed. The toxicity estimations of the treated dye solutions were made using floral and fungal activities, to ascertain their non-toxic nature before releasing into the environment. These outcomes have supported the immense potential of ZnO-NPs towards the removal of EBT in a cost effective manner.

Research progress of TiO2-based photocatalytic materials

TiO2 is the most widely studied photocatalyst, which has a good application prospect in the field of environmental pollution control and has always been a hot spot of photocatalytic materials research. The crystalline structure, surface morphology, and optical properties of TiO2-based photocatalytic materials prepared by different methods are different, and thus exhibit different photocatalytic properties. In this paper, the research progress of TiO2-based photocatalytic materials in China and abroad in recent years was reviewed based on the common preparation methods.

Effect of LaNiO3 interlayer on electrical properties of Pb(Zr0.52Ti0.48)O3/LaNiO3/Pb(Zr0.52Ti0.48)O3 composite films

In this study, Pb(Zr0.52Ti0.48)O3/LaNiO3/Pb(Zr0.52Ti0.48)O3 (PZT/LNO/PZT) composite films with different LNO thicknesses were prepared by a sol-gel method. The influences of LNO interlayer on crystalline structure, microstructure and electrical properties of PZT/LNO/PZT composite films were studied. The results show that the perovskite grains of the upper PZT layer grow along the epitaxy of the LNO interlayer when the LNO layer is inserted into the composite films. Due to the in-plane compressive strain effect in the upper PZT layer and the reduced leakage current caused by the accumulated space charges at the PZT/LNO interface, an obvious enhancement of electrical properties is observed in PZT/LNO/PZT composite films. The PZT/LNO/PZT composite film with the 140-nm-thick-LNO layer possesses the best remnant polarization and dielectric constant, which are 43.3 μC cm−2 and 1841, respectively. The preparation of ferroelectric composite film with a ferroelectric/metallic oxide/ferroelectric structure provides a promising way for improving the electrical properties of ferroelectric materials.

Effect of the molecular weight of poly(vinyl acetate) on the polymorphism and thermomechanical properties of poly(L-lactic acid)/poly(D-lactic acid) blends

The effects of molecular weight (Mw) and content of poly(vinyl acetate) (PVAc) on the crystallization behaviors, competing crystallization of homocrystallites and stereocomplex crystallites (SCs), crystalline structure, and mechanical properties of poly(L-lactic acid) (PLLA)/poly(D-lactic acid) (PDLA) blends were investigated. The crystallization of PLLA/PDLA component is accelerated after the addition of low-Mw PVAc and is suppressed with high-Mw PVAc. The ability of SC formation is enhanced via blending with PVAc, irrespective of its Mw, and becomes prominent with low-Mw PVAc. The exclusive SCs are obtained in the blends with 30 mass % low-Mw PVAc. The improvement in thermomechanical property above 170 °C is ascribed to the enhancement of SC content. This work presents guidance for achieving the melt processability of SC-PLA, thus proving their potential as a high-performance substitute for conventional plastics.

Properties of indium tin oxide thin films grown by Ar ion beam sputter deposition

Indium tin oxide (ITO) thin films were grown by Ar ion beam sputter deposition under systematic variation of ion energy, geometrical parameters, and O2 background pressure and characterized with regard to the film thickness, growth rate, crystalline structure, surface roughness, mass density, composition, electrical, and optical properties. The growth rate shows an over-cosine, forward-tilted angular distribution with a maximum, which increases with increasing ion energy, increasing ion incidence angle, and decreasing O2 background pressure. ITO films were found to be amorphous with a surface roughness of less than 1 nm. Mass density and composition show only small changes with increasing scattering angle. The electrical resistivity behavior in dependence on the process parameters is complex. It is not only driven by the O2 background pressure but also very much by the scattering angle. The observed behavior can be understood only if competing processes are considered: (i) reduction of the number of oxygen vacancies due to the presence of O2 background gas and (ii) defect generation and preferential sputtering of oxygen at the surface of the growing films due to the impact of high-energy scattered particles. Even though absolute numbers differ, optical characterization suggests a similar systematics.

Effect of the electric field in glow discharge plasma sheath on the optoelectronic properties of the AlxZn1-xO thin films

In this paper, we present the effect of the electric field in Ar and N2 plasma sheath on the structural, optical, and electrical properties of the AlxZn1-xO (x = 0, 0.02) thin films. The thin films were prepared via the sol-gel method on glass substrates and then treated in the Ar and N2 plasma. The crystalline structure properties of the thin films were evaluated by the XRD spectra and scanning electron microscope images. The parameters measured for the thin film's crystalline structure were the average crystallite size, the lattice strain, and the dislocation density. The optoelectronic properties, such as the refractive index, optical band gap energy, Urbach energy, dispersion parameters, and third-order nonlinear susceptibility were calculated based on the UV–vis spectrophotometer spectra. Due to the plasma treatment variation in the structural and optoelectronic properties was observed. The electric field in the Ar plasma sheath is stronger than the N2 plasma, so the properties’ alteration in the Ar plasma was more remarkable than the N2 plasma. For example, the third-order nonlinear optical susceptibility was increased by about 69 % and 38 % for the ZnO/Ar and the ZnO/N2, respectively. The severity of these changes was higher in the Ar plasma compared to the N2 plasma for the ZnO thin film, compared to the Al0.02Zn0.98O thin film.

Temporal post-discharge reactions effect on the oxidative catalytic properties of plasma-synthesized α-MnO2 nanorods

The evolution of the morphology, crystalline structure, and textural properties of α-MnO2 nanorods, which were obtained after reduction of a KMnO4 solution via gliding arc plasma process, have been followed along their ageing under temporal post-discharge conditions. When aged at 25 °C a partial transformation of α-MnO2 (cryptomelane) to γ-MnO2 (nsutite) occurred with an increase of specific surface area from 98 to 141 m2/g. In parallel, the starting nanorods were converted to nanoneedles after 24 and 48 h, and into nanosheets after 72 h. These transformations are ascribed to the evolution of maturation process of crystallites, thanks to post-discharge species (H2O2, HOONO,…). At the opposite, ageing at 100 °C induced a remarkable transformation of α-MnO2 to γ-MnO2 with a decrease of specific surface area from 98 to 35 m2/g after 3 h, which was in line with the observed agglomeration of nanorods. Finally, whereas a longer ageing at 100 °C provoked an activity diminution of the material, an augmentation of activity of plasma-synthesized α-MnO2 was recorded when implementing ageing at 25 °C.

Air-Jet Wet-Spinning of Curdlan Using Ionic Liquid

Owing to the environmental impact of the textile industry, which distributes petroleum-based synthetic fibers on a large scale, there is a growing demand for renewable biomass-based biodegradable fiber. Curdlan, a linear β-1,3-glucan, can be potentially converted into a functional fiber with excellent sustainability and biodegradability because of its helical crystalline structure and unique physicochemical properties. Herein, we demonstrate a facile and green preparation of regenerated curdlan fibers and characterize the fiber properties via mechanical and structural analyses. Curdlan (9 wt %) in an ionic liquid (1-ethyl-3-methylimidazolium acetate, [Emim][OAc]), was sequentially extruded under a mild condition at 80 °C, drawn in an air gap, and coagulated in water. The resulting fiber was transparent, soft, and had high water-absorption ability (∼86%). By changing the draw ratio from 1 to 10, the molecular orientation of the regenerated fibers increased, resulting in enhanced tenacity (5.2 ± 0.1 cN tex–1 or 75 ± 1 MPa) and Young’s moduli (2.7 ± 0.1 GPa). Although the mechanical strength of these curdlan-regenerated fibers is not comparable to those of conventional cellulose-regenerated fibers, their exceptionally excellent elongation (20–50%) in the dry state is noteworthy, indicating their potential use in different applications from those desired for the cellulose fibers.

Synthesis and characterization of Fe3O4–ZnS:Mn nanocomposites for biomedical applications

Fe3O4–ZnS:Mn nanocomposites were prepared by two combined chemical precipitation routes and further characterized to prove the formation of composite structure. The formation mechanism was discussed according to sequential steps of the composite formation. The crystalline structure, morphology and magnetic properties of nanocomposites were identified by XRD, TEM-HRTEM and VSM analyses respectively. The presence of ZnS:Mn shell on Fe3O4 surface was confirmed by XPS, EDX and EPR. The potential cytotoxicity of Fe3O4–ZnS:Mnx% nanocomposites has been investigated using human skin melanoma (A375) and normal human keratinocytes (HaCaT) cell lines. The cellular uptake on human skin melanoma (A375) was evidenced by CLFM and revealed that Fe3O4–ZnS:Mnx% nanocomposites penetrated the cells through endocytosis, in a concentration dependent manner. Hyperthermia measurements evidenced that Fe3O4–ZnS:Mnx% nanocomposites are adequate for magnetic hyperthermia applications. Except the latest case the Fe3O4–ZnS:Mnx% platforms are safe to use for biomedical applications as they show toxicity starting only from high concentration.

Ferroelectric properties of pure ZrO2 thin films by chemical solution deposition

Ferroelectricity in pure zirconia (ZrO2) thin films, manufactured on Si (100) substrates via the chemical solution deposition method using all-inorganic aqueous salt precursor, has been demonstrated for the first time. The influence of thickness on the crystalline structure and ferroelectric properties of the thin films were measured and showed that they were strongly affected by the film thickness. The structural data indicated that as the film thickness increased from 30 nm to 50 nm, the m-phase fraction increased, and a phase transition from orthorhombic to cubic and then tetragonal occurred near the main diffraction peak of 30.7°. The lowest m-phase fraction of 15.4% was obtained in the pure ZrO2 film with a thickness of 30 nm, and after 103 field cycling, it exhibited the highest relative permittivity of 39.6 as well as the highest residual polarization of 8.5 μC/cm2.

Epitaxial growth and transport properties of compressively-strained Ba2IrO4 films* *Project supported by the National Natural Science Foundation of China (Grant Nos. 11774153, 11861161004, 51772143, 11974163, and 51672125), the National Key Research and Development Program of China (Grant No. 2016YFA0201104), the Fundamental Research Funds for the Central Universities, China (Grant Nos. 0213-14380167 and 0213-14380198), and the Hong Kong Research Grants Council

Ba2IrO4 is a sister compound of the widely investigated Sr2IrO4 and has no IrO6 octahedral rotation nor net canted antiferromagnetic moment, thus it acts as a system more similar to the high-T c cuprate. In this work, we synthesize the Ba2IrO4 epitaxial films by reactive molecular beam epitaxy and study their crystalline structure and transport properties under biaxial compressive strain. High resolution scanning transmission electron microscopy and x-ray diffraction confirm the high quality of films with partial strain relaxation. Under compressive epitaxial strain, the Ba2IrO4 exhibits the strain-driven enhancement of the conductivity, consistent with the band gap narrowing and the stronger hybridization of Ir-t2g and O-2p orbitals predicted in the first-principles calculations.

Novel photoluminescent In2O3/a-SiC core/shell nanostructure synthesized by HW-assisted PECVD method

Semiconductor core/shell nanostructures have been recently attracted a great interest due to interesting properties and wide potential applications. In this work, In2O3/a-SiC core/shell nanostructure was successfully synthesized for the first time using hot wire-assisted plasma-enhanced chemical vapor deposition technique. The crystalline structure, morphology, chemical composition, and optical properties of the deposited film were investigated by variety of characterization techniques including X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, UV–Vis–NIR spectrophotometry, photoluminescence spectroscopy (PL) and Raman scattering spectroscopy. The results verified the formation of core/shell nanostructures, crystalline In2O3 as a core and amorphous SiC as a shell, successfully. The average diameter and thickness of synthesized core and shell were 101 and 38 nm, respectively. A strong and broad room-temperature PL emission in the visible and near-infrared region was observed for the synthesized structure as a result of synergic effects. This broad band was consisted of Gaussian peaks at the wavelengths of 570, 656, 728, 763, and 842 nm. The origin of different PL peaks was discussed in the paper. The results show that the novel In2O3/a-SiC core/shell nanostructure is a good candidate for optical applications.

Gelatin Films Activated by Cinnamon Essential Oil and Reinforced with 1D, 2D and 3D Nanomaterials: Physical and Release Controlling Properties

The aim of this study was to assess the effect of sodium montmorillonite (MMT), cellulose nanofibers (CNF) and titanium dioxide nanoparticles (TiO2NPs) on the physicochemical properties and release profile of the gelatin-based film activated with cinnamon essential oil (CEO). The results of FT-IR, XRD, FE-SEM and tensile analysis showed that the incorporation of nanofillers caused to different changes in the morphology, crystalline structure, and mechanical properties of gelatin films that were correlated with their morphology. The water barrier properties of films significantly increased by incorporation of nanofillers and MMT had the highest improving effect. As results of release profile study, MMT incorporated active film exhibited the slowest release rate with the lowest diffusion coefficient (8.67 ± 0.52 × 10−8cm2 s−1 at 25 °C), and highest activation energy (14.87 ± 1.11 kJ mol−1). In conclusion, nanolayers such as MMT were suggested as the best candidate to use as simultaneous reinforcement and release controlling agent in the activated biopolymer-based films.