Oxide Nanolayers Research Articles

Window layer based on ZnO and Ag thin films incorporated in solar cells as a part of hybrid energy-saving system

We have started a new research project on a hybrid power generation system consisting of piezoelectric, thermoelectric and solar cell modules. In the first step, we have focused on the antireflection coating based on zinc oxide (ZnO) and metal nanolayers incorporated in solar cells. In layered structure containing ZnO and metal nanoscale layers, we have presented the possibility of increasing wave transmission in the visible region by adding the top and bottom cap layers. The enhancement of optical transmission is very important in improving the performance of sensor protections, solar cells, UV protective films and transparent conductive display panels electrode. It is found that, the structure containing both the top and bottom cap layers (S3) yields larger transmittance than the structures S1 without any cap or S2 just with one cap layer. The maximum transmittance in the visible range can be increased from 33% to 67%. In addition, for the TE mode (TM mode), the maximum value of transmission in the S1 and S2 structures occurs at angles close to normal incidence while in the S3 multilayer it happens around 1 radian, that is, the behavior of the TE mode is the opposite of the TM mode. Also, when the incident angle varies, the band edges experience a blue shift. The amount of TE shift is more pronounced than TM one. Moreover, the metal with higher plasma frequency will move the band gap edges to the higher frequencies.

A nanofluidic sensing platform based on robust and flexible graphene oxide/chitosan nanochannel membranes for glucose and urea detection.

We present the development of a health-monitoring nanofluidic membrane utilizing biocompatible and biodegradable graphene oxide, chitosan, and graphene quantum dots. The nanoconfinement provided by graphene oxide nanolayers encapsulates chitosan molecules, allowing for their conformational changes and switchable hydrophobic-hydrophilic behavior in response to pH variations. This low-dimensional membrane operates as an array of nanofluidic channels that can release quantum dots upon pH change. The photoluminescence emission from quantum dots enables rapid and reliable optical visualization of pH changes, facilitating efficient human health monitoring. To ensure fouling prevention and enable multiple usages, we adopt a design approach that avoids direct contact between biomarkers and the nanochannels. This design strategy, coupled with good mechanical properties (Young's modulus of 5.5 ± 0.7 GPa), preserves the integrity and functionality of the sensors for repeated sensing cycles. Furthermore, leveraging the memory effect, our sensors can be reloaded with graphene quantum dots multiple times without significant loss of selectivity, achieving reusability. The wide-ranging capabilities of 2D materials and stimuli-responsive polymers empower our sustainable approach to designing low-dimensional, robust, and flexible sensing materials. This approach allows for the integration of various biorecognition elements and signal transduction modes, expanding the versatility and applications of the designed materials.

Hydrothermal oxidation of titanium nitride coating for enhanced corrosion resistance in fluoride-containing acidic solution

To improve the corrosion resistance of titanium nitride (TiN) coating in acidic solution containing fluoride ions (F-), surface hydrothermal oxidation was conducted. Pure water was used as the medium and at temperatures as low as 200–250 °C, a thin, uniform and dense titanium oxide (TiO2) nanolayer composed of well-crystallized anatase nanoparticles was fabricated. The TiO2 layer was grown in situ, and its (004) planes aligned well with the (111) planes of underlying TiN; the transition zone was only a few atomic layers thick. Hydrothermal oxidation improved the chemical stability and decreased the corrosion rate of TiN coating in 0.5 mol/L sulfuric acid solution containing 0.05 wt% F-. When fabricated at 250 °C, the TiO2 layer remained intact after immersion test, providing good protection for the underlying TiN.

Manipulating a smart multi-functional nano-carrier based on l-cysteine-GO-ZIF67@ZIF8 core@shell MOFs-LDH for designing an excellent self-healing coating

A novel nano-carrier with tertiary-level corrosion suppression functionalities, i.e., an excellent/long-period barrier against water diffusion/ Cl− ions transfer, high corrosion inhibiting materials loading capacity, and smart (pH-triggered and ion exchange release mechanisms) long-period inhibitor release features were designed. This was done via the nitrate ions intercalated Zn-Al-LDH (LD) 2D-crystals synthesis over the reduced graphene oxide (r-GO) nano-layers, and then in-situ coverage of hierarchically Co-2Im (ZI67-core)/Zn-2Im (shell) and Zn-2Im (core)/Co-2Im (shell) porous MOFs over the r-GOLD nano-hybrids. Monosodium glutamate (SGL) anionic inhibitor was loaded into the inter-galleries of LDH layers and porosities of ZI67/ZI8 and/ or ZI8/ZI67 core@shell structure via ions-exchange and vacuum methods. Characterization of the r-GOLD-ZI67/ZI8 as well as r-GOLD-ZI8/ZI67 core@shell structures was done by various technics. From the polarization test outcomes the mixed corrosion mitigation effect together with high inhibition index of (>95%) was recorded in the saline solution that contained bare metal and SGL-loaded r-GOLD-ZI67/ZI8 core@shell extract. After loading the Core@shell nano-hybrids (containing SGL) into the epoxy coating, the long-term and durable (maintained for about 112 days of exposure) physical water shielding (fb<0.01 Hz,|Z|>1010.5ohm.cm2, Rt>60Gohm.cm2) against ions (Cl-)/water diffusion was obtained due to r-GOLD layers well dispersion, prolonging diffusion paths.

Energy-Efficient Chemiresistive Sensor Array Based on SWCNT Networks, WO3 Nanochannels and SWCNT-Pt Heterojunctions for NH3 Detection against the Background Humidity

Recently, promising results have been achieved in improving the sensitivity to ammonia in gas sensors through the use of structures composed of heterojunctions or nanochannels. However, their sensitivity is highly dependent on the background humidity under air conditions. The sensor structures which could ensure selective ammonia detection with a low detection limit, despite interference from changing background humidity, remain highly demanded. In this work, we consider sensing units containing (i) nanochannels formed by a continuous tungsten oxide nanolayer to appear in contact between single-walled carbon nanotubes (SWCNTs) and a Pt sublayer and (ii) SWCNT-Pt junctions in frames of mass-scale microelectronic technologies. SWCNTs were deposited by spray-coating on a thin WO3/Pt/W sublayer formed by a photolithographic pattern to be accompanied by satellite samples with just SWCNTs for reference purposes. We elucidate the specific differences that appeared in the response of sensors based on SWCNT-Pt junctions and WO3 nanochannels relative to satellite SWCNT samples with a similar SWCNT network density. Particularly, while a similar response to NH3 vapors mixed with dry air is observed for each sensor type, the response to NH3 is reduced significantly in the presence of background humidity, of 45 rel.%, especially in the case of WO3 nanochannel structures even at room temperature. A multisensor array based on the four various sensing structures involving SWCNT-Pt junctions, WO3 nanochannels, and their satellite-only-SWCNT ones allowed us to determine a correct ammonia concentration via utilizing the linear discriminant analysis despite the presence of background air humidity. Thus, such an energy-efficient multisensor system can be used for environmental monitoring of ammonia content, health monitoring, and other applications.

Sodium lignosulfonate-loaded ZnAl-layered double hydroxide decorated graphene oxide nanolayers; toward fabrication of sustainable nanocomposite for smart corrosion prevention

In this study, the NO3− intercalated ZnAl-based layered double hydroxide (LDH) nanostructures decorated graphene oxide (GO) nanosheets were synthesized, loaded with sodium lignosulfonate (SLS), and finally modified with aminopropyltriethoxysilane (APS) to reach a high-performance corrosion inhibitor nanocarriers. The morphology and chemistry of the LDH-rGO nanostructures were evaluated by the FE-SEM, EDX, FT-IR, XPS, XRD, Raman, and TGA techniques. Characterization results of SLS@LDH-rGO nanostructures proved the uniform decoration of GO nanosheets with LDH nanolayers and the loading of the SLS inhibitor. The active/barrier corrosion mitigation ability (CMA) of the synthesized nanostructures was studied by EIS and potentiodynamic polarization (PP) tests in both solution (NaCl) and coating (epoxy) phases. Results showed the increment of the total resistance and decrement of the current density of MSSs immersed in the SLS@LDH-rGO extract by 358 and 79%, respectively, compared to the blank solution after 48 h. EIS results proved the bi-functional active-inhibitive/barrier CMA for the SLS@APS-LDH-rGO filled epoxy coatings. The total impedance of the intact SLS@APS-LDH-rGO filled epoxy coating was enhanced by about 9700% after 8 weeks compared to that of the blank coating.

Graphene oxide/MIL 101(Cr) (GO/MOF) nano-composite for adsorptive removal of 2,4-dichlorophenoxyacetic acid (2,4 D) from aqueous media: synthesis, characterization, kinetic and isotherm studies.

Contamination of water resources with various pollutants and therefore lack of clean water resources are major problems that threaten many human societies. The need to develop efficient methods and materials to decontaminate water resource is an undeniable fact. Metal-organic frameworks (MOFs), as new class of highly crystalline porous solids, have attracted a great deal of attention in different research fields, especially in adsorptive removal and purification. In this study, MIL 101(Cr) MOF decorated with graphene oxide nano-layers (GO/MOF) was synthesized by a simple one-pot hydrothermal method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electron dispersion energy (EDS) were utilized to approve the growing of Cr-MOF on graphene oxide nano-layer. The synthesized nano-composite was used as a potential adsorbent for the removal of a pesticide, 2, 4-dichlorophenoxyacetic acid (2,4 D). The adsorption performance, kinetic and mechanism of 2,4 D adsorption onto GO/MOF were studied. The highest adsorption capacities of 476.9 mg g-1 was obtained at room temperature, pH 6.0 using 0.6 gL-1 of GO/MOF which was 34% higher than that of pristine Cr-MOF. The kinetics and isotherm data fitted well with pseudo-second kinetic and Langmuir isotherm model, respectively. The reusability and stability analyses showed that the synthesized GO/MOF nanocomposite kept 89% of sorption capacities for 2,4 D after four adsorption-desorption cycles. GO/MOF nano-composite was successfully applied to remove 2,4 D from agricultural waste. The results approved that the synthesized nano-composite could introduce as a stable and high performance adsorbent for adsorptive removal of selected pesticide.

Continuous graphene oxide nanolayer arranged on hydrophilic modified polytetrafluoroethylene substrate to construct high performance proton exchange membranes

Graphene oxide (GO) nanolayer, combining extraordinary mechanical properties, separation performance and chemical stability, holds great promise for widespread applications. The current preparation of GO nanolayer is complex and requires expensive and technical equipment, which limits the further development. In this work, we deposit GO nanolayer on TiO2 modified Polytetrafluoroethylene (PTFE) film by controlling the concentration of GO in suction filtration process. Subsequently, Nafion is sprayed on the surface of the complex to construct a composite membrane with excellent proton conductivity and prominent fuel isolation efficiency (methanol permeability: 4.18 × 10−7 cm2 s−1; hydrogen permeability: 2.76 × 10−15 mol m−1 s−1 Pa−1). Compared with commercial Nafion 117, the TiO2 modified PTFE/GO film acts as the substrate to reduce the content of Nafion (reduced by 70%). Through simple suction filtration process, the high-performance fuel cell composite membrane can be prepared with low-cost, which greatly promotes the application process of fuel cell.

Stabilizing Oxide Nanolayer via Interface Confinement and Surface Hydroxylation.

Surface hydroxylation over oxide catalysts often occurs in many catalytic processes involving H2 and H2O, which is considered to play an important role in elementary steps of the reactions. Here, monolayer CoO and CoOHx nanoislands on Pt(111) are used as inverse model catalysts to study the effect of surface hydroxylation on the stability of Co oxide overlayers in O2. Surface science experiments indicate that hydroxyl groups formed on CoO nanoislands produced by deuterium-spillover can enhance oxidation resistance of the Co oxide nanostructures. Theoretical calculation shows that the interfacial adhesion between CoO and Pt is linearly strengthened with the increasing hydroxylation degree of CoO surface. Thus, the interface confinement effect between CoO and Pt can be enhanced by the surface hydroxylation due to the more reduced Co ions and stronger Co-Pt bonding at the CoOHx/Pt interface.

DEPOSITION ANGLE DEPENDENCE OF TANTALUM OXIDE NANOLAYERS ON THE STRUCTURAL AND OPTICAL PROPERTIES AS A FUNCTION OF THICKNESS

Tantalum oxide nanolayers with different thicknesses (30, 60, 90 and 120 nm) were deposited on glass substrates at a deposition angle of 60∘ under high vacuum condition at room temperature by using electron gun evaporation method. The morphological, structural and optical properties of tantalum oxide nanolayers are investigated by XRD, FESEM, EDX, AFM and spectrophotometer. Kramers–Kronig relations are used to calculate the optical parameters. Optical results show that the real and imaginary parts of the dielectric function, the real part of the refractive index and bandgap energy have increased with increasing film thickness.

Dispersion of graphene oxide nanolayers in novel heat-stable poly(benzimidazole-amide) by ultrasonic irradiation route: synthesis and characterization

ABSTRACT Poly(benzimidazole-amide) (PBIA) nanocomposites containing 5, 10, and 15 wt.% of graphene oxide were successfully prepared. A new PBIA was prepared via polymerization of 1,3-bis(5-amino-1H-benzimidazole-2-yl)benzene, as an aromatic diamine, and 5-hydroxy isophthalic acid in the presence of molten tetra-n-butyl ammonium bromide and triphenyl phosphite as a green and environmentally friendly method. To prevent agglomeration of graphene in the PBIA matrix, graphene oxide was prepared by hummer’s method. Then, different PBIA/graphene oxide nanocomposites were synthesized via interaction of pure PBIA and graphene oxide using ultrasonic technique. TEM and FE-SEM images certified that the graphene oxides were uniformly dispersed in the PBIA matrix.

Chitosan biomolecules-modified graphene oxide nano-layers decorated by mesoporous ZIF-9 nanocrystals for the construction of a smart/pH-triggered anti-corrosion coating system

The present research has focused on introducing a novel carbon nano-filler modified by stable nano-crystals based on Co-based MOF (called ZIF-9). For improving the GO dispersion, the graphene layers were modified with chitosan (CS-rGO) and then decorated with MOF particles. The fabricated hybrid particles' structures were probed by detailed spectroscopic techniques (i.e., XRD, UV–Vis, Raman, and FT-IR) and the morphology was observed by FE-SEM. The zeta potential and UV–Vis/ICP achievements displayed the pH sensitivity of the constructed ZIF-9@CS-rGOs structure. The solution phase electrochemical explorations displayed the ZIF-9@CS-rGO nanoparticles' effectiveness in anodic reaction rate mitigation, providing corrosion resistance around 4100 Ω.cm2 in the best condition (EIS), and the FE-SEM images have proved that a high compact film generation could result in the steel surface damage control in chloride media. The active protection ability of the ZIF-9@CS-rGO/EP scratched composite was explored by EIS approaches and the scratched line morphology was probed by aiding FE-SEM. Outcomes have displayed that the scratched composite resistance was raised to 89000 Ω.cm2 after ZIF-9@CS-rGO inclusion and FE-SEM micrographs have displayed sufficient scratched line surface coverage. Also, the intact ZIF-9@CS-rGO/EP composite coating resistance was improved to 26 MΩ.cm2, confirming the notable EP pathways blockage after introducing ZIF-9@Cs-rGO nano-filler.

Effect of the Deposition Angle on Structural and Optical Properties of Tantalum Oxide Nanolayers Deposited by Electron Gun Evaporation as a Function of Thickness

Effect of the Deposition Angle on Structural and Optical Properties of Tantalum Oxide Nanolayers Deposited by Electron Gun Evaporation as a Function of Thickness

Structure-dependent optical nonlinearity of indium tin oxide

We use post-deposition vacuum annealing of epsilon-near-zero (ENZ) indium tin oxide (ITO) nanolayers in order to modify their structural properties and enhance the third-order optical nonlinear response around the ENZ wavelength. We find that room temperature magnetron sputtering deposition results in polycrystalline thin films with an intrinsic tensile strain and a ⟨110⟩ fiber axis preferentially oriented normal to the substrate. Moreover, we demonstrate that post-deposition vacuum annealing treatments produce a secondary anisotropic phase characterized by compressive strain that increases with the annealing temperature. Finally, we use the Z-scan optical technique to accurately measure the complex nonlinear susceptibility χ(3) and the intensity-dependent refractive index change Δn for samples with different structural properties despite featuring similar ENZ wavelengths. Our intensity-dependent analysis demonstrates that an enhancement of the optical nonlinearity can be achieved by tuning the structure of ENZ nanolayers with values as large as χR(3)=(5.2 ± 0.3)×10−17m2/V2. This study unveils the importance of structural control and secondary phase formation in ITO nanolayers with ENZ optical dispersion properties for the engineering of integrated highly nonlinear devices and metamaterials that are compatible with the scalable silicon photonics platform.

Development of a nanocomposite coating with anti-corrosion ability using graphene oxide nanoparticles modified by Echium ammonium extract

Polymer coatings like epoxies (EP) are among the most used approaches to overcome corrosion loss in industries. But these coatings have porosities in their structure due to the evaporation of the solvent. This study aims to construct a nanocomposite epoxy coating incorporated with reduced graphene oxide (rGO) nanoparticles utilizing the aqueous Echium ammonium extract (EAE). The surface characterizations were conducted using X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible spectroscopy (UV–Vis), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), dispersibility experiment, and field emission scanning electron microscope (FE-SEM). The anti-corrosion properties were scrutinized by electrochemical impedance spectroscopy (EIS) and neutral salt spray test (NSS). The surface analyses have proved the successful conversion of the carbonyl groups into CO bonds. The Rt value in the liquid phase has improved by time and reached its maximum after 24 h from immersion which was 66,566 Ω·cm2. The high response of the rGO-EAE sample was attributed to the various chelates and complexes constructed by the allocation of the lone pairs of EAE molecules electrons to the vacant d-orbital of the Fe atom. The indirect use of EAE in EP has enriched the barrier function and constructed a protective layer inside the scratch, elucidating the self-healing operation. The EAE molecules have protected via absorbing on the active anodic zones. The presence of modified graphene oxide nanolayers in the epoxy coating not only brought about enhancement in the nanocomposite barrier function but also, owing to the delivery of EAE molecules to the anodic zones of the steel surface, a desirable grade of protection was provided through active inhibition of the anodic zones.

Cerium-induced lattice disordering in Co-based nanocatalysts promoting the hydrazine electro-oxidation behavior.

In this work, cerium-incorporated Co-based catalysts encapsulated in nitrogen-doped carbon were fabricated for the electrocatalytic hydrazine oxidation reaction (HzOR). The Ce incorporation could lead to the formation of surface oxide nanolayers with a disordered lattice, endowing the catalyst with enriched active sites and enhanced intrinsic activity for promoted HzOR.

An in situ grown amorphous ZrO2 layer on zeolite for enhanced phosphate adsorption.

Zeolite supported amorphous metal oxide nanolayers with high specific surface area, abundant adsorption sites, and excellent reusability hold a bright prospect in the efficient removal of contaminants, yet it is proven to be still challenging to precisely regulate and control their synthesis. Herein, we reported a facile synthetic strategy for rational design and achieving the uniform and firm in situ growth of an amorphous ZrO2 layer decorated on the surface of zeolite (ZEO@AZ) for enhanced phosphate adsorption. The Langmuir isotherm model and pseudo-second order kinetic equation well described the adsorption process towards phosphate solution, and the synthetized ZEO@AZ exhibited an excellent maximum adsorption amount of 24.98 mgP g−1. Furthermore, the adsorption of phosphates on ZEO@AZ was confirmed to be chemisorption, endothermic and spontaneous. This approach for fabricating amorphous metal oxide nanolayers on a robust matrix may provide a new route for constructing composites with superb phosphate adsorption performance.

The nature of column boundaries in micro-structured silicon oxide nanolayers

Columnar microstructures are critical for obtaining good resistance switching properties in SiOx resistive random access memory (ReRAM) devices. In this work, the formation and structure of columnar boundaries are studied in sputtered SiOx layers. Using TEM measurements, we analyze SiOx layers in Me–SiOx–Mo heterostructures, where Me = Ti or Au/Ti. We show that the SiOx layers are templated by the Mo surface roughness, leading to the formation of columnar boundaries protruding from troughs at the SiOx/Mo interface. Electron energy-loss spectroscopy measurements show that these boundaries are best characterized as voids, which in turn facilitate Ti, Mo, and Au incorporation from the electrodes into SiOx. Density functional theory calculations of a simple model of the SiO2 grain boundary and column boundary show that O interstitials preferentially reside at the boundaries rather than in the SiO2 bulk. The results elucidate the nature of the SiOx microstructure and the complex interactions between the metal electrodes and the switching oxide, each of which is critically important for further materials engineering and the optimization of ReRAM devices.

Kinetic and Thermodynamic Characteristics of Fluoride Ions Adsorption from Solution onto the Aluminum Oxide Nanolayer of a Bacterial Cellulose-Based Composite Material.

The described research examined the adsorption of fluoride ions from solution immobilized onto an aluminum oxide-coated bacterial cellulose-based composite material in which aluminum oxide had been deposited using ALD technology. The kinetic regularities of the adsorption of fluoride ions from the solution as well as the mechanism of the processes were analyzed. The established equations show that the dynamics of adsorption correspond to first-order kinetics. Based on the Langmuir adsorption isotherms, we defined the adsorption equilibrium constants, parameter maximum adsorption, and change in Gibbs free energy. It is shown that, with increasing temperature, an increase in the reaction rate is constant, both forward and reverse. This testifies to the activated character of adsorption of the first fluoride on the surface of the sorbent based on bacterial cellulose modified with an alumina nanolayer. The activation energy of the desorption process is higher than the activation energy of the adsorption process, which characterizes the adsorption as ionic. The negative value of entropy indicates that in the course of sorption, an adsorption complex “aluminum-fluorine” is formed, where the system is more ordered than the initial system in which fluorine ions are in solution. The limiting stages of the process are revealed. The high sorption capacity of the resulting bacterial cellulose-based composite material obtained by means of biosynthesis through cultivation of the bacterium Komagataeibacter sucrofermentans B-11267 was demonstrated.

Effect of vertical deposition angle on structural and optical properties of tantalum oxide nano layers deposited by electron gun evaporation

Tantalum oxide nano layers were deposition on glass substrate with different thicknesses (30, 60, 90 and 120 nm) in vertical deposition angle and high vacuum condition at room temperature by using electron gun evaporation method. There were no specific peaks in XRD patterns because of amorphous nature of these layers. AFM results show that surface roughness is reduced by increasing the thickness of the layers. FESEM images show nucleation, growth, accession and integration as interconnected islands in the lower thickness and re-nucleation at higher thicknesses (120 nm). We studied Raman spectra of the produced Ta2O5 amorphous layers. The calculated optical coefficients by using Kramers-Kronig relations show that with increasing film thickness, dielectric properties, absorption coefficient and band gap energy have increased.