Sol-gel Technology Research Articles

Anti-corrosion Properties of Functionalized Organo-silane Coupling Agents for Galvanized Steel

Silane precursor selection is an important criterion for achieving great anticorrosive performance on steel substrates using sol-gel technology. A density functional theory (DFT) study was performed on functional and nonfunctional organosilane precursors. The global reactivity parameters, such as the global hardness (ƞ), dipole moment (μ), and number of electrons transferred (∆N) to the metal substrate, were calculated to identify suitable silane coupling agents. DFT studies revealed that precursors containing functional groups such as epoxy, amine, and mercapto offer better protection against corrosion to galvanized steel by providing stronger interfacial adhesion than precursors without functional moieties. The DFT-calculated adsorption energy (Eads) is more than 40.0kcal/mol for the adsorption of functional organosilanes onto the (ZnO)12 cluster. Evidence of chemical bond formation at the interface for functional organosilanes is found in the electron density overlap in the MOs. Natural charge analyses revealed clear charge transfer from the organosilane moiety to the (ZnO)12 cluster. The theoretical predictions were validated via experiments. Electrochemical studies demonstrated a protective efficiency of 92.5% for Ie with an impedance of 92.9kΩ·cm2. The presence of the respective functional groups and surface morphology were evaluated by FTIR and SEM. The order of corrosion inhibition of organosilanes was found to be MPTMS≈APTES>GPTMS>TEOS.

Sol-gel synthesis and research of inorganic compounds, hybrid functional materials and disperse systems

The results are summarised of the Seventh International Conference of CIS countries “Sol-gel synthesis and research of inorganic compounds, hybrid functional materials and disperse systems “Sol-gel 2023”, the key reports are discussed within the scientific sections: Theoretical aspects of sol-gel process; Films, coatings and membranes obtained using sol-gel technology; Hybrid organic-inorganic sol-gel materials; Xerogels, glasses and bulk ceramic materials synthesized by sol-gel method; Nano- and microstructured materials, nanotechnology; Methods of research of structure and properties of materials obtained using sol-gel synthesis.

The evolution of morphology and structure of spin-coated Zinc Acetate thin films and their impact on ZnO film morphology

The deposition of ZnO thin films using sol-gel technology is a straight forward and widely used method for fabricating ZnO films with diverse morphologies and tunable electrical and optical properties. Notably, the preparation of ZnO compact layers from a zinc acetate and monoethanolamine (ZA:MEA) solution via spin-coating has gained popularity due to its simplicity. The pretreatment of spin-coated ZA:MEA films significantly impacts the morphology and structure of the resulting ZnO films. While the effects of preheating and its rate on ZnO precursor films have been extensively studied, the morphological and structural evolution of ZA:MEA films immediately after spin-coating and its subsequent impact on the final ZnO film have not been previously explored. In this study, we present the topography and phase composition of as-grown ZA:MEA films using atomic force microscopy (AFM). We conduct an in-situ investigation of the morphological evolution of ZA:MEA films. Our results reveal that as-grown ZA:MEA films possess an inhomogeneous structure. AFM phase image shows two distinct domains in the ZA:MEA films. Over time, we observe the growth of crystals in both vertical and perpendicular directions. ZA:MEA film aged for at least 20 h develops arrays of vertically oriented crystals throughout the film covered with sheet-like crystals forming on the film surface. This temporal evolution in the morphology and structure of ZA:MEA films significantly influences the morphology of the final ZnO film.

Remarkable adsorptive capacity and reusability performance of magnetic magnetite@silica@L-histidine nanocomposite towards gaseous benzene pollutant

Herein, magnetic magnetite@silica@L-histidine (Fe3O4@SiO2@L-Hist) core-shell nanoparticles (NPs) as novel adsorbents were first prepared via chemical co-precipitation and sol-gel technology for the adsorption of gaseous benzene pollutant. The Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Hist NPs were characterized using a combination of scanning electron microscopy (SEM), SEM - energy dispersive X-ray (SEM-EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), Brunauer-Emmett-Teller analysis (BET), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). The adsorption capacities of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Hist NPs for benzene were found to be 188, 279 and 481 mg g-1, respectively, with Fe3O4@SiO2@L-Hist NPs demonstrating the highest capacity. Kinetic and isotherm studies indicated that the pseudo-2nd-order kinetic model and the Langmuir isotherm model provided the best fit to the experimental data, suggesting favorable physical adsorption. In addition, Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Hist NPs exhibited remarkable reusability, with reuse efficiencies of 85.67, 89.65 and 91.73%, respectively, after five recycle cycles, demonstrating their potential for practical benzene remediation applications. Overall, this study offers valuable insights into creating effective and sustainable adsorbents for eliminating volatile organic compounds (VOCs). This contributes to mitigating air pollution and safeguarding both human health and the environment.

Designed Polar Cosolvent-Prepared Zinc Oxide Film for Efficient and Stable Inverted Organic Solar Cells.

Here, a simple method of applying dimethylformamide (DMF) as cosolvent in the sol-gel technology is used to improve the quality of ZnO bulk films. First-principles calculations show that with the addition of polar solvent DMF, the adsorption energy (Eads) between the solvent and Zn(OH)₂ increases from -1.42 to -1.74eV, which can stabilize the existence of Zn(OH)₂, thereby promoting the ZnO synthesis. Besides, the elimination of amine residues in the DMF-ZnO film significantly suppress the photocatalytic activity induced by amine-induced coordination or redox reactions. Inverted organic solar cells (OSCs) based on PM6:Y6 and PM6:BTP-eC9 achieves impressive power conversion efficiencies (PCE) of 17.58 and 18.14%, respectively. Furthermore, benefiting from the reduced defects of bulk ZnO, pseudo-bilayer bulk heterojunction (PBHJ) devices based on the optimized ZnO film exhibited superior stability, the PM6:Y6 devices based on DMF-ZnO ETLs can maintain 90.28% of their initial PCE after 1000 h of thermal aging at 85°C, and 80.98% of their initial PCE after 168 h of UV aging. This simple solvent optimization strategy can significantly improve the charge transport of ZnO bulk films, making it a reliable strategy for the preparation of electron transport layers in OSCs.

Effect of Cu doping on morphology and properties of calcium ferrite and its application as oxygen carrier in chemical looping hydrogen production

Chemical looping hydrogen production with inherent CO2 capture has been widely recognized as a clean and efficient approach to high-purity hydrogen production because of the ultra-pure H2 product without any purification facilities. It is crucial to develop oxygen carriers with better performance to improve fuel conversion and hydrogen production efficiency. The potential of Ca2Fe2O5 in steam converting has been confirmed. However, its lower oxygen transfer capacity, that is, it tends to produce lower fuel conversion in fuel reactors, which will limit its practical application. Here, we report the development of Cu-doped Ca2Fe2O5-based oxygen carriers using sol-gel technology. The effects of B-site substitution of Cu element on the morphological properties and redox properties of Ca2Fe2-xCuxO5 (x = 0, 0.1, 0.25, 0.5, 1) oxygen carriers were evaluated based on experiments and density functional theory calculations. The results show that Cu doping not only elevated the surface oxygen content and enhanced the oxygen activity of the oxygen carriers, but also increased the Fe3+ at the B-site, thus enhanced their binding ability with oxygen molecules. Vacancy formation was a rate-determining step in the chemical looping hydrogen production (CLH), and Cu-doped Ca2Fe2O5 reduced the energy of oxygen vacancy formation. In the CLH process, the doping of Cu significantly improved the hydrogen productivity and fuel conversion rate. The fuel conversion rate was positively correlated with the doping amount of Cu. When x = 1, Ca2Fe2-xCuxO5 had the maximum fuel conversion rate, and its average conversion was 54.2% more than that of undoped Ca2Fe2O5. Ca2Fe2-xCuxO5 with x = 0.25 was the most suitable for CLH with the highest H2 yield, which was 20.3% more than that of Ca2Fe2O5. Moreover, its properties remained stable over multiple redox cycles with high activity and stability for CO-CLH.

Design of a Thermally Stable Heat-Resistant (Al2O3+Al3Ti)/Al Composite with Excellent High-Temperature Mechanical Properties: Multimechanism Synergistic Strengthening Strategy.

The effectiveness of the room-temperature strengthening strategy for aluminum (Al) is compromised at increased temperatures due to grain and precipitate phase coarsening. Overcoming the heightened activity of grain boundaries and dislocations poses a significant challenge in enhancing the high-temperature strength through traditional precipitation strengthening. This study presents novel strengthening strategies that integrate intergranular reinforcements, intragranular reinforcements, refined grain, and stacking faults within an (Al2O3+Al3Ti)/Al composite prepared using sol-gel and powder metallurgy technology. Excellent high-temperature tensile properties are achieved; also, a remarkable fatigue performance at increased temperatures that surpasses those of other existing Al alloys and composites is revealed. These superior characteristics can be attributed to its exceptionally stable microstructure and the synergistic strengthening mechanisms mentioned above. This work offers new insights into designing and fabricating thermally stable Al matrix composites for high-temperature applications.

Ionic-liquid/Carbowax 20 M functionalized capsule phase microextraction platform for the extraction of phosphodiesterase-5 inhibitors from human serum and urine prior to their determination by LC–MS

Capsule phase microextraction (CPME) is an efficient bioanalytical technique that streamlines the sample preparation by integrating the filtration and stirring mechanism directly into the device. A novel composite sorbent designed to be selective towards the target analytes consisting of mixed-mode sorbent chemistry synthesized by sol–gel technology is found promising and superior to the conventional C18 sorbents. Herein we describe the encapsulation of an ionic liquid (IL)/Carbowax 20M-functionalized sol–gel sorbent (sol–gel IL/Carbowax 20 M) in the lumen of porous polypropylene tubes for the capsule phase microextraction of three phosphodiesterase-5 inhibitors namely avanafil, sildenafil, and tadalafil in human serum and urine samples. The CPME device was characterized by Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FT-IR). The experimental parameters of CPME procedure (e.g. sample pH and ionic strength, extraction time, stirring rate, elution solvent and volume) were carefully optimized to achieve the highest possible extraction efficiency for the analytes. Method validation was conducted in terms of precision, linearity, accuracy, matrix effect, lower limits of quantification, and limits of detection (LOD). The method linearity was investigated in the range of 50–1000 ng mL−1 for all analytes while the precision was less than 11.8 % in all cases. For all analytes, the LOD values were 17 ng mL−1. The IL/CW 20M-functionalized microextraction capsules could be reused at least 25 times both for urine and serum samples. The green character and the applicability of the proposed method were evaluated using the ComplexGAPI and BAGI indexes. The optimized CPME protocol exhibited reduced consumption of organic solvent and generation of waste, cost-effectiveness, and simplicity. Finally, the proposed method was successfully applied to the analysis of sildenafil in human urine after administration of drug-containing formulation.

Preparation of all-solid-state electrochromic devices based on Li+-contained phosphate electrolyte

In this paper, phosphate solid-state electrolytes with Li+ were prepared by the melt quenching method, and "ITO/TiO2:Nb/ZrO2″ and "ITO/NiO/ZrO2″ multilayers were fabricated on both sides of the electrolyte by sol-gel technology to construct "ITO/TiO2:Nb/ZrO2/phosphate electrolyte/ZrO2/NiO/ITO" all-solid-state electrochromic devices (ECDs). The optical and electrical properties of the electrolyte were investigated, and it was found that the material had a visible light transmittance of up to 89 % and a conductivity greater than 10−7 Scm−1 at temperature above 100 °C. Moreover, the ionic conductivity of the electrolyte gradually increased with increasing temperature. Simultaneously, the effect of the ZrO2 thickness on the device performance was investigated. The optical modulation amplitude (ΔT) and cycling number of the device initially increased and then decreased with increasing ZrO2 thickness. The optimal device was obtained with a 120 nm-thick ZrO2 layer, achieving a ΔT at λ = 630 nm of 48.39 %. Moreover, the ECDs in this paper demonstrated long-term optical memory; after 20 days of open-circuit memory measurement, there was only a 5.3 % increase in transmittance for devices in colored state.

Preparation and electrochromism of amorphous Bi-doped TiO2 film for aqueous-based electrochromic device

Amorphous Bi–TiO2 films with improved electrochromic properties have been successfully fabricated by a facile sol-gel spin-coating technology. The influence of dopant bismuth (Bi) content and sol amount on the electrochromic performance of Bi–TiO2 films was studied. The optimized Bi–TiO2 films show outstanding electrochromic properties, including wide transmittance modulation (ΔT = 74.26 % at 640 nm), short switching times (2.6 s/3 s for bleaching and coloring), and large coloration efficiency (52.77 cm2 C−1). A proton-based electrochromic device was prepared by the amorphous Bi–TiO2 film as the electrochromic film and Cu sheet as the counter electrode. The prepared device has a small operating potential range (1.0 V) in aqueous electrolyte due to the excellent electrochromic performance and high proton activity for the amorphous Bi–TiO2 film. In addition, the device shows excellent performance (ΔT = 67.41 %, 2.5 s/3.9 s for bleaching and coloring), providing an important reference value for the development of high-efficiency electrochromic device.

Study on anti-stab resistance of aramid fabrics treated by sol-gel technology

Study on anti-stab resistance of aramid fabrics treated by sol-gel technology

Optimization of anodizing conditions and hole sealing treatments for enhanced anti-corrosion properties of magnesium alloys

To enhance the corrosion resistance of magnesium alloys, an anti-corrosion composite film was prepared by combining anodic oxidation and sol-gel technology. Experimental results indicate that after anodization at 17.5V for 3 min, the composite film obtained through sealing with an MPTMS-modified sol exhibited significant improvements in physical properties. The thickness of the film reached 24.3 μm, its hardness was measured at 164.7 HV, and it demonstrated good surface uniformity. Electrochemical impedance spectroscopy revealed that the impedance modulus at low frequency (|Z| at 0.01 Hz) increased by nearly two orders of magnitude. Furthermore, this study thoroughly explores the corrosion protection mechanism of the composite film, highlighting the role of the sol-gel layer in occupying micro-pores and micro-cracks to form a denser and more uniform protective layer. The dual-layer protection provided by the combination of anodic oxidation and sol-gel layers significantly enhances the overall corrosion resistance of the magnesium alloy.

Photocatalysis and irradiative TL defect center analysis studies of Cu2+ ionic ZnO nano lattice

The objective of the study is to create a series of ZnO nano powders doped with CuO using sol–gel technology in order to look into their photocatalytic activity for the photodegradation and cleaning process. XRD, BET surface area, surface morphology, chemical analysis, and FT-IR measurements have all been used to look at the nano powders' structure from this point of view. The results suggest that the materials were made at the nanoscale level, and their hexagonal shape makes them good as catalytic nano resources. Photoluminescence and UV–visible diffusion reflection spectroscopy were also used to test the nano powders. The results show that the nano powders that were made are visually active. To find out how photocatalytic the nanoparticles are, they were used to break down CR (10 ppm) and MV (10 ppm) dyes when exposed to light. The nano powder with 1.0 mol% of CuO doped ZnO nanoparticles had the highest photocatalytic efficiency (86 %). It had a band gap energy of 3.15 eV and reacted with both dyes for 90 min. Researchers looked at radical scavengers and the effect of catalyst dose on how well they broke down substances. The reaction that broke down had pseudo-first-order kinetics, and the rate of the reaction was four times faster when 1.0 mol% Cu was added to the ZnO catalyst. The degradation efficiency only dropped by 1 % after three rounds of the process. Because of this, the 1.0 mol% Cu-ZnO was used as a photocatalyst that broke down textile dyes well and had a lot of promise to be used again. The samples were also checked for thermoluminescence while they were exposed to 25 kGy of gamma radiation. Samples were tested for their trap depth characteristics, indicating the test samples' potential for TL activity.

PRODUCTIVE METHODS FOR INCREASING THE EFFICIENCY OF INTERMEDIATE REACTIONS IN THE SYNTHESIS OF FUNCTIONAL CERAMICS

This study focuses on investigating the potential of modified ceramic technology methods for producing composition materials with nano-level heterogeneity, approximating the properties of functional ceramics (FC) obtained through helio-technology. Three different powder synthesis methods were utilized: oxide method, ceramic technology, and sol-gel technology. X-ray diffraction and electron microscopy analyses were employed to compare the microstructure of powders obtained by these methods with samples synthesized using helio-technology. The results revealed that powders obtained through modified ceramic technology methods exhibited a more homogeneous structure and smaller particle size compared to those obtained through helio-technology. Nano-sized, metastable, and amorphous phases formed at the boundaries of such powders are considered responsible for the generation of pulsed infrared radiation. These findings have significant practical implications in various fields that require composition materials with controlled properties and the ability to generate pulsed infrared radiation.

Dual-complexing agent dominated synthesis of carbon coated Na3V2(PO4)3 cathodes for high-performance sodium ion batteries

The currently prevailing single complexing agent-dominated sol-gel technologies for Na3V2(PO4)3 (NVP) cathodes in sodium-ion batteries (SIBs) always result in limited modification effects, especially in regards to the particle size of NVP and the quality of carbon coatings. Herein, we report a citric acid and glycine co-complexed strategy for fabricating carbon-coated NVP. It creates a favorable synergy for optimizing the microstructure and electrochemical performance of the NVP cathode. The introduction of glycine in citric acid not only decreases the solution viscosity for facilitated metal-ion diffusion, but also induces the self-construction of a 3D network through heteromolecular hydrogen bonds. The optimized carbon-coated NVP by co-complexing of citric acid and glycine (named as NVP/CG-5.0) presents distinctly decreased particle size, improved dispersity and moderate carbon coating thickness of ∼2 nm. It also features a large specific surface area of 44.4 m2 g−1 with rich mesopores. Impressively, the NVP/CG-5.0 electrode exhibits substantially improved electrochemical performance, such as the elevated specific capacity of 108.3 mAh g−1 with high initial Coulombic efficiency (95.2%), high capacity retention of 81.3% after 2000 cycles at 2 C and excellent rate performance (88.2 mAh g−1 at 20.0 C). Furthermore, the assembled NVP/CG-5.0║hard carbon full battery also exhibits superior electrochemical performance, suggesting the great potential of the co-complexed strategy for developing high-performance NVP cathodes in SIBs.

Orientation of reduced graphene oxide in composite coatings.

Composite coatings containing reduced graphene oxide (rGO) and 3-(aminopropyl)triethoxysilane functionalised rGO (APTES-rGO) were prepared by sol-gel technology and deposited on Al 2024 T-3. Covalent functionalisation of GO by APTES occurred by formation of amide bonds, accompanied by GO reduction. The thin sheets were retained. The hydrophilicity of the coating increased when APTES-rGO was added. The opposite was observed when GO was added. A key finding is that the rGO flakes agglomerate and lie in a random orientation in the coating, whereas the APTES-rGO flakes are more evenly distributed in the matrix and appear to lie along the plane of the substrate.

A Review of Preparation and Characterization of Sol-Gel coating forCorrosion Mitigation

Sol-gel technology has emerged as a powerful and versatile tool for synthesizing a wide range of materials such as catalyst, ceramics, coatings, composite, glasses, fibers.Many industries like Automotive, Biomedical , Communications, Construction and Electronics sectors benefit from the use of sol-gel chemistry due to its versatility in fabricating a wide range of materials with different properties. In the sol-gel process, a precursor solution (sol) is used, and the precursor molecules undergo controlled hydrolysis and polycondensation to become a solid substance (gel). This paper explores the application of the sol-gel synthesis method in coating technology for corrosion prevention. Corrosion presents a notable risk to infrastructure, machinery, and diverse industrial uses, resulting in considerable economic losses and safety hazards. Several methods exist for corrosion prevention using coatings such as chemical vapor deposition and physical vapor deposition but sol-gel stands out due to its low synthesis temperature ,cost-effectiveness, simplicity ,ability to incorporate and leverage corrosion inhibitors and adaptability to various substrates. Limitations exist in terms of process optimization, and long-term stability, ongoing research efforts are actively addressing these challenges to unlock its full potential. Additionally with our study of related journals we have found that these coatings can be further engineered to exhibit additional functionalities like hydrophobicity, conductivity, or biocompatibility, expanding their applicability across diverse industrial needs.

Biomimetic Sol-Gel Chemistry to Tailor Structure, Properties, and Functionality of Bionanocomposites by Biopolymers and Cells.

Biosilica, synthesized annually only by diatoms, is almost 1000 times more abundant than industrial silica. Biosilicification occurs at a high rate, although the concentration of silicic acid in natural waters is ~100 μM. It occurs in neutral aqueous solutions, at ambient temperature, and under the control of proteins that determine the formation of hierarchically organized structures. Using diatoms as an example, the fundamental differences between biosilicification and traditional sol-gel technology, which is performed with the addition of acid/alkali, organic solvents and heating, have been identified. The conditions are harsh for the biomaterial, as they cause protein denaturation and cell death. Numerous attempts are being made to bring sol-gel technology closer to biomineralization processes. Biomimetic synthesis must be conducted at physiological pH, room temperature, and without the addition of organic solvents. To date, significant progress has been made in approaching these requirements. The review presents a critical analysis of the approaches proposed to date for the silicification of biomacromolecules and cells, the formation of bionanocomposites with controlled structure, porosity, and functionality determined by the biomaterial. They demonstrated the broad capabilities and prospects of biomimetic methods for creating optical and photonic materials, adsorbents, catalysts and biocatalysts, sensors and biosensors, and biomaterials for biomedicine.

Tin Oxide Modification of Indium Oxide Gas Sensitive Layers to Increase Efficiency of Gas Sensors

Monitoring of air pollutions is one of actual trends in the development of industrial and domestic instrumentation. There are sets of tasks for improving gas analytical instruments because of increasing demand for control of a concentration of explosive and toxic gases on a level with maximum allowable concentration. The aim of the paper was to investigate the methods of formation and elemental composition of indium oxide films modified with tin oxide on the surface of gas sensor elements as one of the promising compounds for improving the detection efficiency of explosive and toxic gases in the environment. The processes of formation of gas-sensitive films deposited on the surface of nichrome alloy information electrodes were studied in this article. Substrates of anodic aluminum oxide with area of 10 × 10 mm2 and a thickness of 45 ± 0,5 μm were chosen for research. Two layers on the surface of the samples were formed. The first layer was formed from NiCr alloy (Ni – 80 %, Cr – 20 %) with a thickness of ≈ 0.3 μm by ion-plasma sputtering. The second layer was based on indium oxide with addition of tin oxide with thicknesses from ≈ 0.3 μm to ≈ 1.0 µm and coated with sol-gel technology. Five samples of gas-sensitive films were formed with different methods of deposition and heat treatment. Scanning electron microscopy was used for study of films’ morphology and elemental compositions of samples. The most perfect continuous semiconductor films were obtained by multilayer applying of a sol-gel paste. When semiconductor films were processed at annealing temperatures of 700 °C and higher in vacuum so there was observed cracking of semiconductor films up to a layer of NiCr alloy. The developed surface of gas-sensitive films allows to reach high sensitivity and affectivity of semiconductor sensors for control of air gas composition.

Advanced Nanostructured Coatings Based on Doped TiO2 for Various Applications

For many years, TiO2-based materials and improving their properties in order to expand their application areas have been the focus of numerous research groups. Various innovative approaches have been proposed to improve the photocatalytic and gas-sensing properties of TiO2 nanostructures. In this review, we aim to synthesize the available information in the literature, paying special attention to the sol–gel technology, which is one of the most frequently used methods for TiO2 synthesis. The influence of dopants on the structural, morphological, optical, and electrical properties of TiO2 and the way to modify them in a controlled manner are briefly discussed. The role of shallow and/or deep energy levels within the TiO2 bandgap in the electron transport behavior of doped TiO2 is emphasized. Selected research on photocatalytic applications in water disinfection, wastewater treatment, and self-sterilizing coatings that contribute to improving the quality of human life and environmental preservation is highlighted. A survey of biosensors that are closely related to medical applications such as cancer detection, implantology, and osteogenesis is also provided. Finally, the pressing problems that need to be solved in view of the future development of TiO2-based nanostructures are listed.