Sol-gel Method Research Articles

Optimization of ammonia and TEOS concentration for the development of Ca(OH)2@SiO2 nanocomposites for optimal energy storage performance

In this study, nanocomposites of Calcium hydroxide (Ca(OH)2) and Silica (SiO2) were developed using tetraethylorthosilicate precursor, and the impact of ammonia concentration on the reaction kinetics of Ca(OH)2 to CaO conversion were studied. The Ca(OH)2 nanoparticles were synthesized by the sol-gel method. The formation of Ca(OH)2 particles was confirmed through X-ray diffraction. Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) provided evidence for the presence of a SiO2 layer on Ca(OH)2. Thermogravimetric analyses were carried out under N2 atmosphere to study the dehydration efficiency of the Ca(OH)2 system in the presence of SiO2. The results were found to be consistent with the findings from XRD and Raman analysis. Differential Scanning Calorimetry (DSC) was done to determine the impact of ammonia and silica on the endothermic peak of Ca(OH)2 and CaCO3. TG results were used to determine the weight loss, activation energy (Ea), entropy (, enthalpy (, and Gibbs free energy (.

Organic solvents-free and ambient-pressure drying melamine formaldehyde resin aerogels with homogeneous structures, outstanding mechanical strength and flame retardancy

Atmospheric drying method for fabricating aerogels is considered the most promising way for casting aerogels on a large scale. However, the organic solvent exchange, remaining environmental pollution risk, is a crucial step in mitigating the impact of surface tension during the atmospheric drying process, especially for wet gel formed through the alkoxy-derived sol-gel process, such as melamine-formaldehyde resin (MF) aerogel. Herein, a tough polymer-assisted in situ polymerization was proposed to fabricate MF resin aerogel with a combination of mechanical toughness and strength, enabling it to withstand the capillary force during water evaporation. The monolithic MF resin aerogel through the sol-gel method can be directly prepared without additional network strengthening or organic solvent exchange. The resulting MF resin aerogel exhibits a homogeneous as well as hierarchical structure with macropores and mesopores (~6 μm and ~5 nm), high compressive modulus of 31.8 MPa, self-extinguishing property, and high-temperature thermal insulation with 97 % heat decrease for butane flame combustion. This work presents a straightforward and environmentally friendly method for fabricating MF resin aerogels with nanostructures and excellent performance in open conditions, exhibiting various applications.

Optical and photocatalytic properties of sol-gel AuNPs@TiO2 ultrathin film

The optical and photocatalytic properties of ultrathin TiO2 layers were investigated in order to stress out the effect of nanoscale thickness on the film properties. The method relies on monitoring localized surface plasmon resonance (LSPR) through UV–visible spectroscopy and enhanced Raman spectroscopy (SERS). To achieve this, TiO2 thin films were prepared using the sol–gel method on high density gold nanoparticles arrays (AuNPs). TiO2 anatase phase was obtained by thermal annealing and confirmed by XRD, HRTEM, and SERS. Our results reveal that the thinnest TiO2 layers consist of compact TiO2NPs of small dimensions and lower porosity compared to the thicker TiO2NPs layers. Subsequently, these thin TiO2 layers functionalizing AuNPs were applied in plasmonic photocatalysis, specifically for the N-demethylation of methylene blue in the visible range. When comparing layers with the same thickness (a single deposition layer with layers prepared by stacking various thin layers), the stacked layers demonstrated enhanced photocatalytic activity. This novel, stable form of TiO2 has the potential to open numerous opportunities in the fields of photocatalysis and detection.

STRUCTURAL, MAGNETIC AND MAGNETOCALORIC PROPERTIES OF La0.7Sr0.2Ba0.1MnO3 MANGANITE

In this present work, the structural, magnetocaloric and magnetic properties of La0.7Sr0.2Ba0.1MnO3 (LSBM) manganite were investigated. The material was synthesized using the sol-gel method and X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) devices were used to analyze structural properties such as crystal structure and surface morphology. XRD measurement revealed that the crystal structure of LSBM manganite is hexagonal. Based on the magnetic measurements, the TC value of La0.7Sr0.2Ba0.1MnO3 manganite compounds was calculated as 362 K. The ∆SM value of sample is established as 2.79 Jkg-1K-1 in an applied magnetic field of 5T. Arrott curves revealed that the phase transition was second order.

Structural and physical properties of Pb(Zr0.4Ti0.6)O3 epitaxial film with LaNiO3 electrodes

Epitaxial LaNiO3 (LNO)/PbZr0.4Ti0.6O3 (PZT)/LaNiO3 heterostructures have been deposited on LaAlO3 (LAO) substrates, in which LNO films were prepared by magnetron sputtering and PZT films with thicknesses ranging from 40 nm to 160 nm were deposited via sol-gel method. It is found that the structural and physical properties of PZT films are closely related to the tetragonality (c/a-1). With increasing PZT thickness, both tetragonality and remanent polarization increase, and the maximum tetragonality and remanent polarization correspond to a 120-nm-thick PZT film capacitor with a remanent polarization of 61.6 μC/cm2 measured at 425.00 kV/cm. However, as the thickness of PZT film is further increased, the ferroelectric polarization decreases which is attributed to relaxation of the PZT film. The leakage current mechanism of the capacitor remains unchanged regardless of the PZT thickness. It is Space Charge Limited Current (SCLC) conduction mechanism at high electric fields and Ohmic conduction mechanism at low electric fields.

Synthesis of transparent tin-doped indium oxide (ITO)-containing glass-ceramic coating by the sol-gel route for UV/NIR-shielding

Transparent glass-ceramic containing tin-doped indium oxide nano-crystalline phase was synthesized using the sol-gel method. The prepared sol, which was based on sodium aluminoborosilicate glass composition, was applied on soda-lime-silicate glass substrate through the dip-coating technique. Developing such glass-ceramics can offer several advantages, including reducing the total cost of production, enhanced chemical durability and a low-temperature synthesis process. The thermal behavior of the dried gels was investigated using simultaneous thermal analysis (STA), to determine the decomposition temperature of the nitrate salts in the gel, its glass crystallization temperature, and finally to optimize the heat treatment regime and optical properties as well. UV–Vis–NIR spectroscopy of the coated samples after heat treatment at 500 °C for 10 h revealed high visible transparency (T>70%) while indicating significant UV/NIR shielding, i.e. near zero and 10 % transmission, respectively. Phase analysis and crystallization behavior studies were conducted using XRD and FE-SEM to evaluate the morphology and size of the precipitated crystallites. According to the results, the optimum heating program for ITO crystallization was heating temperature and soaking time of 500 °C and 10 h, respectively. The undesirable crystalline phase of InBO3 was precipitated as the main crystalline phase by increasing the heat treating temperature to 550 °C. Furthermore, the glass structure was studied using FTIR spectroscopy demonstrating a highly polymerized glassy network for the coating. The effect of the precursors-to-solvent ratio during the synthesis process on the final optical properties was also investigated.

Synthesis of a novel Si-N-S flame retardant and its application on cotton cellulose biomacromolecule

A novel flame retardant containing Si, N, and S elements, ((2-(triethoxysilyl)ethyl)thio)ethan-1-amine hydrochloride (TETEA), was synthesized via a click reaction and characterized using nuclear magnetic resonance spectroscopy (NMR) and fourier transform infrared spectroscopy (FTIR). Subsequently, the flame-retardant cotton fabric was fabricated by sol-gel method. The results indicated that TETEA was successfully loaded on cotton fabric and formed a uniform protective layer on the surface of cotton fabric, exhibiting excellent flame retardancy. The flame-retardant cotton fabric achieved limiting oxygen index (LOI) of 28.3 % and passed vertical combustion test without after-flame or afterglow time at TETEA concentration of 500 g/L. Thermogravimetric analysis revealed that the residual carbon content of the flame-retardant cotton fabric was much higher than that of the control under air and N2 conditions. Besides, the flame-retardant cotton fabric was not ignited in cone calorimeter test with an external heat flux of 35 kW/m2. The peak heat release rate and the total heat release decreased from 133.4 kW/m2 to 25.8 kW/m2 and from 26.46 MJ/m2 to 17.96 MJ/m2, respectively. This phosphorus-free flame retardant offers a simplified synthesis process without adverse environmental impacts, opening up a new avenue for the development environmentally friendly flame retardants compared to traditional alternatives.

NiO@PANI based Nanocomposites as an Advanced Functional Material: Experimental and Computational Approach

Background:: Individually, metal nanoparticles (NPs) and conducting polymers show unique properties due to small size, large surface area, and high order of conductivity. But their combination may result in a synergistic effect in properties. Methods:: The NiO NPs and conducting polymer Polyaniline were prepared by modified Sol-gel and chemical oxidative methods, respectively. Powder XRD, FTIR, TEM, and UV-visible methods were used for the structural evaluation. The computational (DFT) study was performed to support experimental results. The NiO/Polyaniline (PANI) nanocomposites (NCs) were explored as corrosion inhibitors, electrical conductors, and photocatalytic agents. Results:: The NiO/Polyaniline NCs showed 91.52% corrosion inhibition efficiency at 1000 ppm concentration. The photocatalytic activity was investigated against methylene blue dye under ultraviolet light. The NiO/Polyaniline NCs decompose 90% of organic dye. The NCs exhibit good conducting, corrosion inhibition, and photocatalytic activity. Conclusion:: The metal oxide (NiO NPs) and PANI-based NCs can be used as corrosion inhibitors, conducting material, and for the degradation of organic compounds (dyes) in impure water.

Lowering Charge Transport Barriers by Eliminating the Electric Double Layer Residues to Reconstruct Adjacent SnO2 Nanocrystals for High‐Efficiency Flexible Perovskite Solar Cells

AbstractThe sol–gel method is efficient and cost‐effective for synthesizing SnO2 sol, wherein SnO2 nanocrystallites (NCs) are stabilized by electric double‐layer of solvated ions tightly bound to their surface. However, this strong binding makes the removal of electric double‐layer residues from the SnO2 electron transport layer (ETL) to be difficult at low temperatures. This hinders both the close contact and subsequent growth among adjacent SnO2 NCs, leading to severe carriers scattering at grain boundary, adversely affecting the electrical properties of SnO2 ETL. Herein, SnO2 sol is synthesized via an ethanol‐based sol–gel method and aqueous ammonia (NH3·H2O) is introduced to effectively clean stubborn electric double‐layer residues within the SnO2 ETL at a low temperature (80 °C). Removing residues reduces the gap among adjacent SnO2 NCs and promotes further reconstructed growth through oriented attachment (OA), thereby reducing the number of grain boundaries. Hence, the energy barriers for electron transport decrease within the SnO2 ETL. Furthermore, MHP prepared on the treated ETL has fine‐tuned energy level alignment, improving the electron extraction capacity. Consequently, flexible perovskite solar cells (f‐PSCs) incorporating this ETL achieved a notable increase in power conversion efficiency, rising from 19.16% to 23.71%, as well as superior mechanical stability.

Porous SiO2 antireflection film with high UV resistance

Sol-gel is one of the most economical methods to prepare antireflection films, but the low ultraviolet radiation-resistance (UV-resistance) of the sol-gel film limits its applicability in the solar industry. A SiO2 antireflection film was prepared with sol-gel method with phenyl salicylate (PS) as the porogen. The effects of the PS addition were investigated on the microstructure, optical property and UV-resistance of the film. When the addition of PS is 1.20 g, the refractive index at 550 nm is 1.30, and the maximum transmittance is 96.30 %. The average transmittance within the 400–1100 nm range reaches its peak at 92.85 %, which is 4.35 percentage points higher than that of the blank glass. In addition, the film without PS has an average transmittance of 91.00 % after 5000 equivalent solar hours (ESHs) UV irradiation, decreasing 1.07 percent point, and has a pencil hardness of 5 H and an adhesion of grade 2 of the tape-tearing method. However, the film with 1.20 g of PS still has an average transmittance of 92.15 % after 5000 ESHs UV irradiation, decreasing only 0.7 percent point, and has a pencil hardness of 7 H and an adhesion of grade 1 of the tape-tearing method.

Robust Photocatalytic MICROSCAFS® with Interconnected Macropores for Sustainable Solar-Driven Water Purification.

Advanced oxidation processes, including photocatalysis, have been proven effective at organic dye degradation. Tailored porous materials with regulated pore size, shape, and morphology offer a sustainable solution to the water pollution problem by acting as support materials to grafted photocatalytic nanoparticles (NPs). This research investigated the influence of pore and particle sizes of photocatalytic MICROSCAFS® on the degradation of methyl orange (MO) in aqueous solution (10 mg/L). Photocatalytic MICROSCAFS® are made of binder-less supported P25 TiO2 NPs within MICROSCAFS®, which are silica-titania microspheres with a controlled size and interconnected macroporosity, synthesized by an adapted sol-gel method that involves a polymerization-induced phase separation process. Photocatalytic experiments were performed both in batch and flow reactors, with this latter one targeting a proof of concept for continuous transformation processes and real-life conditions. Photocatalytic degradation of 87% in 2 h (batch) was achieved, using a calibrated solar light simulator (1 sun) and a photocatalyst/pollutant mass ratio of 23. This study introduces a novel flow kinetic model which provides the modeling and simulation of the photocatalytic MICROSCAFS® performance. A scavenger study was performed, enabling an in-depth mechanistic understanding. Finally, the transformation products resulting from the MO photocatalytic degradation were elucidated by high-resolution mass spectrometry experiments and subjected to an in silico toxicity assessment.

Characterization of Luminescent Li3Ba2Gd3Mo8O32:Tb3+ Phosphors Prepared via Sol–Gel Method

Characterization of Luminescent Li3Ba2Gd3Mo8O32:Tb3+ Phosphors Prepared via Sol–Gel Method

Correlation between biomedical and structural properties of Zn/Sr modified calcium phosphates.

This study investigates the correlation between the biomedical and structural properties of Zn/Sr-modified Calcium Phosphates (ZnSr-CaPs) synthesized via the sol-gel combustion method. X-ray diffraction (XRD) analysis revealed the presence of Ca10(PO4)6(OH)2 (HAp), CaCO3, and Ca(OH)2 phases in the undoped sample, while the additional phase, Ca3(PO4)2 (β-TCP) was formed in modified samples. X-ray absorption near-edge structure (XANES) analysis demonstrated the incorporation of Sr into the lattice, with a preference for occupying the Ca1 sites in the HAp matrix. The introduction of Zn, furthermore, led to the formation of ZnO and CaZnO2 species. The ZnSr-CaPs exhibited significant antibacterial activity attributed to the generation of reactive oxygen species by ZnO, the oxidation reaction of CaZnO2, and the presence of Sr ions. Cytotoxicity tests revealed a correlation between the variation in ZnO content and cellular viability, with lower ZnO concentrations corresponding to higher cell viability. Additionally, the cooperative effects of Zn and Sr ions were found to enhance the bioactivity of CaPs, despite ZnO hindering the apatite formation process. These findings contribute to the deep understanding of the diverse role in modulating the antibacterial, cytotoxic, and bioactive properties of ZnSr-CaPs, offering potential applications in the field of biomaterials.

Optical, thermal, mechanical, and antibacterial properties of polyvinyl alcohol/sodium alginate/ZnMn2O4 nanocomposites films for various optical devices and food packaging applications

This work involves preparing zinc manganite nanoparticles (ZnMn2O4 NPs) using the Sol-gel method. Polymer nanocomposites of polyvinyl alcohol (PVA)/Sodium alginate (NaAlg)- ZnMn2O4 NPs were created using the solution casting technique. The polymer nanocomposites films were made with varying weight percentages of ZnMn2O4 nanoparticles. With the addition of nanofiller, the reduced direct and indirect energy band gap values and increased Urbach energy values were discovered in the UV–Vis data. XRD data showed a reduction in crystallinity degree with dopant. ZnMn2O4 NPs had a strong interaction with PVA/NaAlg blend, as confirmed by FTIR. The addition of ZnMn2O4 NPs led to improved thermal stability of the polymer nanocomposites films. Additionally, the nanocomposites films' mechanical characteristics were examined. The loading of ZnMn2O4 nanoparticles has been associated with an increasing trend in the mechanical properties of the nanocomposites, including its toughness, Young's modulus, Tensile strength (Ts), and elongation. The antibacterial activity of the nanocomposites against fungus and bacteria was studied. Additionally, PVA/NaAlg-ZnMn2O4 nanocomposites films had good antibacterial characteristics against environmental microorganisms such as Gram-positive (G+) S. aureus and Gram-negative(G−) E. coli bacteria as well as fungi C. albicans and A. niger. It was observed that the biodegradability of the nanocomposite films was lower compared to the pure PVA/NaAlg film. Compared to pure film, the water solubility was decreased upon the addition of ZnMn2O4 NPs. After ZnMn2O4 was added to the pure blend, the WVTR decreased. The produced polymer nanocomposites films appear to be a promising material for food packing, according to these results.

The incorporation of cobalt ions into hydroxyapatite nanostructure for a novel range of electrochemical energy storage applications

Supercapacitors (SCs) have garnered extensive attention for their notable advantages, including extended cycle life, high energy density, and cost-effectiveness. Due to their large energy storage capacity and high output power, the development of pseudocapacitive materials for energy-oriented applications has been of great importance. The integration of nanoscale active materials in batteries results in faster redox kinetics. Consequently, alters the material's electrochemical characteristics from battery-like to pseudocapacitive-like behavior driven by enhanced surface area and reduced diffusion routes. This study aims to investigate the efficacy of pure hydroxyapatite and Co2+-doped hydroxyapatite (HAP) nanoparticles as electrode materials for SCs. The pure HAP and Co2+-doped HAP nanoparticles were synthesized via the Sol-Gel method. Electrochemical techniques such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were utilized to investigate the electrochemical behavior of the developed electrode. The highest values of specific capacitance (Csp) and energy density for the SC with Co2+-doped HAP nanoparticles electrode were obtained at 324 F g−1 and 145.8 Wh kg−1, respectively, at a current density of 1.2 A g−1. According to the data above, Co2+-doped HAP nanoparticles can be used as a substitute to improve electrochemical performance in energy storage applications.

Facile sol–gel synthesis process and electrochemical performance of MgNiO2 act as an electrode for supercapacitor

Abstract In this work, MgNiO2 material is prepared by a facile sol–gel method as an electrode material for supercapacitor application. The prepared MgNiO2 material is characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and elemental analysis (EDS). The electronics conductivity is 1.9 × 10−4 S cm−1. The electrochemical performance of the prepared MgNiO2 material was examined in an aqueous electrolyte of 1 M KOH. The electrochemical reaction of the prepared MgNiO2 material shows the EDLC behaviour from the shapes of the CV curves. The prepared MgNiO2 nanomaterial revealed good electrochemical performance with a maximum specific capacitance of 78 F/g at a rate of current density of 0.1 A/g. The above result delivered a simple, low cost and high-performance approach for a supercapacitor application.

Facile synthesis of nanoscale CuO and NiO via the PVA-assisted sol-gel method and their exploration in the catalytic epoxidation of styrene

The full-text of the article will be published in the English version of the journal "Catalysis in Industry" No. 4, 2024.Both nanoscale copper oxide and nickel oxides, with diameter 17 and 25 nm respectively, have been synthesized via an easy sol-gel method using polyvinyl alcohol. The method involves the simple dispersion of metal ions (M2+ = Cu or Ni) into the PVA gel and subsequent calcination of the dried gel at 400 °C for 3 h. The synthesized oxide materials are characterized by different physical tools like TGA, powder XRD, SEM, TEM and DRS UV-visible spectroscopic technique. The oxides are found to be very efficient catalysts in the epoxidation of styrene. CuO gives 87 % styrene conversion and 88 % SO selectivity while, NiO gives 69 % styrene conversion and 80 % with TBHP as an oxidant at the end of 6 h. Both the catalysts can suitably be reused for several successive runs without appreciable loss in activity and selectivity. The cost-effective synthesis, excellent catalytic performance and reusability make these oxides promising catalysts for the industrial use.

Changes in microstructure, magnetocaloric effect and critical behavior of La0.8Sr0.2MnO3 manganites by K/Co doping

We prepared La0.8-xKxSr0.2Mn0.95Co0.05O3 (0 ⩽ x ⩽ 0.1) (LKSMCO) through the modified sol-gel method (S-G) and its structure. Then, the magnetic, magnetocaloric, and critical behavior were analyzed. LKSMCO was confirmed to be the rhombohedral structure within the R-3c space group (No.167) using transmission electron microscopy and X-ray diffraction. For validating the chemical composition of LKSMCO, X-ray photoelectron spectroscopy and EDS were applied, showing that K+ was successfully doped. Phase transition of LKSMCO from paramagnetic to ferromagnetic phase near Curie temperature (Tc) was confirmed with a Magnetic Property Measurement System (MPMS). Using normalization and Banerjee's criterion, LKSMCO was demonstrated to be the second-order magnetic phase transition (SOMPT). As shown from the applied magnetic field, the maximal magnetic entropy (−ΔSMmax) of LKSMCO near Tc was 3.87 J/(kg K) (x= 0.00), 4.28 J/(kg K) (x= 0.05) and 4.44 J/(kg K) (x= 0.10). We employed the Kouvel-Fisher approach (KF) and modified Arrott plots to confirm the values of γ, δ, and β. This indicates that critical exponents of LKSMCO were consistent with the Mean-filed model.

Construction of TiO2-ZrO2 composite nanofiltration membranes for efficient selective separation of dyes and salts

The ceramic nanofiltration (NF) membrane exhibits excellent potential for textile wastewater treatment due to its efficient selective separation of dyes and salts. In this study, a high-performance TiO2-ZrO2 composite nanofiltration membrane was fabricated via a sol–gel method. Stable sols with an average particle size of approximately 2 nm were obtained. The addition of TiO2 effectively inhibits the phase transformation of ZrO2 during heat treatment, thus improving the integrity and ensuring separation accuracy of the membrane. Moreover, an optimal balance between membrane integrity and thickness was achieved, promoting efficient selectivity towards dyes and salts. The optimized NF membrane exhibited a MWCO of 1 kDa, a membrane thickness of 100 nm, and pure water permeance of 44 L∙m−2∙h−1∙bar−1. Additionally, the NF membrane demonstrated exceptional performance in dye/salt separation as evidenced by rejection rates exceeding 97.71% for Reactive Blue 19 while maintaining rejections below 5% for NaCl/Na2SO4 solutions. A stable permeance of 21.65 L∙m−2∙h−1∙bar−1 was achieved during the separation process. In conclusion, this study presents a high-performance ceramic NF membrane which exhibits significant potential for treating dye/salt containing wastewater.

Preparation and properties of an organosilicon-modified coating to protect combustible cartridge cases

To improve the environmental adaptability and mechanical properties of combustible cartridge cases (CCCs), a novel organosilicon-modified coating was proposed to increase heat resistance, water resistance, salt resistance, and mechanical properties. Herein, four organosilicon-modified coatings were prepared using the sol-gel method with an alkaline silica sol, methyltrimethoxysilane, and diphenyldimethoxysilane. Fourier-transform infrared spectroscopy confirmed the synthesis of the organosilicon resins, which possessed cross-linked semi-inorganic polymers with Si-O-Si main chains and various grafted organic functional groups. The optimal sample retained its heat resistance at 230 ℃ for 168.4 s, which was significantly longer than the previous resin-centric composite layer result of 108.8 s. Moreover, after the sample was immersed in water for 120 h, it only absorbed 1.98 wt% water, and 5.78 wt% saltwater after 3 days, and the water contact angle (WCA) reached 101º. Furthermore, the elongation-at-break reached 29.22%, which was significantly higher than the 3.69% of the CCC control sample. Therefore, the organosilicon-modified coating may protect CCCs during industrial fabrication processes, which can significantly improve the overall performance of CCCs.