Sol-gel Synthesis Process Research Articles

Transition Metal-Doped Layered Iron Vanadate (FeV3-xMxO9.2.6H2O, M = Co, Mn, Ni, and Zn) for Enhanced Energy Storage Properties

With its distinctive multiple electrochemical reaction, iron vanadate (FeV3O9.2.6H2O) is considered as a promising electrode material for energy storage. However, it has a relatively low practical specific capacitance. Therefore, using the low temperature sol–gel synthesis process, transition metal doping was used to enhance the electrochemical performance of layered structured FeV3O9.2.6H2O (FVO). According to this study, FVO doped with transition metals with larger interlayer spacing exhibited superior electrochemical performance than undoped FVO. The Mn-doped FVO electrode showed the highest specific capacitance and retention of 143 Fg−1 and 87%, respectively, while the undoped FVO showed 78 Fg−1 and 54%.

Thermal, surface, and structure analysis of molybdenum substituted bioactive glass ceramics SiO2-CaO- MoO3-P2O5

This study explores the incorporation of molybdenum oxide (MoO3) as a dopant in SiO2-CaO-P2O5 (BGC) glass-ceramics through a meticulously designed sol-gel synthesis process to optimize properties for regenerative medicine applications. Comprehensive characterization techniques, including thermal analysis (TGA/DSC), Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), elucidate the morphological and structural modifications induced by MoO3 doping. Results reveal that MoO3 affects the glass transition temperature, crystallization behavior, and surface morphology, leading to enhanced glass stability, crystallinity, and surface properties. The mechanical properties, such as fracture toughness, also significantly improved with MoO3 doping due to the formation of crystalline phases and densification of the material structure. Notably, the doping of MoO3 promotes the formation of CaMoO4 crystalline phases and influences the synthesis of hydroxyapatite—critical for bone tissue regeneration—when immersed in simulated body fluid (SBF). The study highlights the hydrophilic nature of the doped samples, facilitating bone development and cell adhesion, while also showing that increased MoO3 content reduces the rate of hydroxyapatite formation and material degradability. These findings demonstrate that MoO3 doping via the sol-gel method offers a promising approach for tailoring BGC glass-ceramics' properties, making them more suitable for regenerative medicine applications. This research underscores the potential of MoO3 in advancing biomaterial development for tissue engineering and implantology.

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.

Exploring BiFeO3/Fe3O4 nanocomposite for possible application in magnetic hyperthermia

The development of perovskite/spinel nanocomposite BiFeO3/Fe3O4 (BFO/FO) holds particular interest for applications in magnetic hyperthermia therapy (MHT). This work offers a significant avenue for advancing material properties and evaluating the heating efficiency, considering the impact of structure, and magnetic characteristics within the perovskite/spinel system. A sol–gel synthesis process for phase-pure BiFeO3 production was successful, which is subsequently utilized with Fe3O4 to form a nanocomposite (BiFeO3)1−x/(Fe3O4)x. Our findings indicate that increasing the concentration of Fe3O4 in the nanocomposite enhances the saturation magnetization and the specific absorption rate (SAR). Importantly, the addition of BiFeO3 to Fe3O4 further enhances the nanocomposite's heating efficiency. This study underscores the potential of perovskite/spinel nanocomposites in realizing advanced materials with tailored properties and multifaceted functionalities.

Green synthesis of CoFe2O4 nanoparticles assisted with bio-waste (Gomutram): Sintering effect on the properties of structural, microstructural and vibrational bands

Synthesis of CoFe2O4 nanoparticles has been effectively accomplished by the cow-urine (Gomutram) as a chelating agent. The liberation of hazardous gases during the sol-gel synthesis process are minimized using cow-urine (Gomutram) as a chelating agent. The Energy Dispersive X-ray Spectrum offers insights on the current composition of ferrite by providing information on the stoichiometric ratio of its constituent elements. The X-ray diffraction patterns provide substantiation for the formation of the spinel phase of present ferrite system. The ferrite systems that underwent sintering at lower temperatures exhibited a more conspicuous amorphous morphology. The experimental lattice parameter (a) and average crystallite size (D) were found to be within the range of 8.0688–8.3779 Å and 3.7–9.4 nm respectively. Both a and D demonstrate an augmentation in magnitude due to the heat treatment procedure. The function of activation energy in the ripening of crystalline size during the sintering process is significant particularly in relation to grain boundary energy. The aggregation of nanoparticles into large clusters can be attributed to the strong magnetic interactions present among them. The inherent characteristics of scanning electron micrographs unambiguously demonstrate. The vibrational frequencies (υ1 and υ2) observed from Fourier Transform Infrared spectra confirm the spinel phase of the present ferrite system. The changes seen in vibrational frequencies do not offer empirical support for the association between annealing and the expansion of the lattice constant. But, offers an empirical support for the hypothetical redistribution of cations in the spinel structure.

Structural, electrical, magnetic, and anti-cancer properties of Gd-doped Mg–Cd ferrites

In this study, we report structural, electrical, magnetic, and anti-cancer properties of pure and Gd3+ ion-substituted Mg–Cd ferrites produced via a sol-gel auto-combustion synthesis process. The prepared Gd-doped and undoped Mg–Cd-based ferrite's physical properties were characterized by X-ray diffraction spectroscopy (XRD) to find structural properties, Brunauer–Emmett–Teller (BET) for surface area analysis, field emission scanning electron microscopy (FE-SEM) was used to understand morphological status and X-ray photoelectron spectroscopy (XPS) used for elemental confirmation. XRD reveals that 900 °C sintering temperature for 5 h gives us the purest form of cubic spinel structure. Fourier transform infrared spectroscopy (FTIR) suggests no changes in bonds while increasing the dopant. The study of temperature-dependent dielectric constants showed a significant peak in the dielectric constant at around 109 between 300 °C and 400 °C. Subsequently, the trend shifted towards a decreasing order. Surprisingly, the dielectric loss has yielded meager numbers. Magnetic characteristics were measured using a vibrating sample magnetometer (VSM); magnetic saturation increased as dopant concentration rose. This material is beneficial in high-frequency device applications, low-loss antennas, and radomes due to its dielectric and magnetic characteristics. The anti-cancer study suggests that it is more efficient at inhibiting cancer cells than normal cells. Also, the anti-microbial and anti-cancer characteristics suggest it can be useful in biomedical applications.

Synthesis of Magnesium Oxide Nanoparticles for Fabric Coating and its Antibacterial Activities

Conceptually, the present work leads to the synthesis of magnesium nanoparticles (MgO NPs) using pomegranate (Punica granatum L) rind extract for antibacterial fabric coating. The antibacterial performance of MgO NPs on cotton, polyester and blend wool types of fabric was evaluated towards three species of gram-positive bacteria; Staphylococcus epidermidis, Brevibacterium linens and Cutibacteriumacnes. Fourier transform infrared spectroscopy (FTIR) analysis confirmed the successful of sol-gel synthesis process with the presence of flavonoid compounds in MgO NPs solution. The breaking load test was run for all fabric samples, while for tearing strength test, it was carried out only for cotton and polyester fabrics. Air permeability test device was used to determine the air permeability of all fabric samples to ensure the ventilation of the fabrics after coating process. The MgO NPs produced from sol-gel synthesis method established a good antibacterial activity against gram-positive bacteria in all types of fabric samples.

Eu/Ni doping on the structure, magnetocaloric effect and critical behaviour of La0.65Sr0.35MnO3 ceramics

Magnetic refrigeration (MR) technology possesses the potential to substitute conventional gas compression technology. It is necessary to find MR materials suitable for a variety of applications. In this study, La0.65Sr0.35-xEuxMn0.95Ni0.05O3 (x = 0.05, 0.075, 0.10) (LSExMNO) ceramics were prepared using a sol-gel synthesis process. The LSExMNO ceramics were confirmed to be the R‾3c space group (rhombohedral structure) by X-ray diffraction (XRD) analysis. The particles of LSExMNO ceramic particles were irregular polyhedral particles by Scanning electron microscopy (SEM). The chemical composition of LSExMNO was determined by energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The Magnetic Property Measurement System (MPMS) demonstrated that the LSExMNO ceramics display second-order magnetic phase transitions (SOMPT) around Curie temperature (TC). When the Eu3+ doping level increased, the Mn–O–Mn bond angle and length increased, weakening the exchange coupling of the Mn4+-O2--Mn3+ channel and decreasing the TC. As the amount of Eu3+ doping varied, the maximum magnetic entropy (–ΔSMMax) of the LSExMNO ceramics peaked at 4.03 J kg−1K−1 and cooling efficiency parameter (RCP) = 291.2 J kg−1 at x = 0.075. The Modified Arrott plots (MAP) and Kouvel-Fisher (K–F) approaches were applied for the purpose of certifying the critical exponents of LSE0.075MNO ceramics conform to the Mean Filed model. Compared with other magnetic materials, it displays an excellent magnetocaloric effect (MCE) with a TC of 299 K.

Synthesis of layered double oxide with high specific surface area by innovative sol-gel method through its application to arsenate anion adsorption

Layered double oxides (LDO) are effective in removing toxic anions from aqueous solutions; however, related synthesis studies have not been thoroughly presented. In this study, we successfully established a new method for the sol-gel synthesis of LDO. This new synthesis method, in which organic chains are added in the sol-gel synthesis process, is simple and fast and improves the adsorption capacity. The specific surface area of the LDO synthesized by the sol-gel method was approximately 2.6 times larger than that of the LDO synthesized by the coprecipitation method. In addition, LDO synthesized by adding organic chains in the sol-gel synthesis process showed further improvement in specific surface area. A specific surface area value approximately 2.7 times higher than that of LDO synthesized by the coprecipitation method was obtained. The maximum adsorption amount calculated from the Langmuir equation for the arsenic adsorption on the LDO synthesized by the sol-gel method was 282.6 mg/g. It was confirmed that the adsorption capacity of LDO increased with an increase in the specific surface area, and LDO with an increased adsorption capacity were successfully synthesized using this method.

Optimization of the sol gel synthesis process parameters by orthogonal experiment of novel spinel oxide catalyst CuFe1.2Al0.8O4 with improved performance for methanol steam reforming

Optimization of the sol gel synthesis process parameters by orthogonal experiment of novel spinel oxide catalyst CuFe1.2Al0.8O4 with improved performance for methanol steam reforming

Ion transport through carbon nanotubes enable highly crystalline Na3V2(PO4)2F3 cathode for ultra-stable sodium-ion storage

Highly crystallized Na3V2(PO4)2F3 (NVPF) is desired for high-performance sodium-ion battery cathode material. However, the slow growth-rate induced by lack of multi-ion-transport pathway during sol-gel synthesis process makes it especially difficult to produce NVPF cathode with high crystallinity. Herein, we find that the presence of carbon nanotube (CNT) can significantly promote the ion transport during synthesis, which drastically increases the NVPF crystallinity. The CNT assisted synthetic route produces quality cathode material with high structural stability and electronic conductivity. As expected, the optimal NVPF cathode with trace CNT (0.1%) delivers favorable rate performance of 113.7 and 96.0 mAh g−1 at 1 and 20 C-rate, respectively, and impressive cycling stability up to 5000 cycles with a high-capacity retention of 77.3%. Furthermore, kilogram-scale produced NVPF@CNT cathode showed excellent adaptability in NVPF@CNT-1 || NaTi2(PO4)3 full-cell with high-rate capability and cycling stability. This work provides a practicable and simple strategy to fabricate highly crystallized electrode materials for commercial applications.

A comparative study of the mechanical properties of sol-gel derived hydroxyapatite produced from a novel mixture of two natural biowastes for biomedical applications

In this work, hydroxyapatite (HAp) was produced in a cost-effective and environmentally friendly manner from bovine and catfish bones. Carbonization and calcination were used to deproteinize the bones before converting the bones into HAp via the conventional thermal treatment process in a muffle furnace. The sol-gel synthesis process was used to ensure homogeneity of the powder mixtures after the thermal treatment. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and mechanical measurements were used to characterize the powders in terms of their phase composition, purity, crystallinity, mechanical properties, and wear rates. Also, the specific surface area and the volume of samples were calculated. Sample B25/C75 (HAp from bovine and catfish bones, respectively- 25/75%) had the highest hardness value of 0.54 GPa, while B50/C50 and B75/C25 had equal hardness values of 0.47 GPa. From the data obtained, the micro-hardness for all the samples is within the range reported for hard tissue engineering. The sample B50/C50, on the other hand, had the highest compressive strength of 1.75 MPa. The sample B50/C50 was observed to have a lower wear rate under dynamic loading, while B100 had the highest wear rate.

Evolution of the Structure and Magnetic Properties of the High-Tc Superconductor YBa2Cu3O6.92 in the Sol–Gel Synthesis Process

Evolution of the Structure and Magnetic Properties of the High-Tc Superconductor YBa2Cu3O6.92 in the Sol–Gel Synthesis Process

The Role of the Sol-Gel Synthesis Process in the Biomedical Field and Its Use to Enhance the Performance of Bioabsorbable Magnesium Implants

In the present day, the increment in life expectancy has led to the necessity of developing new biomaterials for the restoration or substitution of damaged organs that have lost their functionalities. Among all the research about biomaterials, this review paper aimed to expose the main possibilities that the sol-gel synthesis method can provide for the fabrication of materials with interest in the biomedical field, more specifically, when this synthesis method is used to improve the biological properties of different magnesium alloys used as biomaterials. The sol-gel method has been widely studied and used to generate ceramic materials for a wide range of purposes during the last fifty years. Focused on biomedical research, the sol-gel synthesis method allows the generation of different kinds of biomaterials with diverse morphologies and a high potential for the biocompatibility improvement of a wide range of materials commonly used in the biomedical field such as metallic implants, as well as for the generation of drug delivery systems or interesting biomaterials for new tissue engineering therapies.

Formation of Y3Fe5O12 matrix including ε-phase Fe2O3 with the giant coercive field via optimized sol–gel method

The effect of compression and heat treatment on the microstructural morphology and magnetic characteristics of the imperfectly crystallized yttrium–iron–garnet (Y3Fe5O12, YIG) matrix was observed by optimizing the sol–gel synthesis process. In particular, among the various temperatures when calcination was performed at 850 °C, we observed that an ε-phase Fe2O3 with a giant coercive field but low saturation magnetization was formed in the YIG matrix.

Modified sol-gel process for synthesis of molybdenum oxide-doped titanium dioxide

A modified sol-gel method was developed for the synthesis of pure and transition-metal-doped titanium dioxide. The process involves the hydrolysis of titanium tetraisopropoxide, which was used as a catalyst precursor, and molybdenum chloride, which was used as a doping agent. The shape and size of the final product were characterized by scanning electron microscopy, and the catalyst activity for the photocatalytic degradation of methylene blue in aqueous solutions was tested. The results indicate significant improvements in both the morphology and performance of the catalyst synthesized by the proposed method when compared to those obtained via the conventional approach using the same materials and quantities.•The main highlights of the proposed method are as follows.•Utilization of a double-jacketed cooling system to control and prevent temperature fluctuations during hydrolysis.•Ultrasonication during the reaction minimizes particle agglomeration during nanoparticle formation.•The use of two different alcohols and separation into two mixtures were experimentally demonstrated to delay gel formation, and hence, morphologically homogeneous catalyst nanoparticles were achieved.

N doping of TiO2 nanocrystal for efficient photodegradation of organic pollutants under ultraviolet and visible light irradiation

To decrease the band gap of TiO2 and enhance its photocatalytic performance, in this work, N-doped nanocrystalline TiO2 is synthesized successfully through a simple sol-gel synthesis process with dicyandiamide used as N source. The N-doped TiO2 photocatalysts have been characterized in detail by means of powder X-ray diffraction, Raman spectroscopy, infrared spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscope. The photocatalytic activities of N-doped TiO2 to different organic pollutants are significantly different. Using 2 × 10-5 mol/L methylene blue as the target pollutant, N-doped TiO2 can produced approximately 100% conversion within 40 min, the photocatalytic degradation ability of which is equal or superior to commercial or bare TiO2. The ameliorated photocatalytic activity of N-doped TiO2 photocatalysts is attributed to the appropriate crystallinity, good dispersibility, modified Zeta potential, and increased absorption.

Bioglass Ti coatings: Influence of thermal annealing on the evolution of calcium phosphate formation, phase and morphology

Bioglass films were prepared on Ti disks used for dental implants using very simple sol-gel synthesis and dip-coating process. The influence of annealing temperatures, 37 °C and 600 °C, on the surface morphology and chemical composition was investigated using SEM, AFM, DRIFT and XPS techniques. Biocompatible calcium phosphate phases were successfully formed when the disks were kept in contact with simulated biological fluid at three different immersion times: 7, 24 and 160 h. For the films annealed at 37 °C calcium phosphate was formed which was confirmed through the analysis of the intensity ratios of P-O, Ti-O-Ti and Si-O absorption bands in the DRIFT spectra. Ca/P and O/Ca surface atomic ratios obtained by XPS data indicated the formation of dibasic calcium phosphate dehydrate and dibasic calcium phosphate, revealing a coated material at low temperatures, 37 °C, promising for medical applications.

Fe3O4/bioactive glass nanostructure: a promising therapeutic platform for osteosarcoma treatment

An effective strategy of hyperthermia-chemotherapy-regeneration for bone-related cancer treatment is presented. For this purpose, a new approach of magnetic particles (MPs) encapsulated in bioactive glass (BG) structure, with anti-cancer activity, is evaluated. MPs are initially synthesized using a co-precipitation method and then embedded into BG structure through a sol–gel synthesis process. Results confirmed the formation of a crystalline and pure MP structure. MP-BG particles were found to be bioactive by forming a hydroxyapatite layer on their surface. The hyperthermia application of a MP-BG system was also studied. It was found that the particles reach a temperature of 42 °C in an alternating magnetic field. Doxorubicin (DOX), a widely used anticancer drug, was loaded in MP-BG. To enhance the loading efficiency, the BG was surface modified to create NH2 groups on the surface. The encapsulation and release of DOX was studied over 48 h. In vitro tests were performed using human osteosarcoma cell line (MG63). The results demonstrated the non-cytotoxic nature of MP and MP-BG tested at various concentrations. DOX release from MP-BG resulted in decreased MG63 viability. Also, fluorescence microscopy visualization confirmed the intracellular uptake of MP-BG particles and the release of DOX. These results indicate that our suggested strategy of combined hyperthermia-chemotherapy-regeneration using MP-BG structure represents a powerful approach in cancer treatment and tissue regeneration.

Improving the thermal stability and luminescent efficiency of (Ba,Sr)3SiO5:Eu2+ phosphors by structure, bandgap engineering and soft chemistry synthesis method

The quantum yield and thermal stability are significant properties for phosphors, determining the luminescence efficiency of the devices for indoor lighting, displays backlight and near-infrared (IR) sensor applications. It is well known that the large bandgap and Debye temperature (Structure rigidity) values are beneficial to high thermal resistance. Here, the crystal structure, luminescence, thermal quenching property, bandgap and structural rigidity of (Ba,Sr)3SiO5:Eu2+ were studied via Rietveld refinement, temperature-dependent photoluminescence spectra and first-principle calculations. The quantum yield and thermal stability of (Ba,Sr)3SiO5:Eu2+ were increased by ~17% and 14%, respectively, via the combination of structure and bandgap engineering. These properties were further optimized by sol-gel synthesis process, achieving 28% increase of emission intensity compared to the same composition synthesized by a solid-state method and only 5% loss of luminescence intensity at 150 °C. By adding the as-synthesized phosphors, the correlated color temperature and color rendering index of the LED device were lower and higher, respectively, indicating the potential value in practice.