Sol-gel Method Research Articles

Design of a new nanocomposite based on Keggin-type [ZnW12O40]6− anionic cluster anchored on NiZn2O4 ceramics as a promising material towards the electrocatalytic hydrogen storage

Extensive research efforts have been dedicated to developing electrode materials with high capacity to address the increasing complexities arising from the energy crisis. Herein, a new nanocomposite was synthesized via the sol–gel method by immobilizing K6ZnW12O40 within the surface of NiZn2O4. ZnW12O40@NiZn2O4 was characterized by FT-IR, UV–Vis, XRD, SEM, EDX, BET, and TGA-DTG methods. The electrochemical characteristics of the materials were examined using cyclic voltammogram (CV) and charge–discharge chronopotentiometry (CHP) techniques. Multiple factors affecting the hydrogen storage capacity, including current density (j), surface area of the copper foam, and the consequences of repeated cycles of hydrogen adsorption–desorption were evaluated. The initial cycle led to an impressive hydrogen discharge capability of 340 mAh/g, which subsequently increased to 900 mAh/g after 20 cycles with a current density of 2 mA in 6.0 M KOH medium. The surface area and the electrocatalytic characteristics of the nanoparticles contribute to facilitate the formation of electrons and provide good diffusion channels for the movement of electrolyte ions throughout the charge–discharge procedure.

Heterojunction T-ZIF-8/SnO2 Composite Photocatalysts by Sol–gel Method for CO2 Reduction

Heterojunction T-ZIF-8/SnO2 Composite Photocatalysts by Sol–gel Method for CO2 Reduction

Gd and Ni co-doped BiFeO3 ferrite/r-GO nanocomposite for photocatalytic environmental remediation applications

Synergistic effects of the co-doping of rare earth and transition metals on the structural, electrical and optical, in multi-ferroic BiFeO3 nanoferrites (NFs) combined with reduced graphene oxide (r-GO) nanosheets, photocatalytic degradation properties can be boosted. In this current study gadolinium and nickel-co-doped Bi1-xGdxFe1-yNiyO3 were synthesised via the tartaric acid-assisted sol-gel method and their composite Bi1-xGdxFe1-yNiyO3/r-GO with 10 % reduced graphene oxide (r-GO) via the ultra-sonication route. Phase and structural investigation were carried out using x-ray diffraction (P-XRD), Raman scattering, and Fourier transform infrared (FTIR) analysis, which confirms the successful fabrication of co-doping in the rhombohedral geometry of the perovskite-type Bi1-xGdxFe1-yNiyO3. Electrical conductivity of the fabricated composite material was observed to increase because of the co-doping and the addition of r-GO. Photoluminescence (PL) spectra of co-doped and r-GO composite material exhibited a decline in PL intensity because optical bandgap energies exhibited narrowing of 1.99 eV and 1.91 eV respectively, which indicates the excellent separation and stabilization of photo-excited charge pairs. Special conduction properties of r-GO nanosheets improved electrical and optical properties, a well-porous nature, large surface area, lower bandgap, and increased dye degradation in the Bi1-xGdxFe1-yNiyO3/r-GO photocatalyst showing excellent photo-degradation of cationic malachite green (M.G.) dye, achieving a degradation efficiency of 96.4 % under natural solar light. Hence, the photocatalyst shows excellent stability where quenching of radicals using selective scavengers shows that OH* radicals and e−/h+ pairs are primarily involved in the mechanism of photo-degradation in a basic pH medium, making the as-fabricated material a potential material for photo-catalytic environmental remediation.

Green Valorization of Waste Plastics to Graphene as an Upcycled Eco-Friendly Material for Advanced Gas Sensing

The valorization technique successfully transformed waste polyethylene terephthalate (PET) into valuable carbon nanomaterial (CN)/graphene, while doped and undoped ZnO nanopowders were synthesized via sol–gel methods. Utilizing XRD, BET, TEM, EDX, FTIR, and TGA analyses, the synthesis of sp2 2D sheet, pristine, and doped ZnO nanostructures was confirmed. Solid-state gas sensor devices, tested under 51% relative humidity (RH), 30 °C ambient temperature, and 0.2 flow rate, exhibited a 3.4% enhanced response to H2 gas compared to CO2 at 50 ppm concentrations over time. Notably, the ZnO/CN sensor surpassed CN and ZnO alone, attributed to CN dopant integration with decreasing order of response performance as ZnO/CN > CN > ZnO. This study underscores the efficacy of valorization techniques in generating high-value carbon nanomaterials and their efficacy in bolstering gas sensor performance, with ZnO/CN demonstrating superior response capabilities.

Enhanced DeNO(x) Performance of CZ-xS Catalyst Prepared by Sol–Gel Method

Enhanced DeNO(x) Performance of CZ-xS Catalyst Prepared by Sol–Gel Method

Performance of ammonia catalytic combustion over Cu-CeOx catalyst and the impact of oxygen concentration

Ammonia has long been regarded as a high-quality zero-carbon fuel; however, limitations in its combustion characteristics have restricted its practical applications. Catalytic combustion is considered an effective solution to overcome the challenges associated with ammonia combustion. In this study, we successfully synthesized a copper-cerium binary catalyst (Cu-CeOx) using the sol-gel method, demonstrating outstanding performance for NH3 catalytic combustion. Through in-situ DRIFTS results, we observed that the 15Cu-CeOx catalyst exhibits both i-SCR and -NH mechanisms. The oxygen concentration affects the N2 selectivity by modulating the overoxidation of NH3. Under high oxygen concentrations, high temperatures promote the excessive oxidation of NH3, and ammonia combustion through the i-SCR mechanism. Conversely, the oxygen concentration was equal to NH3 reaction stoichiometry, the overoxidation of NH3 is limited, and ammonia combustion proceeds through the NH mechanism, resulting in higher N2 selectivity.

Odontogenic and anti-inflammatory effects of magnesium-doped bioactive glass in vital pulp therapy.

This study aimed to investigate the effects of magnesium-doped bioactive glass (Mg-BG) on the mineralization, odontogenesis, and anti-inflammatory abilities of human dental pulp stem cells (hDPSCs). Mg-BG powders with different Mg concentrations were successfully synthesized via the sol-gel method and evaluated using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Apatite formation was observed on the surfaces of the materials after soaking in simulated body fluid. hDPSCs were cultured with Mg-BG powder extracts in vitro, and no evident cytotoxicity was observed. Mg-BG induced alkaline phosphatase (ALP) expression and mineralization of hDPSCs and upregulated the expression of odontogenic genes, including those encoding dentin sialophosphoprotein, dentin matrix protein 1, ALP, osteocalcin, and runt-related transcription factor 2. Moreover, secretion of inflammatory cytokines (interleukin [IL]-4, IL-6, IL-8, and tumor necrosis factor-alpha) was substantially suppressed by Mg-BG. Collectively, the results of this study suggest that Mg-BG has excellent in vitro bioactivity and is a potential material for vital pulp therapy for inflamed pulps.

A Light Emitting Device with TiO2:Er3+/ZnO Heterostructure for Enhanced Near-Infrared Electroluminescence

Abstract Near-infrared (NIR) electroluminescence (EL) devices based on Er3+ ions doped TiO2 emitting layer have been fabricated by employing a facile sol-gel method. The effect of Er3+ ion doping concentration on the EL performance of TiO2:Er3+ thin film devices was investigated. Moreover, a novel device with the core of TiO2:1%Er3+/ZnO heterostructure was designed and fabricated. The EL performance of the device with optimized Er3+ ion doping concentration and improved structure was significantly improved. The NIR EL-enabling voltage of the improved device is as low as ~5 V. The attenuated concentration quenching effect and the ZnO film as an electron blocking layer should contribute to the improved EL performance of the optimized device.

Utilizing banana peel in conjunction with TiO2 photocatalyst for the efficient decolorization of malachite green

Porous materials are frequently integrated into TiO2 photocatalysts due to their enhanced surface area and reaction efficiency. This study aimed to enhance the efficiency of wastewater treatment by developing a TiO2 combined with banana peel (BP) through the sol-gel method. The TiO2/BP composite was extensively analyzed using a range of methods, such as X-ray diffraction (XRD), field emission transmission electron microscopy (FESEM), energy dispersive X-ray (EDX) analysis, diffuse reflectance spectroscopy (DRS UV–vis), photoluminescence spectra (PL), and Brunauer–Emmett–Teller (BET) analysis. Subsequent evaluation of the photoactivity of the TiO2/BP composite compared to bare TiO2 particles revealed a noteworthy enhancement in decolorizing malachite green (MG) dye under visible light. Furthermore, recyclability testing further demonstrated consistent performance for up to four cycles, highlighting the potential application of this porous material-based photocatalytic composite in wastewater treatment.

Study on the preparation and anticorrosive performance of silica/modified kaolin/epoxy resin composite coating

Abstract A silica/aminated kaolin (SiO2@AK) composite was prepared by modifying kaolin and loading silica, using intercalation complex method and sol–gel method. Quantitative composites were dispersed in epoxy resin to obtain a silica/aminated kaolin/epoxy resin composite coating (SiO2@AK/EP) on stainless steel. The results showed that the thickness of the dry coating was approximately 110 ± 10 μm, and the surface was flat without evident agglomeration. As the SiO2@AK composite was introduced, the water contact angle increased from 40° to 88°, the average surface roughness of the prepared composite coating was reduced from 10.3 nm to 3.19 nm, and the corrosion current decreased by nearly three orders of magnitude. After the coating was soaked in 3.5 wt% NaCl solution for 30 days, the impedance modulus of the composite coating remained above 2.511 × 109 Ω cm2, reflecting that the introduction of the composite could effectively improve the anticorrosion property of the epoxy resin.

Sol-gel synthesis of Cobalt-Bismuth substituted strontium hexaferrites and insight into structural refinement, Microstructural, dielectric and spectroscopic properties

Bi and Co-substituted strontium (SrFe12O19) hexaferrites were synthesized using the auto-combustion sol–gel method. The structural, Rietveld refinement, microstructural, spectroscopic, and dielectric characterizations were analyzed with X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and Dielectric analysis, respectively. The XRD investigation of Sr1-xBixFe12-yCoyO19 with (x = 0–0.5, y = 0–1.0) confirmed the single phase of M−type hexagonal ferrites. The change in the value of lattice constant ‘a’ in between 5.87 and 5.95 and ‘c’ 22.07 to 23.81 to be noted. The crystallite size of prepared specimens was determined in (20–29) nm range. The specific stretching vibrations in the FTIR results approves (Fe/Co-O and Bi-O) at three different positions 437.59, 549.94, and 587.53 cm−1. The existence of these band from 437 to 588 cm−1 confirmed the hexagonal structure of these ferrites. The force constants at octahedral sites increased from 1.75 to 2.02 (Dyne cm−1) x 105 and shows insignificant behavior at tetrahedral sites in between (3.33–3.54) Dyne cm−1 x 105 with Bi-Co substitution. The first band 582 cm−1 (ʋ1), is due to the maximum restoring force and vibrations at the tetrahedral site. The second band at a lower wavenumber of ∼ 402 cm−1 (ʋ 2) is due to the vibrations at the octahedral site. The microstructure of all synthesized samples of M−type hexagonal ferrites confirmed using the SEM analysis. The dielectric measurements in 0 to 3 GHZ frequency was done and effect of Bi-Co has been observed. The dielectric constant of all specimens shows the increasing trend from 1.5 GHz to 2.5 GHz with the frequency of the applied AC field. A slight increase was observed in the AC conductivity of these ferrites with the increasing concentration of Bi and Co ions.

Optimization of electrical transport and magnetoresistance of La0.72Ca0.28-xPbxMnO3 ceramics by Pb2+ doping

Here, La0.72Ca0.28-xPbxMnO3 (LCPMO, 0 ≤ x ≤ 0.06) polycrystalline ceramics are prepared by the sol-gel method and the influence of Pb2+ doping on microstructure, chemical composition, and electrical transport properties of LCPMO ceramics is systematically investigated. The study was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy-Dispersive Spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and four-probe method. The four-probe test shows that all samples have MIT (metal-insulator transition) behavior, and the peak resistance gradually decreases with the increase of Pb2+ doping amount. With the increase of Pb2+ doping amount, the temperature coefficient of resistance (TCR) and magnetoresistance (MR) first increased and then decreased, the TCR increased from 24.6 % to 36.5 %·K−1, and the MR value increased from 47 % to 71.5 %, and both corresponded to high temperature direction. Referring to previous studies, higher TCR and MR values near room temperature are what researchers have been pursuing for a long time. it can be seen that the LCPMO ceramics prepared in this article can have good application prospects in infrared detection and magnetic storage.

Synthesis, characterization and LDA+U calculations of zinc oxide nanoparticles

Zinc oxide (ZnO) was prepared by the sol-gel method as thin films deposited using spray pyrolysis. The characterization of the synthesized ZnO has been carried out using x-ray diffraction (XRD), Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), and UV-Visible absorption spectroscopy. The experimental results revealed that the prepared ZnO has a wurtzite hexagonal structure with an average crystallite size of about 26.7 nm. High purity and flake-like structures were achieved as SEM and energy dispersive indicated. FTIR confirmed the prepared ZnO’s high purity as the Zn-O stretching peak was very intense. The optical parameters were comprehensively investigated, including absorption, reflection, extinction coefficient, refractive index, and optical energy gap. The wurtzite hexagonal structure of ZnO was optimized using the local-density approximation with the Hubbard correction method (LDA+U). Our experimental result for the energy gap is 3.28 (eV), which is in excellent agreement with the first principle calculations. We utilize the results from the LDA+U calculation along with our experimental outcomes to calculate the thickness of the thin film in UV-Vis spectroscopy.

Enhancing dry-out heat flux on nano-SiO2 porous surfaces

In this study, we investigated the heat transfer behavior of droplet evaporation on a heated surface. Hydrophilic surfaces were coated with SiO2 nanoparticles using the sol-gel method. The droplet evaporation process on the heated surface was captured using a high-speed camera. We found that there is a critical value of the liquid film thickness that leads to a higher heat flux at the end of the droplet evaporation process (dry-out). This critical value is known as the dry-out heat flux. The thickness of the liquid film only reached the thin-film region of the evaporation meniscus theory at the end of the evaporation, resulting in strong evaporation and high heat flux. In this study, we observed that the surface exhibited hydrophilic wettability due to the nano-SiO2 porous structure. The dry-out heat flux can be further improved by approximately 30 % at 90 °C on the heated surface. This improvement is attributed to the higher capillary force of the nano-SiO2 porous structure, which increases the interfacial area. Additionally, surfaces heated to the same temperature develop a thinner liquid film, thereby achieving a higher heat flux. This investigation provides guidelines for applications in printing, heat exchangers, and microfluidics.

Plastic deformation of dry fine-grained olivine aggregates under high pressures

Abstract This study investigates the effect of pressure on diffusion creep of dry San Carlos and synthetic (prepared by sol-gel method) olivine. We prepared dry (water content < 9 ppm wt) fine-grained (< 1 μm grain-size) olivine and deformed the samples (both San Carlos and solgel olivine in the same assembly) in the same sample assembly under high-pressure (P = 2.9–8.8 GPa) and modest temperatures (T = 980–1250 K) at a fixed strain-rate. Evolution of strength was studied using the radial X-ray diffraction from various diffraction planes. We found that San Carlos and sol-gel olivine show similar rheological behaviour (when normalized to the same grain-size). Stress estimated by the radial X-ray diffraction increases with time and initially shows similar values for all diffraction planes. In many cases, stress values start to depend on the diffraction planes in the later stage and time dependence becomes minor. The micro-structural observations show that grain-size increases during an experiment. The results are interpreted using a theory of radial X-ray diffraction and the theoretical models of diffusion and dislocation creep. We conclude that the initial stage of deformation is by diffusion creep, but deformation in the later stage is by dislocation creep. For dislocation creep, our results are in reasonable agreement with previous low temperature dislocation creep results after a correction of temperature effect. For diffusion creep, we obtain an activation volume of 7.0 ± 2.4 cm3/mol that is substantially smaller than the values reported on dislocation creep but agrees well with the results on grain-growth. By comparing the present results on dry olivine with the previous results on wet (water-saturated) olivine, we found that water enhances diffusion creep but only modestly in comparison to dislocation creep. The difference in the pressure and water content dependence between diffusion and dislocation creep has an important influence on the dominant deformation mechanisms of olivine in the upper mantle.

Mo-doping modulated cationic vacancy in Zn3V2O8 with enhanced electrochemical performance for lithium-ion batteries

Given diverse redox reactions and abundant raw materials, Zn3V2O8 with high specific capacity is considered as a potential anode material for lithium-ion batteries. Same as other transition metal oxides, Zn3V2O8 suffers from infertile conductivity, sluggish ion diffusion and fast capacity loss derived from volume expansion during discharge/charge process, further hindering its application. In this work, a novel Mo doped Zn3V2O8 (Zn3V2-xMo5x/6O8) anode material with cationic vacancy (V vacancy) has been designed through a facile sol-gel method. It is found that a small Mo-doping amount has nearly no influence on the crystal structure, morphology and element valence states of Zn3V2O8. Mo doped Zn3V2O8 samples possess smaller charge transfer resistance and higher lithium ion diffusion coefficient. The results of electrochemical performance illustrate that Mo doped Zn3V2O8 can deliver higher reversible specific capacities and better rate capability compared with Zn3V2O8, which can be ascribed to the introduction of V vacancy. In particular, when Mo-doping amount is set as 0.03, the obtained Zn3V1.97Mo0.025O8 exhibits a reversible capacity of 481.1 mAh g−1 after 600 cycles at 1 A g−1. It is believed that this work could provide an effective and feasible strategy to construct high performance transition metal vanadate anode materials for lithium-ion batteries.

Multifunctional Superamphiphobic Coating Based on Fluorinated TiO2 toward Effective Anti-Corrosion

The application of superamphiphobic coatings improves the surface’s ability to repel fluids, thereby greatly enhancing its various functions, including anti-fouling, anti-corrosion, anti-icing, anti-bacterial, and self-cleaning properties. This maximizes the material’s potential for industrial applications. This work utilized the agglomeration phenomenon exhibited by nano-spherical titanium dioxide (TiO2) particles to fabricate 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PFDTES) modified TiO2 (TiO2@fluoroPOS) fillers with low surface energy. This was achieved through the in-situ formation of protective armor on the surface of the agglomerates using the sol-gel method and fluorination modification. Polyvinylidene fluoride-tetrafluoropropylene (PVDF-HFP) and TiO2@fluoroPOS fillers were combined using a spraying technique to prepare P/TiO2@fluoroPOS coatings with superamphiphobicity. Relying on the abundance of papillae, micropores, and other tiny spaces on the surface, the coating can capture a stable air film and reject a variety of liquids. When the coatings were immersed in solutions of 2 mol/L HCl, NaCl, and NaOH for a duration of 12 h, they retained their exceptional superamphiphobic properties. Owing to the combined influence of the armor structure and the organic binder, the coating exhibited good liquid repellency during water jetting and sandpaper abrasion tests. Furthermore, the coating has shown exceptional efficacy in terms of its ability to be anti-icing, anti-waxing, and self-cleaning.

Unlocking the potential of iron-containing mesoporous bioactive glasses: Orchestrating osteogenic differentiation in bone marrow mesenchymal stem cells and osteoblasts

Iron (Fe) is a crucial element in the human body, playing a significant role in bone metabolism. The release of Fe ions at bone defect sites can promote bone regeneration. In this study, we synthesized Fe-containing mesoporous bioactive glasses (Fe-MBGs) in SiO2-CaO-Fe2O3 composition using a sol-gel method. Regardless of the amount of incorporated Fe2O3 (up to 5 mol%), the Fe-MBGs maintained a mesoporous structure, and the inclusion of Fe2O3 did not alter their amorphous characteristics. However, the presence of Fe2O3 led to a reduction in both pore volume and specific surface area of Fe-MBGs. Notably, Fe-MBGs demonstrated degradability in physiological fluids and could sustain release of Si, Fe, and Ca ions. Higher concentrations of incorporated Fe2O3 were found to reduce the degradation of Fe-MBGs. All Fe-MBGs exhibited favorable bioactivity, as evidenced by the rapid formation of hydroxyapatite when exposed to simulated body fluid. Fe-MBGs also demonstrated concentration-dependent effects on BMSCs and Saos-2 cells. Extracts of Fe-MBGs at 0.1 and 1 mg/mL exhibited non-cytotoxicity and promoted cell proliferation. Additionally, extracts of Fe-MBGs at 1 mg/mL significantly enhanced the alkaline phosphatase activity of BMSCs and Saos-2 cells, along with an upregulation of the expression of osteogenesis-related genes. These findings unlock the significant potential of Fe-MBGs as functional biomaterials for bone regeneration applications. The controlled release of Fe ions from these mesoporous bioactive glasses orchestrates osteogenic differentiation in bone marrow mesenchymal stem cells and osteoblasts.

Effect of Ga doping on the structural, optical, and electrical properties of ZnO nanopowders elaborated by sol-gel method

Nanostructured ZnO has received a considerable amount of interest, owing to its unique physical and chemical characteristics, as well as its remarkable performance in the fields of electronics, optics, and photonics. This work aims to study the influence of Ga dopant on the structural, optical, and electrical properties of ZnO nanopowders. Undoped and Ga-doped ZnO (GZO) nanopowders were successfully synthesised with the soft chemical sol-gel method. The solution was prepared using zinc acetate dihydrate and gallium (III) nitrate hydrate as precursors. The ethylene glycol is used as solvent. The X-ray diffractometer, scanning electronic microscope (SEM), UV–Vis, FTIR, and four-point probe method are used to analyse the properties of the synthesised powders. XRD and FTIR measurements show the growth of pure and Ga-doped ZnO crystals, which have a hexagonal wurtzite structure, and the average crystallite size varies from 9.09 nm to 24.8 nm. The nanospherical morphology of the nanopowders synthesised can be seen in the SEM images. The UV–visible spectroscopy shows that the optical gap energy increases with Ga concentration, from 3.59 eV to 3.67 eV. The I-V electrical measurements indicate that the breakdown voltage and the non-linear coefficient increase with Ga doping. This study will open the way for the investigation of a relationship between the electrical and nanostructural features of ZnO-based varistors for future device applications.

Effects on structure by spectroscopic investigations, valence state and morphology properties of FeCo-containing SnO2 catalysts for glycerol valorization to cyclic acetals

The effects on the structure, valence state and morphological properties of FeCo-containing SnO2 nanostructured solids were investigated. The physicochemical features were tuned by distinct synthesis routes e.g., sol–gel, coprecipitation and nanocasting, to apply them as catalysts in the glycerol valorization to cyclic acetals. Based on Mössbauer and XPS spectroscopy results, all nanosized FeCoSn solids have Fe-based phases, which contain Co and Sn included in the structure, and well-dispersed Fe3+ and Fe2+ surface active sites. Raman, FTIR and EPR spectroscopies measurements of the spent solids demonstrated structural stability for the sol–gel based solid, which is indeed responsible for the highest catalytic performance, among the nanocasted and coprecipitated counterparts. Morphological and elemental analyses illustrated distinct morphologies and composition on solid surface, depending on the synthesis route. The Fe/Co and Fe/Sn surface ratios are closely related to the catalytic performance. The improved glycerol conversion and selectivities of the solid obtained by sol–gel method was ascribed to the leaching resistance and the Sn action as a structural promoter.