Journal of Sol-Gel Science and Technology最新文献

This research presents an in depth study of the electrical and antibacterial activity of Co_xCu_1-xFe₂O₄ and their polymer nanocomposites. The citrate precursor auto-combustion method was successfully used to synthesize the nanostructured Co_xCu_1-xFe₂O₄. To investigate the impact of PEG on the physical characteristics, polymer-blended ferrite nanoparticles were produced using PEG-4000 as a capping agent. X-ray diffraction analysis of Co_xCu_1-xFe₂O₄ verified their cubic spinel structure, and Rietveld analysis was used to further refine the results using FULLPROF software. The lattice constant (a) increases, while the crystal size decreases by increasing Co²⁺ concentration. According to the measured elastic properties, PEG in PEG/Co_xCu_1-xFe₂O₄ nanocomposites made it softer and more durable. CuFe₂O₄ was found to have maximum conductivity and dielectric loss but lower dielectric permittivity. PEG enhances the dielectric permittivity of some Co_xCu_1-xFe₂O₄. The Nyquist plots were fitted by the ZSimpWin program, and the equivalent circuit demonstrates that the electrode, grain, and grain boundaries contributed to the polarization process. Co_xCu_1-xFe₂O₄ samples are suitable for high-frequency applications due to their low dielectric loss. Thermal conductivity tests reveal that CuFe₂O₄ has the highest value among the ferrite samples. The thermal conductivity of the composites exceeds that of pure ferrites. The nanoparticles and their composites exhibited antimicrobial activity against both gram-negative bacteria (E. coli) and gram-positive bacteria (Staph. Aureus). These intriguing findings suggest that these materials are excellent candidates for technological and therapeutic applications.

Reduced graphene oxide supported Y₂TiO₅ nanocomposite was synthesized via the sol-gel method and subsequently employed as a photocatalyst. Its crystal structure morphology, chemical composition, and optical properties were studied using XRD, FT-IR, SEM with EDAX, UV-DRS, TEM, BET, and XPS spectroscopy. The crystallite dimensions were determined using Scherer’s formula resulting in values of 26, 36, 47 and 69, nm respectively, for rGO, TiO₂, Y₂TiO_5, and rGO/Y₂TiO₅. The rGO exhibited a sheet-like structure, while in the rGO/Y₂TiO₅, Y₂TiO₅ was distributed over the surface of the rGO.The band gap values calculated from UV –DRS analysis were found to be 3.38, 2.17, 2.77 and 1.99 eV for rGO, TiO₂, Y₂TiO_5, and rGO/Y₂TiO₅, respectively. The photoactivity of the materials was investigated using methylene blue (MB) dye degradation in the presence of solar radiation. The findings revealed that under exposure to sunlight and UV light, the TiO₂, Y₂TiO_5, and rGO/Y₂TiO₅ photocatalysts resulted in the decomposition of up to 65, 85, 98 and 61, 75, 91% respectively, of the MB initially present. These results indicate that the synthesized materials have good photocatalytic and antibacterial activities, with potential applications in environmental remediation.

Harmful metal ions and persistent organic pollutants in textile wastewater create a significant environmental problem. This study explore the photocatalytic activity of Sol-Gel synthesized CuFeS₂ composites doped with varying concentrations of Zn (1, 5, and 10 mol%) for the degradation of harmful Cr(VI) ions under visible light irradiation. XRD results showed that CuFeS₂@Zn 10 mol% composites exhibited a smaller crystallite size (11 nm) than the pure CuFeS₂ sample (23 nm) and FTIR analysis indicates Zn²⁺ incorporation into the CuFeS₂ structure. FESEM analysis shows a transition from a platelet to an amorphous morphology upon Zn doping. Band gap energy decreased from 2.41 eV to 2.09 eV for CuFeS₂@Zn 10 mol% composites. XPS peak shifts in Cu 2p, Fe 2p, and S 2p spectra after Zn doping indicate successful incorporation of Zn into the CuFeS₂ structure. BET analysis revealed an increase in surface area from 49 m²/g for pure CuFeS₂ to 139 m²/g for CuFeS₂@Zn 10 mol%.The CuFeS₂@Zn 10 mol% catalyst facilitated the reduction of Cr₂O₇²⁻ to Cr³⁺ within 100 min with a rate constant of 3.041 min⁻¹. 6 mg of CuFeS₂@Zn 10 mol% catalyst (prepared at pH 6) degraded Cr(VI) completely within 60 min. The Zn doped CuFeS₂ catalysts generated a greater number of h⁺ and e⁻, promoting Cr(VI) reduction through enhanced light absorption, improved charge separation, and greater redox capability. This study offers important findings for the design and development of highly efficient photocatalysts for toxic metal ion wastewater remediation.

This work reports double network hydrogel/silica nanocomposites with increased mechanical toughness and strength compared to their soft polymer-only counterparts. Applications are in tissue repair, such as cartilage, soft robotics and motion sensing. Covalent coupling of the sol-gel silica nanoparticles and the gel is vital because the gel swells on contact with water. Here, coupling was achieved through vinyl functionalisation of the silica nanoparticles (VSNPs) that enabled cross-linking to the network using photopolymerisation. The double network gel was an interpenetrating network hydrogel (IPNG) with 2-acrylamido-2-methylpropane-sulfonic acid (AMPS) as the first network, and acrylamide (AAm) as the second network. The effect of vinyl silica nanoparticle size and loading concentration were investigated on swelling behaviour, microstructure, compressive properties and nanoparticle retention. Increased size and loading concentration of VSNPs allowed for tailorability of swelling properties; nanocomposite IPNGs swelled less (88%) compared to control gels (97%). The nanocomposite IPNGs, with 20Wt% VSNPs, exhibited a max compressive strength of 810 ± 80 kPa at a strain of 75 ± 6%, similar to the lower range of articular cartilage, and an order of magnitude higher strength than control gels (90 ± 20 kPa, at a strain of 40 ± 3). SEM images show VSNP-polymer integration, with nanoparticles within the mesh walls. The nanocomposite structure provides reinforcement and toughness to soft IPNGs, making them suitable candidates for soft material repair.

In this study, a n-Si based photodiode was fabricated to investigate the electrical role of a surface layer protein (SLp)-interlayer, which is a biomaterial, for the first time. The SLp material extracted from the Lpb. plantarum strain was analyzed and found to have a molecular mass of 54 kDa. The Raman spectrum of the SLp thin film showed the existence of specific secondary component vibration bands associated with β-sheet, α-helix, β-turns and antiparallel β-sheet. The Schottky photodiodes were constructed with and without an SLp-interlayer, named SID and RFD. The thickness of the interlayer is ~190 nm. The best RFD and SID diodes have n and ϕ_B of 1.75, 0.663 eV and 1.95, 0.737 eV, respectively. The rectification ratio is ~10 times greater for the SLp-interlayered photodiode. In the dark conditions, the SLp-interlayered photodiode has lower leakage current ( ~ 10⁻⁸A) and higher rectification ratio ( ~ 10⁴). Furthermore, the N_ss value decreased from 10¹⁵eV⁻¹cm⁻² to 10¹³eV⁻¹cm⁻² with shifting distribution from E_c-0.52 eV to E_c-0.64 eV. Photo-characterization was carried out under light having irradiance values ranging from 10 to 100 μW/cm² (629 nm, 515 nm, 456 nm). The SLp-interlayered photodiode has higher and stabile detectivity (2.67 × 10¹⁰ Jones), lower noise-equivalent power (0.495 pWHz^−0.5) and bistable switching (on/off ~1,5 × 10²) at on-position. The performance parameters revealed that the SLp-interlayered devices can be used for optoelectronic applications under low incident optical power (μW), especially for bio-electronic applications such as biosensors which are biologically compatible with the human body. This bio-hybrid approach opens a new pathway in optoelectronic device engineering by combining the molecular precision of biological systems with the robustness of semiconductor technology.

Y₂O₃: MgO (YMO) composite materials exhibit outstanding optical and thermal stability, and are widely used in optics, catalysis, ceramics and other fields. Attaining high-performance YMO materials hinges upon the use of high purity finely ground raw materials, precise component ratios, and uniform distribution. In this study, YMO composite nanoparticles with a volume ratio of 50:50 were synthesized using oxidizer (magnesium nitrate hexahydrate and yttrium nitrate hexahydrate) and fuel (citric acid). Optimizing the particle size and specific surface area of the nanoparticle was achieved by adjusting the oxidizer to fuel ratio (O/F) in the precursor (the molar ratio ranges from 0.18 to 0.33), and the optimal O/F was obtained. When the molar ratio is at 0.28, nanoparticles with particle size of 14 nm and specific surface area of 44 m²/g are synthesized. Furthermore, this study revealed that nanoparticles synthesized at different molar ratios of O/F produce different agglomeration degree after calcination at 800 °C, with the agglomeration factor (AF) gradually decreasing as the molar ratio of citric acid to nitrate increases; the results show that AF is at least 2.0 when O/F = 0.28.

Silica nanoparticles (SNP) are widely recognized as versatile carriers for drug delivery and theranostics due to their exceptional properties, including tuneable pore structures, high surface area, biocompatibility, and chemical stability. In this study, we synthesized and characterized three types of SNP with distinct morphologies and pore distributions: classical mesoporous silica nanoparticles (MSNP) and two wrinkle silica nanoparticles (WSNP) prepared using isopropanol (WSNP-ipa) or pentanol (WSNP-p) as co-solvents. The ability of these SNP to adsorb and encapsulate three different luminescent ruthenium(II) complexes, promising candidates in photodynamic therapy (PDT) for cancer, was systematically evaluated. Advanced characterization techniques, including transmission electron microscopy (TEM), FT-IR spectroscopy, dynamic light scattering (DLS), and N₂ adsorption/desorption analysis, highlighted the morphological, physico-chemical, and surface properties of the synthesized SNP. WSNP displayed hierarchical pore structures, larger pore volumes, and superior surface charge compared to MSNP, significantly enhancing their drug-loading capacity and encapsulation efficiency. Spectroscopic analyses confirmed that the ruthenium complexes retained their intrinsic optical properties upon encapsulation. These studies underscore the pivotal role of silica nanoparticle architecture in modulating drug-loading efficiency, stability, and photophysical behaviour of therapeutic agents. Furthermore, the encapsulation of ruthenium complexes within optimized WSNP offers a promising approach for advanced PDT applications, combining efficient drug delivery with enhanced luminescence for potential theranostic use.

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Photocatalysis has emerged as a promising solution to address wastewater-related environmental challenges, such as wastewater treatment. A major challenge in advancing photocatalytic technologies is improving the efficiency, stability, and reusability of photocatalytic materials. This study explores the novel potential of alginate hydrogel as a sustainable and versatile support for two different heterojunction photocatalysts, specifically graphitic carbon nitride (gC₃N₄) combined with CuO (CGCN) and ZnO (ZGCN). The innovation lies in the stabilization of these heterojunction photocatalysts within the alginate hydrogel using sol-gel processing, which not only enhances photocatalytic activity but also provides the photocatalysts with improved moisture retention and reusability. The newly developed ACGCN and AZGCN composites were investigated for the photocatalytic degradation of methylene blue (MB) dye, with a focus on their unique stability and efficiency in extended use. The alginate-based photocatalysts were characterized using instrumental techniques to investigate their physical, chemical, and structural properties. These studies confirmed the successful incorporation of CGCN and ZGCN into the alginate hydrogel, which exhibited characteristic features of photocatalysts. The photocatalytic activity, kinetics, trapping mechanisms, and overall performance of these alginate-based photocatalysts were explored, demonstrating significant potential for sustainable and efficient environmental remediation. The results underscore the novelty of alginate-based photocatalysts with tailored properties for long-term reusability and effective wastewater treatment, setting them apart from traditional photocatalytic systems.

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In this work, we synthesized barium calcium M-type hexaferrites (BaCaM) and examined the effect of Cu and Zr doping on its physical and chemical changes. The sol-gel auto-combustion method (SGACM) was employed for the preparation of Ba_0.8Ca_0.2Zr_xCu_xFe_12-2xO₁₉ (x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0). The phase purity and structural parameters of Ba_0.8Ca_0.2Zr_xCu_xFe_12-2xO₁₉ (BaCaZrCuM) were determined using the Rietveld refinement of XRD data. FESEM data revealed the microstructure of the grains and grain sizes. IR absorption bands around 400 cm⁻¹ and 800 cm⁻¹ confirm the presence of octahedral and tetrahedral Fe-O sites, respectively, in the samples. Bands in the Raman spectra broadened and decreased in intensity with increasing dopant concentration, consistent with the successful incorporation of dopants within the lattice structure. M-H plots revealed that the magnetization saturation value initially increased up to x = 0.4 (55.06 emu/g) and then decreased up to x = 1.0 (42.13 emu/g). The value of H_c decreased with increasing Cu and Zr concentration. The ε (dielectric constant) decreased with increasing frequency and decreased at low frequencies with increasing dopant concentration. Dielectric loss was also found to be reduced at higher frequency in the x = 0.4 sample, thus showing different behavior than other concentrations. These materials have potential applications in magnetic recording, permanent magnets and electromagnetic interference (EMI) shielding.