Journal of Sol-Gel Science and Technology最新文献

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.

Graphical Abstract

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.

Graphical Abstract

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.

The removal of dyes and recovery of valuable metals from wastewater are critical environmental challenges. This study optimized the synthesis of Ag-photodeposited ZnO thin films for enhanced photocatalytic dye degradation and self-cleaning applications. ZnO thin films were synthesized using the sol-gel dip-coating method with precursor concentrations ranging from 0.3 to 1.2 M. XRD analysis revealed a c-axis preferential orientation with crystallite sizes increasing from 24 nm (0.3 M) to 35 nm (0.6 M). SEM images showed uniform surfaces at 0.6 M, while 1.2 M samples exhibited aggregation. Film thickness increased from 91 nm at 0.3 M to 660 nm at 1.2 M, with an associated decrease in optical band gap from 3.85 eV to 3.23 eV. Photocatalytic performance was evaluated by degrading methylene blue (MB) under sunlight. The ZnO film at 0.6 M achieved the highest MB degradation efficiency of ~99% after 4 h. Silver nitrate photodeposition further enhanced photocatalytic activity, with XRD confirming Ag₂O formation and SEM showing Ag₂O nanoparticles (9–15 nm) well-dispersed on ZnO surfaces. The Ag₂O/ZnO composite with 0.2 g/L AgNO₃ achieved 85% MB degradation in 3 h. Self-cleaning tests revealed increased hydrophobicity, with the contact angle rising from 63° (0.3 M) to 85° (1.2 M). This study demonstrates the novelty of combining sol-gel synthesis with photodeposition to produce ZnO-based photocatalysts with superior structural, morphological, and functional properties. These findings contribute to advanced materials development for wastewater treatment and self-cleaning applications.

Graphical Abstract

Water pollution from dyes, pesticides, and antibiotics poses a significant threat to living organisms, including humans and animals. There is an urgent need to develop efficient materials that are capable of degrading various organic pollutants. The main focus of this investigation was to synthesize iron oxide nanoparticles (Fe₃O₄ NPs) by utilizing the litchi fruit shell extract and assessing their photocatalytic potential in the degradation of malachite green dye and an oxaprozin antibiotic. Furthermore, the antibacterial potency of the material was tested against Streptococcus pyogenes (S. pyogenes), Staphylococcus aureus (S.aureus), and Escherichia coli (E.coli) bacteria. The FTIR spectrum of the material exhibits distinct peaks 514 and 584 cm⁻¹, which are associated with Fe-O stretching vibrations of the material. SEM analysis reveals that the average particle diameter was 45 nm. The material shows potent photocatalytic activity against malachite green dye, and oxaprozin 82% dye and 34% antibiotics being removed from the water sample under the conditions used. The material shows maximum antibacterial efficiency against the Staphylococcus aureus with a 19 mm zone of inhibition. The innovation of this approach lies in the use of the litchi fruit shell extract as a natural reducing and stabilizing agent, which enhances the stability and properties of the Fe₃O₄ nanoparticles. This plant-based strategy for developing Fe₃O₄ NPs directly contributes to the Sustainable Development Goals and circular economy principles.

Graphical Abstract

When conducting a university laboratory practice to introduce students to the world of nanomaterials and sol-gel synthesis, several important challenges arise. The primary ones lie in reconciling simplicity and resource efficiency with high educational value and the ability to perform a detailed analysis of the results. With this in mind, the study of SBA-15, a porous material based on SiO₂, with low toxicity and cheap precursors, emerges as a versatile platform. As such it allows: 1. evaluating the impact of the sol-gel synthesis variables on the final morphology, 2. obtaining its hybrid derivative by taking advantage of well-known silicon chemistry and the extensive available library of organosilanes, and 3. studying the notable properties of these materials, such as their high specific surface area, tailored surface modification and adsorption capacity of ions or molecules. This work describes the activities carried out for the synthesis, functionalization, and characterization of SBA-15 mesoporous silica within the framework of the experimental practice of an intensive course for PhD students at the South American Sol-Gel School. Emphasis is placed on the time-optimized synthesis protocol and the various possible morphological and chemical characterization approaches. Additionally, the physicochemical and adsorption properties of cationic species of environmental interest are characterized.

Ferroelectric relaxors have been extensively investigated for energy storage applications in pulsed-power electronics owing to their low remnant polarization. Herein, a lead-free Ba(Zr_0.3Ti_0.7)O₃ (BZT) ferroelectric relaxor thin film was synthesized by a sol-gel method for energy storage application. It was found that the annealing temperature has a profound effect on the microstructure and the energy storage performance of the BZT thin film. Increasing annealing temperature promotes the burn-out of the organic residues as well as the densification of the thin films. However, excessive abnormal grain growth occurs at high annealing temperatures and leads to a reduced breakdown strength. Consequently, an optimized energy storage density of 51.4 J/cm³ and energy storage efficiency of 73.4% are achieved in Ba(Zr_0.3Ti_0.7)O₃ thin film annealed at 850 °C with a thickness of 210 nm, which also shows high frequency stability (0.2–20 kHz), high temperature stability (25–140 °C) and long-term anti-fatigue stability up to 10⁷ switching cycles. These results provide guidance to improve the energy storage performance of ferroelectric relaxor film capacitors for applications in advanced high power electronics.