Journal of Sol-Gel Science and Technology最新文献

This work reports a novel method for enhancing solar energy applications by synthesizing high-performance nanostructured PPy@AF hydrogel as photocatalyst under controlled conditions. The incorporation of acid fuchsin (AF) as a dopant into polypyrrole (PPy) imparts unique supramolecular properties to the hydrogels, enabling efficient chemical transformations, including C-H bond activation. The incorporation of AF as a dopant into PPy imparts unique supramolecular properties to the hydrogels, enabling efficient chemical transformations, including C-H bond activation. These dopant-enhanced hydrogel frameworks exhibit superior catalytic efficiency, offering a sustainable and eco-friendly solution for energy conversion processes. The study highlights the synergistic impact of dopant inclusion in enhancing the stability, selectivity, and reaction kinetics of the hydrogels. This innovation has the potential to contribute to the development of advanced materials in solar energy systems, where efficient catalytic reactions are essential. Overall, the findings support the advancement of high-performance, dopant-modified nanostructured hydrogels with promising applications in renewable energy and green chemistry.

Over the past few decades, the issue of toxic and reactive gases has been of concern for environmental safety and human health, which in turn has led to ongoing developments in gas detection technology. Spinel ferrites are well known as suitable candidates for gas sensing. This study examines Zn_xCu_0.2-xMn_0.8Fe₂O₄ (x = 0.0 to 0.2) nanoparticles, including their synthesis by sol-gel processing, characterization, and gas-sensing properties, as a sensor for nitrogen dioxide (NO₂). The formation of a cubic spinel structure was confirmed by X-ray diffraction analysis, with the crystallite size decreasing from 73 nm to 67 nm with increasing zinc content. Field emission scanning electron microscopy revealed a decrease in particle size with increasing Zn content, which contributed to increased surface area and porosity. The presence of distinct absorption bands in the Fourier transform infrared spectra at 597–613 cm⁻¹ and 389–401 cm⁻¹ was attributed to metal-oxygen vibrations in the spinel configuration. The gas response of Zn_xCu_0.2-xMn_0.8Fe₂O₄ nanoparticles exhibited improved sensitivity due to increased surface area as the crystallite size decreased, and the sensors exhibited a strong response towards NO₂ in gas sensing tests. The best performance was observed with Zn_0.2Mn_0.8Fe₂O₄, exhibiting higher sensitivity and shorter response time. These results suggest that Zn_xCu_0.2-xMn_0.8Fe₂O₄ ferrites are viable candidates for high-performance NO₂ gas sensors, with implications for understanding gas-sensing behavior associated with tuning composition and structural properties.

Organic-inorganic hybrid sol-gel coatings are effective and environmentally friendly alternatives to chromium(VI) pretreatment for aluminum alloys. The advantage of preparing coatings via the sol-gel method is that it allows obtaining coatings with optimized properties by varying synthesis parameters. In this work, a γ-GPS-ZrO₂ hybrid sol for surface pretreatment of AA2024-T3 was prepared by mixing pre-synthesized nano-zirconia (ZrO₂) sol into hydrolyzed γ-glycidyl etheroxypropyltrimethoxysilane (γ-GPS). Sol-gels with Si-Zr molar ratios of 2, 3, and 4 were applied to the aluminum alloy surface by coating and cured in an oven at 70 °C to form films. Electrochemical impedance spectroscopy (EIS) was used to evaluate the corrosion behavior of the sol-gel coatings on the aluminum alloy surface in 0.5 M NaCl solution. The morphology and chemical structure of the prepared hybrid coatings were analyzed by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Results show that increasing the Zr-Si molar ratio enhances the crosslinked inorganic network in the sols, leading to increased initial coating resistance and corrosion resistance. However, this also reduces the connectivity of the organic network, enhancing coating hydrophilicity and promoting water-induced degradation, which negatively impacts corrosion resistance. In this study, balancing these opposing trends (corrosion resistance vs. hydrophilicity) was achieved at a Si-Zr molar ratio of 3, yielding coatings with optimal comprehensive performance.

Water pollution from industrial effluents remains a major global challenge and demands effective and eco-friendly treatment plans. In this work, we report for the first time the integration of micro–nanobubble (MNB) technology with a ternary PbFe₁₂O₁₉/g-C₃N₄/rGO (PGR) nanocomposite for photocatalytic dye degradation and antibacterial applications. The PGR nanocomposite was synthesized via a hydrothermal process and systematically characterized by XRD, SEM, Raman and FTIR analyses. The band gap of pristine PbFe₁₂O₁₉ (2.94 eV) was successfully tuned in the composite (2.40 eV). The PGR nanocomposite achieved rapid degradation of methyl orange (95%) and crystal violet (98%) following pseudo-first-order kinetics with rate constants of 0.024 and 0.022 min⁻¹ respectively. The unique synergy between rGO-mediated charge transfer, g-C₃N₄ sensitization and MNB-induced reactive oxygen species generation led to enhanced electron mobility, suppressed recombination and superior catalytic efficiency. Moreover, the composite exhibited strong antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa. This study introduces a novel micro–nanobubble driven photocatalytic platform, offering a promising and sustainable route for wastewater purification coupled with antibacterial functionality.

This work targets a clear structure–property link in BaMn_0.5Ti_0.5O₃ (BMTO) by correlating sol–gel–derived crystal chemistry with temperature-dependent dielectric and electrical responses. Phase-pure rhombohedral perovskite (R3c) was confirmed by Rietveld refinement, with nanoscale crystallites (≈45–47 nm) and dense microstructure (≈124 nm grains) evidenced by XRD/SEM; EDS verified near-stoichiometric composition. Dielectric spectra (1 kHz–1 MHz, 200–320 K) show strong frequency dispersion, ε′ decreases with frequency but increase systematically with temperature, consistent with Maxwell–Wagner interfacial polarization and thermally activated hopping. AC conductivity follows Jonscher’s power law and rises with temperature, indicating small-polaron hopping and overall negative temperature coefficient of resistance behavior. Impedance and modulus analyses reveal non-Debye relaxation dominated by grain-boundary processes; Nyquist plots are well described by an R_s–(R_gb||CPE) equivalent circuit, with grain-boundary resistance falling from ~255 Ω (200 K) to ~55 Ω (320 K) and the relaxation frequency shifting from ~3 kHz to ~30 kHz as temperature increases, while the CPE exponent approaches unity (0.86 → 0.93), indicating more ideal capacitive behavior at higher temperatures. These results show that B-site Mn/Ti substitution and associated defect chemistry (octahedral tilts, oxygen-vacancy assisted hopping) govern polarization and transport. BMTO therefore offers thermally tunable dielectric response and semiconducting conduction desirable for capacitors, sensors, and other multifunctional electronic components.

In the last decades, alkoxide sol-gel chemistry provided an exceptional tool for the synthesis of nanostructured building blocks and designing application of novel materials. To keep up with the latest advancements in this field, a group of Argentine researchers established the Buenos Aires School of Materials Synthesis and Sol-Gel Processes, which has been held every 2 years at Buenos Aires—Argentina, since 2003. The course, aimed at young graduate students, postdoctoral researchers, and industry professionals, focuses on both the fundamentals and the newest developments of sol-gel processes. Also, during 40 h of laboratory-based work, they become immersed in the typical techniques and skills in sol-gel synthesis and materials characterization. These “hands-on” experimental sessions are the defining feature of this school as they explore key sol-gel related processes: hydrolysis and condensation kinetics, wet-lab synthetic approaches, and materials characterization techniques. In the work presented here, the students employ the well-known Stöber´s method for obtaining SiO₂ colloidal particles. Tetraethoxysilane hydrolysis and condensation kinetics are followed using a conductometer, and the time-dependent data obtained are interpreted using a simple consecutive reaction kinetics mechanism. Later, the students explore simple one-pot post-grafting colloidal surface chemical modifications, which are confirmed through infrared spectrometry and zeta-potential measurements. Carefully controlled additions of the alkoxide precursor allow for experimentation on increasing particle diameter, which can be readily confirmed using scanning electron microscopy. Moreover, encapsulation within the SiO₂ framework with cationic luminescent dyes as [Ru(bpy)₃]²⁺ results in photochemical hybrid platforms. In essence, this laboratory activity encompasses several sol-gel and colloidal chemistry concepts suited for an advanced chemical course on materials synthesis.

In the face of surging global energy demands and increasing environmental pollution, the development of efficient energy storage and conversion technologies has become critically important. In this study, a series of three-dimensional transition metal-doped Ni₉S₈/Co₉S₈ nanowire electrode materials were synthesized via a hydrothermal method, and their performance as supercapacitor electrodes and bifunctional electrocatalysts for water splitting was systematically investigated. The electronic structure and morphology of the materials were effectively modulated through doping with Cr, Ce, Fe, Mo, and W, leading to significantly enhanced electrochemical performance. Among them, the Cr–Ni₉S₈/Co₉S₈–0.04 electrode, with a Cr doping concentration of 0.04 mM, exhibited an areal specific capacitance of 1128 C cm^-2 at 1 mA cm^-2 and a gravimetric specific capacitance of 485 C g^-1 at 1 A g^-1. As an electrocatalyst, it delivered overpotentials of 227.6 mV for the oxygen evolution reaction (OER) and 117.4 mV for the hydrogen evolution reaction (HER) at 10 mA cm^-2. Further comparative analysis of the effects of different transition metal dopants revealed that Mo-Ni₉S₈/Co₉S₈-0.04 exhibited the best overall performance, with OER and HER overpotentials reaching 161.6 mV and 125.4 mV, respectively. Additionally, its gravimetric and areal specific capacitances reached 674.5 C g^-1 at 1 A g^-1 and 1834 C cm^-2 at 1 mA cm^-2. Moreover, the Cr-Ni₉S₈/Co₉S₈-0.04 electrocatalyst required only 1.42 V to drive a current density of 10 mA cm^-2 in overall water splitting, demonstrating excellent bifunctional catalytic activity. This study provides a novel strategy for synergistically modulating the electrochemical properties of sulfide composite materials through multi-element doping.

Graphical abstract

This paper reports the preparation of a series of three-dimensional transition metal-doped Ni₉S₈/Co₉S₈ nanowire electrode materials via a hydrothermal synthesis method, and systematically investigates their performance as bifunctional materials for supercapacitor electrodes and electrocatalytic water splitting.

In this study, AgFe₂O₄/ZnO composites were synthesized, characterized, and evaluated for their photocatalytic performance. XRD analysis confirmed the formation of crystalline ZnO, AgFe₂O_4, and AgFe₂O₄/ZnO composites, with calculated crystallite sizes of 7, 8, and 10 nm, respectively. SEM and TEM analyses showed a uniform particle distribution with minimal agglomeration and well-defined interfaces, indicating stable morphology and effective particle integration. EDS and XPS confirmed the homogeneous distribution of Zn, Fe, Ag, and O elements, supporting efficient charge transfer. PL analysis showed reduced emission intensity in the composite, suggesting suppressed electron-hole recombination and enhanced charge separation due to the heterojunction between AgFe₂O₄ and ZnO. Photocatalytic tests demonstrated that the AgFe₂O₄/ZnO composite achieved over 80% degradation efficiency for organic pollutants within 120 minutes, outperforming pure ZnO. Recyclability tests indicated that the composite retained over 97% of its efficiency after ten cycles, demonstrating long-term stability. The scavenger experiments identified •OH and •O₂^- radicals as the principal reactive oxygen species, confirming their central role in the photocatalytic degradation pathway. VSM analysis revealed weak ferromagnetism, enabling efficient magnetic separation and enhancing the material’s reusability in photocatalytic applications. The novelty of this work lies in the synthesis of AgFe₂O₄/ZnO heterojunction nanocomposites, which have not been previously reported in the literature. These materials exhibit enhanced charge separation and excellent stability for repeated photocatalytic applications. These findings suggest that AgFe₂O₄/ZnO composites are promising materials for sustainable wastewater treatment through photocatalytic degradation of organic pollutants.

As dangerous vectors, mosquitoes pose a serious risk to both human and animal populations worldwide by transmitting dangerous viruses into uninhabitable areas. Because of the emergence of insecticide resistance, controlling the use of synthetic pesticides is essential. S. diastaticus was used in this investigation for the actinobacterial-mediated biosynthesis of Se-NPs. The biosynthesized Se-NPs were characterized using a variety of techniques, including UV, XRD, FT-IR, SEM with EDX, TEM, DLS, and zeta potential. The biosynthesized Se-NPs were effective against C. quinquefasciatus, A. stephensi, and A. aegypti, with LC₅₀ values of 8.13 µg/mL, 9.36 µg/mL, and 13.71 µg/mL, respectively. The highest concentration of Se-NPs revealed high pupicidal activity and increased larval pupal duration against all three mosquito species. The effect of Se-NPs considerably increased the SOD and GPx levels but drastically decreased the AChE and GST level after 24 h of treatment. Histopathological analyses of the treated larvae revealed damaged epithelial cells, peritrophic membranes, and gut cells as compared to the control group. Additionally, A. salina showed low mortality. Conclusively, the biosynthesized Se-NPs using S. diastaticus were used as a potential biopesticide for controlling C. quinquefasciatus, A. stephensi, and A. aegypti.