Search Results (231)

The hybrid inorganic–organic material concept plays a bold role in multifunctional materials, combining different features on one platform. Once varying properties coexist without cancelling each other on one matrix, a new type of supermaterial can be formed. This concept showed that silver nanoparticles can be embedded together with inorganic and organic surface coatings and silicon quantum dots for symbiotic antibacterial character and UV-excited visible light fluorescent features. Additionally, fluorosilane material can be coupled with this prepolymeric structure to add the hydrophobic feature, showing water contact angles around 120°, providing self-cleaning features. Optical properties of the components and the final material were investigated by UV-Vis spectroscopy and PL analysis. Atomic investigations and structural variations were detected by XPS, SEM, and EDX atomic mapping methods, correcting the atomic entities inside the coating. FT-IR tracked surface features, and statistical analysis of the quantum dots and nanoparticles was conducted. Multifunctional final materials showed antibacterial properties against E. coli and S. aureus, exhibiting self-cleaning features with high surface contact angles and visible light fluorescence due to the silicon quantum dot incorporation into the sol-gel-produced nanocomposite hybrid structure. Full article

Silica/alumina composite particles were synthesized via the sol–gel method to promote fine dispersion and homogenous mixing. Aluminum chloride hydroxide served as the alumina precursor, while amorphous silica, obtained from rice husk, was directly incorporated into the alumina sol. Following synthesis, the material was calcined at 1000 °C, yielding an α-cristobalite form of silica and corundum-phase alumina. These hybrid particles were introduced into polymer composites at reinforcement levels of 1 wt.%, 3 wt.%, and 5 wt.%. Mechanical behavior was evaluated through three-point bending tests, Shore D hardness measurements, and controlled-energy impact testing. Among the formulations, the 3 wt.% composite exhibited optimal performance, displaying the highest flexural modulus and strength, along with enhanced impact resistance. Hardness increased with rising particle content. Fractographic analysis revealed that the 3 wt.% loading produced a notably rougher fracture surface, correlating with improved energy absorption. In contrast, the 5 wt.% composite, although harder than the matrix and other composites, exhibited diminished toughness due to particle agglomeration. Full article

Experimental research in the field of science and technology of polymeric materials and their hybrid organic-inorganic systems has been and will continue to be based on the execution of tests to establish robust structure-morphology-property-processing correlations. Although absolutely necessary, these tests are often time-consuming and require specific efforts; sometimes, they must be repeated to achieve a certain reproducibility and reliability. In this context, the introduction of methods like the Design of Experiments (DoEs) has made it possible to drastically reduce the number of experimental tests required for a complete characterization of a material system. However, this does not seem enough. Indeed, further improvements are being observed thanks to the introduction of a very recent approach based on the use of artificial intelligence (AI) through the exploitation of a “machine learning (ML)” strategy: this way, it is possible to “teach” AI how to use literature data already available (and even incomplete) for material systems similar to the one being explored to predict key parameters of this latter, minimizing the error while maximizing the reliability. This work aims to provide an overview of the current, new (and up-to-date) use of AI/ML strategies in the field of sol-gel-derived hybrid materials. Full article

The interest in macromolecular alkoxysilyl-functionalized hybrids (self-assembling or nanostructured), which could be used as precursors in biomimetic silica precipitation and for the synthesis of hollow spherical silica particles, is growing. Nevertheless, reports on all-organosilicon systems for bioinspired silica precipitation are scarce. Therefore, a new kind of polyalkoxysilane macromonomer–linear polysilsesquioxane (LPSQ) of ladder-like backbone, functionalized in side chains with trimethoxysilyl groups (LPSQ-R-Si(OMe)₃), was designed following this approach. It was obtained by photoinitiated thiol-ene addition of 3-mercaptopropyltrimethoxysilane to the vinyl-functionalized polysilsesquioxane precursor, carried out in situ in tetraethoxysilane (TEOS). The mixture of LPSQ-R-Si(OMe)₃ and TEOS (co-monomers) was used in a sol–gel process conducted under acidic conditions (0.5 M HCl/NaCl) in the presence of Pluronic^® F-127 triblock copolymer as a template. LPSQ-R-Si(OMe)₃ played a key role for the formation of microparticles of a spherical shape that were formed under the applied conditions, while their size (as low as 3–4 µm) was controlled by the stirring rate. The hybrid materials were hydrophobic and showed good thermal and oxidative stability. Introduction of zinc acetate (Zn(OAc)₂) as an additive in the sol–gel process influenced the pH of the reaction medium, which resulted in structural reinforcement of the hybrid microparticles owing to more effective condensation of silanol groups and a relative increase of the content of SiO₂. The proposed method shows directions in designing the properties of hybrid materials and can be translated to other silicon–organic polymers and oligomers that could be used to produce hollow silica particles. The established role of various factors (macromonomer structure, pH, and stirring rate) allows for the modulation of particle morphology. Full article

Polyethersulfone (PES) membranes are essential in separation processes; however, their inherent hydrophobicity can limit their effectiveness in water-intensive applications. This study aims to enhance PES membranes by modifying them with a NiFe₂O₄–nanoclay composite nanoparticle to improve both their hydrophilicity and photocatalytic potential as a photocatalytic membrane. The nanoparticles were synthesized using the sol–gel auto-combustion method and incorporated into PES membranes through mixed-matrix embedding (1 wt% and 3 wt%) and surface coating. X-ray diffraction confirmed the cubic spinel structure of the composite nanoparticles, which followed the second order kinetic reaction during the photodegradation–adsorption of crystal violet. The mixed-matrix membranes displayed a remarkable 170% increase in water flux and a 25% improvement in mechanical strength, accompanied by a slight decrease in contact angle at 1 wt% of nanoparticle loading. In contrast, the surface-coated membranes demonstrated a significant reduction in contact angle to 18°, indicating a highly hydrophilic surface and increased roughness. All membranes achieved high dye removal rates of 98–99%, but only the coated membrane system exhibited approximately 50% photocatalytic degradation, following mixed kinetics. These results highlight the critical importance of surface modification in advancing PES membranes, as it significantly reduces fouling and enhances water–material interaction qualities essential for future filtration and photocatalytic applications. Exploring hybrid strategies that combine both embedding and coating approaches may yield even greater synergies in membrane functionality. Full article

Magnetic zeolite nanocomposites (NCs) have emerged as a promising class of hybrid materials that combine the high surface area, porosity, and ion exchange capacity of zeolites with the magnetic properties of nanoparticles (NPs), particularly iron oxide-based nanomaterials. This review provides a comprehensive overview of the synthesis, characterization, and diverse applications of magnetic zeolite NCs. We begin by introducing the fundamental properties of zeolites and magnetic nanoparticles (MNPs), highlighting their synergistic integration into multifunctional composites. The structural features of various zeolite frameworks and their influence on composite performance are discussed, along with different interaction modes between MNPs and zeolite matrices. The evolution of research on magnetic zeolite NCs is traced chronologically from its early stages in the 1990s to current advancements. Synthesis methods such as co-precipitation, sol–gel, hydrothermal, microwave-assisted, and sonochemical approaches are systematically compared, emphasizing their advantages and limitations. Key characterization techniques—including X-Ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning and Transmission Electron Microscopy (SEM, TEM), Thermogravimetric Analysis (TGA), Nitrogen Adsorption/Desorption (BET analysis), Vibrating Sample Magnetometry (VSM), Zeta potential analysis, Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), and X-Ray Photoelectron Spectroscopy (XPS)—are described, with attention to the specific insights they provide into the physicochemical, magnetic, and structural properties of the NCs. Finally, the review explores current and potential applications of these materials in environmental and biomedical fields, focusing on adsorption, catalysis, magnetic resonance imaging (MRI), drug delivery, ion exchange, and polymer modification. This article aims to provide a foundation for future research directions and inspire innovative applications of magnetic zeolite NCs. Full article

Combining the properties of organic and inorganic components with high surface areas and large pore volumes opens up countless possibilities for designing materials tailored to a wide range of advanced applications. As the majority of mesoporous hybrid materials are siliceous, the development of cost-effective synthetic approaches to produce water-stable hybrids with controlled porosity and functionality remains essential. Herein, we describe an original strategy for the synthesis of bridged mesoporous titania–bisphosphonate hybrids based on a one-step, template-free, non-hydrolytic sol–gel process. The reaction between Ti(OiPr)₄ and several flexible or rigid bisphosphonate esters, in the presence of acetic anhydride (Ac₂O) leads to the formation of TiO₂ anatase nanorods interconnected by fully condensed bisphosphonate groups. The general method that we depict is quantitative and low cost. All materials are mesoporous with very high specific surface areas (up to 520 m²·g⁻¹) and pore volumes (up to 0.93 cm³·g⁻¹). Full article

Low-temperature dried alginate/silica hybrid aerogel beads with a large specific surface area (160.8 m²/g), low density (0.160 m²/g), and high degree of sphericity were successfully fabricated. Single networks of silica aerogels beads were synthesized via by calcining hybrid aerogel beads in air. Moreover, alginate-derived carbon/silica aerogel beads were also obtained by the thermal treatment of the hybrid aerogel beads in nitrogen, which were indicative of the double networks of the as-synthesized crack-free hybrid aerogel beads for the first time. The adsorption performances of above aerogel beads were also investigated. Meanwhile, using a common silane coupling agent as a modifying agent, a series of hybrid aerogel beads with tunable functional surfaces were obtained. The results showed that the obtained samples adsorbed Pb²⁺ well, and the hybrid aerogel beads modified with KH-590 exhibited an experimental maximum adsorption capacity of Pb²⁺ of 193.73 mg·g⁻¹. Full article

Hybrid silane-based coatings were developed via the sol–gel process using two precursors, vinyltrimethoxysilane (VTMS) and tetraethoxysilane (TEOS), and subsequently deposited onto three titanium-based substrates: commercially pure titanium Grade 2, Ti6Al4V, and Ti13Nb13Zr. Comprehensive physicochemical characterization was performed, including microstructural (optical and SEM), topographical (3D roughness), spectroscopic (FTIR), and electrochemical (potentiodynamic) analyses. The coatings were continuous, transparent, smooth, and exhibited high gloss with no visible cracks or surface defects. Surface roughness (Sa ≈ 0.3 μm) was consistent across all samples and remained unaffected by both the VTMS to TEOS ratio and the substrate type. Coating thickness ranged from 8 to 15 μm, as confirmed by both digital microscopy and thickness gauge measurements. All coatings demonstrated strong adhesion to the substrates. FTIR analysis confirmed the presence of key functional groups, such as CH₂, C=C, C–H, Si–O–Si, Si–OH, Si–O–Ti, CH=CH₂, and O–Si–O, regardless of the substrate type. Electrochemical tests in Ringer’s solution showed excellent corrosion resistance, particularly for coatings with a VTMS to TEOS ratio of 1:1. Post-corrosion imaging confirmed the integrity of the coatings and their effectiveness as protective barriers in simulated physiological environments. These findings support the potential of VTMS/TEOS sol–gel coating as a surface modification strategy for biomedical titanium implants. Full article

3d transition metal oxides composed of Mn, Fe, Co, and Ni have emerged as promising candidates for supercapacitor electrode materials due to their high theoretical specific capacitance, abundant redox-active sites, variable oxidation states, environmental friendliness, and low cost. Various synthesis strategies have been developed to fabricate these nanostructures, including hydrothermal/solvothermal methods, sol–gel processing, and microwave-assisted synthesis. Among them, microwave irradiation technology, with its rapid heating characteristics and unique thermal/non-thermal effects, offers significant advantages in controlling crystallinity and particle size distribution, suppressing particle agglomeration, and enhancing material purity. Furthermore, microwave effects facilitate the self-assembly and morphological evolution of transition metal oxides, promote the formation of crystal defects, and strengthen interfacial interactions. These effects enable precise microstructural tuning, leading to an increased specific surface area and a higher density of active sites, ultimately enhancing specific capacitance, rate capability, and cycling stability. In recent years, microwave-assisted synthesis has made significant progress in constructing 3d transition metal oxides and their composites, particularly in the development of single-metal and binary-metal oxides, as well as their hybrids with carbon-based materials (e.g., graphene and carbon nanotubes) and other metal oxides. This review systematically summarizes the research progress on microwave-assisted techniques for 3d transition metal oxide-based nanomaterials, with a particular focus on the role of microwave effects in morphology control, interfacial optimization, and electrochemical performance enhancement. Additionally, key challenges in current research are critically analyzed, and potential optimization strategies are proposed. This review aims to provide new insights and perspectives for advancing microwave-assisted synthesis of 3d transition metal oxides in energy storage applications. Full article

Nitrophenols are persistent organic pollutants that pose serious environmental and health risks due to their toxic and lipophilic nature. Their persistence arises from strong aromatic stability and resistance to biodegradation, while their lipophilicity facilitates bioaccumulation, exacerbating ecological and human health concerns. To address this challenge, this study focuses on the synthesis and characterization of two different types of hybrid multi-core magnetic catalysts: (i) cobalt ferrite (Co-Fe₂O₄), which exhibits ferrimagnetic properties, and (ii) magnetite (Fe₃O₄), which demonstrates close superparamagnetic behavior and is coated with a novel and less hazardous phloroglucinol–glyoxal-derived resin. This approach aims to enhance catalytic efficiency while reducing the environmental impact, offering a sustainable solution for the degradation of nitrophenols in aqueous matrices. Transmission electron microscopy (TEM) images revealed the formation of a multi-core shell structure, with carbon layer sizes of 6.6 ± 0.7 nm for cobalt ferrite and 4.2 ± 0.2 nm for magnetite. The catalysts were designed to enhance the stability and performance in catalytic wet peroxide oxidation (CWPO) processes using sol–gel and solution combustion synthesis methods, respectively. In experiments of single-component degradation, the carbon-coated cobalt ferrite (CoFe@C) catalyst achieved 90% removal of 2-nitrophenol (2-NP) and 96% of 4-nitrophenol (4-NP), while carbon-coated magnetite (Fe₃O₄@C) demonstrated similar efficiency, with 86% removal of 2-NP and 94% of 4-NP. In the multi-component system, CoFe@C exhibited the highest catalytic activity, reaching 96% removal of 2-NP, 99% of 4-NP, and 91% decomposition of H₂O₂. No leaching of iron was detected in the coated catalysts, whereas the uncoated materials exhibited similar and significant leaching (CoFe: 5.66 mg/L, Fe₃O₄: 12 mg/L) in the single- and multi-component system. This study underscores the potential of hybrid magnetic catalysts for sustainable environmental remediation, demonstrating a dual-function mechanism that enhances catalytic activity and structural stability. Full article

Enhancing the photocatalytic efficiency of oxide materials under Vis light remains a significant challenge within the scientific community. Natural zeolite–metal oxide composites exhibit enhanced properties, especially due to the zeolite’s large active surface area, which facilitates the incorporation of metal oxide nanoparticles into its structure, thereby significantly increasing photocatalytic efficiency. The present study presents the synthesis of Na-zeolite-decorated black-TiO₂ by the impregnation method, in order to improve the structural characteristics to absorb into visible light. The experimental protocol involves two main steps: first, the synthesis of black-TiO₂ and white-TiO₂ nanocrystals using the sol-gel method, and second, the preparation of hybrid materials, consisting of Na-zeolite decorated with black-TiO₂ and white-TiO₂, through impregnation followed by thermal treatment. The morpho-structural and optical properties of the as-synthesized materials were investigated using XRD, SEM/EDX, FTIR, and DRUV-VIS analysis. The characterization results indicated that natural zeolite has a good thermal stabilization, the lamellar texture of natural zeolite and spherical form of anatase-TiO₂ materials being highlighted by SEM. In the case of Na-zeolite-decorated black-TiO₂, the adsorption edge is slightly shifted to the visible range, while Na-zeolite-decorated white-TiO₂ absorbs only in the ultraviolet region. The above results showed that these hybrid materials are adequate for application in photocatalytic processes. Full article

Hydrogels find widespread use in bioapplications for their ability to retain large amounts of water while maintaining structural integrity. In this article, we investigate hybrid hydrogels made of nanocellulose and either amino–polyethylenglycol or sodium alginates and we present two novel results: (1) the biocompatibility of the amino-containing hybrid gel synthesized using a simplified receipt does not require any intermediate synthetic step to functionalize either component and (2) the fluctuation in the second-order correlation function of a dynamic light scattering experiment provides relevant information about the characteristic internal dynamics of the materials across the entire sol–gel transition as well as quantitative information about the ion-specific gel formation. This novel approach offers significantly better temporal (tens of $\mathsf{\mu }$s) and spatial (tens of $\mathsf{\mu }$m) resolution than many other state-of-the-art techniques commonly used for such analyses (such as rheometry, SAXS, and NMR) and it might find widespread application in the characterization of nano- to microscale dynamics in soft materials. Full article

This work investigates nanostructured Ho_0.5Ca_0.5MnO₃, considered a model system of the Ln_0.5Ca_0.5MnO₃ series of manganites with perovskite structures featuring small lanthanide (Ln) ions half-substituted by Ca ions. Here, we propose a modified hybrid sol–gel–solid-state approach to produce multiple samples with a single batch, obtaining very high crystalline quality and ensuring the same chemical composition, with an average particle size in the range 39–135 nm modulated on-demand by a controlled calcination process. Our findings evidence that, provided the crystalline structure is preserved, the charge-ordering transition can be observed even at the nanoscale. Additionally, this research explores the presence of glassy phenomena, which are commonly seen in this class of materials, to enhance our understanding beyond simplistic qualitative observations. Comprehensive characterization using DC and AC magnetometry, along with relaxation and aging measurements, reveals that the complex dynamics typical of glassy phenomena emerge only at the nanoscale and are not visible in the bulk counterpart. Nevertheless, the analysis confirms that even the sample with the smallest nanoparticles cannot be intrinsically classified as canonical spin glass. Full article

A huge challenge is how to prepare flexible silicone aerogel materials with good flame retardancy, thermal stability, and hydrophobic properties. In this paper, resorcinol–formaldehyde was introduced into the silicone network composed of methyltrimethoxysilane (MTMS), phenyltriethoxysilane (PTES), and dimethyldimethoxysilane (DMDMS). Flexible hybrid aerogels with excellent thermal insulation, flame retardant, and hydrophobic properties were prepared by the sol–gel method and ambient pressure drying (APD), and the preparation process does not require long-term solvent exchange, only about 3 h of soaking and washing of the wet gel. The results show that the prepared phenolic-silicone aerogel has low density (0.093 g/cm³), low thermal conductivity (0.041 W/m·K), high flexibility, and compression fatigue resistance. The phenolic microspheres are bonded to the silicone skeleton to maintain the original flexibility. After 50% compression deformation, it returns to the original size normally, and there is no significant change in the stress of the sample after 50 compression cycles. Compared with pure silicone aerogels, the hybrid aerogels doped with phenolic have better char yield (65.28%) and higher decomposition temperature (609 °C). The hybrid aerogel sample has good flame-retardant properties, which can withstand alcohol lamp burning without being ignited. The micron-sized phenolic beads give the hybrid aerogels better hydrophobic properties, showing a higher static water contact angle (152°). The excellent thermal and mechanical properties mean that the hybrid aerogels prepared in this paper have good application prospects for aerospace, outdoor equipment, and other fields. Full article