Search Results (1,085)

This study investigates the influence of Lewis acids on a novel stratified (Co²⁺,Pd²⁺)₂SiO₄-Pd⁰ olivine catalyst for the Heck–Mizoroki coupling of iodobenzene and methyl acrylate. Comprehensive characterization (ICP-OES, Raman, P-XRD, XPS) confirms the successful synthesis of a material with surface-incorporated Pd²⁺ and bulk Pd⁰ nanoparticles within a Co₂SiO₄ matrix. The promoter-free system with triethylamine base achieved the highest initial rate of 3.92 × 10⁻⁷ mol.s⁻¹ with an average rate of 1.18 × 10⁻⁷ mol.s⁻¹, despite a 30 min induction period. However, ZnCl₂, the weakest acid, showed the most substrate activation and lowered the induction period to 10 min, while AlCl₃ also reduced the induction period to 20 min. FeCl₃ showed the poorest performance, attributed to redox-mediated site poisoning rather than hydrolysis. Selectivity over the catalyst was maintained at >99 mol% towards methyl cinnamate irrespective of the Lewis acid or base used. However, recycling of the catalyst led to a gradual decrease in selectivity toward methyl cinnamate from >99 mol% to ~94.6 mol% over three cycles, while conversion remained consistently high at >99 mol% across all cycles, indicating that the catalyst’s primary activity was largely preserved despite surface evolution toward side-product formation. Lewis acids were found to function primarily as surface modifiers and/or productive substrate activators, with stronger Lewis acids also targeting the olivine framework, as seen from the preferential leaching of Co relative to Pd. Full article

In this study, pure ZnO and Ho-doped ZnO powders (1 and 2 mol % Ho) were synthesized via hydrothermal and sol–gel methods and evaluated for their tribocatalytic activity toward the degradation of paracetamol, an emerging pharmaceutical contaminant in aquatic environments. Structural, morphological, and optical properties of the obtained materials were investigated by X-ray diffraction (XRD), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS), ultraviolet–visible (UV–Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. SEM observations revealed pronounced morphology differences between the synthesis routes, with hydrothermally prepared samples exhibiting well-defined rod-like structures. XPS and EPR analyses provided evidence for successful Ho modification of ZnO and the presence of defect-related electronic states associated with Ho doping. The tribocatalytic performance was examined in distilled, tap, and mineral water using friction rods with different geometries in order to assess the influence of synthesis route, Ho concentration, and water composition. Among all the investigated materials, hydrothermally synthesized ZnO doped with 2 mol % Ho exhibited the highest tribocatalytic activity, achieving 96.91% degradation of paracetamol at an initial concentration of 15 mg/L within 24 h. The enhanced performance was attributed to improved charge separation induced by Ho modification, combined with the favorable rod-like morphology of the particles. Higher degradation efficiencies were observed in distilled water compared to tap and mineral water, indicating the important role of dissolved ions during the tribocatalytic process. These findings demonstrate that the synthesis route, Ho doping, and water composition collectively govern the tribocatalytic performance of ZnO-based materials, highlighting their potential for water purification. Full article

Ion-imprinted polymers (IIPs) are advanced adsorbents featuring selective recognition cavities for targeted metal ion capture, offering a promising route to high-efficiency separation in extractive metallurgy. In the present work, the evolution, design principles, synthesis strategies, separation mechanisms, and practical applicability of IIPs for metal recovery from complex aqueous matrices are overviewed. Key material components, including functional monomers, crosslinkers, template ions, initiators, solvents, and support materials, are discussed in relation to adsorption capacity, selectivity, kinetics, stability, and recyclability. Major preparation routes, such as surface imprinting, bulk polymerization, in situ polymerization, and sol–gel methods, are critically compared to clarify their advantages and limitations. Recent applications for base metals, precious metals, and rare-earth elements demonstrate that IIPs can achieve high specificity and rapid equilibrium under optimized conditions. However, their translation from simulated solutions to real leachates remains constrained by interfering ions, organic contaminants, mass transfer resistance, incomplete template removal, and matrix complexity. Mitigation strategies, including sample pretreatment, improved polymer architecture, and hybrid supports, are therefore emphasized. Additionally, chemometric modelling, machine learning, or artificial intelligence-assisted design may be implemented to advance the prospects of IIPs in industry. Conclusively, IIPs represent a strong separation platform, yet industrial deployment requires robust validation with real feed streams and scalable regeneration protocols during column operation, as well as under chemically aggressive conditions at scale. Full article

Lithium-ion batteries (LIBs) are essential for current technological infrastructure, driving the development of portable electronics, electric vehicles or grid-scale energy storage. The performance and sustainability of LIBs are critically dependent on their anode materials. This comprehensive review analyzes the evolution and characteristics of key anode materials, highlighting the specific properties they confer to the final battery products. Beyond material properties, the synthesis methods employed for these materials, from conventional techniques (such as solid-state reactions, sol–gel, hydrothermal/solvothermal, co-precipitation, etc.) to innovative and greener approaches (like electrospinning and a novel induction furnace-oxidation hybrid method for complex oxides), are a crucial part in the development of sustainable materials. While these methods offer different advantages, the challenges in achieving optimal electrochemical performance, including issues related to material stability, capacity retention and scalability, remain significant for both research and manufacturing industries. Furthermore, a significant focus is placed on strategies for mitigating the environmental impact associated with anode material production, emphasizing the importance of unconventional and sustainable synthesis routes. Ultimately, the sustainable evolution of LIB technology to achieve future energy demands hinges on overcoming existing limitations. This necessitates integrated research combining advanced material modeling and design, scalable and environmentally conscious synthesis techniques and in-depth electrochemical characterization. Full article

The development of efficient visible-light-driven semiconductor photocatalysts is essential for scalable and sustainable green hydrogen production. Among ternary metal oxides, MV₂O₆ (M = Zn, Ni, Cu, Mn, Co, etc.) metavanadates have attracted considerable interest because of their narrow band gaps (~1.8–2.5 eV), strong visible-light absorption, and unique edge-sharing VO₆ octahedral framework that promotes charge separation. This review summarizes recent advances in the design, synthesis, and electronic engineering of MV₂O₆-based photocatalysts for solar water splitting. Since direct particulate overall water splitting has only been demonstrated for MnV₂O₆, whereas ZnV₂O₆, NiV₂O₆, and CuV₂O₆ have mainly been investigated as photoelectrodes, both particulate photocatalytic and photoelectrochemical (PEC) systems are critically examined. The review clearly distinguishes these two configurations, highlighting how PEC studies provide valuable insights into charge transport, interfacial processes, and reaction kinetics while recognizing the additional challenges associated with suspension-based photocatalysis. Fundamental crystal structures, electronic band alignments, and charge-transfer characteristics of MV₂O₆ compounds are discussed, followed by recent advances in synthesis strategies, including hydrothermal, sol–gel, and deep eutectic solvent (DES)-assisted methods, together with morphology and defect engineering. Particular attention is given to oxygen-vacancy formation and its influence on visible-light absorption and charge separation. Modification strategies, including elemental doping, cocatalyst loading, and the construction of Z-scheme and step-scheme (S-scheme) heterojunctions, are critically evaluated for improving photocatalytic efficiency. Finally, the review discusses the key challenges that limit practical applications, including unfavorable band-edge positions, rapid carrier recombination, sluggish surface reaction kinetics, photostability, and the need to establish composition–structure–activity relationships. Future perspectives emphasize rational materials design through advanced characterization, theoretical calculations, and scalable synthesis approaches to accelerate the development of efficient MV₂O₆ photocatalysts for solar-driven hydrogen production. Full article

Hollow glass microspheres, as demonstrated in recent studies, have shown significant importance in the field of composite materials and have emerged as transformative materials in biomedical applications. This is necessitated by their ability to provide a physicochemical gradient, a desirable tool for complex tissues and biological interfaces, through the spatiotemporal release of bioactive factors and nanophase ceramics. HGMs are structures with diameters ranging from 1 to 1000 µm that can be used as support for cell growth, either in the form of a scaffold or a drug delivery system. In this review, we describe the various methods for HGM fabrications, synthesis (e.g., flame spraying, sol-gel processes, spray drying, etc.), structural characterizations, and chemical and physical properties (e.g., densities ranging from 0.1 to 0.6 g/cm³ and compressive strength ranging from 10 MPa to 30 MPa for low and high densities, respectively), highlighting how these methods influence their drug delivery, tissue engineering, bone implants, and nanocarrier abilities. Furthermore, a comprehensive list of other materials and their various biomedical uses is reported. Some of the limitations of existing techniques and future investigations into how HGM can perform as a biomedical material are discussed. Full article

Metal oxide nanoparticles have been the subject of intense research interest because of their remarkable physicochemical properties, such as their high surface area, particle size tunability, outstanding chemical stability, optical activity, catalytic efficiency, and antimicrobial behavior. These properties make them very useful in environmental, biomedical, energy, sensing, agricultural and industrial applications. The chosen synthesis method is important in controlling the morphology, crystallinity, surface charge, band gap and overall performance of metal oxide nanoparticles. They have been prepared using various physical, chemical and biological means, such as sol–gel, co-precipitation, hydro/solvothermal, microwave-assisted, sonochemical, combustion and green synthesis. Of these, green synthesis is gaining more interest as it employs plant extracts, microorganisms, and other biological materials as reducing agents, stabilizing and capping agents that make the process more eco-friendly and cost-effective. Recent advancements in the synthesis and application of metal oxide nanoparticles are discussed. There is an emphasis on the major synthesis routes, the main factors that influence the formation of nanoparticles, the characterization techniques used, and the structure–property relationships uncovered. A special focus is given to the influence of synthesis parameters, such as the type of precursor and the pH, temperature, reaction time, solvents and capping agents, on the properties of nanoparticles. In addition, the uses of metal oxide nanoparticles in photocatalysis, wastewater treatment, antimicrobial activity, drug delivery, biosensing, energy storage, gas sensing, and agriculture are also included. Finally, present challenges, toxicity issues, the problems of large-scale production, and future research directions are discussed to support the practical and sustainable uses of metal oxide nanoparticles. Full article

The effect of drying, thermal decomposition, and sintering conditions during the sol–gel synthesis of BaTi₅O₁₁ nanocrystals was investigated to optimize levofloxacin (LEV) photodegradation. Sintering emerges as the dominant factor, and BaTi₅O₁₁ nanocrystals synthesized at 700 °C for 120 min exhibit the smallest grain size, highest specific surface area and abundant active sites, achieving 93.2% LEV degradation within 30 min under UV irradiation. In contrast, excessive sintering temperatures or time induce grain coarsening and size homogenization, which reduce surface area and active sites, thereby impairing photocatalytic performance. The optimized nanocrystals also efficiently degrade other antibiotic pollutants, including ciprofloxacin, norfloxacin, and tetracycline. Radical trapping experiments confirm that •OH is the primary reactive species. Photoluminescence and photoelectrochemical analyses reveal a competition between grain size variation and charge carrier dynamics; however, photocatalytic degradation underscores the dominant role of surface-active sites and specific surface area. Kelvin probe force microscopy (KPFM) further corroborates efficient charge separation, showing a cross-line contact potential difference (ΔV_CPD) of approximately 90 mV, indicative of facile hole migration to the crystal surface. Collectively, these findings elucidate the processing–microstructure–property relationships in BaTi₅O₁₁ nanocrystals and provide a robust basis for the rational design of high-performance photocatalytic systems for antibiotic pollutant remediation. Full article

This article reports on the synthesis and characterization of the properties of ceramic powders and aerogels of rare earths using the Sc₂O₃:Eu₂O₃ system synthesized through the sol–gel method, as well as on the toxicological effects of the cytokinesis-block micronucleus cytome assay (CBMC). A sol–gel variant using epoxide-assisted gelling and supercritical CO₂ drying was employed to produce the aerogels. In vitro CBMCs were employed to assess the genotoxic and cytotoxic effects of the materials’ dosages and inherent properties. The morphology of the powders and aerogels consisted of agglomerates of irregularly shaped particles. At the same time, structural analysis revealed crystal sizes of 16 and 10 nm, respectively, for the ceramic powders and aerogels, in which microplastic deformations were observed. The cubic crystalline structure of the Sc₂O₃:Eu₂O₃ system remained unchanged. However, applying CBMC and observing the genotoxic and cytotoxic effects of the nanoparticles revealed that the main genotoxic xenobiotic agent was the aerogel. The primary mode of cellular death was necrosis, suggesting that reactive oxygen species might have been involved in the genotoxic and cytotoxic damage. Full article

Silica–starch composites were synthesized via a modified sol–gel route and evaluated as low-cost, biodegradable adsorbents for the removal of organic dyes from aqueous solutions. The formation of mesoporous hybrid networks and structural reorganization of starch upon integration with the silica phase were confirmed. The physicochemical properties of the composites were examined using nitrogen adsorption–desorption analysis, SEM imaging, SAXS, and XRD, providing complementary insights into their porous structure, morphology, and structural organization. Adsorption performance and kinetics were evaluated through continuous UV–Vis spectroscopic monitoring of dye concentration during the sorption process. Adsorption studies using methylene blue demonstrated that dye uptake proceeds through a combination of electrostatic interactions, hydrogen bonding between dye molecules and hydroxyl-rich starch domains, and diffusion-driven retention within the mesoporous silica framework. The proposed materials offer significant advantages arising from their simple, inexpensive synthesis and fully biodegradable nature. These features position silica–starch composites as sustainable sorbents suitable for environmentally oriented water purification applications. Full article

Porous silicate scaffolds represent a promising class of grafting materials for hard tissue engineering due to their superior bioactivity, adjustable degradation rates, and ability to stimulate both osteogenesis and angiogenesis. In this work, scaffolds based on an akermanite-targeted (Ca₂MgSi₂O₇) starting composition, including copper-doped variants, were synthesized using sol–gel and combustion routes, followed by 3D printing to achieve porous architectures with controlled pore size and interconnectivity. The powders were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermal analysis to evaluate their morphology, composition, and crystalline phases. The scaffolds were further assessed in terms of bioactivity by immersion in simulated body fluid (SBF), antibacterial activity, and in vitro cellular response. The results confirmed that copper doping enhanced antibacterial properties, while maintaining favorable biological behavior. Comparative analysis revealed differences between the two synthesis methods, with sol–gel providing more homogeneous structures and combustion leading to highly porous morphologies. These findings highlight copper-doped silicate scaffolds as promising candidates for bone tissue regeneration, combining architectural integrity with biological functionality. Full article

This study investigates the synthesis–structure relationships governing sol–gel-derived nanostructured MgFe₂O₄ ferrite powders for high-temperature thermochemical energy conversion applications. The effects of key processing parameters, including propylene oxide (PO) concentration, gel aging time, calcination temperature, and calcination duration, were systematically examined to tune the phase composition, specific surface area (SSA), pore volume, crystallite size, and nanoparticle morphology of MgFe₂O₄. Increasing the PO concentration from 5 to 20 mL shortened the gelation time from 585 to 323 s and increased the SSA from 5.30 to 17.88 m²/g, while the pore volume increased from 0.0074 to 0.0210 cm³/g. In contrast, gel aging time between 24 and 120 h produced negligible changes in SSA, pore volume, and crystallite size, indicating that extended aging is not required for microstructural control. Calcination temperature strongly influenced the nanostructure: increasing the temperature from 600 to 1000 °C decreased SSA and pore volume while increasing crystallite size from 21.33 to 48.76 nm. Longer calcination times produced a similar but less pronounced effect, decreasing SSA from 18.83 to 14.89 m²/g and increasing crystallite size from 17.55 to 30.12 nm. Overall, phase-pure MgFe₂O₄ with favorable textural properties was obtained using 20 mL of PO, 24 h of aging, and calcination in the 700–800 °C range. Under the identified synthesis conditions, namely 20 mL of PO, 24 h of aging, and calcination in the range of 700–800 °C for 2 h, phase-pure MgFe₂O₄ nanoparticles with particle sizes of approximately 10–50 nm were obtained. These results establish a processing–microstructure framework for engineering MgFe₂O₄ nanomaterials with tunable textural properties for solar thermochemical redox cycles and related high-temperature energy applications. Full article

Nanostructured Co₃O₄ was synthesized via a sol–gel approach employing the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethylsulfonate ([EMIm]TfO) and subsequently evaluated as a high-performance anode material for lithium-ion batteries. Ionic liquids, distinguished by their low volatility, high thermal stability, and tunable chemical properties, represent a greener alternative to conventional organic solvents for the synthesis of functional nanomaterials. The electrochemical performance of the as-prepared material was systematically assessed through galvanostatic charge–discharge cycling, cyclic voltammetry, and rate capability tests. The Co₃O₄ electrode exhibited a high reversible capacity of approximately 1100 mAh g⁻¹ after 50 cycles at a current density of 200 mA g⁻¹, along with excellent coulombic efficiency approaching ~100% after the initial cycles. Furthermore, the material demonstrated strong rate capability, delivering about 600 mAh g⁻¹ at 1 C, and recovering its capacity upon returning to lower current densities. The improved electrochemical performance is primarily attributed to the nanoscale architecture induced by the ionic liquid-assisted synthesis, which facilitates rapid lithium-ion transport and effectively buffers volume variations during repeated cycling. Notably, the ionic liquid serves a dual function as both a green reaction medium and a structure-directing agent, enabling precise control over the material’s morphology and properties. This study demonstrates a versatile strategy for the rational design of potential transition-metal oxide anodes, paving the way for high-performance electrode materials. The findings contribute to the development of next-generation lithium-ion batteries tailored for clean and sustainable energy storage applications. Full article

Adsorption therapies in hemodialysis have emerged as an innovative approach for removing protein-bound uremic toxins (PBUTs). The present work focuses on the enhancement of the adsorption capacity of hemodialysis membranes through the incorporation of Metal–Organic Frameworks (MOFs). The removal capacity of PBUT p-cresyl sulfate by cellulose acetate (CA)/silica (SiO₂)/MOF mixed matrix membranes was investigated with two types of MOFs, UiO-66 which synthesis and characterization has been previously reported, and UiO-66-NH₂. The UiO-66-NH₂ MOFs were synthesized and characterized by infrared spectroscopy, X-ray diffraction, nitrogen adsorption–desorption equilibrium at −196 °C, and thermogravimetry analysis. Both mixed matrix membranes were synthesized by coupling the phase inversion technique with the sol–gel method and with casting solutions incorporating the MOF dispersions. The two membrane types of MOFs were characterized in terms of hydraulic permeability, molecular weight cut-off, and rejection coefficients to pCS and bovine serum albumin (BSA). The mixed matrix membranes CA/SiO₂/UiO-66-NH₂ exhibited lower permeability and molecular weight cut-off when compared to the CA/SiO₂/UiO-66 ones. In permeation tests simulating a hemodialysis session with a feed solution of 100 ppm pCS and 35 g/L BSA, it is shown the improved performance of MOFs membranes as the rejection coefficients of free pCS is 0.2% for the CA22/SiO₂/UiO-66 membrane with 1.5% of MOF and 2.6% for the CA22/SiO₂/UiO-66-NH₂ membrane with 2% of MOF. The capacity of these MOF membranes in removing pCS bound to BSA was addressed through the development of a new methodology to quantify the pCS free and bound to BSA. The CA22/SiO₂/UiO-66 membrane with 1.5% of MOF has a removal capacity of 99.8% and the CA22/SiO₂/UiO-66-NH₂ membrane with 2% of MOF 95.9%. Based on these results, it is concluded that the mixed matrix membranes CA22/SiO₂/UiO-66 and CA22/SiO₂/UiO-66-NH₂ are promising candidates for PBUTs removal in hemodialysis. Full article

With the growing emphasis on environmental sustainability, the proper treatment of industrial wastewater and the protection of groundwater resources have become pressing global concerns. Congo red (CR), a widely used azo dye, enters water bodies via wastewater discharge, posing persistent ecological risks to surface and groundwater systems. Adsorption, as a direct and sustainable remediation approach, necessitates the development of high-performance adsorbents to inhibit CR migration into groundwater. In this study, a Fe₂O₃/γ-Al₂O₃ composite was synthesized via sol-gel method for efficient CR adsorption, thereby mitigating groundwater contamination risk. The composite exhibited a high specific surface area (246.22 m²/g) and a maximum adsorption capacity of 1027.72 mg/g. Adsorption behavior followed the pseudo-second-order kinetic and Langmuir isotherm models, consistent with chemisorption-driven monolayer adsorption. The Weber–Morris intraparticle diffusion model confirmed rapid initial surface adsorption, beneficial for practical groundwater remediation. pH-dependent adsorption efficiency further indicated the role of electrostatic interactions, informing process optimization under varying groundwater chemistries. DFT calculations demonstrated that Fe₂O₃/γ-Al₂O₃ possesses a higher adsorption affinity for CR than γ-Al₂O₃. Collectively, Fe₂O₃/γ-Al₂O₃ shows strong potential as a novel, efficient adsorbent for CR interception and groundwater quality protection. Full article