Thermogravimetric Analysis Research Articles

High temperature capture of CO2 on Li4SiO4 sorbents via a simple dry ball-milling coupled with K2CO3 physical addition

The reversible CO2 absorption/desorption of lithium orthosilicate (Li4SiO4) sorbents holds potential for high temperature capture of CO2 from hot flue gases, sorption-enhanced reforming and solar thermochemical energy storage. In this study, we have prepared a series of Li4SiO4 sorbents using a combination of K2CO3 addition and dry ball-milling procedure to improve the relatively slow kinetics under low CO2 partial pressure conditions. The synergistic effects of dry ball-milling and K2CO3 addition on the intrinsic properties of Li4SiO4 sorbents were explored by thermogravimetric analysis and structural characterizations. Thermogravimetric analysis indicate that the highest CO2 uptakes were achieved with dry ball-milling combined with K2CO3 physical addition. The structural characterizations further reveal that this sorbent (P-3K-1.5 M) had the smallest crystallite/particle size, largest surface area, and highest availability of surface alkaline-sites. The kinetics analysis also demonstrates that P-3K-1.5 M exhibited the fastest sorption kinetics during a double process. Additionally, P-3K-1.5 M maintained a high capacity over 10 sorption/desorption cycles. Therefore, this synthesis technique, which is simple, cost-effective, and easily scalable, shows great promise for high-temperature CO2 capture.

Investigation of the influence of crushed sand on carbonation of Mortar: Physical and microstructural analysis

The use of crushed sand instead as a substitute for river sand has gained importance in construction practices due to the limited availability of river sand. This study examines the physical and microstructural impacts of crushed sand on mortar carbonation. Using X-ray Diffraction (XRD), Thermo-Gravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM). We highlight the influence of substituting river sand with crushed sand after exposure to 3 % CO2 in an accelerated carbonation chamber for 28 days. The mass fractions of Ca(OH)2 and CaCO3 were determined by thermogravimetric analysis, and a decrease in porosity was observed with an increasing proportion of crushed sand in the mixture. Partial or total substitution of river sand with crushed sand, for environmental purposes, shows improved resistance against CO2 attack. Our study reveals the beneficial effects of crushed sand in reducing porosity and carbonation compared to river sand.

Molecularly imprinting polymethacrylamide onto Cu-based metal-organic framework as a pH-sensitive core-shell nanocarrier for potential anti-cancer drug delivery.

Surface molecularly imprinted polymers (MIPs) are an efficient and rapidly advancing approach, increasingly being utilized in drug delivery systems (DDSs). This research involved synthesizing a core-shell structure, consisting of a metal-organic framework (MOF) core and a doxorubicin (DOX) imprinted polymethacrylamide shell, prepared via precipitation polymerization method in green media. The resulting MOF@MIP was utilized as a nanocarrier for DOX delivery, exhibiting high drug loading capacity and pH responsiveness delivery. The materials were characterized using different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared (FTIR), transmission electron microscopy (TEM), dynamic light scattering (DLS), thermal gravimetric analysis (TGA), and zeta potential (ZP). In vitro studies on DOX loading and release demonstrated that a higher amount of DOX was released in a sustained manner under tumor tissue conditions (pH 5, 41 °C) compared to normal physiological conditions (pH 7.4, 37 °C). Additionally, cytotoxicity evaluations revealed significant cytotoxic effects of DOX-loaded MOF@MIP on MCF-7 cells (IC50: 2 μg/mL). Based on these findings, the synthesized MOF@MIP shows promise as a potential candidate for the development of anticancer therapeutic delivery platforms.

Catalytic properties of selenium and phosphorus ionic liquids heterogenized on algae-based biochar

Catalytic performance of pyridinium hydrogen selenate (PHSe) and pyridinium dihydrogen phosphate (PH2P) ionic liquids immobilized on algae-based biochar (AC) was studied for the first time. For that purpose, acetic acid esterification with butanol was used as a test reaction. To investigate the surface effects, textural properties and thermal behavior for PHSe/AC and PH2P/AC, physicochemical methods such as X-ray powder diffraction (XRD), nitrogen adsorption–desorption isotherms (SBET) scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were applied. In addition, influence of the catalyst content (5–12 wt%) and reaction temperature (60–80 °C) on the butyl acetate yield and rate constant of esterification were evaluated. SBET and SEM measurements revealed that all of the samples (AC, PHSe/AC and PH2P/AC) obtained are mixed microporous-mesoporous materials. XRD and XPS data showed more highly dispersed PH2P particles than PHSe on the carrier surface due to stronger surface ionic liquid-support interaction for PH2P/AC in comparison with PHSe/AC. The latter was responsible for higher thermal stability of PH2P/AC with respect to PHSe/AC. In addition, more obvious PH2P sites (than PHSe) on the biochar surface favored the ester production in the presence of PH2P/AC (77.4 % and 53.26 × 10−4 l/mol × min) more evidently than PHSe/AC (58.1 % and 28.82 × 10−4 l/mol × min).

Synergistic CO2 capture using PANI-polymerized UiO-66 embedded in PEBAX mixed matrix membranes

In this study, mixed-matrix membranes (MMMs) were fabricated using a composite of UiO-66 and polyaniline (PANI) integrated into a polyether-block-amide (PEBAX) matrix. The successful synthesis of the UiO-66 and PANI@UiO-66 composites and their incorporation into the PEBAX matrix were validated through X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR) Spectroscopy, Brunauer–Emmett–Teller (BET) analysis, and Thermogravimetric Analysis (TGA). Quantitative permeation tests revealed that the CO2 permeability in UiO-66 based MMMs increased by 90 % at 30 % filler loading (from 82 to 156 Barrer), and by 45 % (from 82 to 119 Barrer) in PANI@UiO-66 based MMMs, alongside substantial improvements in selectivity. For UiO-66 membranes we observed a selectivity drop for both gas pairs (CO2/CH4 and CO2/N2) that led to our motivation to modify the MOF. The CO2/CH4 selectivity of the PANI@UiO-66 based MMMs enhanced from 22 to 29 (34%) and the CO2/N2 selectivity from 48 to 57 (18%). Mixed-gas permeation tests further confirmed the efficacy of the membranes in real-world separation scenarios. The diffusivity and solubility results provide insights into the gas transport mechanisms, revealing the synergistic effects of filler incorporation on membrane performance. The integration of UiO-66 and PANI with PEBAX offers a promising pathway for developing efficient and effective gas separation technologies, aligning with the industrial requirements for environmental sustainability and energy efficiency.

Silver Doped Polypyrrole Nanocomposite-based Gas sensor for Enhanced Ammonia Gas Sensing Performance at Room Temperature

Nanocomposite, which comprise organic and inorganic materials have gained increasing interest in the application for enhanced sensing response to both reducing and oxidation gases. In this study, a nanocomposite is chemical polymerization synthesized by reinforcing Ag nanoparticles with different concentration doped into the matrix of Polypyrrole (PPy). This nanocomposite is used as a sensing platform for ammonia detection with different concentration (ppm). The homogeneous distribution of Ag nanoparticles onto the PPy matrix provides a smooth and dense surface area, further accelerating the transmission of electrons. The synergistic effect of PPy@Ag matrix is responsible for the outstanding conductivity, compatibility and catalytic power of the proposed gas sensor. The structure, morphology, and surface composition of as-synthesized samples were respectively, examined via X-ray diffraction, field emission scanning electron microscopy, Ultraviolet-visible spectroscopy, Thermogravimetric analysis and Fourier transform infrared spectroscopy. The results indicated that sensor based on the PPy@Ag5 (2 gm) nanocomposite showed the highest response toward ammonia as compare to pure PPy at room temperature with a response value is 58 % to 100 ppm. Overall, the obtained findings demonstrated that the PPy@Ag nanocomposite are promising materials for gas sensing applications in environmental monitoring.

Whey protein-based bigels for co-encapsulation of curcumin and gallic acid: Characterization, stability and release kinetics

Bigels are a class of soft matter systems with great promise for the food industry as food analogs or as enhanced ingredient substitutes. This work aimed to improve the curcumin (CUR) and gallic-acid (GA) stability, antioxidant capabilities, and controlled release by co-encapsulating them within bigels. This delivery system included a bigel made by whey protein isolate (WPI) aggregates-based oleogel and WPI-based hydrogel in equivalent amounts (50:50). The following techniques were used to evaluate how different bigels affected the chemical stability of CUR and GA: X-ray diffraction (XRD), thermogravimetric analysis (TGA), 1H-nuclear magnetic resonance (1H-NMR), and Fourier infrared (FTIR) spectroscopy. As a result of the protein's ligand-binding abilities, some components may co-adsorb to oil droplet surfaces. Next, it was determined how well the bigels performed as a carrier and looked at their physicochemical stability, digestion, and performance. Examining the release rate of CUR and GA during digestion showed that bigel had a slower release rate (6-15%) than oleogel (16%) and hydrogel (34%), and CUR had a lower release (50%) due to its higher molecular weight and greater entanglement than GA (70%). The stability of bigel (against heat and light) was also higher than oleogel and hydrogel due to having a higher solid component that requires more stress to be applied to the system. CUR and GA had more antioxidant activity in bigel (96.24%) than oleogel (77.71%) and hydrogel (77.34%); which can be attributed to the formation of ultra-fine colloidal dispersions by bigel, allowing more CUR and GA to interact with free radicals by creating more contact surface. The multi-functional bigels showed great potential for delivering antioxidants to the intestine while enhancing their stability. Hydrophobic interactions and hydrogen bonding between WPI and CUR-GA were validated by FTIR analysis, that kept bigels stable. Overall, our findings demonstrated that WPI-based bigels with intriguing UV light, color, and thermal stability could be developed. This would increase the use of bigels in innovative food products with high nutritional value.

A novel bio-based autocatalytic amide-type phthalonitrile monomer: Synthesis, curing kinetics and thermal properties

A bio-based bisphenol compound (DFA) was prepared using bisphenolic acid and furfurylamine in biomass as raw materials. Then, a bio-based amide phthalonitrile monomer (DFAP) was obtained in an environmentally friendly solvent. Nuclear magnetic resonance and Fourier transform infrared spectroscopy (FT-IR) proved the successful synthesis of DFA and DFAP. The curing behavior and curing kinetics of the polymer were studied using FT-IR and differential scanning calorimetry. Calculate the activation energy using the isoconversion method. The SB(m, n) autocatalytic reaction model describing the curing process of poly(DFAP) was modified and fitted by introducing the variable activation energy model. The thermal stability, thermomechanical properties and processing properties of the resin were studied using technologies such as thermogravimetric analyzer, dynamic mechanical analyzer and rheometer. The results show that the prepolymer has a wide processing window and a low melt viscosity. Poly (DFAP) has a high glass transition temperature and excellent thermal stability.

A sustainable black liquor-based carbon scavenger to promote urea formaldehyde as green wood adhesive with low formaldehyde emission

The current study focuses on finding an ecological method to dispose of black liquors (BLs), containing lignin macromolecules, which are produced as byproducts of rice straw-based paper production. In addition to maximizing their value as precursors in the preparation of novel formaldehyde scavengers to avoid the environmental risks associated with using urea formaldehyde in agro-wood composites. To optimize the route, various black liquors are prepared from pulping of rice straw by different pulping agents (alkali, neutral, acidic and kraft reagents) used as additions or precursors for carbon compounds. Elemental analysis, thermogravimetric analysis [TGA], Fourier transform infrared [FTIR] and scanning electron microscope (SEM), are the techniques used to characterize the BLs; while the gel time, bond strength, and differential scanning calorimetry (DSC) methodologies are applied to determine the impact of black liquor (BL) and black liquor‑carbon nanostructures (BL-CNSs) on performance of urea formaldehyde (UF) adhesive. The behavior of the investigated BL-CNSs as HCHO-scavengers is assessed from their affinity to capture the HCHO, and reduction of free-HCHO in UF-palm fibers agro-composites. BL-CNSs, as novel scavengers, exhibit promising properties where the bonding strength of BL-CNSs-UF adhesives increased to 19.7 MPa even though the UF was only 8.4 MPa. Moreover, the formaldehyde adsorption capacity ranges from 35.4 to 63.6 mg/g as well as lowering the gel time. It is interesting to note that the investigated scavengers not only reduced the free-HCHO of composites by about 40–91 %, but also enhancement in their mechanical and water resistance properties; where the modulus of rupture (MOR), internal bond (IB) and reduction in thickness swelling improved to about 50 % and 83.3 %, and 38.8 %, respectively. According to the American National Standards Institute (ANSI) standard these new scavengers, especially from BL of neutral pulping, permit the production of an eco-board (E1) with static bending exceeding the H-3 class.

A green approach for delignification of corn husks and their application as an unpowered thermo-responsive sensor

The world is adopting biodegradable materials to replace existing petroleum-based plastics, owing to their toxicity and unfriendly environmental aspects. Biodegradable corn husk (CH) is considered a promising alternative due to its environmental friendliness and widespread availability as agricultural waste. In this work, a green process for the delignification of corn husk was developed and preparation of CH-based reversible thermo-responsive delignified corn husk (RTDCH) sensors was done which exhibit different colors corresponding to particular temperature ranges. These RTDCH sensors employed with reversible thermo-responsive nanoparticles (RTNPs) were characterized thoroughly using X-ray Diffraction (XRD), scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA), and Fourier transform spectroscopy (FTIR), which ensures their successful synthesis. Upon deploying them for sensing temperatures from 20 to 80℃, different color displays appeared rapidly within 5seconds, which helps to identify the particular temperature range. The RTDCH exhibited excellent reusability for several cycles and maintained consistency in color displays at certain exposed temperatures. The RTDCH, being unpowered, fast responsive, accurate, biodegradable, economical, and scalable production feasibilities, has the necessary traits to become practical at the industrial level. Such materials have tremendous potential for the food industry, scientific laboratories, and monitoring the temperature of industrial processes. The strategy adopted in this work is crucial since it is paving the way for the development of advanced functional materials from natural wastes through green synthesis approaches.

Cerium nitrate microcapsules for coating application: characterization and corrosion study

Microcapsules show great potential in metal anticorrosive coating in recent years. In the following paper first, urea-formaldehyde (UF) microcapsules containing cerium nitrate were synthesized under different parameter conditions. Three different quantities of the microcapsules were introduced to the epoxy coatings and applied on the AZ31B substrate to meet the increasing demands for anticorrosive coatings. An analysis of the SEM surface morphology of UF microcapsules synthesized by nine different parameter conditions shows that the ratio of formaldehyde to urea is 1.5:1, and 2 wt.% of emulsifier, 25 wt.% of cerium nitrate, and 150 r/min of rotation speed are the best choice for the synthesis of microcapsules, resulting in spherical particles with an average particle size of about 25 μm. The characteristics of microcapsules were studied by optical microscope (OM), Fourier transform infrared (FTIR), and Thermogravimetric analysis (TGA). The result of electrochemical impedance spectroscopy indicated that the 2 wt.% microcapsule content in the defective coating shows better corrosion protection performance than neat epoxy coating and cerium nitrate inhibitor coating.

Synthesis, characterization, magnetic and morphological properties of poly(m-phenylenediamine)/ZnCoFe2O4 nanocomposites

In this work, poly(m-phenylenediamine) (PmPD)/ZnCoFe2O4 nanocomposites (NCs) were synthesised by in-situ chemical oxidative polymerisation method. The ZnCoFe2O4 nanoparticles (NPs) were prepared by auto-combustion method. The crystalline size of PmPD/ZnCoFe2O4 NCs and ZnCoFe2O4 NPs were calculated using the Powder X-ray diffraction (XRD) analysis. The functional group of the samples was analysed by Fourier transform infrared spectral (FTIR) analysis. The XRD and FTIR results were clearly indicated that the formation of ZnCoFe2O4 NPs and PmPD/ZnCoFe2O4 NCs. The spherical morphology of the PmPD/ZnCoFe2O4 NCs was confirmed through Field emission electron microscopy (FE-SEM). The magnetic hysteresis (M-H) loops of ZnCoFe2O4 NPs and PmPD/ZnCoFe2O4 NCs were revealed their ferromagnetic behaviour. Thermogravimetric analysis (TGA) was indicated that thermal stability of PmPD/ZnCoFe2O4 NCs and increases with increase in concentration of ZnCoFe2O4 NPs. The dielectric properties of PmPD/ZnCoFe2O4 NCs were also examined with different frequency.

Comprehensive characterization of bioplasticizer from the Murraya koenigii leaves: From biomass to biomaterial for polymer composite applications

The world is moving toward sustainable products in almost all fields. As non-renewable resources are used and getting exhausted, the search for renewable, greener, and sustainable alternatives has become the most preferred option currently. Overall, polymer-based materials are used almost in all products for both in industrial and domestic purposes. One of the main additives used during the processing of any polymeric materials is plasticizers (PSs). Most of the PSs are toxic, which is not welcoming one in current situation. Bioplasticizers (BPs) have become a recent research study option focus to overcome this drawback. In this investigation, Murraya koenigii (MK), a native tree, was chosen for the extraction of BPs (MKBP) from its leaves (MKTL) and subjected to various analyses including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV–visible spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The presence of FTIR peaks showed the possibility of PS similarities with peaks at 1396cm−1 and 1214cm−1. XRD confirmed the crystallinity of the MKBP with a crystallinity index (CYI) of 92.4% and the crystallite size of 0.033µm. UV analysis resulted in a maximum peak at 358.41nm. TGA reported the maximum degradation temperature of 377.3 °C. DSC analysis showed a glass transition temperature (Tg) of 68.89 °C. SEM analysis confirmed a high probability of blending with the extracted MKBP as the extract possessed a rough surface. AFM revealed the surface roughness that matched the SEM results.

Preparation and properties of calcium oxide and calcium peroxide from eggshell waste for enhanced antimicrobial activity

Calcium peroxide (CaO2), which releases hydrogen peroxide (H2O2) upon contact with water, has garnered attention as a potential alternative to liquid H2O2. Researchers have explored various methods to enhance the production of CaO2 with reduced environmental impact. This study focuses on the preparation of two potent antimicrobial agents, calcined calcium oxide (C-CaO) and synthesized calcium peroxide (S-CaO2) from eggshell waste. These agents were then incorporated into ethylene vinyl alcohol (EVOH) composite films for antimicrobial packaging. The synthesized CaO and CaO2 were analyzed using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Scanning electron microscopy (SEM). The results confirmed the successful synthesis of high-purity CaO and CaO2 from eggshell waste. Compared to CaO (a well-known antimicrobial agent), CaO2 exhibited approximately 1.6 to 2 times higher antimicrobial activity, which is attributed to its release of H2O2. EVOH films containing 3% of CaO2 demonstrated significant microbial growth deactivation, reaching 99.99% and 97.24% for gram-negative and gram-positive bacteria, while EVOH films containing 3% of CaO exhibited relatively low deactivation ability of 79.01% and 48.82, respectively. This study underscores the potential of eggshell waste as a valuable resource for producing high-value materials. Moreover, CaO2 emerges as an effective antimicrobial agent, particularly in antimicrobial packaging applications, showcasing its versatility across various sectors.

Copolymeric hydrogels with high capacities of hydration and methylene blue adsorption in water

Copolymers based on monomethyl hydrogen itaconate (βHI) with 2-hydroxyethyl methacrylate (HEMA) and βHI with 2-hydroxypropyl methacrylate (HPMA) were prepared in different monomer molar ratios. The reactivity parameters of copolymerization (r1 and r2) were determined. The values obtained for r1 and r2 indicate that P(βHI-co-HEMA) exhibits a high tendency towards alternate copolymerization. Structural characterization of the copolymeric hydrogels was carried out using Fourier transform infrared (FTIR) and 1H-NMR spectroscopies, where the characteristic signals of the constituent functional groups were observed. The typical thermal stability of the polymeric systems was observed by thermogravimetric analysis (TGA). In addition, the swelling capacity in water was evaluated, and a swelling percentage over 655 % and 1249 % presented P(βHI-co-HEMA) and P(βHI-co-HPMA) respectively, in a period of 15 days at pH 10, and presence of 0.05 M NaNO3.Additionally, methylene blue (MB) adsorption capacity was studied in batch mode by varying different experimental parameters. MB adsorption capacity of 122.79 mg g-1 and 112.24 mg g-1 were achieved for P(βHI-co-HEMA) and P(βHI-co-HPMA), respectively. The data obtained were fitted to the Elovich kinetic model and to a Redlich-Peterson isotherm. The thermodynamic parameters indicated that the adsorption phenomenon is spontaneous, endothermic and with a high probability of occurrence. The adsorption efficiency decreases by approximately 60% in the presence of interfering ions (Na+, K+, Ca2+ and Cl-). The adsorbents are reusable and achieve high MB adsorption efficiency (90% and 80% for P(βHI-co-HEMA) and P(βHI-co-HPMA) respectively) in a textile-simulated wastewater. Based on the results obtained, it is concluded that P(βHI-co-HEMA) and P(βHI-co-HPMA) show great potential for use in adsorption of water molecules, for MB retention and purification of simulated effluents from the textile industry.

Effect of expandable graphite content on the physical, thermal and mechanical properties of novolac matrix composites: Halogen-free flame-retardant polymer composites

Flame-retardant properties are particularly important for materials used in high-temperature applications. This study focuses on novolac matrix composites reinforced with expandable graphite (EG) particles, produced through a hot pressing process using powders prepared by mechanical milling. The research examines the particle size of both the matrix and the reinforcing particles used in composite production. Additionally, the morphology of the powders, the microstructural properties of the composites, and the fracture surfaces after tensile testing were analyzed using scanning electron microscopy (SEM). Phase analysis of the samples was performed using X-ray diffraction (XRD). Hardness and tensile tests were conducted to evaluate the mechanical properties. The effect of EG particles on the thermal stability of the composites was assessed using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and thermal conductivity tests. Furthermore, flammability was evaluated by determining the Limit Oxygen Index (LOI) values. The experimental results identified the optimum reinforcement ratio as 20 wt% EG. TGA results showed residue values of approximately 37.39 % for pure novolac and 57.87 % for novolac matrix composites reinforced with 20 wt% EG. The highest thermal conductivity (0.72 W/mK) and LOI values (40.64 %) were achieved with 20 wt% EG reinforcement, resulting in an LOI value approximately 1.25 times greater than that of the pure novolac sample (32.45 %). Additionally, tensile strength increased by approximately 2.7 times compared to the pure novolac sample. This research highlights the potential of the novolac/EG composites for advanced high-temperature applications where enhanced flame retardancy and structural integrity are essential.

Low-Melting Maleimide-Containing Phthalonitrile Resins: Synthesis, Curing Behaviour, and Thermal Performance

Phthalonitrile (PN) resins are highly valued in high-performance applications due to their exceptional thermal stability and mechanical properties. However, traditional PN monomers suffer from high melting points and slow curing rates, often requiring external curing accelerators that can compromise thermal performance. This study focuses on the synthesis and characterization of novel low-melting maleimide-containing PN monomers designed to enhance curing efficiency and thermal properties. Maleimide groups were introduced to improve self-catalytic properties, facilitating a more efficient curing process. The polymerization behavior, thermal stability, adhesive, and mechanical properties of these compounds were thoroughly investigated. Differential Scanning Calorimetry (DSC) and rheological tests showed that incorporating alkyl groups significantly improved flow properties, facilitating easier processing. The difference in the three-dimensional network structures of the cured PN resins was confirmed by Fourier Transform Infrared (FT-IR) spectroscopy. Thermogravimetric Analysis (TGA) demonstrated outstanding thermal stability, with 5% weight loss temperatures ranging from 387°C to 418°C under air and from 420°C to 471°C under nitrogen. Dynamic Mechanical Analysis (DMA) confirmed high glass transition temperatures (Tg) exceeding 400°C, indicating superior thermal performance and making these resins suitable for advanced applications in harsh environments. These findings suggest that low-melting maleimide-containing PN systems are promising candidates for high-performance materials in aerospace, electronics, and other demanding fields.

Eu-containing polyoxometalate composed of mixed trivacant Keggin fragments: Synthesis, structure, and catalysis for Knoevenagel condensation

A novel Eu-containing antimono-seleno-tungstate [H2N(CH3)2]8Na8Cs4H9[Eu2SeW4O11(OH)(H2O)4(SbW9O33) (SeW9O33)(Se1/2Sb1/2W9O33)]2·32H2O (1) has been synthesized under the aqueous solution conditions. The polyoxoanion is a hexameric architecture constituted by mixed trivacant Keggin fragments, namely 2 {SbW9}, 2 {SeW9} and 2 {Se1/2Sb1/2W9}, enclosing a heterometallic central Eu4Se2W8O22(OH)2(H2O)8 cluster core. Compound 1 was characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR spectrometry and thermogravimetric analysis. Furthermore, catalytic study shows that compound 1 can efficiently accelerate the Knoevenagel condensation reactions of various aldehydes with malononitrile under mild reaction conditions.

Design of superparamagnetic Fe3O4@SiO2@3,4-DABP nanocatalysts, fabrication by co-precipitation and sol-gel methods, characterization of detailed surface texture properties and investigation of solar cell performance

This research focuses on the synthesis, characterization, and evaluation of Fe3O4, Fe3O4@SiO2, and Fe3O4@SiO2@3,4-DABP magnetic nanocatalysts (MNCs) for their potential use as sensors within the intricate architectures of solar cell devices. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) surface area measurements were carried out to characterize the structural, morphological and magnetic properties of the MNCs. The MNCs exhibit an average particle size of approximately 10 nm. Fe3O4, Fe3O4@SiO2, and Fe3O4@SiO2@3,4-DABP MNCs have saturation magnetization values ​​of 61.64 emu/g, 37.31 emu/g, and 20.13 emu/g, respectively. Thermal analysis reveals mass change losses of 6.5%, 12% and 28.1%, respectively, indicating different thermal stability profiles. It confirms that their crystal structure is face-centered cubic spinel, with type IV hysteresis loops and H3 loops indicating a mesoporous structure according to the IUPAC classification. Efficiency tests of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@3,4-DABP MNCs in solar cell devices show efficiencies of 1.49%, 1.77% and 2.15%, respectively. As the hierarchical modification of the MNCs increases, the efficiency of the solar cell devices increases. These results highlight the potential of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@3,4-DABP as promising sensitizers in solar cell technology. Fe3O4@SiO2@3,4-DABP MNCs have high catalytic activity, chemical stability, electronic conductivity and low cost. This study also marks the first demonstration of the effectiveness of environmentally friendly Fe3O4@SiO2@3,4-DABP MNCs in enhancing solar cell performance, prepared via a cost-effective, simple and eco-friendly approach.

A three-dimensional octamolybdate-modified silver crystalline material with catalytic and antibacterial activities

The hydrothermal reaction of 1-(4-carboxyphenyl)-3-(pyrazine-2-yl)-pyrazole (HX) with AgNO3 in the presence of [PMo12O40]3− anions results in a new 3D octamolybdate-based metal–organic complex, [Ag2(HX)(X)(H2Mo8O26)0.5]·H2O (1). 1 was characterized using X-ray photoelectron spectra, scanning electron microscopy, powder X-ray diffraction, elemental mapping, IR spectroscopy, thermogravimetric analysis and single-crystal X-ray diffraction. In compound 1, [H2Mo8O26]2− was in situ generated from the Keggin-type [PMo12O40]3−. Compound 1 is a 3D framework composed of 2D metal–organic layers [Ag2(HX)(X)]nn+ and [H2Mo8O26]2− clusters. Its electrochemical properties were investigated and the results showed that 1 could serve as an electrochemical sensor to detect NO2−. Compound 1 exhibits photocatalytic activity in the degradation of methylene blue, methyl orange and Rhodamine B. The mechanism of the photocatalytic degradation was also studied. Additionally, the antibacterial properties against Escherichia coli, Ralstonia solanacearum and Xanthomonas axonopodis pv. Citri were investigated.