Powder Diffraction Research Articles

A semiconducting supramolecular Co(II)-metallogel based resistive random access memory (RRAM) design with good endurance capabilities.

A highly efficient approach for synthesizing a supramolecular metallogel of Co(II) ions, denoted as CoA-TA, has been established under room temperature and atmospheric pressure conditions. This method employs the metal-coordinating organic ligand benzene-1,3,5-tricarboxylic acid as a low molecular weight gelator (LMWG) in DMF solvent. A comprehensive analysis of the mechanical properties of the resulting supramolecular Co(II)-metallogel was conducted through rheological investigation, considering angular frequency and thixotropic study. The hierarchical rocky network structure of the supramolecular Co(II)-metallogel was unveiled using field emission scanning electron microscopy (FESEM). Transmission electron microscopic (TEM) analysis showed rod-shaped structures via low-magnification high angle annular dark field (HAADF) bright field scanning transmission electron microscopic (STEM) imaging, while energy dispersive X-ray (EDX) elemental mapping confirmed its primary chemical constituents. The formation mechanism of the metallogel was examined via fourier transform infrared spectroscopy (FTIR) spectroscopy. The nature of the synthesized CoA-TA metallogel was affirmed through powder X-ray diffraction (PXRD) analysis. Furthermore, this study involved fabrication of Schottky diode structures in a metal-semiconductor-metal geometry based on cobalt(II) metallogel (CoA-TA), enabling observation of charge transport behavior. Remarkably, a resistive random access memory (RRAM) device utilizing cobalt(II) metallohydrogel (CoA-TA) demonstrated bipolar resistive switching at room temperature and under ambient conditions. The switching mechanism was investigated, revealing the formation and rupture of conductive filaments between metal electrodes that govern the resistive switching behavior. This RRAM device exhibited an impressive ON/OFF ratio (~ 414) and exceptional endurance over 5000 switching cycles. These structures offer great potential for diverse applications such as non-volatile memory design, neuromorphic computing, flexible electronics and optoelectronics. Their advantages lie in their fabrication process, reliable resistive switching behavior and overall performance stability.

Phytomediated synthesis of WO3 nanoparticles using Solanum lycopersicum fruit extract for enhanced photocatalytic activity of 2,4-dichlorophenol

ABSTRACT In the present study, bio-citric acid/tungsten oxide (WO3) (BCAWO) nanoparticles (NPs) were prepared by using Solanum lycopersicum fruit extract as a reducing as well as a capping agent. The photocatalysts were characterized by UV–vis diffuse reflection spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), high-resolution transmission electron microscopy, and photoluminescence spectroscopy techniques. Diffraction peaks in the XRD spectrum were identified as the crystal planes of crystalline tungsten oxide. The BCAWO had an average size of 23.14 nm. For W–O bonds, the Fourier transform infrared spectrum displays the vibrational peak at 671.23 cm−1. A prominent absorption band was observed at 268 nm, indicating the 1.2 eV bandgap. Under xenon (Xe) lamp irradiation, the synthesized BCAWO nanoparticles showed notable photocatalytic degradation of 2,4-dichlorophenol (2,4-DCP), with a degradation rate of 96%. With BCAWO concentrations of 2.5 g/L, pH of 4, reaction period of 180 min, and 2,4 DCP concentration of 10 mg/L, the degradation of 2,4-DCP had the highest efficacy, 96%. The degradation of phenols in wastewater may be facilitated by using the green WO3 nanoparticles as a photocatalyst, according to the results.

Valorizing sardine scales: a circular approach to sustainable collagen for cosmetics and nutrition applications

Background and ObjectiveIn recent years, the consumption of fish products has led to a worrying trend where approximately two-thirds of the total amount of fish is discarded as waste. At the same time, scientific interest in exploring natural collagen sources for cosmetics and dietary supplements has increased. This study explores the potential of valorizing sardine scales (Sardina pilchardus), a by-product of the canning industry, through the extraction of collagen for potential use in dermocosmetic formulations and food supplements.MethodsCollagen from sardine scales was obtained though acid and enzymatic extraction. The collagen extracts were characterized by UV-Vis, FTIR spectroscopy, SDS-PAGE, powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM). The collagen was hydrolysed with papain to small peptides. Subsequently, the biological activities of acid-soluble collagen as well as the collagen peptides in terms of antioxidant and antimicrobial activity were evaluated. Furthermore, the capacity of collagen peptides to permeate the intestinal barrier, simulated with caco-2 cells, was evaluated.ResultsPurified collagen extracts were obtained from sardine scales, with enzymatic extraction method having a yield three times higher than the acid method. The SDS-PAGE analysis confirmed the extraction of type I collagen as well as its hydrolysis into small fragments (25–12 kDa). In terms of biological activities, collagen and collagen peptides have not demonstrated antimicrobial activity. However, regarding antioxidant activity, collagen peptides showed three times more capacity compared to non-hydrolyzed collagen. Meanwhile, in 6 h, about 6.37% of collagen peptides could permeate the intestinal barrier.ConclusionThis work represents a continuous effort to advance our understanding and utilization of Portuguese marine waste resources, with focus on the valorization of sardine co-products for the development of food supplement or cosmetic formulations, contributing to the sustainable evolution of the circular blue economy.

Construction of Chiral Covalent Organic Frameworks Through a Linker Decomposition Chiral Induction Strategy for Circularly Polarized Light Detection

AbstractExploring new strategies for construction of chiral covalent organic frameworks (COFs) is of paramount importance yet remains a challenge. Herein, we report the rational design and construction of chiral COFs through a linker decomposition chiral induction (LDCI) strategy. Three pairs of azine‐linked chiral COFs are successfully synthesized by the condensation reactions of C3‐symmetric 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzaldehyde (Tz) with flexible chiral dihydrazide linkers derived from malic acid, aspartic acid and tartaric acid, respectively. Remarkably, upon complete or partial decomposition from flexible chiral dihydrazides to hydrazine during COF synthesis, the homochirality of these COFs, originating from the single‐handedness conformation of propeller‐like Tz cores, is well preserved. Such a stereoselective chiral memory realized via the LDCI strategy is confirmed by time‐dependent powder X‐ray diffraction (PXRD), Fourier transform infrared (FT‐IR) and diffuse reflectance circular dichroism (DRCD). Moreover, the resultant azine‐linked chiral COFs are used as the active materials to fabricate photodetectors to directly distinguish circularly polarized light (CPL), showing impressive recognition performances on the identification of left‐handed circularly (LHC) and right‐handed circularly (RHC) polarized lights. Notably, the residual undecomposed flexible chiral linkers within the COFs are found to be conducive to improving the polarization discrimination ratio. This work highlights LDCI as a new and effective strategy for constructing homochiral COFs with promising future in chiral optical application.

Construction of Chiral Covalent Organic Frameworks Through a Linker Decomposition Chiral Induction Strategy for Circularly Polarized Light Detection

AbstractExploring new strategies for construction of chiral covalent organic frameworks (COFs) is of paramount importance yet remains a challenge. Herein, we report the rational design and construction of chiral COFs through a linker decomposition chiral induction (LDCI) strategy. Three pairs of azine‐linked chiral COFs are successfully synthesized by the condensation reactions of C3‐symmetric 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzaldehyde (Tz) with flexible chiral dihydrazide linkers derived from malic acid, aspartic acid and tartaric acid, respectively. Remarkably, upon complete or partial decomposition from flexible chiral dihydrazides to hydrazine during COF synthesis, the homochirality of these COFs, originating from the single‐handedness conformation of propeller‐like Tz cores, is well preserved. Such a stereoselective chiral memory realized via the LDCI strategy is confirmed by time‐dependent powder X‐ray diffraction (PXRD), Fourier transform infrared (FT‐IR) and diffuse reflectance circular dichroism (DRCD). Moreover, the resultant azine‐linked chiral COFs are used as the active materials to fabricate photodetectors to directly distinguish circularly polarized light (CPL), showing impressive recognition performances on the identification of left‐handed circularly (LHC) and right‐handed circularly (RHC) polarized lights. Notably, the residual undecomposed flexible chiral linkers within the COFs are found to be conducive to improving the polarization discrimination ratio. This work highlights LDCI as a new and effective strategy for constructing homochiral COFs with promising future in chiral optical application.

CHARACTERIZATION OF CLAYS FROM “MINES MARITSA IZTOK” AS RAW MATERIALS FOR CERAMIC INDUSTRY

The chemical and phase compositions of the clays from coal mining were evaluated by XRF and powder XRD method, respectively. Hot Stage Microscope was used to estimate the thermal behaviour. In addition, the thermal losses of the clays after 1 h thermal treatment at different temperatures were measured. This preliminary analysis elucidates potential prospects for using some of clays as raw materials for ceramic industry. It seems that samples which are montmorillonite type are more plastic, while the others, where higher sand content is observed, and the drying shrinkage is negligible could be characterized as less plastic. The initial results for the thermal behaviour and the structure of a brick sample (obtained by mixing two types of clays) and a foamed geopolymer are also reported. The first sample shows a beginning of the firing shrinkage at about 1000°C, while the second demonstrates intensive bloating after 950°C, leading to specimen with about 56 % closed porosity. Finally, X - ray Computed Tomography and SEM was used to highlight the structure of some test samples.

Studying the properties of green synthesized silver oxide nanoparticles in the application of organic dye degradation under visible light.

In present study the green synthesis of silver oxide nanoparticles has been effectively achieved using novel plant extract Phragmanthera Macrosolen. This method provides sustainable alternative for nanoparticle synthesis, demonstrating the potential of Phragmanthera Macrosolen as a reducing and stabilizing agent in the production of Ag2O NPs. The synthesized nanoparticles were characterized for their structural, morphological, and optical properties, confirming their successful formation and potential applications in various fields. The effects of different pH values and annealing temperature of the samples on the properties of Ag2O NPs formations, as well as photo-catalytic activities towards Toluidine Blue dye degradations, were studied. Powder XRD reveals that the crystallite natures of Ag2O NPs a long with crystalline size ranges from 25.85 to 35.90nm. FIB-SEM and HR-TEM images displayed that the Ag2O NPs as spherical shapes. UV-vis spectroscopy displayed that Ag2O NPs belong to a direct-band gap of 2.1-2.6eV. FTIR- study shown that the green synthesized Ag2O NPs may be steadied via the interfaces of -OH as well as C = O groups in the carbohydrate, flavonoid, tannin, as well as phenolic acid existing in P. macrosolen L. leaf. The chemical states, electron-hole recombinations and purity of Ag and O in the synthesized Ag2O NPs were confirmed through X-ray Photoelectron Spectroscopy (XPS) and PL analysis respectively. Fascinatingly, the synthesized Ag2O NPs at pH 12 displayed high photo-catalytic degradations for TB dyes. The photo-catalytic degradations of the TB dyes were monitored spectro-photo-metrically in wave-length ranges of 200-900nm, as well as high efficiency (98.50%) with half-life of 9.5798min and kinetic rate constant of 0.07234min-1, was obtained after 45min of reactions. From this study, it can be concluded that Ag2O NPs synthesized from Phragmanthera Macrosolen aqueous extract are promising in the remediation of environmental pollution and water treatment. In this light, the study reports that Phragmanthera Macrosolen green synthesis of Ag2O NPs can effectively address environmental pollution in cost-effective, eco-friendly, and sustainable ways.

Sonochemical Synthesis of Potassium-Intercalated Carbon Allotropes: Bulk Formation at Ambient Room Temperature.

Intercalation can be used to alter the electronic properties of graphitic materials. Intercalation is, however, a notoriously brute-force process typically carried out at a high temperature in an inert environment for an extended period. As an exception to this, a simple sonication-assisted intercalation of potassium into graphite at ambient room temperature (RT) has been reported. Here we extend this approach to intercalation of potassium into other carbon allotropes, including planar graphene nanoplatelets (GNPs) and curved graphitic tubes and shells, such as multiwalled carbon nanotubes (MWCNTs) and nanodiamond-derived carbon nano-onions (NCNOs). We report the rapid room-temperature sonication-assisted potassium metal intercalation of GNPs, MWCNTs, and NCNOs. Powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and electron dispersive X-ray spectroscopy (EDS) were used to visualize the location of potassium in the intercalated products.

Double‐Walled Honeycomb‐Like Metal‐Organophosphonium Framework with High H2 Gas Adsorption Capacities

AbstractThis study successfully synthesized a new Metal‐Organic Framework (MOF) named CJLU−L2, which was constructed from phosphorus‐containing ligands and Co(II) ions. The structure revealed through single‐crystal X‐ray diffraction (SCXRD), features a double‐walled honeycomb‐shaped structure with a one‐dimensional channel of ~6.5 Å. According to the PLATON calculation, the pore volume per unit cell of CJLU−L2 was determined to be 6825.0 Å3, constituting 57.5 % of the total crystal volume (11874.9 Å3). The Brunauer‐Emmett‐Teller (BET) surface area of CJLU−L2 was determined to be 954 m2/g by N2 adsorption measurement at 77 K. The phase purity of CJLU−L2 was verified by powder X‐ray diffraction (PXRD) and infrared spectroscopy (IR), while its thermal stability was confirmed by thermogravimetric analysis (TGA). Hydrogen adsorption experiments demonstrate that CJLU−L2 exhibits a high hydrogen adsorption capacity, indicating significant potential for gas adsorption applications.

Synthesis of Fe3O4 Derived from Acid Mine Drainage (AMD) Sludge and Catalytic Degradation of Tetracycline.

Acid mine drainage (AMD) sludge is waste generated in the process of acid mine wastewater treatment, and the use of AMD sludge to prepare Fe3O4 to activate H2O2 degradation pollutants is an effective means of resource utilization. In this study, the heterogeneous catalyst Fe3O4-based composites were synthesized by a one-step method using AMD sludge as a raw material, and the Fe3O4-based materials before and after catalysis were characterized by powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The effects of several key factors (pH values, H2O2 content, TC concentration, and Fe3O4 content) of tetracycline (TC) degradation were evaluated. The results revealed that the TC removal rate reached up to 95% within 120 min under optimal conditions (pH 3; H2O2, 5 mmol/L; TC concentration, 25 mg/L; Fe3O4 content, 1g/L). Moreover, •OH and •O2- radicals were generated during the Fenton-like degradation process, and the plausible degradation mechanism was discussed. Besides, the Fe3O4 catalyst exhibited fantastic stability after five cycles. In conclusion, this study is expected to promote the resource utilization of industrial sludge and provide a new material for the treatment of antibiotic-contaminated wastewater.

NaW2S4 and RbxWS2: Alternative Sources for 2M-WS2 and 1T'-WS2 Monolayers.

With the recent strive to develop novel quantum materials, including two-dimensional nanosheets, alkali-layered intercalated materials have found a new purpose as starting materials for such compounds. Enriching the library of alkali materials, we present a solid-state synthesis for preparing NaW2S4 (P1̅, No. 2) and RbxWS2 (C2/m, No. 12). Solving their crystal structure from their powder X-ray diffraction patterns, we show that both materials are layered, the former being a slightly distorted version of the latter. We compare the two structures and find that the main difference is the interlayer spacing in the a-direction. We further show that, like their cousin, KxWS2, both compounds can be deintercalated with dilute acid to form superconducting 2M-WS2, with structural and property characterization showing similar behavior, regardless of the starting material. Lastly, we find that both materials can be exfoliated in the same manner as KxWS2 to form superconducting 1T'-WS2 monolayers. We describe an easy one-step method for preparing two new layered materials and, thus, provide more opportunities to access valuable superconducting materials.

Covalent Stabilization of the Iridium-Containing Oxyhydrides Sr2Mn0.5Ir0.5O3.25H0.75 and Sr2Mn0.5Ir0.5O2.66H1.33.

Reaction between Sr2Mn0.5Ir0.5O4 and CaH2 or LiH yields the iridium-containing oxyhydride phases Sr2Mn0.5Ir0.5O3.25H0.75 or Sr2Mn0.5Ir0.5O2.66H1.33, respectively. Analysis of Mn K-edge XANES data indicate the presence of Ir3+ centers in these oxyhydride phases, whose low-spin d6 configuration is consistent with the "covalent stabilization" of the metastable oxyhydride phases, as seen previously in analogous ruthenium and rhodium containing materials. Neutron powder diffraction data indicate the hydride ions are located exclusively within the "equatorial" anion sites of Sr2Mn0.5Ir0.5O3.25H0.75. In contrast, hydride ions are observed on both the equatorial and axial anion sites of Sr2Mn0.5Ir0.5O2.66H1.33. This highly unusual anion distribution is attributed to a combination of the strong trans-influence of Ir-H σ-bonds and the stabilization of fac-IrO3H3 centers by spin-orbit coupling effects. Magnetization data indicate that Sr2Mn0.5Ir0.5O4 and Sr2Mn0.5Ir0.5O3.25H0.75 adopt spin glass states at low temperature, behavior which is attributable to the cation disorder in Sr2Mn0.5Ir0.5O4 and the cation and anion disorder in Sr2Mn0.5Ir0.5O3.25H0.75. In contrast, magnetization data collected from Sr2Mn0.5Ir0.5O2.66H1.33 show no evidence of any magnetic phase transition down to 5 K, consistent with the dilution of the magnetic network by the introduction of diamagnetic Ir3+ on the formation of the oxyhydride phase.

Ba3Ti0.4W1.6O8.6: An Oxygen- and B-Site-Deficient 9R Hexagonal Perovskite Exhibiting Triple Conduction.

The hexagonal perovskite derivatives Ba3M'M″O8.5 featuring a hybrid structure composed of 9R hexagonal perovskite and palmierite structure motifs exhibit significant oxide ionic conductivity due to the highly disordered oxide-ion and M-cation sublattices. Herein, we report the structure and electrical properties of the perovskite Ba3Ti0.4W1.6O8.6. Three-dimensional (3D) electron diffraction (ED), neutron powder diffraction (NPD), and neutron pair distribution functions (nPDF) revealed a 9R hexagonal perovskite structure for Ba3Ti0.4W1.6O8.6 with fully occupied central M2 sites, partially occupied outer M1 sites, and oxygen-deficient cubic c-BaO2.6 sublayers. These cation and oxygen arrangements differ significantly from those in Ba3M'M″O8.5 and enable Ba3Ti0.4W1.6O8.6 to capture atmospheric water and O2, resulting in triple conduction (oxide ion, proton, and hole) under wet air conditions. Proton and oxide ion conductions predominate at temperatures <400 and >650 °C in wet Ar and dry air, respectively. Bond-valence site energy calculations, together with structure analysis, deciphered that the two-dimensional oxide-ion diffusion pathways along the c-BaO2.6 layers are disrupted by the M1 vacancies, thereby resulting in relatively low oxide ionic conductivity. Our findings open up a new strategy of utilizing the cation's propensity of coordination geometry to design new oxygen- and B-site-deficient perovskites and thus achieve desired conductivity.

Metal–Organic Framework-Derived CeO2/Gold Nanospheres in a Highly Sensitive Electrochemical Sensor for Uric Acid Quantification in Milk

In this work, CeBTC (a cerium(III) 1,3,5-benzene-tricarboxylate), was used as a precursor for obtaining CeO2 nanoparticles (nanoceria) with better sensor performances than CeO2 nanoparticles synthesized by the solvothermal method. Metal–organic framework-derived nanoceria (MOFdNC) were functionalized with spheric gold nanoparticles (AuNPs) to further improve non-enzymatic electrode material for highly sensitive detection of prominent biocompound uric acid (UA) at this modified carbon paste electrode (MOFdNC/AuNPs&amp;CPE). X-ray powder diffraction (XRPD) and transmission electron microscopy (TEM) analysis were used for morphological structure characterization of the obtained nanostructures. Cyclic voltammetry and electrochemical impedance spectroscopy, both in an [Fe(CN)6]3−/4− redox system and uric acid standard solutions, were used for the characterization of material electrocatalytic performances, the selection of optimal electrode modifier, and the estimation of nature and kinetic parameters of the electrode process. Square-wave voltammetry (SWV) was chosen, and the optimal parameters of technique and experimental conditions were established for determining uric acid over MOFdNC/AuNPs&amp;CPE. Together with the development of the sensor, the detection procedure was optimized with the following analytical parameters: linear operating ranges of 0.05 to 1 µM and 1 to 50 µM and a detection limit of 0.011 µM, with outstanding repeatability, reproducibility, and stability of the sensor surface. Anti-interference experiments yielded a stable and nearly unchanged current response with negligible or no change in peak potential. After minor sample pretreatment, the proposed electrode was successfully applied for the quantification of UA in milk.

Green synthesized nano-TiO2 from Tamarindusindica leaf extract for photo-degradation of combination of dyes by suspension and immobilization on inert supports

ABSTRACT The present study aims to use green synthesized TiO2 as a photocatalyst in suspended and immobilized form under UV light to efficiently degrade a combination of reactive dyes, namely titan yellow, methyl orange, rhodamine B, and methylene blue. TiO2 nanoparticles (NPs) were synthesized using Tamarindus indica leaf extract and were utilized to parametrically study photo-degradation at room temperature. The green synthesized NPs were characterized by Powder XRD, SEM, and FTIR techniques to understand the crystalline phase/purity, morphology, and functional groups respectively. The TiO2 in suspension under UV light showed >90% degradation towards a 10 ppm composite dye at a loading of 1.5 gL−1, pH 7, and an irradiation time of 120 min. Subsequently, TiO2 was further immobilized in-situ, on inert supports of perlite granules and glass and studied for catalytic activity in batch and continuous modes. The TiO2 nanoparticles immobilized on perlite granules and glass showed 59 and 48% degradation in batch operation under the same conditions as in suspended form. In continuous mode, the highest degradation activity was recorded at 2 Lh−1 after 4 passes. Further, kinetic studies reveal that the degradation reaction is best described by Langmuir Hinshelwood kinetics for both suspended and immobilized TiO2.

A d10-Cd Cluster Containing Sandwich-Type Arsenotungstate Exhibiting Fluorescent Recognition of Carcinogenic Dye in Methanol

A d10-Cd cluster containing sandwich-type arsenotungstate [C3H12N2]6[Cd4Cl2(B-α-AsW9O34)2] was synthesized and its structure characterized through elemental analyses, X-ray powder diffraction (XRPD), IR spectroscopy, X-ray photoelectron spectroscopy (XPS), and single-crystal X-ray diffraction. The X-ray analysis revealed that the molecular unit of the compound consists of a captivating tetra-Cd-substituted sandwich-type polyoxoanion, accompanied by six elegantly protonated 1,2-diaminopropane as counter ions. The further novelty of the tetranuclear cadmium cluster lies in its occupied chlorine atom sites. This makes it highly susceptible to coordinate reactions with nitrogen on polycyclic aromatic hydrocarbons, thereby exhibiting different fluorescent signals that facilitate the identification and detection of these carcinogenic substances in methanol.

Quantifying the Hydration‐Dependent Dynamics of Cu Migration and Activity in Zeolite Omega for the Partial Oxidation of Methane

AbstractCopper‐exchanged zeolite omega (Cu‐omega) is a potent material for the selective conversion of methane‐to‐methanol (MtM) via the oxygen looping approach. However, its performance exhibits substantial variation depending on the operational conditions. Under an isothermal temperature regime, Cu‐omega demonstrates subdued activity below 230 °C, but experiences a remarkable increase in activity at 290 °C. Applying a high‐temperature activation protocol at 450 °C causes a rapid deactivation of the material. This behavioral divergence is investigated by combining reactivity studies, neutron diffraction and in situ high‐resolution anomalous X‐ray powder diffraction (HR‐AXRPD), as well as electron paramagnetic resonance spectroscopy, to reveal that the migration of Cu throughout the framework is the primary cause of these behaviors, which in turn is predominantly governed by the degree of hydration of the system. This work suggests that control over the Cu migration throughout the zeolite framework may be harnessed to significantly increase the activity of Cu‐omega by generating more active sites for the MtM conversion. These results underscore the power of in situ HR‐AXRPD for unraveling the behavior of materials under reaction conditions and suggest that a re‐evaluation of Cu‐zeolites priorly deemed inactive for the MtM conversion across a broader range of conditions and looping protocols may be warranted.

On the product phases and the reaction kinetics of carbothermic reduction of UO2+C at relatively low temperatures

The synthesis of UC using carbothermic reduction of UO2 and C mixtures has been well studied at high temperatures. However, the product phase behavior of carbothermic reduction at low temperatures (≤1773 K) is not well studied. Such a study is important as low temperatures permit single phase UC synthesis without forming secondary higher carbides, and it further supports the knowledge base of the process that needs to be used for transuranic elements such as plutonium that have high vapor pressures at elevated temperatures. Therefore, a low temperature carbothermic reduction of two different C/UO2 molar ratios under inert and reducing environments have been studied here. Two different sample holding crucibles, alumina (Al2O3) and graphite, were also used here to differentiate the hypostoichiometric (UC1-a) and oxygen dissolved (UC1-xOx) uranium monocarbide phases adding more details on the two systems. Also, the reaction kinetics involved in the formation of UC via the carbothermic reduction of UO2+C using product phases instead of evolved gases such as carbon monoxide is reported here. Under inert atmospheres but with significant oxygen partial pressures, the low temperature carbothermic reduction of UO2+C produced up to 90 wt.% UC1-xOx type oxycarbides as was confirmed by Xray powder diffraction. Reducing Ar-4%H2 environments at these temperatures were not successful in synthesizing UC as it reduces the amount of C required for the carbothermic reduction, leaving UC phase at a non-equilibrium state. Inert atmospheres with low or negligible oxygen partial pressures on the other hand produced near stoichiometric UC at high phase purity, especially at 1673 – 1773 K temperature range. An activation energy of 377±75 kJmol-1 was also calculated using product phase concentrations of the carbothermic reduction of UO2+C under these inert Ar(g) atmospheres.

Two new Mn-LMOF based on an AIEgens ligand for selective detection of Al3+ and other ions in aqueous solution

Two novel multifunctional chemical sensor Mn-LMOF, namely, [Mn2(TPPE)(ndc)2(H2O)]n (LMOF-1) and [Mn2(TPPE)(oba)2]n (LMOF-2) were solvothermally synthesized by introducing an AIE luminogens (AIEgens) ligand, 1,1,2,2-tetra[4-(pyridin-4-yl)phenyl]ethylene(TPPE), and analyzed by single crystal X-ray diffraction, thermogravimetric and powder X-ray diffraction and other methods. LMOF-1 and LMOF-2 have high stability and strong luminescence properties in solutions. The sensing experiments testify that LMOF-1 can be used as a selectively sensor for Al3+, with the limit of detection is 1.83 × 10−5 M. And LMOF-1 and LMOF-2 can identify Fe3+, CrO42− and Cr2O72− ions in aqueous solution, and LMOF-1 has a higher Ksv for all three ions than LMOF-2.

Synthesis of MOF@COF composites and study on dye adsorption properties

MOF@COF hybrid materials not only have high stability and adjustable function, but also have the characteristics of MOFs and COFs materials, which make them have important application value in the field of adsorption. This article employs 1,3,5-benzene tricarbonyl chloride and p-Phenylenediamine as covalent organic framework monomers. Through the in-situ growth of covalent organic frameworks (COF) on the surface of NH2-MIL-88(Fe) material, a novel, stable, and porous COF-on-MOF hybrid material (NH2-MIL-88(Fe)/COF) was synthesized. The structure, morphology, and performance of the hybrid material were thoroughly examined using characterization techniques, including Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). Subsequently, We explored the MOF@COF hybrid material as an effective adsorbent for removing organic dyes, namely methylene blue (MB), methyl orange (MO), and crystal violet (CV). The influence of various adsorption parameters, such as adsorption time, initial dye concentration, and different pH values, on dye adsorption performance was systematically investigated. Experimental results revealed that at pH = 7, NH2-MIL-88(Fe)/COF demonstrates maximum adsorption capacities of 114 mg·g−1, 106 mg·g−1, and 102 mg·g−1 for methylene blue, methyl orange, and crystal violet, respectively. The adsorption process follows pseudo-second-order kinetics and Langmuir isotherm models. Lastly, NH2-MIL-88(Fe)/COF maintains high removal efficiency for the three dyes even after five repeated uses, establishing it as a stable and efficient adsorbent. The research findings suggest that MOF@COF hybrid materials hold promising applications in the treatment of dye-containing wastewater.