Powder Diffraction Research Articles

Effect of Boron-Doping on Gate-Opening CO2 Adsorption in Zinc-Benzimidazolate Coordination Networks.

Flexible metal-organic frameworks (MOFs) have attracted much attention as selective gas adsorption and storage. This report describes boron doping in zeolitic imidazolate framework-7 (B-ZIF-7), which exhibits reversible phase transition during CO2 adsorption/desorption. We have successfully prepared B-ZIF-7 coordination networks using boron-bridged benzimidazolate (B(bim)4-) as organic ligands. Powder X-ray diffraction (PXRD) measurements and infrared spectroscopy revealed that B-ZIF-7 has a crystal structure similar to that of ZIF-7 while containing boron bridging in the coordination network. Since B-ZIF-7 forms a cationic coordination network, the guest anions are encapsulated within the pore. CO2 adsorption/desorption measurements at 300 K showed that B-ZIF-7(NO3), which contains nitrate ions (NO3-) as guest anions in its pores, exhibits a S-shaped CO2 adsorption/desorption isotherm, which is characteristic of gate-opening type MOFs. Compared with ZIF-7, B-ZIF-7(NO3) has superior CO2 adsorption capacity in the low-pressure and superior CO2 storage capacity. The CO2 adsorption and desorption behavior of B-ZIF-7(NO3) was analyzed by in situ temperature-controlled PXRD measurements and thermogravimetric analysis under a CO2 atmosphere, and a reversible phase transition was observed. We have also successfully prepared B-ZIF-7(Cl) and B-ZIF-7(OTf) (OTf = CF3SO3-) with different guest anions. The CO2 adsorption/desorption behaviors of B-ZIF-7(Cl) and B-ZIF-7(OTf) were significantly different from those of B-ZIF-7(NO3) and ZIF-7. B-ZIF-7(Cl) showed gate opening at a higher pressure than ZIF-7, and B-ZIF-7(OTf) did not show S-shaped CO2 adsorption isotherm and showed adsorption behavior in micropores. These results indicate that the CO2 adsorption behavior of B-ZIF-7 depends on the interaction between the guest anions and CO2 molecules or the cationic framework and the bulkiness of the guest anions. Boron doping in a coordination network with boron-bridged imidazolate ligands is a promising strategy to increase the gas adsorption capability of porous materials.

Amino-functionalizing Ce-based MOF for enhanced CO2 adsorption and selectivity.

Metal-organic frameworks (MOF) hold great promise for CO2 adsorption due to their high surface areas, tunable pore sizes, and the ability to modify their chemical properties to enhance CO2 affinity. MOFs tagged with functional groups either at linker or metal sites have shown improved CO2 uptake capacity and selectivity. This study focuses on investigating the potential of selective CO2 adsorption using amino functionalization of linker forming Ce-UiO-66. The physicochemical properties and characteristics of MOFs to determine the degree of amino functionalization and structural stability were examined using powder X-ray diffraction (PXRD), Fourier transformer infra-red (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and N2 porosimetry and specific surface area (BET). This work unveils a novel array of results on CO2, N2 and water vapour adsorption on Ce-UiO-66-NH2. The amino-functionalized Ce-UiO-66-NH2 shows 63 % higher CO2 uptake and 84 % higher CO2/N2 selectivity at 273 K and 1 bar over Ce-UiO-66. Ce-UiO-66-NH2 also shows excellent structural stability after gas and vapour sorption making Ce-UiO-66-NH2 potential adsorbent for CO2 capture.

Preparation of single crystals of palmatine-sulfophenyl acids pharmaceutical salts by substituting Cl− in palmatine chloride to improve hygroscopic stability and antibacterial activity of palmatine and to preserve its solubility

To enhance the hygroscopic stability of palmatine chloride (PMTCl) while maintaining its solubility, several unexplored pharmaceutical salts of palmatine (PMT) were synthesised using benzenesulfonic acid (PMT-BSA), p-toluenesulfonic acid (PMT-PTSA), and aminobenzenesulfonic acid (PMT-SUL). These novel salts were thoroughly characterized using techniques such as single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), infrared spectroscopy (IR), and Hirshfeld surface analysis to determine their structural properties. Surprisingly, it was discovered that these salts exhibited improved antibacterial activity in addition to their enhanced hygroscopic stability. As anticipated, all three pharmaceutical salts demonstrated improved hygroscopic stability. This improvement might be attributed, to some extent, to the introduction of safe, stable, and less electronegative anions (BSA, PTSA, and SUL) to replace the more electronegative chloride (Cl−) in PMTCl. The replacement of Cl− hindered the binding of the pharmaceutical with external water molecules, thus increasing its resistance to moisture. Moreover, the interaction between PMT and the anions from the benzenesulfonic acid group via hydrogen bonding might have played a role in the improved hygroscopic stability. The crystal structure formed by the PMT molecules exhibited long-range order, while the benzenesulfonic acid anions cleverly avoided potential binding sites for water molecules. Additionally, the antibacterial activities of all three pharmaceutical salts were enhanced. This improvement can be attributed to the alteration of electron cloud density (ρe) in the isoquinoline group of PMT upon the introduction of benzenesulfonate anions to form the pharmaceutical salts. This hypothesis was supported by analyzing the molecular electrostatic potential, electron cloud density, and Hirshfeld surface. The successful outcome of this study suggests that modifying the ρe of the isoquinoline group in protoberberines through the introduction of benzenesulfonic acid anions to form pharmaceutical salts can potentially alter their physicochemical properties and biological activities. This finding paves the way for future research on improving the physicochemical properties of protoberberines-based pharmaceuticals.

A Lead‐Free Tin Organic‐Inorganic Hybrid Material with Reversible Phase Transition and Fluorescent Properties

AbstractThis article reports a novel lead‐free phase‐transition material (C8H10ClN)2SnCl6 (1), which undergoes a high‐temperature phase change at close to 377 K. The multi temperature powder X‐ray diffraction (PXRD) also confirmed the phase transition occurred in compound 1. Significantly, compound 1 produces light emission at 452 nm. Variable temperature fluorescence studies indicate that the spectral emission maximum of compound 1 remains substantially fixed at 452 nm with increasing temperatures, implying the presence of a certain degree of photoluminescence stability in compound 1. Furthermore, compound 1 is characterized by exceptional semiconductor attributes, possessing a band gap of 3.76 eV. This pioneering study presents an innovative option for optimizing the growth and practical implementation of Sn (IV)‐based organic‐inorganic hybrid perovskite phase‐transition materials, and offers a strategic avenue to create novel lead‐free, eco‐friendly materials.

On the resolution of the three-axis neutron diffractometer setting optimized for some powder diffractometry studies

Presented three-axis neutron diffractometer performance documents the feasibility of using it in special cases high-resolution powder diffraction studies, namely, for elastic and plastic deformation studies of bulk polycrystalline samples when the whole powder diffraction spectrum is not required. Contrary to the conventional double-axis setting the suggested alternative consists of an unconventional three axis set-up employing a bent perfect crystal (BPC) monochromator and analyzer with a polycrystalline sample in between. The analysis of the profile of the beam diffracted by a sample is carried out by rocking the BPC-analyzer and the neutron signal is registered by a point detector. Though the diffractometer alternative is, for measurements, much more time consuming, its resolution is, however, substantially higher and permits also plastic deformation studies on the basis of analysis of the sample diffraction profiles. The so-called analyzer rocking curve then provides a sample diffraction profile and could reflect the lattice or structural changes. Moreover, much larger widths (up to 10 mm) of the irradiated gauge volumes can be investigated when just slightly affecting the resolution of the experimental setting.

Crystal structure of brimonidine hydrogen tartrate, (C11H11BrN5)(HC4H4O6)

Crystal structure of brimonidine hydrogen tartrate, (C₁₁H₁₁BrN₅)(HC₄H₄O₆)

Host-Host Interactions Enhanced the Structural Rigidity in a 6-Fold Interpenetrated Diamondoid Metal-Organic Framework Exhibiting C2H2/C2H4 Separation.

Multi-interpenetrated metal-organic frameworks (MOFs) have exhibited excellent performance in selective adsorption due to the variable post-interspersed flexibility, but the design and control remain challenging. Herein, two anthracene-based ligands, 4,4'-(anthracene-9,10-diyl)dibenzoic acid (H2L1) and 9,10-di(pyridin-4-yl)anthracene (L2), are used to construct a new three-dimensional 6-fold interpenetrated MOF [Zn(L1)(L2)]n (NBU-X1), which exhibits multiple C-H···π interactions that enhance the structural rigidity, thereby entangling with a C2H2/C2H4 separation performance. In this material, the incorporation of abundant anthracene rings within the framework not only partitions and restricts the pore window size to a quasi-double pore but also stabilizes it through host-host interactions. The structural stability upon heating or guest displacement/removal has been investigated by single-crystal X-ray diffraction and in situ variable-temperature powder X-ray diffraction, in contrast to the extreme flexibility of most multi-interpenetrated MOFs. The performance of purifying C2H4 from C2H2/C2H4 mixtures has been proved by dynamic breakthrough tests.

Reedmergnerite and stillwellite-(Ce) from the Dara-i-Pioz alkaline massif: insights into high-temperature behavior of borosilicates

Research subject. Reedmergnerite and stillwellite-(Ce) were obtained from the rocks of the Dara-i-Pioz alkaline massif located on the southern slope of the Alai Range in Tajikistan, which is characterized by the presence of rare mineral species including borosilicates and lithium minerals. Aim. To investigate the thermal behavior of reedmergnerite and stillwellite-(Ce) using high-temperature X-ray diffraction, including the determination of phase transition temperatures and expansion/compression of the unit cell parameters, as well as the calculation of thermal expansion coefficients. Materials and methods. Chemical analysis was performed using a TESCAN MIRA 3 microscope (EDS mode) and a JEOL JXA-8230 electron probe microanalyzer (WDS mode). High-temperature powder X-ray diffraction data were collected using a D8 ADVANCE Bruker diffractometer with an HTK16 heating chamber, covering temperatures from 30°C to 750°C in ambient air. Results. The thermal expansion coefficients of reedmergnerite and stillwellite-(Ce) were determined. Heating reedmergnerite resulted in slight changes in the unit cell parameters, with the parameter c experiencing the smallest change and the parameter a showing the greatest increase. The unit cell volume increased by 1.8% when heated to 750°C and returned to its initial value upon cooling. When stillwellite-(Ce) is heated in the temperature range of 400–450°C, a phase transition occurs, which is confirmed by previously recorded temperature values. The conducted heating and subsequent cooling experiments revealed that the volume and unit cell parameters of stillwellite-(Ce) did not fully revert to their original values. Conclusions. The coefficients of thermal expansion tensor (αij) of rhodmerdgnertite and stillwellite-(Ce) were investigated as a function of temperature using high-temperature in-situ experiments. The phases exhibited relatively low values of thermal expansion parameters compared to the general data for feldspars and borosilicates obtained from literature. These findings contribute to the understanding of the thermoelastic behavior of this group of minerals and their potential applications in various fields.

Flavone Cocrystals: A Comprehensive Approach Integrating Experimental and Virtual Methods.

The dapsone/flavone cocrystal system served as a benchmark for both experimental and virtual screening methods. Expanding beyond this, two additional active pharmaceutical ingredients (APIs), sulfanilamide and sulfaguanidine, structurally related to dapsone were chosen to investigate the impact of substituents on cocrystal formation. The experimental screening involved mechanochemical methods, slurry experiments, hot-melt extrusion, and the contact preparation method. The virtual screening focused on crystal structure prediction (CSP), molecular complementarity, hydrogen-bond propensity, and molecular electrostatic potentials. The CSP studies not only indicated that each of the three APIs should form cocrystals with flavone but also reproduced the known single- and multicomponent phases. Experimentally, dapsone/flavone cocrystals ACC, BCC, CCC, and DCC were reproduced, CCC was identified as a nonstoichiometric hydrate, and a fifth cocrystal (ECC), a t-butanol solvate, was discovered. The cocrystal polymorphs ACC and BCC are enantiotripically related, and DCC, exhibiting a different stoichiometric ratio, is enthalpically stabilized over the other cocrystals. For the sulfaguanidine/flavone system, two novel, enantiotripically related cocrystals were identified. The crystal structures of two cocrystals and a flavone polymorph were solved from powder X-ray diffraction data, and the stability of all cocrystals was assessed through differential scanning calorimetry and lattice energy calculations. Despite computational indications, a diverse array of cocrystallization techniques did not result in a sulfanilamide/flavone cocrystal. The driving force behind dapsone's tendency to cocrystallize with flavone can be attributed to the overall strength of flavone interactions in the cocrystals. For sulfaguanidine, the potential to form strong API···API and API···coformer interactions in the cocrystal is a contributing factor. Furthermore, flavone was found to be trimorphic.

Investigating the effect of lead substitution on the optical, electrical, and photoresponse properties of Quasi-2D double perovskites

Quasi-2-dimensional (2D) halide perovskites have recently attracted attention due to their higher operational stability as alternatives to 3-dimensional (3D) perovskites having exceptional optoelectronic and charge transport properties. To reduce the lead content, here following the double perovskite approach lead is substituted with silver and bismuth simultaneously, and three quasi-2D perovskites, with general formula (C7H10N)2Pb(1-2x)AgxBixBr4, (0 ≤ x ≤ 0.5) were prepared. The optical studies show that the partially lead substituted sample has the lowest optical band gap, aptly supported by the theoretical calculations. The powder X-ray diffraction technique along with field-emission scanning electron microscopy suggests enhancement in crystallinity along with the decrease in grain boundaries with the substitution of lead. The improvement in crystallinity with concomitant reduction in grain boundaries has led to the decrease in point defects as identified from the positron annihilation lifetime spectroscopy and coincidence Doppler broadening analysis. The tuned band gap, improved crystal quality along with lower defects jointly contributed to the enhancement in electrical properties of the perovskites with varying lead percentages. Finally, the photoresponse of all the materials was studied after fabricating metal (Al)-semiconductor (MS) junction thin film photodetector devices.

Structure – Catalytic Behavior Relationships in TiO2-Carbon Composite Supported Pt Electrocatalysts: A Case Study

Composite types of supports made of TiO2 and carbonaceous materials provide higher stability for the Pt electrocatalysts under the working conditions of polymer electrolyte membrane fuel cells than the traditional carbon supports. We have demonstrated in our previous work that composites with general formula of 75 wt.% Ti(1-x)MoxO2-25 wt.% C (x = 0–0.2; C = traditional Black Pearls (BP) carbon) were promising supports which provided increased stability for the Pt electrocatalysts. In this study, the effect of nitrogen doping of the carbonaceous component of the composite was explored. 75 wt.% TiO2-25 wt.% carbon composite supports were prepared using graphite oxide (GO), N-doped GO and N-doped multilayer graphene. Electrocatalysts were made by loading the supports with 20 wt.% Pt. The systems were compared based on their physicochemical properties determined by low-temperature nitrogen adsorption, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and conductivity measurements. The activity of the catalysts was investigated by conventional methods in a 3-electrode electrochemical cell. The results of various characterization methods contributed to the understanding of the difference in the electrochemical properties of N-free and N-containing catalyst samples. While GO was favorable for this composite supported catalyst, its N-doping strongly influenced the growth of TiO2, forming an almost continuous coating of small TiO2 crystals. This quasi-insulating TiO2 layer between the Pt catalytic sites and the conductive part of the composite resulted in poor electrochemical activity. Mixing the sample with carbon improved its conductivity, which resulted in a significant increase in the oxygen reduction activity.

Productizing Nano-Bioactive Glass-Based Bilayer Scaffolds: A Graft for Reconstruction of Mandibular and Femoral Bone Defects.

This investigation aimed to construct a bilayer scaffold integrating alginate and gelatin with nanobioactive glass (BG), recognized for their efficacy in tissue regeneration and drug delivery. Scaffolds, namely, alginate/gelatin (AG), alginate-/actonel gelatin (AGD), alginate actenol/gelatin-45S5 BG (4AGD), and alginate-actonel/gelatin-59S BG (5AGD), were assembled using a cost-effective freeze-drying method, followed by detailed structural investigation via powder X-ray diffraction as well as morphological characterization using field emission scanning electron microscopy (FESEM). FESEM revealed a honeycomb-like morphology with distinct pore sizes for nutrient, oxygen, and drug transport. The scaffolds evidently exhibited hemocompatibility, high porosity, good swelling capacity, and biodegradability. In vitro studies demonstrated sustained drug release, particularly for scaffolds containing actonel. In vivo tests showed that the bilayer scaffold promoted new bone formation, surpassing the control group in bone area increase. The interaction of the scaffold with collagen and released ions improved the osteoblastic function and bone volume fraction. The findings suggest that this bilayer scaffold could be beneficial for treating critical-sized bone defects, especially in the mandibular and femoral regions.

Oil palm waste-derived adsorbents for the sequestration of selected polycyclic aromatic hydrocarbon in contaminated aqueous medium

Carbonaceous adsorbents were synthesized from palm kernel shell and palm mesocarp fiber for the adsorption of phenanthrene (PHE) and the highly carcinogenic-benzo(a)pyrene (BaP). The structure and properties of the activated biochar were characterized using standardized analytical tools. The microscopic examinations carried out with SEM and BET results revealed mesoporous structures and interstitial spaces in the activated samples (AB-PKS and AB-PMS). Powder X-ray diffraction (PXRD) results showed that prepared sorbents are amorphous and that activation affected the amorphous cellulose on the surface of the microfibrils which led to a decrease in the intensity of some peaks. Fourier-transform infrared spectroscopy (FTIR) affirms the availability of surface moieties that may promote polycyclic aromatic hydrocarbon (PAH) removal or decontamination of aqueous media. The sorption isotherm and effect of pH on the adsorption of PHE and BaP onto the activated palm kernel shell (AB-PKS) and activated palm mesocarp fiber (AB-PMF) were investigated. The isotherm studies and error analysis (SSE and R2) confirm that the Freundlich model best fits experimental results for AB-PMF; while, the Langmuir model best describes AB-PKS sorption of BaP and PHE, respectively. The optimal removal efficiency for PHE was between 84 and 100% while that of BaP was between 68 and 87% with maximum adsorption capacity (qmax) of 19.38–21.98 mg/g and 1.24–13.26 mg/g, respectively. The optimum pH condition for removing PHE is less than 7 and above 7 for BaP. Therefore, the conversion of waste materials to useful sorbents, as well as preliminary adsorption test results obtained suggests a cleaner and cost-effective pathway for waste management and water treatment.

Exploring the Influence of Cation and Halide Substitution in the Structure and Optical Properties of CH3NH3NiCl3 Perovskite.

This manuscript details a comprehensive investigation into the synthesis, structural characterization, thermal stability, and optical properties of nickel-containing hybrid perovskites, namely CH3NH3NiCl3, CsNiCl3, and CH3NH3NiBrCl2. The focal point of this study is to unravel the intricate crystal structures, thermal behaviors, and optical characteristics of these materials, thereby elucidating their potential application in energy conversion and storage technologies. X-ray powder diffraction measurements confirm that CH3NH3NiCl3 adopts a crystal structure within the Cmcm space group, while CsNiCl3 is organized in the P63/mmc space group, as reported previously. Such structural diversity underscores the complex nature of these perovskites and their potential for tailored applications. Thermal analysis further reveals the stability of CH3NH3NiCl3 and CH3NH3NiBrCl2, which begin to decompose at 260 °C and 295 °C, respectively. The optical absorption properties of these perovskites studied by UV-VIS-NIR spectroscopy revealed the bands characteristic of Ni2+ ions in an octahedral environment. Notably, these absorption bands exhibit subtle shifts upon bromide substitution, suggesting that optical properties can be finely tuned through halide modification. Such tunability is paramount for the design and development of materials with specific optical requirements. By offering a detailed examination of these properties, the study lays the groundwork for future advancements in material science, particularly in the development of innovative materials for sustainable energy technologies.

Toward an understanding of the role of structural organization and point defects in the formation of functional pure and Tm3+-doped (Ca3-xSrx)(VO4)2 for diode-pumped and SRS lasers

Whitlockite-type polycrystalline and single-crystal (Ca3−xSrx)(VO4)2 solid solutions were successfully obtained by solid-state synthesis and Czochralski method, respectively. Synchrotron powder X-ray diffraction allowed to reveal actual compositions of polycrystalline (Ca3−xSrx)(VO4)2 solid solutions with х = 0.3, 0.54, 0.9, 1.2, 1.35 refined by Rietveld method, which are slightly different from the initial ones. Synchrotron X-ray single-crystal diffraction analysis of Czochralski-grown undoped (Ca1.8Sr1.2)(VO4)2 (CSVO) revealed its actual composition (Ca2.982(11)Sr0.031)(VО4)2. Difference between initial and refined compositions is analyzed and discussed. In the CSVO structure, Sr2+ ions partially occupy monocapped Ca2 and two-capped Ca3 trigonal prismatic sites and Ca2+ ions are in the Ca5 and Ca5A sites, forming two independent strongly distorted tetrahedral Ca5O4 and octahedral Ca5AO6 oxygen environments. Synchrotron X-ray single-crystal diffraction analysis together with X-ray absorption spectroscopic study of (Сa2.4Sr0.6)(VO4)2 doped with 0.5 and 1.0 wt% Tm2O3 (СSVO:0.5Tm and CSVO:1.0Tm) allowed to establish the absence of cations in the Ca5A site, the localization of Sr2+ ions in the Ca2 and Ca3 sites and additionally in octahedral Ca4 site together with Tm3+ ions, forming an individual eight-coordinated environment, in the refined compositions (Ca2.776(7)Sr0.210(4)Tm3+0.008(1))(VO4)2 and (Ca2.855(7)Sr0.140(7)Tm3+0.009(1)□0.022(7))(VO4)2, respectively, with vacancies (marked by a square,□) in the two-capped Ca1 trigonal prismatic site in the CSVO:1.0Tm structure. Additional interstitial oxygen, participating in the formation of the Tm3+ environment, found in the residual electron density, together with vacancies in the Ca1 site provides electroneutrality to CSVO:0.5Tm and CSVO:1.0Tm crystals. Several structural models of the coordination environment of Tm3+ ions were analyzed and the most correct one was proposed.

Giant dielectric tunability in ferroelectric ceramics with ultralow loss by ion substitution design

Due to their responsiveness to modulation by external direct current fields, dielectric tunable materials are extensively utilized in integrated components, such as ferroelectric phase shifters. Barium strontium titanate ceramics have been considered the most potential tunable materials for a long time. However, the significant dielectric loss and high voltage drive have limited their further applications. Recently, Bi6Ti5WO22 ceramic has regained attention for its high dielectric tunability with low loss. In this study, we judiciously introduce Nb5+ with a larger ionic radius, replacing Ti4+ and W6+. This successful substitution enables the modulation of the phase transition temperature of Bi6Ti5WO22 ceramics to room temperature, resulting in superior tunable properties. Specifically, the 0.7Bi6Ti5WO22−0.3Bi6Ti4Nb2O22 ceramics exhibit giant tunability (~75.6%) with ultralow loss (<0.002) under a low electric field (1.5 kV/mm). This tunability is twice that of barium strontium titanate ceramics with a similar dielectric constant and only one-tenth of the loss. Neutron powder diffraction and transmission-electron-microscopy illustrate the nanodomains and micro-strains influenced by ion substitution. Density functional theory simulation calculations reveal the contribution of ion substitution to polarization. The research provides an ideal substitute for tunable material and a general strategy for adjusting phase transition temperature to improve dielectric properties.

Highly efficient peanut shell activated carbon via hydrothermal carbonization and chemical activation for energy storage applications

In this study, the activated carbon samples from peanut shells (PS) are synthesized through hydrothermal carbonization (HTC) with and without activating agents, and their electrochemical properties are studied for supercapacitor applications. The raw precursor (PS) powder is loaded with an activating agent (ZnCl2 or H3PO4 or KOH) during the hydrothermal treatment at 200 °C for 7 h. The treatment with the activating agent facilitates the generation of oxygen-containing functional groups on the precursor surface, enhancing the porosity and electrochemical performance of the sample. Further, the samples are subjected to carbonization at 400 °C for 3 h. The powder XRD patterns show peaks at around 24–26° and 43°, corresponding to the amorphous and graphitic carbon, respectively. The morphological examination reveals more meso and macro pores when treated with the activating agent. Raman spectra manifest the amorphous carbon nature of the samples exhibiting ID and IG bands. The porous carbon treated with H3PO4 shows a specific surface area of 17.8 m2/g and a pore volume of 0.037 cm3g−1. The H3PO4 treated sample shows a high specific capacity (Cs) of 240 F/g at 1 A/g current density, an energy density (E) of 4.08 W h kg−1, and a power density (P) of 101.3 W kg−1. The Retention rate of the sample is approximately 90 % up to 1200 cycles. These types of hybrid supercapacitor materials are suitable for battery-type applications.

Negative thermal expansion of β-Rb&lt;sub&gt;2&lt;/sub&gt;SO&lt;sub&gt;4&lt;/sub&gt;

Research subject. The low-temperature modification of β-Rb2SO4 sulfate (Pmcn). Aim. Low-temperature study of the thermal expansion of β-Rb2SO4 by high-temperature powder X-ray diffraction in comparison with the crystal structure, as well as interpretation of the anisotropy of β-Rb2SO4 thermal expansion. Materials and Method. Powder X-ray diffraction and high-temperature powder X-ray diffraction. Results. The thermal expansion of β-Rb2SO4 sulfate was studied for the first time using low-temperature powder thermal X-ray diffraction in comparison with the crystal structure. The phase composition was confirmed by powder X-ray diffraction. The thermal expansion of β-Rb2SO4 is practically isotropic. Across the temperature range from –177 to –140°C, the sulfate experiences negative thermal expansion. A further increase in temperature leads to a change in its thermal expansion, which becomes positive. It is proposed to consider the crystal structure of β-Rb2SO4 sulfate as a mixed framework of [RbSO4]–1, which, in turn, consists of fundamental building units (microblocks) of Rb(SO4)6. Across the temperature range from room temperature to –100°C, the maximum expansion of β-Rb2SO4 sulfate occurs along the a axis. The minimum thermal expansion is observed along the c-axis, along the columns consisting of microblocks (αa = 65.4(3)∙10–6°C–1, αb = 59.7(2)∙10–6°C–1, αc = 58.6(2)∙10–6°C–1 at +25°C). In the temperature range from –177 to –140°C, thermal expansion is negative in all three directions (αa = –10.3(3)∙10–6°C–1, αb = –8.6(2)∙10–6°C–1, αc = –9.7(2)∙10–6°C–1 at –170°C). Conclusion. The thermal expansion of β-Rb2SO4 sulfate in the low-temperature range (from –177 to –25°C) was studied for the first time, its structural interpretation was performed. A comparison was given with the thermal expansion of isostructural β-K2SO4.

A quinoline derivative-based supramolecular gel for fluorescence ‘turn-off’ detection of Fe3+ and Cu2+

In this research, we synthesized and constructed a novel gelator (named QN) combining quinoline and naphthalene that self-assembled in N, N-dimethylformamide (DMF) to form a stable supramolecular gel (named OQN). Under UV light, gel OQN exhibited extremely bright yellow fluorescence. The gel OQN showed excellent sensing performance for both Fe3+ and Cu2+, with a fluorescence ‘turn-off’ detection mechanism and the lowest detection limit of 7.58 × 10−8 M and 1.51 × 10−8 M, respectively. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra, x-ray powder diffraction (XRD), rheological measurements, x-ray photoelectron spectroscopy (XPS), and fluorescence spectroscopy were used to characterize the gel OQN. The OQN ion-responsive membrane created is an excellent fluorescent writing material.

Facile and green hydrothermal synthesis of MgAl/NiAl/ZnAl layered double hydroxide nanosheets: a physiochemical comparison

Abstract Layered double hydroxide (LDH) exhibits a remarkable trait referred to as the ‘memory effect,’ demonstrating its capacity to reconstruct its layered structure from calcined oxides through hydrothermal treatment. Its uniqueness has garnered significant interest from researchers in both industrial and academic domains. Various methods have been utilized to synthesize LDH but most LDH studies still utilize alkali precipitants which might taint the final LDH product. Thus, in this study, layered double hydroxides involving MgAl/NiAl/ZnAl were synthesized via an alkali-free hydrothermal approach in which the formed precipitates of LDH were thermally destroyed via calcination at 450 °C before undergoing a rehydration treatment at 110 °C for 24 h to restore its original structure. Particularly, the physiochemical properties of MgAl/NiAl/ZnAl LDH have been undertaken by multiple techniques such as Powder X-ray Diffraction (PXRD), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), Field Emission Scanning Electron Microscope (FESEM) and Fourier-transform infrared spectroscopy (FTIR). The resultant products exhibited exceptional crystallinity, accompanied by notably larger crystallite sizes and crystallinity index, particularly post-hydrothermal treatment. Among the fresh and calcined products studied, those subjected to HTM (4:1) treatment demonstrated the highest specific surface area and crystallinity surpassing both the fresh and calcined samples. In essence, this research showcased how utilizing the hydrothermal approach resulted in the most substantial increase in crystallite size and specific surface area.