Search Results (1,864)

A series of nickel (II) bis-phosphine organometallic complexes along with two pseudo [M₇] (M = Ni(II), Zn(II)) metallocalix[6]arene complexes and a dysprosium acetate coordination polymer have each been crystallised in the presence of localized magnetic fields set up using neodymium magnets, using custom made Magnetic Crystallization Towers (MCTs). In all cases, whether the product complex is diamagnetic or paramagnetic, a complex spatial patterning of the crystals occurs based on the orientation of the magnetic field lines. When using magnetic block towers, the crystallization generally occurs adjacent to the magnet face. The effects of nucleation and solution concentration gradients on the crystallization process are also explored. These observations show how the crystallization process is affected by magnetic fields and thus these results have far-reaching effects which most certainly will include crystallization and ion migrations in biology. Full article

One of the most critical environmental needs is to remove metal ions from industrial wastewater. In this investigation, chitosan modified by cyanoguanidine (CCs) was employed for the first time to adsorb cupric ions. The optimal conditions for eliminating cupric ions were adsorbent dose = 0.015 g, cupric ion concentration = 0.2 g L⁻¹, pH = 6, and temperature = 25 °C. The adsorption kinetics fit the pseudo-second-order model, showing a value of correlation coefficient (R²) of 1.00, which is the highest. The experimental q_e value was determined to be 99.05 mg g⁻¹, which is comparable to 100 mg g⁻¹ (the theoretical one). The adsorbent’s removal efficacy was 96.05%, and the adsorption isotherms, which conform to the Freundlich model, show that adsorption is multi-layered and homogeneous. The chemosorption and physisorption processes are major factors in the elimination of copper ions. Therefore, a good approach to generate an appropriate efficient adsorbent, which is a good alternative approach in cupric ion elimination, is to incorporate cyanoguanidine, which possesses additional binding sites for cupric ions between chitosan chains. Further, the mechanism of Cu²⁺ adsorption onto CCs was proposed on the basis of FTIR analysis and computational studies. Full article

Pre-lithiation using Li–Si alloy-type additives is a promising technical approach to address the drawbacks of Si-based anodes, such as a low initial Coulombic efficiency (ICE) and inevitable capacity decay during cycling. However, its commercial application is limited by the air sensitivity of the highly reactive Li–Si alloys, which demands improved environmental stability. In this work, a protective membrane is constructed on Li₁₃Si₄ alloys using low-surface-energy paraffin and highly conductive carbon nanotubes through liquid-phase deposition, exhibiting enhanced hydrophobicity and improved Li⁺/e⁻ conductivity. The Li₁₃Si₄@Paraffin/carbon nanotubes (Li₁₃Si₄@P-CNTs) composite achieves a high pre-lithiation capacity of 970 mAh g⁻¹ and superb environmental stability, retaining 92.2% capacity after exposure to ambient air with 45% relative humidity. DFT calculations and in situ XRD measurements reveal that the paraffin-dominated coating membrane, featuring weak dipole–dipole interactions with water molecules, effectively reduces the moisture-induced oxidation kinetics of Li₁₃Si₄@P-CNTs in air. Electrochemical kinetic analysis and XPS depth profiling reveal the enhancement in charge transfer dynamics and surface Li⁺ transport kinetics (SEI rich in inorganic lithium salts) in P-SiO@C pre-lithiated by Li₁₃Si₄@P-CNTs pre-lithiation additives. Benefitting from pre-lithiation via Li₁₃Si₄@P-CNTs, the pre-lithiated SiO@C(P-SiO@C) delivers high ICE (103.7%), stable cycling performance (981 mAh g⁻¹ at 200 cycles) and superior rate performance (474.5 mAh g⁻¹ at 3C) in a half-cell system. The LFP||P-Gr pouch-type full cell exhibits a capacity retention of 83.2% (2500 cycles) and an energy density of 381 Wh kg⁻¹ after 2500 cycles. The Li₁₃Si₄@P-CNTs additives provide valuable design concepts for the development of pre-lithiation materials. Full article

The rapid growth of industrial activities has increased environmental pollution, and solar-driven heterogeneous photocatalysis using TiO₂ has emerged as a promising solution. However, its wide band gap limits its efficiency, prompting research into various optimization strategies. One of these approaches is surface functionalization. Thus, this study investigates the adsorption of CuSO₄ on the anatase TiO₂ (101) surface using density functional theory calculations. The adsorption process induced a magnetic moment of 0.97 µ_B and a slight reduction in overall bandwidth. A preferential adsorption geometry pattern with an energy of −4.31 eV was identified. Charge transfer analysis revealed a net transfer from the TiO₂ surface to the CuSO₄ molecule, with increased net atomic charges for atoms involved in new chemical bond formation, indicating a chemisorption process. These electronic structure modifications are expected to influence the electronic and catalytic properties of the material. The findings provide insights into the CuSO₄ adsorption mechanism on an anatase TiO₂ (101) surface and its impact on the properties of the material, contributing to a deeper understanding of this system. Full article

The primary aim of this research was to identify the optimal experimental conditions for obtaining aligned carbon nanotubes, temporarily leaving aside aspects such as the purity of carbon nanotubes, which is nonetheless crucial for potential applications in the field of nanoelectronics. The predefined alignment of CNTs can significantly influence the performance and efficiency of electronic components. In this study, two different catalytic supports based on cobalt nanoparticles, Co/SiO₂/Si and Co/C, have been utilized and compared in the catalytic chemical vapor deposition (CCVD) synthesis of CNTs. Various parameters have been examined, including the nature and thickness of the catalyst, the reaction temperature, and the pressure of the acetylene mixture entering the reactor. The results indicate that the optimal temperature for the Co/SiO₂/Si catalyst is 800 °C, while for the Co/C catalyst, it is 450 °C. The optimal Co layer thickness should be between 20 and 30 Å. CNT growth occurs from the top in the Co/C system, whereas bottom-up growth is characteristic of the Co/SiO₂/Si catalyst, making the latter more suitable for the synthesis of CNTs intended for nanoelectronic devices. Full article

Crystal violet dye poses significant environmental and human health risks due to its toxicity, persistence, and bioaccumulative nature. It contributes to potential carcinogenicity, cytotoxicity, and systemic toxicity upon human exposure. To address this issue, a novel SrCO₃/MgO/CaO/CaCO₃ nanocomposite was synthesized using the Pechini sol-gel method, producing AE500 and AE700 at 500 and 700 °C, respectively, for the efficient removal of crystal violet dye from aqueous media. X-ray diffraction (XRD) analysis confirmed the formation of crystalline phases, with average crystallite sizes of 64.53 nm for AE500 and 75.34 nm for AE700. Energy-dispersive X-ray spectroscopy (EDX) revealed elemental compositions with variations in carbon, oxygen, magnesium, calcium, and strontium percentages influenced by synthesis temperature. Field-emission scanning electron microscopy (FE-SEM) showed morphological differences, where AE500 had irregular polyhedral structures, while AE700 exhibited more compact spherical formations, with average grain sizes of 99.98 and 132.23 nm, respectively. High-resolution transmission electron microscopy (HR-TEM) confirmed the structural integrity and nano-scale morphology, showing aggregated irregularly shaped particles in AE500, while AE700 displayed well-defined polyhedral and nearly spherical nanoparticles. The calculated average particle diameters were 21.67 nm for AE500 and 41.19 nm for AE700, demonstrating an increase in particle size with temperature. Adsorption studies demonstrated maximum capacities of 230.41 mg/g for AE500 and 189.39 mg/g for AE700. The adsorption process was exothermic, spontaneous, and physical, following the pseudo-first-order kinetic model and Langmuir isotherm, indicating monolayer adsorption onto a homogenous surface. Full article

Pt catalysts are investigated for methanol oxidation in direct methanol fuel cells, utilizing the electrochemical quartz microbalance method (EQCM) with exceptional resolution and sensitivity. Pt catalysts were deposited onto the gas-diffusion layer of carbon using stationary potential electrodeposition. Physical characterization and electrochemical tests were performed. SEM results showed that Pt presented dendrite crystals with nanoscale facets. Cyclic voltammetry (CV) demonstrated that the current density for the methanol oxidation reaction highly reached 1020 mA·cm⁻² for the deposited Pt catalyst by EQCM. The dendrite crystal structures of deposited Pt provide much area for high catalytic activity. It found that the peak density of the Pt catalysts for the methanol oxidation reaction decreased after five cycles. Furthermore, the response frequency for the adsorption of the deposited Pt catalysts was investigated using EQCM and compared with commercial PtRu catalysts. The results showed that the response frequency of the Pt catalysts decreased more rapidly than that of the PtRu catalysts. It is possible for the adsorption of small organic molecules on Pt catalysts to occur during the methanol electro-oxidation with CO_ad intermediates. The reaction mechanism is preliminarily discussed by the electrochemical measurement combined with EQCM. Full article

In order to design antimicrobial species, a series of methacrylate (Macr) complexes, [Cu(HBzIm)₂(Macr)₂] (1), [Cu₂(HBzIm)₂(Macr)₄] (2), [Cu(2-MeBzIm)₂(Macr)₂] (3), [Cu₂(2-MeBzIm)₂(Macr)₄] (4), and [Cu(5,6-Me₂BzIm)₂(Macr)₂] (5) (HBzIm = benzimidazole, 2-MeBzIm = 2-methylbenzimidazole, and 5,6-Me₂BzIm = 5,6-dimethylbenzimidazole) were synthesized and characterized by several spectral techniques, as well as by single crystal X-ray diffraction. The mononuclear species exhibit a distorted octahedral stereochemistry, while the binuclear types, with a paddle-wheel structure, adopt a square pyramidal surrounding. The methacrylate acts either as a chelate or a bridge, while all benzimidazole derivatives are coordinated as unidentate. The supramolecular networks are developed by both intermolecular π–π stacking interactions and hydrogen bonds. The antimicrobial assays provided both complexes the ability to inhibit planktonic strain proliferation, as well as to adhere on inert substratum. All complexes exhibit a moderate antimicrobial activity, both in regards to standard and clinical isolate strains, the most active being compound 5 against Candida albicans, with a minimum inhibitory concentration (MIC) of 0.156 mg/mL. It is worth mentioning that complex 1 inhibited the microbial adhesion of the clinical Escherichia coli strain and complex 2 constrained that of the clinical C. albicans strain. Full article

Two-dimensional (2D) metal-halide perovskites with highly efficient room-temperature phosphorescence (RTP) are rare due to their complex structures and intricate intermolecular interactions. In this study, by varying the alkyl chain length in organic amines, we synthesized two 2D metal-halide perovskites, namely 4-POMACC and 4-POEACC, both of which exhibit significant RTP emission. Notably, 4-POMACC demonstrates a stronger green RTP emission with a significantly longer lifetime (254 ms) and a higher photoluminescence quantum yield (9.5%) compared to 4-POEACC. A thorough investigation of structural and optical properties reveals that shorter alkyl chains can enhance the optical performance due to reduced molecular vibrations and more effective exciton recombination. Computational calculations further show that the smaller energy gap between S₁ and T_n in 4-POMA facilitates intersystem crossing, thereby improving RTP performance. Based on their remarkable phosphorescence properties, we demonstrated their applications in information encryption. This work offers a novel design strategy that could inspire the development of next-generation RTP materials. Full article

The effects of CoFe₂O₄ nanoparticles on the properties of an electro-optical liquid crystal cell based on the nematic composition of 4-Cyano-4′-pentylbiphenyl (5CB) under the influence of different forms of bias voltage were studied. Detailed results were established for the application of sinusoidal voltages with various frequencies and amplitudes. At the input signal, with a frequency of 500 kHz, a resonant current increase was obtained in the electrical circuit, followed by a decrease in the current with an increase in the frequency. This indicates the formation of a consistent oscillatory circuit. The quality factor of the nanoparticle system does not depend on the amplitude of the controlled voltage. Liquid crystal cells with constant quality can be used in a number of devices and technologies, including extended sensing devices, where stable electrical properties are required. Full article

Chemical–structural characteristics of three differently synthesized research-benchmark Mn-Na-W-O_x/SiO₂ catalysts for the Oxidative Coupling of Methane (OCM) were systematically studied in this research. XRD, EDX, ICP-OES, and SEM/FIB-SEM techniques, as well as Carrier Gas Hot Extraction (CGHE) and high-temperature XRD analyses, were performed to explain the functional features of the studied catalysts, in particular, the features affecting the quantity and quality of the interactions of oxygen and methane with the catalyst surface and with other molecular and radical species. These enable tracking the potential for the oxygen activation and dynamic transformation of the solid-state chemistry on the surface and sub-surface of these Mn-Na-W-O_x/SiO₂ catalysts. These catalysts were synthesized, respectively, via the sol–gel synthesis method (Cat₁) and the incipient wetness impregnation of the non-structured silica support (Cat₂) and structured SBA-15 silica support (Cat₃), under different sets of temperatures and gas compositions. The catalysts with the homogenous distribution of active components, namely Cat₁ and Cat₃, showed similar trends in terms of their dynamic interaction with oxygen species. They also showed higher levels of crystallinity of the active materials and higher catalytic selectivity towards ethane and ethylene. An explanation is given as to how the structural characteristics of the catalysts on the nanometer–micrometer scale contribute to these. The gained knowledge will be crucial in the selection and treatment of the support and developing a proper synthesis approach for the ultimate goal of designing a selective OCM catalyst. Full article

This study explores the enhancement of antimicrobial and biomedical properties in Fe-based bulk metallic glasses (BMGs) through the addition of Ag. Fe_55-xCr₂₀Mo₅P₁₃C₇Ag_x (x = 0, 1, 2, 3 at.%) master alloy ingots were synthesized by the induction melting technique and industrial-grade raw materials, the master alloy ingots were prepared as bulk metallic glasses (referred to as Ag0, Ag1, Ag2, and Ag3) by the water-cooled copper-mold suction casting technique, and their glass-forming ability, corrosion resistance, biocompatibility, and antimicrobial properties were systematically investigated. The results indicate that the glass forming ability (GFA) decreased with increasing Ag content, reducing the critical diameter for fully amorphous formation from 2.0 mm for Ag0 to 1.0 mm for Ag3. Electrochemical tests in Hank’s solution revealed the superior corrosion resistance of the Fe-based BMGs as compared with conventional 316 L stainless steel (316L SS) and Ti6Al4V alloy (TC4), with Ag3 demonstrating the lowest corrosion current density and the most stable passivation. Biocompatibility assessments, including fibroblast cell viability and adhesion tests, showed enhanced cellular activity and morphology on Fe-based BMG surfaces as compared with 316L SS and TC4, with minimal harmful ion release. Antimicrobial tests against E. coli and S. aureus revealed significantly improved performance with the Ag addition, achieving bacterial inhibition rates of up to 87.5% and 86.7%, respectively, attributed to Ag⁺-induced reactive oxygen species (ROS) production. With their excellent corrosion resistance, biocompatibility, and antimicrobial activity, the present Ag-containing Fe-based BMGs, particularly Ag3, are promising candidates for next-generation biomedical implants. Full article

Coordination-driven Cu(I) complexes constitute an interesting class of materials with rich opto-electronic properties and diverse applications. Various homo- and heteroleptic Cu(I) complexes have been reported in the literature. In continuation with our quest for new materials, we report herein two novel coordination-driven self-assembled Cu(I) complexes: the homoleptic (1) and the heteroleptic (2) complexes based on the 6,6′-bis(phenylethynyl)-2,2′-bipyridine (L1) and 2,9-dimethyl-1,10-phenanthroline (dmph) ligands. L1 was prepared by a Pd(II)-catalyzed Sonogashira cross-coupling reaction between phenylactylene and 6,6′-dibromo-2,2′-bipyridine. Homo- and heteroleptic Cu(I) complexes were obtained by the self-assembly of L1 and dmph ligands. Complexes (1) and (2) were obtained in high yields, and are soluble in common organic solvents and stable at room temperature over a long period of time. The optical (absorption and emission) properties of both complexes were evaluated. The optical properties in solution are a function of the ligands and varied for the complexes. Complex (2) was also characterized by single-crystal X-ray diffraction and the intermolecular interaction was studied using Hirschfeld surface analysis. In the solid state, complex (2) exhibited four-coordinate distorted tetrahedral geometry around Cu(I). Density functional theory (B3LYP/6-311++G(d,p) was utilised to determine various molecular descriptors. Full article

The block layer situated between the active material and electrode in photoelectrochemical devices serves as a critical component for performance enhancement. Using dye-sensitized solar cells as a representative model, this review systematically examines the strategic positioning and material selection criteria of block layers following a concise discussion of their fundamental mechanisms. We categorize block layer architectures into three distinct configurations: single layer, doped layer, and multilayer structures. The electron generation and transport mechanisms to photoelectrodes are analyzed through structural design variations across these configurations. Through representative literature examples, we demonstrate the correlation between material properties and photoconversion efficiency, accompanied by comprehensive performance comparisons. In the single-layer section, we comparatively evaluate the merits and limitations of TiO₂- and ZnO-based block layers. The doped layer discussion traces the evolutionary trajectory from single-dopant systems to co-doping strategies. For multilayer architectures, we elaborate on the flexibility of its functional regulation. Finally, we present a forward-looking perspective on the hot issues that need to be urgently addressed in photoelectrochemical device block layers. Full article