Materials Advances最新文献

Efficient synthesis of extended π-conjugated systems containing sulphur-rich aromatics is of special interest for organic electronics. Herein, we report the synthesis of new π-conjugated 5,5′-diphenyl-2,2′-bithiophene-based tricatenars. The materials have the same aromatic backbone ending at one terminus with a 3,5-diheptyloxy substituted-benzene ring and a single hexyloxy chain at the other end. They differ from each other in the halogen substitution pattern used at the single alkylated end, where fluorine at different positions was used. The fluorine atom was also replaced by chlorine or bromine atoms to investigate the effect of different types of halogen substituents on the phase behaviour. The molecular self-assembly of the materials was investigated using differential scanning calorimetry, polarized optical microscopy, X-ray diffraction and fluorescence techniques. Depending on the type and position of the halogen substituent, different types of mesophases were observed, including nematic, smectic, and chiral isotropic liquid phase (Iso₁^[*^]) and achiral double-gyroid bicontinuous cubic phases with a double helical network structure and Iad symmetry. In particular, the steric effect of halogen substituents adapts two different molecular packing for the cubic phase with local helicity and short-range order, respectively. All materials are fluorescent active, and their fluorescence behaviour could be altered by the type and position of the halogen substituent. Thus, this report provides new functional materials, which could be of interest for optoelectronic applications.

Anhydrous and hydrated UF₄ microrods (5–25 μm) were prepared from the reactions of UO₂ microrods (5–15 μm) with HF(g), produced from the decomposition of silver bifluoride (AgHF₂, SBF). In order to optimize the preparation of UF₄ mr, several experimental parameters including atmosphere (air or N₂), temperature (150 or 250 °C) and amount of SBF were evaluated. In all reactions, rodlike morphologies were retained. At 250 °C, the reaction products always consist of an anhydrous UF₄/hydrated UF₄ mixture, while at 150 °C only hydrated UF₄ was detected. Anhydrous UF₄ microrods were obtained by dehydration of the anhydrous UF₄/hydated UF₄ mixture using TGA-DSC. Changing the atmosphere from air to N₂ or reducing the amount of SBF by half did not affect the nature of the reaction products.

This comprehensive review delves into the critical relationship between process, structure, and properties in the context of manufacturing neodymium (NdFeB) permanent magnets using laser powder bed fusion (LPBF) technology. The article systematically explores how LPBF process parameters influence microstructural characteristics and, in turn, affect the magnetic performance of NdFeB magnets. Key areas of focus include the optimization of processing techniques, the selection and characteristics of material feedstock, and the microstructural features that are crucial to achieving desired magnetic properties. The review emphasizes how specific variations in LPBF processing can result in microstructures that either enhance or impair magnetic performance, providing valuable insights into the development of more efficient manufacturing strategies.

Merocyanines are polar organic π-conjugated molecules consisting of electronic donor (D) and acceptor (A) subunits connected via a conjugated bridge. They have been investigated because of their unique self-assembly and optoelectronic properties, making them ideal active materials for organic electronic applications. The understanding of their charge transport properties at the nanoscale is very challenging and mostly an unexplored field. We report a theoretical study on modelling the hole transport parameters and mobility, together with the investigation of the structure–property relationships of seven merocyanine single crystals, consisting of different combinations of D–A units. We critically discuss the impact of both static (energetic) and dynamic (thermal) disorder effects on charge mobility and transport networks, by emphasizing the importance of including such contributions for an in-depth understanding of the charge transport properties of polar organic semiconductors.

The development of efficient and durable catalysts for the oxygen evolution reaction (OER) is urgent for renewable and sustainable energy storage and conversion. High-entropy oxides (HEOs) have gained significant attention for OER electrocatalysis owing to their multielement synergy and tunable electronic structure. The presence of multiple cations and anions in HEOs’ crystal structure leads to a slow diffusion effect, lattice distortion, high configurational entropy, and cocktail effect. The high configurational entropy of HEOs reveals outstanding electrochemical activity due to the large number of active sites compared with their individual counterparts. Herein, a series of equimolar (quaternary, quinary, and senary) and non-equimolar HEOs were fabricated using a rapid microwave irradiation method. The crystal structure, morphology, elemental composition and oxidation states of the HEOs were explored via different physical characterizations. The OER activity of the HEOs was investigated through cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). All the prepared HEOs demonstrated outstanding OER activity, where the optimum composition exhibited a low overpotential of 350 mV, Tafel slope of 49.4 mV dec⁻¹ at 10 mA cm⁻² and excellent stability for 3600 s. Other electrocatalytic parameters including high diffusion coefficient (D°) (2.2 × 10⁻⁸ cm² s⁻¹), mass transport coefficient (m_T) (2.9 × 10⁻⁴ cm s⁻¹), heterogeneous rate constant (k°) (5.85 × 10⁻⁴ cm s⁻¹), high active surface area (A) (0.0116 cm²), and turnover frequency (TOF) (1.388 s⁻¹) were observed for optimized composition. EIS analysis revealed low solution resistance and charge transfer resistance values. This outstanding performance is attributed to multiple cationic contribution due to the synergistic effect, high durability, improved conductivity, and high entropy stabilization. However, the electrochemical behavior of HEOs depends on each metal ion and its concentration on the catalyst's surface, thus providing new opportunities for tailoring their functional properties by simply changing their elemental composition for different electrochemical applications.

Global concerns are increasing worldwide owing to the utilization of non-renewable fossil fuel-derived polymeric films for the packaging of perishables and other related commodities. The emergence of bio-based packaging films, characterized by affordability, environmental friendliness, and abundant renewable sources, offers a promising alternative to address these concerns. This study aims to mitigate the adverse impacts associated with petroleum-based films by developing an effective bio-nanocomposite with enhanced mechanical and barrier properties. The developed composite, achieved through the incorporation of montmorillonite (MMT) nanoclay into two distinct biopolymer blends (chitosan–xanthan gum and chitosan–vanillin), was further optimized to determine the optimal ratio. The bio-nanocomposite film with 3% nanoclay reinforcement in the chitosan–vanillin blend demonstrated superior performance compared to all other films. In contrast to an untreated chitosan film, this bio-nanocomposite exhibited reduced transmittance, mitigating oxidative damage from UV radiation in packaged food items. Notably, a substantial improvement in water resistance and a remarkable 6.64-fold increase in tensile strength were observed. The film's biodegradability, as evidenced by a 25% weight loss in the first month in a soil burial test, underscores its environmental friendliness. Results from a range of instrumental techniques and measurements collectively suggest that the synthesized and optimized film has significant potential for application in the future sustainable food-packaging industry.

Porous silicone polymer composites (elastomeric foams) with tunable properties and multifunctionalities are of great interest for several applications. However, the difficulties in balancing functionality and printability of silicone polymer based composite resins hinder the development of 3D printed multifunctional porous silicone materials. Here, the direct ink write (DIW) technique and NaCl filler as a sacrificial template were utilized to develop 3D printed porous silicone composites. Three different fillers (hydrophilic and hydrophobic fumed silica, and carbon nanofibers (CNF)) were used to impart additional functionality and to explore their effects on the rheology of the DIW resin, and the mechanical properties of the 3D printed elastomeric foams. While hydrophilic silica was effective in modulating the rheology of the resin, CNFs were effective in improving the tensile strength of the elastomeric foam. Unlike tensile strength, which was found to be dependent on filler type, the uniaxial compressive behavior was found to be more dependent on the porosity of the elastomeric foams. A hyperelastic constitutive model (the Compressive, Hyperelastic, Isotropic, Porosity-based Foam model) was used to simulate the uniaxial compressive behavior of the elastomeric foams, and the model accurately reproduced the experimental stress–strain profiles. The expanded design flexibility of tunable porosity in DIW parts enables the foams to be utilized in a wider variety of applications. For example, the foam with CNF filler demonstrated excellent oil/water separation capacity, with absorbing efficiencies of 450% and 330% respectively for chloroform and toluene. Similarly, a foam with hydrogen getter capacity was developed using the CNF filled foam with hydrogen getter as an additional functional filler, and high performance of the 3D printed hydrogen getter composite was demonstrated.

Integrins are crucial for cell adhesion, spreading, and cell–cell interactions, contributing significantly to cellular functions. Various tension sensors have been developed to measure integrin tensions across different cell types and conditions. However, there is a lack of tools to accurately calibrate the high-level force range of integrins required for cell adhesion. In this study, we engineered a multiplexed tension sensor (TS) by combining a yellow fluorescence protein tension sensor (YFP TS) with a DNA integrative tension sensor (ITS) previously used. This innovative approach enabled us to detect integrin-mediated forces in adherent cells. Our findings revealed that high-motile fish keratocytes exhibited integrin-mediated forces ranging from 44 to 100 pN, whereas low-motile 3T3L1 and NRK cells generated integrin-mediated forces exceeding 100 pN. This difference may be attributed to the shorter dwelling time or interaction time between an integrin and a RGD ligand in keratocytes, suggesting a need to examine the loading rate information for the integrin and the ligand in focal adhesions.

Rare-earth double tungstate NaEu(WO₄)₂ was synthesized via a trisodium citrate (Na₃cit)-assisted hydrothermal technique, followed by calcination, to promote crystallinity and detailed investigations on their crystal structures and luminescence properties. In this study, the structural evolution of our samples synthesized with different amounts of Na₃cit was studied by employing X-ray diffraction, Rietveld refinement, Fourier transform infrared and Raman spectroscopy techniques. It was found that NaEu(WO₄)₂ belongs to the scheelite family with Na and Eu atoms occupying the same sites and antisite defects deforming EuO₈ dodecahedra. The modulation of W–O, Eu–O and angle splitting in the presence of antisite defects was identified. From in-depth X-ray photoelectron spectroscopy, we validated the deformation of the EuO₈ dodecahedron due to the presence of oxygen vacancies (V_Os), which originated from antisite defects. Herein, we show that the band gap of NaEu(WO₄)₂ is highly sensitive to defects; however, the ⁵D₀–⁷F₂ transition of Eu³⁺ at 615 nm with color coordinates (0.67, 0.33) is very robust, making NaEu(WO₄)₂ a suitable red phosphor material for near UV-type light-emitting devices (LEDs). We also identified that V_Os present in the EuO₈ dodecahedron act as active sites for acetone sensing (∼68% response to 100 ppm) with a response and recovery time of ∼3.3/10 s at room temperature, suggesting the potency of NaEu(WO₄)₂ as a multifunctional material with applications in LEDs and acetone sensors. In order to validate our experimental observations theoretically, we calculated the band structure and density of states of bare and antisite defects containing NaEu(WO₄)₂ using ab initio density functional theory and identified the sensing mechanism. We believe that our studies will be helpful in introducing new multifunctional applications of NaEu(WO₄)₂, while theoretical calculations will provide new electronic insights that may be used to understand the features of other double rare-earth tungstate materials.

Electrocatalysis presents an efficient and eco-friendly approach for the two-electron oxygen reduction reaction (2e⁻ ORR) to produce hydrogen peroxide (H₂O₂). However, challenges persist in enhancing catalyst activity and refining design strategies. In this study, a general four-step strategy is introduced to develop efficient single-atom catalysts (SACs) for H₂O₂ production based on transition metals and nonmetals embedded into γ-graphyne monolayers (TM–NM–GY) through first-principles calculations. Our results indicate that the intrinsic activity for the 2e⁻ ORR can be properly and handily evaluated using the robust intrinsic electronegativity descriptor. On this foundation, we propose two strategies of B doping and creating C vacancies (v) to further enhance catalytic activity. Remarkably, Ni–B–GY and Ag–v–GY exhibit exceptional selectivity, stability, and activity with overpotentials as low as 0.08 V and 0.15 V, respectively, approaching the ideal limit of H₂O₂ catalysts. Mechanistic investigations reveal that B doping facilitates electron transfer and strengthens the hybridization between Ni 3d and O 2p orbitals, leading to stronger adsorption strength of *OOH and thus enhancing the 2e⁻ ORR catalytic performance. These findings not only present several promising SAC candidates for H₂O₂ production, but also pave the way for the rational design of highly efficient SACs for various catalytic reactions.