Regular Crystals Research Articles

Hierarchical structural design of cobalt sulphide nanoparticles/nickel sulphide for high-performance supercapacitors

Metal-organic framework (MOF) materials have become increasingly attractive in supercapacitor electrode research because of their regular crystal topology and tunable pore distribution. The strategy for the synthesis of the Ni3S4/Co3S4 electrode material with a layered structure was successfully devised using the layered Ni-MOF as a template and precursor. The characterisation techniques of XRD, FTIR, XPS, SEM, TEM and BET have provided confirmation of the assertion that the Ni3S4/Co3S4 composites exhibit an advanced hierarchical pore structure and considerable specific surface area. The specific capacity of the Ni3S4/Co3S4 composite is as high as 122.8 mAh g−1, and it can still maintain 72.6 % of the specific capacity after 3,000 cycles. Furthermore, the SEM morphology remains largely unchanged after cycling, which demonstrates excellent stability. Moreover, honeycomb-shape porous carbon (N-HAPC) with ultra-high specific surface area was selected as negative electrode material to fabricate a novel hybrid supercapacitor (Ni3S4/Co3S4//N-HAPC), which exhibits a broad operational voltage range of 1.6 V and superior energy density of 28.6 Wh kg−1. Simultaneously, HSCs exhibited remarkable charge-discharge stability, exhibiting a mere 17.2 % decline in capacitance stability following 7,000 GCD cycles. The combination of two Ni3S4/Co3S4//N-HAPC HSCs in series has been demonstrated to be capable of illuminating a small LED lamp, indicating the potential for their use in practical applications. Furthermore, this approach offers a novel strategy for the structural design of MOF-like materials.

Morphological and Structural Characterization of Encapsulated Arginine Systems for Dietary Inclusion in Ruminants

This research evaluated two methods of arginine encapsulation, melt emulsification and nanoprecipitation, using a lipid matrix of carnauba wax and commercial polymers (Eudragit®) as a protective material. The ratios of wax–arginine were 1:1, 2:1, 3:1, and 4:1, while those of Eudragit® RS:RL were 30:70 and 40:60 in proportions of 1:0.5 and 1:1 Eudragit®–arginine. The microcapsules were morphostructurally characterized by scanning electron microscopy, and a microelement analysis was performed via energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. Additionally, in vitro digestibility was used to determine the protection efficiency. Both encapsulated systems presented regular (crystals) and spherical (microcapsules) polyhedral morphologies. Qualitative nitrogen decreased significantly as the wax ratio increased in the wax–arginine formulations. The formulations with a 1:1 Eudragit:–arginine ratio (1000 mg arginine) produced a higher nitrogen content in the encapsulated systems than the formulations containing 500 mg of arginine. The 2:1 and 3:1 wax–arginine formulations had the lowest degradability after 5 h of rumen fluid exposure (40.7 and 21.26%, respectively) in comparison with 100% unencapsulated arginine. The 3:1 wax–arginine formulation is an efficient encapsulating system which protects against rumen degradation. The more intense absorption bands at 1738 cm−1 and 1468 cm−1 associated with the C=O and C-H groups in carnauba wax indicate that arginine was more protected than in the other systems.

High-Entropy Design for 2D Halide Perovskite.

Hybrid halide perovskites are good candidates for a range of functional materials such as optical electronic and photovoltaic devices due to their tunable band gaps, long carrier diffusion lengths, and solution processability. However, the instability in moisture/air, the toxicity of lead, and rigorous reaction setup or complex postprocessing have long been the bottlenecks for practical application. Herein, we present a simultaneous configurational entropy design at A-sites, B-sites, and X-sites in the typical (CHA)2PbBr4 two-dimensional (2D) hybrid perovskite. Our results demonstrate that the high-entropy effect favors the stabilization of the hybrid perovskite phase and facilitates a simple crystallization process without precise control of the cooling rate to prepare regular crystals. Moreover, high-entropy 2D perovskite crystals exhibit tunable energy band gaps, broadband emission, and a long carrier lifetime. Meanwhile, the high-entropy composition almost maintains the initial crystal structure in deionized water for 18 h while the original (CHA)2PbBr4 crystal mostly decomposes, suggesting obviously improved humidity stability. This work offers a facile approach to synthesize humidity-stable hybrid perovskites under mild conditions, accelerating relevant preparation of optoelectronics and light-emitting devices and facilitating the ultimate commercialization of halide perovskite.

Fe-based amorphous reinforced CoCrFeNi HEA composite coating prepared by laser cladding

316L stainless steel (316L SS) is easy to be damaged due to poor corrosion and wear resistance, the preparation of composite coating with excellent corrosion and wear resistance properties on the surface can lengthen its service life. In this aspect, Fe-based amorphous CoCrFeNi high entropy alloy (HEA) composite coating was prepared on 316L SS by laser cladding. The microstructure, phase, microhardness, wear and corrosion resistance of the coatings were analyzed by scanning electron microscope (SEM) equipped with energy disperse spectroscopy (EDS), X-ray diffraction (XRD), Vickers hardness tester, electrochemical workstation, and the friction and wear tester. The results show that the phase composition of the coatings was FCC solid solution. The microstructure of the coatings gradually evolved from regular cellular crystals to irregular amorphous structures, while the microhardenss of each coating changed little. The wear and corrosion resistance of the coatings was better than that of the substrate. When the content of Fe-based amorphous is 8%, the properties of the coating are the best.

Symmetries and wave functions of photons confined in three-dimensional photonic band gap superlattices

We perform a computational study of confined photonic states that appear in a three-dimensional (3D) superlattice of coupled cavities, resulting from a superstructure of intentional defects. The states are isolated from the vacuum by a 3D photonic band gap, using a diamondlike inverse woodpile crystal structure, and they exhibit “Cartesian” hopping of photons in high-symmetry directions. We investigate the confinement dimensionality to verify which states are fully 3D-confined, using a recently developed scaling theory to analyze the influence of the structural parameters of the 3D crystal. We create confinement maps that trace the frequencies of 3D-confined bands for select combinations of key structural parameters, namely the pore radii of the underlying regular crystal and of the defect pores. We find that a certain minimum difference between the regular and defect pore radii is necessary for 3D-confined bands to appear, and that an increasing difference between the defect pore radii from the regular radii supports more 3D-confined bands. In our analysis, we find that their symmetries and spatial distributions are more varied than electronic orbitals known from solid-state physics. We surmise that this difference occurs since the confined photonic orbitals derive from global Bloch states governed by the underlying superlattice structure, whereas single-atom orbitals are localized. Based on this realization, we suggest that the extent symmetries of “photonic orbitals” could possibly translate to novel macroscopic behaviors of “photonic solid-state matter,” never before seen in the standard electronic solid-state systems. We also discover pairs of degenerate 3D-confined bands with p-like orbital shapes and mirror symmetries matching the symmetry of the superlattice. Finally, we investigate the enhancement of the local density of optical states for cavity quantum electrodynamics applications. We find that donorlike superlattices, i.e., where the defect pores are smaller than the regular pores, provide greater enhancement in the air region than acceptorlike structures with larger defect pores, and thus offer better prospects for doping with quantum dots and ultimately for 3D networks of single photons steered across strongly coupled cavities. Published by the American Physical Society 2024

Bending, Twisting, and Propulsion of Photoreactive Crystals by Controlled Gas Release

AbstractThe rapid release of gas by a chemical reaction to generate momentum is one of the most fundamental ways to elicit motion that could be used to sustain and control the motility of objects. We report that hollow crystals of a three‐dimensional supramolecular metal complex that releases gas by photolysis can propel themselves or other objects and advance in space when suspended in mother solution. In needle‐like regular crystals, the reaction occurs mainly on the surface and results in the formation of cracks that evolve due to internal pressure; the expansion on the cracked surface of the crystal results in bending, twisting, or coiling of the crystal. In hollow crystals, gas accumulates inside their cavities and emanates preferentially from the recess at the crystal terminus, propelling the crystals to undergo directional photomechanical motion through the mother solution. The motility of the object which can be controlled externally to perform work delineates the concept of “crystal microbots”, realized by photoreactive organic crystals capable of prolonged directional motion for actuation or delivery. Within the prospects, we envisage the development of a plethora of light‐weight, efficient, autonomously operating robots based on organic crystals with high work capacity where motion over large distances can be attained due to the large volume of latent gas generated from a small volume of the crystalline solid.

Bending, Twisting, and Propulsion of Photoreactive Crystals by Controlled Gas Release.

The rapid release of gas by a chemical reaction to generate momentum is one of the most fundamental ways to elicit motion that could be used to sustain and control the motility of objects. We report that hollow crystals of a three-dimensional supramolecular metal complex that releases gas by photolysis can propel themselves or other objects and advance in space when suspended in mother solution. In needle-like regular crystals, the reaction occurs mainly on the surface and results in the formation of cracks that evolve due to internal pressure; the expansion on the cracked surface of the crystal results in bending, twisting, or coiling of the crystal. In hollow crystals, gas accumulates inside their cavities and emanates preferentially from the recess at the crystal terminus, propelling the crystals to undergo directional photomechanical motion through the mother solution. The motility of the object which can be controlled externally to perform work delineates the concept of "crystal microbots", realized by photoreactive organic crystals capable of prolonged directional motion for actuation or delivery. Within the prospects, we envisage the development of a plethora of light-weight, efficient, autonomously operating robots based on organic crystals with high work capacity where motion over large distances can be attained due to the large volume of latent gas generated from a small volume of the crystalline solid.

Current-induced nonreciprocal transmittance in graphene-embedded photonic multilayers comprising the Octonacci sequence

In this work, we have studied the nonreciprocal properties of quasi-periodic Octonacci multilayer incorporating current-induced drifted graphene monolayers at the interfaces. We have analyzed the transmittance of the structure and compared it with that of regular periodic photonic crystals. Our investigation has revealed that the transmission of light is significantly improved through configurations comprising dielectric layers and graphene monolayers. The proposed structures exhibit nonreciprocal optical responses across a broad range of frequencies. The coupling of surface plasmon polaritons in the quasi-periodic structure exceeds that of periodic structures. We have examined nonreciprocal behaviors versus the drift velocity of electrons and the Fermi energy of graphene layers. It has been demonstrated that the reciprocity of the system can be adjusted by manipulating the Fermi energy and the drift velocity of the graphene layers. Moreover, the direction of nonreciprocity is dictated by the sign of the drift velocity. Nonreciprocal behavior is absent under zero DC bias and can be tuned up to 4.5 THz with bias. These distinctive properties suggest potential applications of these structures in optoelectronic devices.

Enhancing Vapochromic Properties of Platinum(II) Terpyridine Chloride Hexaflouro Phosphate in Terms of Sensitivity through Nanocrystalization for Fluorometric Detection of Acetonitrile Vapors

The vapochromic properties of [Pt(tpy)Cl](PF6) crystals in the presence of acetonitrile and its effect on the crystal structure as well as the fluorescence spectrum of this complex have already been studied in the past. We synthesized nanocrystals of this compound for the first time, and discussed different parameters and methods that affect nanocrystal structure modulation. The study demonstrates the vapochromic properties of the nanocrystals toward acetonitrile vapor by investigating the morphology and fluorescence spectra of the nanocrystals. Vapochromic studies were conducted on [Pt(tpy)Cl](PF6) nanocrystals for five cycles of absorption and desorption of acetonitrile, demonstrating shorter response times compared to regular bulk crystals.

Graphene synthesis by electromagnetic induction heating: Domain size and morphology control

In this paper we discuss the effect of hydrogen and methane content during low-pressure chemical vapor deposition (LPCVD) of graphene on inductively heated copper foils. By increasing the H2/CH4 ratio by a factor of 5 from 25 to 125, different graphene morphologies ranging from dendritic fractals to compact hexagonal islands are obtained. In addition, increasing the hydrogen concentration allows the nucleation rate to be slowed down by a factor of ∼10 thereby high-quality regular hexagonal graphene single crystals of significant size of 0.1 mm are found. From these measurements, we estimate the activation energy for graphene nucleation in low-pressure CVD (2 eV) and propose a phenomenological law for graphene nucleation. As compared to conventional CVD methods, considerable advantages of inductive heating are outlined, and some fundamental aspects of this approach are discussed.

Interfacial Polarization Locked Flexible β-Phase Glycine/Nb2CTx Piezoelectric Nanofibers.

Biomolecular piezoelectric materials show great potential in the field of wearable and implantable biomedical devices. Here, a self-assemble approach is developed to fabricating flexible β-glycine piezoelectric nanofibers with interfacial polarization locked aligned crystal domains induced by Nb2CTx nanosheets. Acted as an effective nucleating agent, Nb2CTx nanosheets can induce glycine to crystallize from edges toward flat surfaces on its 2D crystal plane and form a distinctive eutectic structure within the nanoconfined space. The interfacial polarization locking formed between O atom on glycine and Nb atom on Nb2CTx is essential to align the β-glycine crystal domains with (001) crystal plane intensity extremely improved. This β-phase glycine/Nb2CTx nanofibers (Gly-Nb2C-NFs) exhibit fabulous mechanical flexibility with Young's modulus of 10 MPa, and an enhanced piezoelectric coefficient of 5.0 pCN-1 or piezoelectric voltage coefficient of 129×10-3VmN-1. The interface polarization locking greatly improves the thermostability of β-glycine before melting (≈210°C). A piezoelectric sensor based on this Gly-Nb2C-NFs is used for micro-vibration sensing in vivo in mice and exhibits excellent sensing ability. This strategy provides an effective approach for the regular crystallization modulation for glycine crystals, opening a new avenue toward the design of piezoelectric biomolecular materials induced by 2D materials.

Mechanism and thermodynamics of scorodite formation by oxidative precipitation from arsenic-bearing solution

Arsenic pollution is a challenging environmental issue caused by arsenic-bearing wastes from nonferrous metallurgy. Oxidative precipitation via introducing O2 into an ionic Fe(II)–As(V) solution is an advanced method for arsenic immobilization. However, the underlying mechanism is still not well understood. This study proposed a mechanism for scorodite formation by oxidative precipitation, and its thermodynamics were calculated using Gaussian software. Scorodite formation was divided into three stages: precursor formation (3–90 min), oxidative conversion (90–270 min) and crystallization (270–720 min) from the variation in precipitates and solution characterization and parameters such as initial pH, arsenic concentration, and ferrous dosage. In the scorodite formation mechanism, the precursors originate from the coordination polymerization of aqueous Fe(H2O)62+ and H2AsO4−, which contributes to the oxidative conversion of coordinated polymers ([Fe(H2O)4(H2O)]nn+) to basic Fe(H2O)2AsO4 until regular octahedral crystals are formed via nucleation and growth during crystallization. The ΔrGmθ for polymerization varied from −491.96 kJ mol−1 to −33.30 kJ mol−1, and the ΔrGmθ of oxidative conversion changed from −982.16 kJ mol−1 to −224.82 kJ mol−1, demonstrating the feasibility in scorodite formation. This research is significant for understanding scorodite formation in As(V) solutions. It can provide schemes for controlling and modifying the conditions of arsenic-bearing waste immobilization in the laboratories and industries.

Molecular dynamics study on desublimation and crystal nucleation of carbon dioxide on a low temperature surface

To capture CO2 crystal nucleation during the desublimation, we conducted a molecular dynamics study on the desublimation process of CO2 on a low temperature plate. The desublimation process is characterized by three models corresponding to different degrees of supercooling. When the plate temperature is below 82 K, the solid CO2 with a glassy state structure forms after CO2 gas molecules adsorb onto the cool plate. In the temperature range of 83–113 K, CO2 crystal nucleus forms within the disordered solid CO2, and subsequently the nucleus grows into Pa3-type crystal. For the plate temperature between 114 and 128 K, a liquid CO2 phase initially forms, the nucleus then generates and grows to develop into Pa3 crystal. The CO2 crystal nucleation is accompanied by the reduction of molecular potential energy and the increase of molecular kinetic energy. Additionally, the recalescence phenomenon occurs during CO2 crystal nucleation. It is crucial that the molecular kinetic energy and molecular distance fall within a specific range to enable the formation of CO2 nucleus and regular Pa3 crystal. Consequently, the CO2 crystal nucleation can only occur within a specific range of plate temperatures.

Mo doping V0.76Mn0.032Ni0.029O2 vanadium based ternary metal oxides as cathode active materials for lithium-ion hybrid supercapacitor with high lithium storage performance

Lithium-ion hybrid supercapacitors as high-performance energy storage devices are proposed to bridge the electrochemical performances between lithium-ion batteries and supercapacitors. In this paper a novel Mo doping V0.76Mn0.032Ni0.029O2 vanadium based ternary metal oxide is constructed as cathode active material for lithium-ion hybrid supercapacitor. Structural analysis demonstrates Mo doping as interlayer support can ameliorate the V0.76Mn0.032Ni0.029O2 crystal structure and raise the lattice size thus providing more adequate mass transfer channels for lithium-ion storage. In addition, 5 % Mo doping V0.76Mn0.032Ni0.029O2 represents relatively regular crystal particle arrangement with some integrated crystalline form and closely packing together. These structural features enable them to exhibit higher lithium storage performance and when as cathode active material for lithium-ion hybrid supercapacitor, it exhibits the lowest electrochemical and concentration polarization and the highest discharge specific capacities of 150.7, 140.2, 125.4 and 102.5 mAh.g−1 at different current densities along with a high capacity retention rate of 77.3 % at 1000 mA g−1 current density after 2000 cycles.

Morphology of Four Strains of Phellinoid Agaricomycetes and Microstructural and Physiological Properties of Their Exudates.

To study and compare the morphology of the phellinoid Agaricomycetes strains and find other strategies to improve Phellinus spp. growth and metabolism. In this study, the morphological characteristics of four Phellinus igniarius strains (phellinoid Agaricomycetes) were observed under a light microscope. The exudates from these fungi were observed using light microscopy, scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDS). The exudates were initially transparent with a water-like appearance, and became darker with time at neutral pH. Microscopy of air-dried exudates revealed regular shapes and crystals. Cl- (chloride) and K+ were the two key elements analyzed using EDS. Polyphenol oxidase (POD), catalase (CAT), and laccase activities were detected in mycelia from each of the four Phellinus strains. The K+ content of the three strains was higher than that of the wild strain. Cl- content correlated negatively with that of K+. Laccase activities associated with each mycelia and its corresponding media differed under cold and contaminated conditions.

Chiral organic molecular structures supported by planar surfaces.

We employ the molecular dynamics simulations to study the dynamics of acetanilide (ACN) molecules placed on a flat surface of planar multilayer hexagonal boron nitride. We demonstrate that the ACN molecules, known to be achiral in the three-dimensional space, become chiral after being placed on the substrate. Homochirality of the ACN molecules leads to stable secondary structures stabilized by hydrogen bonds between peptide groups of the molecules. By employing molecular dynamics simulations, we reveal that the structure of the resulting hydrogen-bond chains depends on the isomeric composition of the molecules. If all molecules are homochiral (i.e., with only one isomer being present), they form secondary structures (chains of hydrogen bonds in the shapes of arcs, circles, and spirals). If the molecules at the substrate form a racemic mixture, then no regular secondary structures appear, and only curvilinear chains of hydrogen bonds of random shapes emerge. A hydrogen-bond chain can form a zigzag array only if it has an alternation of isomers. Such chains can create two-dimensional (2D) regular lattices or 2D crystals. The melting scenarios of such 2D crystals depend on density of its coverage of the substrate. At 25% coverage, melting occurs continuously in the temperature interval 295-365K. For a complete coverage, melting occurs at 415-470 K due to a shift of 11% of all molecules into the second layer of the substrate.

Bandgap Engineering of Two‐Step Processed Perovskite Top Cells for Perovskite‐Based Tandem Photovoltaics

AbstractFor high‐performance application of perovskite solar cells (PSCs) in monolithic perovskite/silicon tandem configuration, an optimal bandgap and process method of the perovskite top cell is required. While the two‐step method leads to regular perovskite film crystallization, engineering wider bandgaps (Eg > 1.65 eV) for the solution‐based two‐step method remains a challenge. This work introduces an effective and facile strategy to increase the bandgap of two‐step solution‐processed perovskite films by incorporating bromide in both deposition steps, the inorganic precursor deposition (step 1, PbBr2) and the organic precursor deposition (step 2, FABr). This strategy yields improved charge carrier extraction and quasi‐Fermi level splitting with power conversion efficiencies (PCEs) of up to 15.9%. Further improvements are achieved by introducing CsI in the bulk and utilizing LiF as surface passivation, resulting in a stable power output exceeding 18.5% for Eg = 1.68 eV. This additional performance boost arises from enhanced perovskite film crystallization, leading to improved charge carrier extraction. Laboratory scale monolithic perovskite/silicon solar cells (TSCs) (1 cm2 active area) achieve PCEs up to 23.7%. This work marks a significant advancement for wide bandgap two‐step solution‐processed perovskite films, enabling their effective use in high‐performance and reproducible PSCs and perovskite/silicon TSCs.

Effect of rapid freezing technology on quality changes of freshwater fish during frozen storage

The impacts of pre-frozen with −80 °C liquid nitrogen spray freezer (LNF), −80 °C refrigerator freezer (RF), and −30 °C micro-freezer (MF) on the freezing rate, physical and chemical properties and microscopic structures of freshwater fish (grass carp, tilapia and bighead carp) stored at −18 °C (14 days) were evaluated. LNF and MF were effective in shortening the entire freezing period and their muscle tissue microscopic structures were more homogeneous and thicker than the RF group, also with smaller and more regular ice crystal. Additionally, the LNF-treated samples had good water holding capacity and textural characteristics and significantly delayed changes in immobilized water content, effectively suppressing the increase in L* values in grass carp samples (p < 0.05). However, MF was not as effective as LNF and RF in inhibiting the formation of TBARS and TVBN. In conclusion, LNF played a more positive role in quality retention of freshwater fish.

Interfacial evolution: A hydrothermal activation strategy to boost OER activity for stainless steel

BackgroundWater electrolysis is one of the most competitive approaches to generate hydrogen. The economical stainless steel, which consists of transition metals such as Ni and Fe, has impressive catalytic tunability and tremendous application potential in hydrogen production. MethodsIn this work, a hydrothermal activation strategy is proposed for breaking the inert oxide layer of stainless steel and producing an active catalytic layer dominated by NiFe2O4 spinel nanoparticles on the surface. The molybdate further complexes with the metal ions, disrupting the initial regular crystals of NiFe2O4 and exposing more defects. At the same time, Mo atoms can further optimize the electronic structure, which is conducive to the kinetic process of the reaction. Significant FindingsConsequently, the modified stainless steel requires only 270 mV to achieve a current density of 10 mA·cm−2, much lower than 387 mV of bare 304 stainless steel (SS304). Moreover, the robust catalytic layer, evolved from the stainless steel's own elements, grows firmly on the surface and shows excellent stability in the test of 120 h. This work provides a novel strategy for developing low-cost stainless steel electrodes with superior performance and stability for oxygen evolution.

Ideal: A promising diamond-silicon carbide composite for enhanced ceramic armor

Comparative tests were conducted to assess the protective properties of a promising new ceramic material called “Ideal,” which is based on diamond particles. The tests involved a well-known ceramic material, corundum, for comparison. The material “Ideal” is a composite of diamond and silicon carbide, created through reaction-diffusion transformations. It has been observed that regular crystals of silicon carbide, which are genetically linked to the diamond lattice, grow at the interface. Additionally, both large and small diamond particles exhibit a tendency to form a dense hexagonal arrangement within the SiC matrix, with a coordination number of 6. The inclusion of small particles further enhances the space-filling factor, contributing to the superior mechanical properties of the composites. Experimental evaluations of ceramic structures made from the “Ideal” composite material have demonstrated its outstanding protective capabilities, surpassing all existing armor materials. Remarkably, it achieves these superior properties at a considerably lower areal density.