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In the synthesis of colloidal PbS nanosheets, the supernatant of the reaction solution is reused to boost the lead conversion efficiency. It doubles the conversion efficiency of the lead precursors to the PbS nanosheets. The nanosheets synthesized by reusing the supernatant have similar morphology, nearly identical thickness, and optical properties as the original ones, confirmed by transmission electron microscopy, X‐ray diffraction, and photoluminescence spectroscopy. This method reduces the toxic Pb‐containing waste during the synthesis, a step toward the green and scalable synthesis of colloidal 2D PbS nanosheets. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of barrier properties of graphene coating against hydrogen permeation into E110 zirconium alloy. For the first time, the kinetics of hydrogen absorption by the graphene-coated zirconium alloy with a single-layer graphene coating obtained by chemical vapour deposition (CVD) is studied in this work. It was shown that the graphene coating exhibits barrier properties and reduces hydrogen absorption rate by E110 zirconium alloy in the temperature range (350–550)°C. The activation energy for hydrogen absorption was reduced from 72 to 61 kJ/mol. Phase transformations in zirconium alloy during hydrogenation can result in degradation of protective properties of graphene coating. [ABSTRACT FROM AUTHOR]

Two-dimensional compounds with nanostructural features are attracting attention from researchers worldwide. Their multitude of applications in various fields and vast potential for future technology advancements are successively increasing the research progress. Wastewater treatment and preventing dangerous substances from entering the environment have become important aspects due to the increasing environmental awareness, and increasing consumer demands have resulted in the appearance of new, often nonbiodegradable compounds. In this review, we focus on using the most promising 2D materials, such as MXenes, Bi2WO6, and MOFs, as catalysts in the modification of the Fenton process to degrade nonbiodegradable compounds. We analyze the efficiency of the process, its toxicity, previous environmental applications, and the stability and reusability of the catalyst. We also discuss the catalyst's mechanisms of action. Collectively, this work provides insight into the possibility of implementing 2D material-based catalysts for industrial and urban wastewater treatment. [ABSTRACT FROM AUTHOR]

An increase in population and demand for energy are the major challenges in today's world. As the Internet of Things (IoTs) grows, there is a pressing need for new kinds of novel materials. These issues greatly attract the scientific community. Therefore, the hottest topic now is energy conversion and energy storage by using two-dimensional (2D) materials beyond that of graphene. In the year 2011, Gogosti et al., and his research team discovered 2D transition metal carbides, nitrides and carbonitrides called MXenes Ti 3 C 2 T x etching from Ti 3 AlC 2 with the help of toxic hydrofluoric acid. Now, so many novel routes have been developed with mild reducing agents, etchants, and intercalants. Many new members of 2D materials have been added to the constellation. MXene based composites have drawn extensive attention from the scientific community owing to their high conductivity and other unique properties such as hydrophilic surfaces, large interlayer spacing, environmental flexibility, large surface area, safety, thermal conductivity, improved electrochemical activity, enhancing faradic capacitance (pseudocapacitance) and reducing the shortcomings in the normal capacitance etc. In this review, we systematically summarize the recent developments and various synthesis mechanisms of different multi-layered material, intercalations, and its different applications as electrocatalysts, Li-ion batteries (LIBs), supercapacitors, biosensors, and other electrochemical storage systems. [ABSTRACT FROM AUTHOR]

Two-dimensional compounds with nanostructural features are attracting attention from researchers worldwide. Their multitude of applications in various fields and vast potential for future technology advancements are successively increasing the research progress. Wastewater treatment and preventing dangerous substances from entering the environment have become important aspects due to the increasing environmental awareness, and increasing consumer demands have resulted in the appearance of new, often nonbiodegradable compounds. In this review, we focus on using the most promising 2D materials, such as MXenes, Bi2WO6, and MOFs, as catalysts in the modification of the Fenton process to degrade nonbiodegradable compounds. We analyze the efficiency of the process, its toxicity, previous environmental applications, and the stability and reusability of the catalyst. We also discuss the catalyst’s mechanisms of action. Collectively, this work provides insight into the possibility of implementing 2D material-based catalysts for industrial and urban wastewater treatment.

Perovskite‐related 2D‐compounds of the series 5‐AVA2MAn–1PbnBr3n–1 were synthesised and characterised for the representatives with n = 1, 2, and 3 [5‐AVA = 5‐amino valerian acid cation, HOOC(CH2)4NH3+]. In addition, we have investigated the chloride compound 5‐AVA2PbCl4 and the binary compounds 5‐AVAX (X = Cl, Br). The crystal structures of the 2D compounds represent well‐known cut‐outs of the cubic 3D perovskites with layers of corner‐sharing PbBr6 octahedrons in (100) orientation. According to the value of n the layer thickness comprises one, two or three layers. Similar to most of the perovskite‐related representatives the PbBr6 octahedrons are rotated, but with slight differences. We have analysed the rotation pattern with respect to the different aspects of hydrogen bonding and orientation of the organic cations 5‐AVA+ and MA+. Measurements of the optical properties reveal a decrease of the band gap from 3.02 eV (n = 1) over 2.80 eV (n = 2) to 2.70 eV (n = 3). For 5‐AVA2PbBr4 we observed strong blue fluorescence (413 nm) with a remarkably small Strokes shift (47 nm). All investigations were influenced by the reduced stability of the representatives with n = 2 and n = 3 with respect to the degradation into the simpler compounds 5‐AVA2PbBr4 and MAPbBr3. This is in contrast to similar 2D‐iodides, where many representatives are known and n can reach values up to 6 and 7. Our series with n = 1, 2, and 3 represent the third example for a series of compounds with n = 1–3. [ABSTRACT FROM AUTHOR]

As there is a great demand of 2D metal networks, especially out of gold for a plethora of applications we show a universal synthetic method via phase boundary gelation which allows the fabrication of networks displaying areas of up to 2 cm2. They are transferred to many different substrates: glass, glassy carbon, silicon, or polymers such as PDMS. In addition to the standardly used web thickness, the networks are parametrized by their fractal dimension. By variation of experimental conditions, we produced web thicknesses between 4.1 nm and 14.7 nm and fractal dimensions in the span of 1.56 to 1.76 which allows to tailor the structures to fit for various applications. Furthermore, the morphology can be tailored by stacking sheets of the networks. For each different metal network, we determined its optical transmission and sheet resistance. The obtained values of up to 97 % transparency and sheet resistances as low as 55.9 Ω/sq highlight the great potential of the obtained materials. [ABSTRACT FROM AUTHOR]

Random noise attenuation utilizing predictive filtering achieves great performance in denoising seismic data. Conventional predictive filtering methods are based on fixed filter operators and neglect the complexity of structures. In this way, the denoised data cannot meet the requirement of balancing the signal preservation and noise removal. In this study, we proposed a structural complexity‐guided predictive filtering method that utilizes an adapted filter operator to adjust the changes of structural complexity. The proposed structural complexity‐guided predictive filtering mainly consists of two stages. A slope field information is acquired according to plane‐wave destruction to assess the structural complexity. In addition, an adaptive filter operator is obtained to denoise the seismic data according to the adaptive factor. Both synthetic data and real seismic profiles are employed to examine the denoising capacity and flexibility of the refined predictive filtering using adaptive lengths. The analysis of the predicted results shows that adaptive predictive filtering is powerful and has the ability to eliminate random noises with negligible distortions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Two-dimensional black phosphorus (TDBP) is promising candidate for energy storage material was elaborated. • Extreme summary of preparation methods of black phosphorus was narrated. • Various applications of black phosphorus as energy storage material was elaborated. • Present, past and future study of black phosphorus as energy storage material was discussed. Two-dimensional black phosphorus (TDBP) is desirable for electrical devices due to its adjustable direct band gap (0.3 to 2.0 eV), high mobility of carriers (∼1000 cm2 V−1 s−1), and the mild on/off ratio (1 0 5) in devices. Developing techniques for electrochemical energy storage, especially Li-ion batteries and supercapacitors, has been substantially accelerated by the invention of TDBP. As the electrode material, TDBP distinguishes out as a shining star due to its distinct high capacity. Here, considering the most current research advancements on TDBP in energy storage, BP's fundamental construction properties and the preparation techniques of TDBP are discussed. The utilization of TDBP in energy transformation and storage apparatus such as batteries and supercapacitors is demonstrated. However, some pressing issues still need to be resolved using TDBP, including synthesizing the finest phosphorene in wide-ranging volume growth and inadequate environmental stability. Environmental instability and passivation methods of TDBP are also discussed. [ABSTRACT FROM AUTHOR]

The "shuttle effect" and slow redox reactions of Li-S batteries limit their practical application. To solve these problems, a judicious catalyst design for improved battery cycle life and rate performance is essential. Herein, this issue is addressed by modifying the Li-S battery separator using a 2D Fe 2 O 3 -CoP heterostructure that combines the dual functions of polar Fe 2 O 3 and high-conductivity CoP. The synthesized ultrathin nanostructure exposes well-dispersed active sites and shortens the ion diffusion paths. Theoretical calculations, electrochemical tests, and in situ Raman spectroscopy measurements reveal that the heterostructure facilitates the inhibition of polysulfide shuttling and enhances the electrode kinetics. A sulfur cathode constructed using the Fe 2 O 3 -CoP-based separator provides an astonishing capacity of 1346 mAh g -1 at 0.2 C and a high capacity retention of ≈84.5%. Even at a high sulfur loading of 5.42 mg cm -2 , it shows an area capacity of 5.90 mAh cm -2 . This study provides useful insights into the design of new catalytic materials for Li-S batteries., (© 2023 Wiley-VCH GmbH.)

In this paper, the thermal conductivity behavior of synthetic and natural esters reinforced with 2D nanostructures—single hexagonal boron nitride (h-BN), single molybdenum disulfide (MoS2), and hybrid h-BN/MOS2—were studied and compared to each other. As a basis for the synthesis of nanofluids, three biodegradable insulating lubricants were used: FR3TM and VG-100 were used as natural esters and MIDEL 7131 as a synthetic ester. Two-dimensional nanosheets of h-BN, MoS2, and their hybrid nanofillers (50/50 ratio percent) were incorporated into matrix lubricants without surfactants or additives. Nanofluids were prepared at 0.01, 0.05, 0.10, 0.15, and 0.25 weight percent of filler fraction. The experimental results revealed improvements in thermal conductivity in the range of 20–32% at 323 K with the addition of 2D nanostructures, and a synergistic behavior was observed for the hybrid h-BN/MoS2 nanostructures.

We present a simple and feasible approach to analyse and identify two-dimensional effects in central loop transient electromagnetic sounding data and the correspondingly derived quasi two-dimensional conductivity models. The proposed strategy is particularly useful in minimising interpretation errors. It is based on the calculation of a semi-synthetic transient electromagnetic tipper at each sounding and for each observational transient time point. The semi-synthetic transient electromagnetic tipper is derived from the measured vertical component of the induced voltage and the synthetically calculated horizontal component. The approach is computationally inexpensive and involves one two-dimensional forward calculation of an obtained quasi two-dimensional conductivity section. Based on a synthetic example, we demonstrate that the transient electromagnetic tipper approach is applicable in identifying which transient data points and which corresponding zones in a derived quasi two-dimensional subsurface model are affected by two-dimensional inhomogeneities. The one-dimensional inversion of such data leads to false models. An application of the semi-synthetic transient electromagnetic tipper to field data from the Azraq basin in Jordan reveals that, in total, eight of 80 investigated soundings are affected by two-dimensional structures although the field data can be fitted optimally using one-dimensional inversion techniques. The largest semi-synthetic tipper response occurs in a 300 m-wide region around a strong lateral resistivity contrast. The approach is useful for analysing structural features in derived quasi two-dimensional sections and for qualitatively investigating how these features affect the transient response. To avoid misinterpretation, these identified zones corresponding to large tipper values are excluded from the interpretation of a quasi two-dimensional conductivity model. Based on the semi-synthetic study, we also demonstrate that a quantitative interpretation of the horizontal voltage response (e.g. by inversion) is usually not feasible as it requires the exact sensor position to be known. Although a tipper derived purely from field data is useful as a qualitative tool for identifying two-dimensional distortion effects, it is only feasible if the sensor setup is sufficiently accurate. Our proposed semi-synthetic transient electromagnetic tipper approach is particularly feasible as an a posteriori approach if no horizontal components are recorded or if the sensor setup in the field is not sufficiently accurate. [ABSTRACT FROM AUTHOR]

• Novel use of 4-pyridiniumcarboxaldehyde oxime as a tool in cristal engineering. • Coordination compound 2D structure through charge assisted H-bonds and X-bonds. • Non-aromatic stacking through Pt···pyridinium and Pt– Cl···pyridinium interactions. To test the hypothesis that we could use the 4-pyridiniumcarboxaldehyde oxime (4-HoxpyH) coordinated through the oxime N atom to organize Pt(II) compounds via charge-assisted [>N–H] +···[Cl 2 Pt]– hydrogen bonds, we synthesized and determined the crystal structure of the compound [PtCl 3 (4-HoxpyH)], 1. The structure of 1 shows that the ligand HoxpyH coordinates through the nitrogen atom of the oxime group and forms the expected H-bonds. In the crystal, six molecules interact through hydrogen bonds and O···Cl interactions, forming rings that extend into two-dimensional structures. These 2D structures are stacked on top of each other through Pt···pyH and Pt–Cl···pyH interactions, without interpenetrating or forming channels. [ABSTRACT FROM AUTHOR]

Diamanes, ultrathin diamond films represent a very promising class of two-dimensional carbon materials that attracts attention due to broad potential applications starting from sensing and optics and finishing with mechanical applications. We investigate here the ability of diamanes with hydrogenated and fluorinated surfaces to confront oxidation by performing density functional calculations. Simulations for adsorption of atomic and molecular oxygen show greater oxidation resistance for fluorinated diamanes in comparison with hydrogenated ones making these 2D materials promising for various applications where intensive oxidation is present. [ABSTRACT FROM AUTHOR]

A finite-difference approach with non-uniform meshes was presented for simulating magnetotelluric responses in 2D structures. We presented the calculation formula of this scheme from the boundary value problem of electric field and magnetic field, and compared finite-difference solutions with finite-element numerical results and analytical solutions of a 1D model. First, a homogeneous half-space model was tested and the finite-difference approach can provide very good accuracy for 2D magnetotelluric modeling. Then we compared them to the analytical solutions for the two-layered geo-electric model; the relative errors of the apparent resistivity and the impedance phase were both increased when the frequency was increased. To conclude, we compare our finite-difference simulation results with COMMEMI 2D-0 model with the finite-element solutions. Both results are in close agreement to each other. These comparisons can confirm the validity and reliability of our finite-difference algorithm. Moreover, a future project will extend the 2D structures to 3D, where non-uniform meshes should perform especially well.

Two-dimensional (2D) homologous perovskites are arousing intense interest in photovoltaics and light-emitting fields, attributing to significantly improved stability and increasing optoelectronic performance. However, investigations on 2D homologous perovskites with ultrathin thickness and large lateral dimension have been seldom reported, being mainly hindered by challenges in synthesis. A generalized self-doping directed synthesis of ultrathin 2D homologous (BA)2(MA) n−1Pb nBr3 n+1 (1< n<∞) perovskites uses 2D (BA)2PbBr4 perovskites as the template with MA+ dopant. Ultrathin (BA)2(MA) n−1Pb nBr3 n+1 perovskites are formed via an intercalation-merging mechanism, with thickness shrinking down to 4.2 nm and the lateral dimension to 57 μm. The ultrathin 2D homologous (BA)2(MA) n−1Pb nBr3 n+1 perovskites are potential materials for photodetectors with promising photoresponse and stability. [ABSTRACT FROM AUTHOR]

Piezoelectricity is a unique material property that converts mechanical energy to electrical one or vice versa. In order to call a matter piezoelectric, it should be in non-centrosymmetric structure and have sufficiently large band gap. Graphene has none of these properties in its natural composition. It is shown that, coaxing the graphene structure can give piezoelectric property to this non-piezoelectric material. In this study, the size effect of the triangular holes and their placements on the structure to the piezoelectricity are investigated theoretically via density functional theory based calculations. According to the calculation results, while the size of the cavity effects the piezoelectricity, layout of the similar shaped triangular cavities do not change the piezoelectric coefficient. [ABSTRACT FROM AUTHOR]

Abstract: Two‐dimensional ultrathin PdAg bimetallic nanosheets are fabricated and used as model catalysts for understanding the synergetic effects in bimetallic nanocatalysts. The ultrathin nature of the nanosheets allows us to probe the electronic and geometric structures using XPS and X‐ray absorption spectroscopy. The as‐prepared bimetallic nanosheets show high catalytic activity for selective dehydrogenation of formic acid, especially when the Ag/Pd ratio reaches 1. The superior activity is attributed to the electronic and geometric effect generated from the Pd–Ag interfaces in the catalysts. Our studies reveal increased bond distances of Pd–Pd and decreased Ag–Ag bond lengths in the PdAg bimetallic nanosheets. Pd is electronically promoted by Ag to give enhanced catalysis. Moreover, the geometric effect generated from the PdAg alloyed surface enhances the catalysis by suppressing CO poisoning on the catalysts, which is confirmed by electrochemical FTIR measurements. [ABSTRACT FROM AUTHOR]

Two polycarboxylic acids, bis( p -carboxyphenyl)diphenylsilane and bis(3,4-dicarboxyphenyl)dimethylsilane, were prepared according to published procedures and characterized, besides elemental and spectral analysis, for the first time by X-ray single crystal diffraction. Their copper(II) complexes were obtained in the presence of 1,10-phenantroline as co-ligand, the crystallographic data revealing the formation of 2D structures through hydrogen bonds. The hydrogen bond dynamics of the copper complexes was studied by FTIR-ATR spectrometry. The thermal stability of the acids and derived copper complexes was evaluated by thermogravimetrical analysis. The moisture uptake capacity and porosity of the complexes were estimated on the basis of the water vapour sorption measurements in dynamic regime. Magnetic measurements performed on the two metal complexes correspond to not interacting copper(II) with S = 1/2 and g factor equal to 2.14 and 2.19 being consistent with pentacoordinated Cu(II) paramagnetic centres. [ABSTRACT FROM AUTHOR]

Flat silicon nanocrystals coated with the perfluorophenyl ligands have been obtained. Flat silicon nanocrystals are formed due to specific interactions between the perfluorophenyl ligands. The fact of binding of the perfluorophenyl ligands to the surface of silicon nanoparticles is supported by XPS and FTIR spectroscopy. Morphology and structure of the synthesized Si-nanoparticles were studied using transmission electron microscopy. The samples comprise two types of nanoparticles: spherical and flat (2D structures). Electron diffraction pattern demonstrates that spherical Si-nanoparticles are amorphous. The spot diffraction patterns are observed for flat Si-nanoparticles which have the crystalline structure. The size of these particles varies from 15 to 50 nm. The thickness of flat nanocrystals was evaluated using atomic force microscopy; it appeared to be close to 3.3 nm in average. Small and large silicon nanoparticles are interrelated; large flat plates are the products of aggregation and crystallization of small nanoparticles. Nanocrystals exhibit photoluminescence with the emission maximum at 430 nm. [ABSTRACT FROM AUTHOR]

In this study, four hybrid organic-inorganic compounds (8-H 2 Q) 2 [PdCl 4 ] (1), (H 2 ClQ) 2 [PdCl 4 ] (2), (H 2 NQ) 2 [PdCl 4 ] (3) and (H 2 MeQ) 2 [PdCl 4 ]·2H 2 O (4) (where 8-H 2 Q = 8-hydroxyquinolinium, H 2 ClQ = 5-chloro-8-hydroxyquinolinium, H 2 NQ = 5-nitro-8-hydroxyquinolinium and H 2 MeQ = 2-methyl-8-hydroxyquinolinium) were synthesized through organic cation modulation. Single-crystal X-ray structure analysis of compounds 1 and 3 indicates that their structures are planar and consist of [PdCl 4 ]2− anions and 8-H 2 Q or H 2 NQ cations, respectively. Both ionic components are held together through ionic interactions and hydrogen bonds forming infinite chains linked through π-π interactions to form 2D structures. Furthermore, NMR spectroscopy, UV–Vis spectroscopy, elemental analysis, and FT-IR spectroscopy were used to explore the synthesized compounds. The DNA interaction, antimicrobial activity, antiproliferative activity, and radical scavenging effect of the compounds were evaluated. The hybrid compounds and their free ligands can interact with the calf thymus DNA via an intercalation mode involving the insertion of the aromatic chromophore between the base pairs of DNA; compound 1 has the highest binding affinity. Moreover, they have high antimicrobial efficacy against the tested 14 strains of microorganisms with minimum inhibitory concentration values ranging from <1.95 to 250 μg/mL. The antiproliferative activity of the compounds was investigated against three different cancer cell lines, and their selectivity was verified on mesenchymal stem cells. Compounds 1 and 2 displayed selective and high cytotoxicity against human lung and breast cancer cells and showed moderate cytotoxicity against colon cancer cells. Accordingly, they might be auspicious candidates for future pharmacological investigations in lung and breast cancer research. Four (H 2 XQ) 2 [PdCl 4 ] complexes (H 2 XQ = 8-hydroxyquinolinium cation and its derivatives) were synthesized and characterized by structure analysis, IR, UV-VIS, NMR and elemental analyses, and their interaction to DNA, antitumor, antimicrobial and antiradical activities were evaluated. [Display omitted] • Four hybrid organic-inorganic complexes were synthesized and characterized. • They are selectively cytotoxic against A549, HCT116 and MDA-MB-231 cells. • Complexes exhibit high antimicrobial efficacy. • The radical scavenging experiments reveal relatively low antioxidant properties. • The complexes interact with DNA via an intercalation mode. [ABSTRACT FROM AUTHOR]

Abstract: Three new cyano-bridged heteronuclear polymeric complexes, [Zn(NH3)2(μ–ampy)Ni(μ–CN)2(CN)2] n (1), [Zn(NH3)2(μ–ampy)Pd(μ–CN)2(CN)2] n (2) and [Zn(NH3)2(μ–ampy)Pt(μ–CN)2(CN)2] n (3) (ampy=4-aminomethylpyridine) have been synthesized and characterized by vibrational spectroscopy (FT-IR and Raman), thermal (TG, DTG and DTA) and elemental analyses. The crystal structures of complexes 1 and 2 have been determined by the X-ray single crystal diffraction technique. Complexes 1 and 2 crystallize in the triclinic system with the space group . Structural studies reveal that the Ni(II) or Pd(II) ions are four coordinate with four cyanide–carbon atoms in a square planar geometry and the Zn(II) ion exhibits a distorted octahedral coordination geometry completed by the six N atoms from two ammine, one ampy and two cyano ligands. The adjacent metal centers are bridged by bis-monodentate cyano ligands to form a one-dimensional linear chain. These chains are linked by ampy ligands into a 2D sheet structure. The 2D units are connected together via intramolecular C–H⋯N and intermolecular N–H⋯N hydrogen bonding to form 3D supramolecular networks. In additional, there are also interactions between the Ni(II) or Pd(II) ion and the aromatic π-system. Vibrational spectral data indicate the presence of two ν(C N) bands for the complexes, which can be assigned to the terminal and bridging cyanide ligands. Decomposition reactions take place in the temperature range 40–900°C in a static air atmosphere. [Copyright &y& Elsevier]

Two photosensitive methacrylates containing urea and two cinnamates (N,N–di(cinnamoyloxyethyl) N'-methacryloyloxyethyl urea, DC-MA), or urethane and saliciliden-aniline (anil) groups (methacryloyloxyethyl-2-carbamoyloxy(m-methyl, o-hydroxybenziliden)-aniline, UAn-MA) were synthesized and used besides N,N'-(methacryloxyethyldietoxy-methylsilylpropyl)-urea (UH-MA) in the preparation and photostructuring of hybrid photopolymers. Polymerization of the monomers was investigated by differential scanning photo calorimetry (photo-DSC), Fourier transform infrared (FTIR) and near-infrared (NIR) spectroscopies. The rate of photopolymerization increased upon adding UH-MA in formulation (DC-MA/UH-MA, Rp = 9.1 × 10−2s−1; UAn-MA/UH-MA, Rp = 2.32 × 10−2s−1), the degree of conversion being between 33 and 76%. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical microscopy confirmed the formation of bidimensional hybrid microstructures by using two-photon polymerization (2PP). [ABSTRACT FROM AUTHOR]

2D MBenes, early transition metal borides, are a very recent derivative of ternary or quaternary transition metal boride (MAB) phases and represent a new member in the flatland. Although holding great potential toward various applications, mainly theoretical knowledge about their potential properties is available. Theoretical calculations and preliminary experimental attempts demonstrate their rich chemistry, excellent reactivity, mechanical strength/stability, electrical conductivity, transition properties, and energy harvesting possibility. Compared to MXenes, MBenes' structure appears to be more complex due to multiple crystallographic arrangements, polymorphism, and structural transformations. This makes their synthesis and subsequent delamination into single flakes challenging. Overcoming this bottleneck will enable a rational control over MBenes' material-structure-property relationship. Innovations in MBenes' postprocessing approaches will allow for the design of new functional systems and devices with multipurpose functionalities thus opening a promising paradigm for the conscious design of high-performance 2D materials., (© 2022 Wiley-VCH GmbH.)

An eigenvalue solution algorithm is formulated based on the finite-difference frequency-domain (FDFD) method for determining guided modes, including the surface plasmon modes, supported by periodic metallic structures. The Yee-mesh grids which have been popularly adopted in the finite-difference time-domain (FDTD) method are used in the FDFD method and standard eigenvalue matrix equations are obtained for easily searching for the guided eigenmodes. Both two-dimensional (2-D) and three-dimensional (3-D) structures are considered and the periodicity is along the propagation direction. The metals are assumed to be perfect ones or real ones without loss. For 2-D structures, an array of grooves drilled in a perfect conductor and a real-metal structure with a periodic arrangement of subwavelength slits in air are analyzed and the dispersion diagrams and mode-field profiles are obtained. For the latter structure, surface plasmon modes and dielectric slab modes are identified to be in agreement with published results based on a different numerical scheme. This subwavelength-slit structure is then extended to a 3-D one having an additional depth and it is demonstrated that the formulated algorithm can solve the same two kinds of modes for the more complicated 3-D problem. The modes guided along drilled periodic rectangle holes on a perfect conductor surface are also calculated. [ABSTRACT FROM PUBLISHER]

Abstract: The problem of layout and shape optimization of stiffeners in plates loaded in plane and in bending Kirchhoff’s plates is considered in the paper. Two types of reinforcement are analyzed here, namely introduction of elements made of stiffer material like fibers or beams and introduction of ribs. The problem of minimization (maximization) of arbitrary objective functional of displacements, strains, stresses or reactions with constraint imposed on the structure cost is considered. Using adjoint method, expressions for sensitivities with respect to introduction of stiffeners are derived and on this basis conditions of modification are formulated. In order to find optimal reinforcement, heuristic algorithm is proposed in the paper. At first, using information from sensitivity analysis, initial localization of a new fiber or rib is determined. Next, in order to correct their positions and to determine other parameters characterizing stiffened structure standard optimization is performed. Usually, optimal position of the stiffener only a little differs from the initial position. Numerical examples illustrate applicability of the method. [Copyright &y& Elsevier]

The goal of this study is to obtain globally optimum shapes for two-dimensional structures subject to quasi-static loads and restraints. For this purpose a technique is proposed, using which the volume (or weight) of a structure can be minimized. The emphasis is on how one can define the shape precisely, and find a shape that accurately reflects the globally optimum shape. As design constraints, stresses developed in the structure should not exceed the maximum allowable stress, and connectivity of the structure should not be lost during shape changes. Optimization is achieved by a stochastic search algorithm called direct simulated annealing (DSA), which seeks the global minimum through randomly generated configurations. In order to obtain random configurations, a boundary variation technique is used. In this technique, a set of key points is chosen and connected by cubic splines to describe the boundary of the structure. Whenever the positions of the key points are changed in random directions, a new shape is obtained. Thus, coordinates of the key points serve as design variables. In order to apply the optimization procedure, a general computer code was developed using ANSYS Parametric Design Language. A number of cases were examined to test its effectiveness. The results show that this technique can be applied to two-dimensional shape optimization problems with high reliability even for cases where the entire free boundary is allowed to vary. [Copyright &y& Elsevier]

By combining tight-binding modelling with density functional theory based first-principles calculations, we investigate the band evolution of two-dimensional (2D) hexagonal lattices with ( p x , p y ) orbitals, focusing on the electronic structures and topological phase transitions. The ( p x , p y )-orbital hexagonal lattice model possesses two flat bands encompassing two linearly dispersive Dirac bands. Breaking the A/B sublattice symmetry could transform the model into two triangular lattices, each featuring a flat band and a dispersive band. Inclusion of the spin-orbit coupling and magnetization may give rise to quantum spin Hall and quantum anomalous Hall (QAH) states. As a proof of concept, we demonstrate that half-hydrogenated stanene is encoded by a triangular lattice with ( p x , p y ) orbitals, which exhibits ferromagnetism and QAH effect with a topological gap of ∼0.15 eV, feasible for experimental observation. These results provide insights into the structure-property relationships involving the orbital degree of freedom, which may shed light on future design and preparation of 2D topological materials for novel electronic/spintronic and quantum computing devices., (© 2022 IOP Publishing Ltd.)

We present a new tomographic procedure for the analysis of natural source electromagnetic (EM) induction field data collected over any complex 2D buried structure beneath a flat air-earth boundary. The tomography is developed in a pure physical context and the primary goal is the depiction of the space distribution of two occurrence probability functions for the induced electrical charge accumulations on resistivity discontinuities and current channelling inside conductive bodies, respectively. The procedure to obtain tomographic image consists of a scanning operation governed analytically by a set of multiple interference cross-correlations between the observed EM components and the corresponding synthetic components of a pair of elementary charge and dipole. To show the potentiality of the proposed physical tomography, we discuss the results from three 2D synthetic examples.

By using first-principles calculations based on hybrid density functional theory, we investigate the electronic structures and photocatalytic properties of two-dimensional (2D) g-C 3 N 4 /Ti 2 CO 2 van der Waals (vdW) heterostructure. Results show that g-C 3 N 4 /Ti 2 CO 2 heterostructure has a staggered type-II band alignment, and a built-in electric field is formed at the interface due to significant charge transfer from g-C 3 N 4 to Ti 2 CO 2. Interestingly, we observed spatially distinguished conduction band and valence band edges, and a direct Z-scheme photocatalytic mechanism can be established in the heterojunction, favorable for suppressed charge carrier recombination. We further demonstrate high catalytic activity of g-C 3 N 4 /Ti 2 CO 2 towards both hydrogen evolution and water oxidation reactions, and the heterojunction exhibits excellent light-harvesting capability with entire visible light absorption. These results not only provide fundamental insight into the photocatalyst with Z-scheme mechanism, but also shed light on future design and fabrication of 2D vdW heterojunctions as high-performance catalysts for technologically important chemical reactions. [Display omitted] • Electronic properties of 2D g-C 3 N 4 /TiCO 2 vdW heterostructure are investigated by hybrid functional calculations. • It exhibits spatially distinguished conduction/valence band edges, and a built-in electric field is formed. • As a direct Z-scheme photocatalyt, g-C 3 N 4 /TiCO 2 has high catalytic activity towards hydrogen and oxygen evolution. • It demonstrates strong optical adsorption in the entire visible light region. [ABSTRACT FROM AUTHOR]

• Dynamic stiffness matrix is evaluated by considering the actual mass distribution. • Propagation of both axial and flexural waves through the members is followed. • The coupling of both waves at the structural intersection joints is considered. • The history of the solution is stored on the coefficients of the basic functions. • Innovative concept of source functions is introduced. In this paper, an efficient time domain formulation is proposed for computing time history dynamic responses of 2D structures, i.e. various types of trusses and frames. Unlike the methods using frequency domain, the proposed method employs the time weighted residual approach to solve the governing differential equations of the axial and flexural wave propagation problems, directly in time. Upon choosing the time step, the solution procedure begins with expressing the variation of axial and transverse displacement components, through the member's length, as the summations of Fourier exponential basis functions in each time step. The unknown coefficients of the next steps are computed by the implementation of recurrent relations obtained based on a pre-integration process. The equilibrium and necessary continuity conditions at the common nodes/joints of adjacent elements are also fulfilled by introducing an innovative concept utilizing source functions. The role of these source functions is to simulate the boundary effects of the axial and flexural waves propagating within the structural members, simultaneously. The efficiency of the method is demonstrated in the dynamic analysis of some samples of truss and framed structures in terms of accuracy and computational time. [ABSTRACT FROM AUTHOR]

This perspective work reviews the current status of research on magnetic particles at fluid interfaces. The article gives both a unified overview of recent experimental advances and theoretical studies centered on very different phenomena that share a common characteristic: they involve adsorbed magnetic particles that range in size from a few nanometers to several millimeters. Because of their capability of being remotely piloted through controllable external fields, magnetic particles have proven essential as building blocks in the design of new techniques, smart materials and micromachines, with new tunable properties and prospective applications in engineering and biotechnology. Once adsorbed at a fluid-fluid interfase, in a process that can be facilitated via the application of magnetic field gradients, these particles often result sorely confined to two dimensions (2D). In this configuration, inter-particle forces directed along the perpendicular to the interface are typically very small compared to the surface forces. Hence, the confinement and symmetry breaking introduced by the presence of the surface play an important role on the response of the system to the application of an external field. In monolayers of particles where the magnetic is predominant interaction, the states reached are strongly determined by the mode and orientation of the applied field, which promote different patterns and processes. Furthermore, they can reproduce some of the dynamic assemblies displayed in bulk or form new ones, that take advantage of the interfacial phenomena or of the symmetry breaking introduce by the confining boundary. Magnetic colloids are also widely used for unraveling the guiding principles of 2D dynamic self-assembly, in designs devised for producing interface transport, as tiny probes for assessing interfacial rheological properties, neglecting the bulk and inertia contributions, as well as actuated stabilizing agents in foams and emulsions. Unlabelled Image • Magnetic particles are model systems for exploring the adsorption at fluid-fluid interfaces. • The confined dipolar particles form new static and dynamic assemblies. • Dynamic assemblies can be used in the transport of adsorbed particles and molecules • Adsorbed magnetic particles are used as stabilizing agents in smart foams and emulsions. [ABSTRACT FROM AUTHOR]

The feasibility of printing structures made of high-alloy TRIP steel by Electron Beam Melting (EBM) is demonstrated in this study. Three different structure geometries are discussed. During the melting process, approximately 1.4 wt.% manganese evaporate independent of the printed structure. The structures differ in the arrangement of cell walls and the local material distribution in the in-plane array. To evaluate the strength of the structures, quasi-static compression tests were carried out in out-of-plane and in-plane direction. It is shown, that a homogenous distribution of cell walls over the structure cross section and stiffened cell walls with short distances between the cell wall nodes contribute to a high compressive strength. [ABSTRACT FROM AUTHOR]

We introduce a Chebyshev pseudo-spectral (CPS) approach for 2D TM-mode magnetotelluric modelling, which was the first applied on the magnetotellric data in 2D model. In this method, 2D partial differential equations are solved using the Chebyshev differentiation matrix over the Gauss-Chebysev-Lobatto points. In order to test computational efficiency and its accuracy, we compare the simulatation of this method to the analytical solution and finite element (FE) and finite difference (FD) methods. The comparison of CPS numerical solution and corresponding analytical solution on a homogeneous half-space model and a layered model show that the CPS approach can provide an accurate modelling result. The discrete nodes for modelling were also analyzed on two models, which suggest that a few nodes can produce modelling results with a high accuracy. Especially for 2D and 3D modelling problems, the reduction in the number of nodes can improve the computational efficiency significantly. However, the CPS approach will lead to an unsymmetrical and non-sparse matrix, which is not favored by the iterative solver. We further compare the numerical result of the CPS method to the FD method and the averaged numerical solutions of the COMMEMI on the COMMEMI 2D-1 model. We find the numerical result of CPS method is closer to the averaged numerical solutions of the COMMEMI than that of observed by the FD. Finally, a realistic smooth model is considered to compare the modelling results using the CPS method to the published data. All these comparison results suggest that the CPS method can not only give a high accuracy for modelling results and also provide more detail information. Especially, a few nodes can be required in this method relative to the FD and FE method, which can decrease the relative errors. We then deduce that CPS method might be an alternative approach to simulate the magnetotelluric responses in 2D structures. The CPS approach can provide a good accuracy for simulating 2D magnetotelluric responses, including apparent resistivities and impedance phases. Unlabelled Image • A Chebyshev pseudo-spectral (CPS) approach for 2D TM-mode magnetotelluric modelling in TM mode. • CPS approach can produce modelling results with a high accuracy and a few nodes. • CPS approach can easily extend to 3D complex Magnetotelluric modelling to deal with a large computational model. [ABSTRACT FROM AUTHOR]

In this paper, the thermal conductivity behavior of synthetic and natural esters reinforced with 2D nanostructures—single hexagonal boron nitride (h-BN), single molybdenum disulfide (MoS2), and hybrid h-BN/MOS2—were studied and compared to each other. As a basis for the synthesis of nanofluids, three biodegradable insulating lubricants were used: FR3TM and VG-100 were used as natural esters and MIDEL 7131 as a synthetic ester. Two-dimensional nanosheets of h-BN, MoS2, and their hybrid nanofillers (50/50 ratio percent) were incorporated into matrix lubricants without surfactants or additives. Nanofluids were prepared at 0.01, 0.05, 0.10, 0.15, and 0.25 weight percent of filler fraction. The experimental results revealed improvements in thermal conductivity in the range of 20–32% at 323 K with the addition of 2D nanostructures, and a synergistic behavior was observed for the hybrid h-BN/MoS2 nanostructures. [ABSTRACT FROM AUTHOR]

Zn-Ion Supercapacitors: 2D Metal Zn Nanostructure Electrodes for High-Performance Zn Ion Supercapacitors (Adv. In article number 1902981, SeungNam Cha and co-workers fabricate novel 2D-Zn metal structures through a two-step deposition process for Zn-ion supercapacitors. The 2D-Zn electrode shows promising overall-energy storing performance, achieved by the high conductivity of pure Zn, large interface active sites and favorable Zn ion diffusion paths while the 2D-Zn structures also can be successfully applied to wire-type flexible supercapacitor devices. [Extracted from the article]

Recent supercapacitors show a high power density with long‐term cycle life time in energy‐powering applications. A supercapacitor based on a single metal electrode accompanying multivalent cations, multiple charging/discharging kinetics, and high electrical conductivity is a promising energy‐storing system that replaces conventionally used oxide and sulfide materials. Here, a hierarchically nanostructured 2D‐Zn metal electrode‐ion supercapacitor (ZIC) is reported which significantly enhances the ion diffusion ability and overall energy storage performance. Those nanostructures can also be successfully plated on various flat‐type and fiber‐type current collectors by a controlled electroplating method. The ZIC exhibits excellent pseudocapacitive performance with a high energy density of 208 W h kg−1 and a power density from 500 W kg−1, which are significantly higher than those of previously reported supercapacitors with oxide and sulfide materials. Furthermore, the fiber‐type ZIC also shows high energy‐storing performance, outstanding mechanical flexibility, and waterproof characteristics, without any significant capacitance degradation during bending tests. These results highlight the promising possibility of nanostructured 2D Zn metal electrodes with the controlled electroplating method for future energy storage applications. [ABSTRACT FROM AUTHOR]

To study the possibility for silicene to be employed as a field-effect transistor (FET) pressure sensor, we explore the chemistry of monolayer and multilayered silicene focusing on the change in hybridization under pressure. Ab initio computations show that the effect of pressure depends greatly on the thickness of the silicene film, but also reveals the influence of real experimental conditions, where the pressure is not hydrostatic. For this purpose, we introduce anisotropic strain states. With pure uniaxial stress applied to silicene layers, a path for sp 3 silicon to sp 3 d silicon is found, unlike with pure hydrostatic pressure. Even with mixed-mode stress (in-plane pressure half of the out-of-plane one), we find no such path. In addition to introducing our theoretical approach to study 2D materials, we show how the hybridization change of silicene under pressure makes it a good FET pressure sensor.

Recent years have witnessed a surge of research in two-dimensional (2D) ferroelectric structures that may circumvent the depolarization effect in conventional perovskite oxide films. Herein, by first-principles calculations, we predict that an orthorhombic phase of lead(II) oxide, PbO, serves as a promising candidate for 2D ferroelectrics with good stability. With a semiconducting nature, 2D ferroelectric PbO exhibits intrinsic valley polarization, which leads to robust ferroelectricity with an in-plane spontaneous polarization of 2.4 × 10 -10 C/m and a Curie temperature of 455 K. Remarkably, we reveal that the ferroelectricity is strain-tunable, and ferroelasticity coexists in the PbO film, implying the realization of 2D multiferroics. The underlying physical mechanism is generally applicable and can be extended to other oxide films such as ferroelectric SnO and GeO, thus paving an avenue for future design and fabrication of functional ultrathin devices that are compatible with Si-based technology.

Assembling different kinds of 2D nanosheets into heterostructures presents a promising way of designing novel artificial materials with new and improved functionalities by combining the unique properties of each component. In the past few years, black phosphorus nanosheets (BPNSs) have been recognized as a highly feasible 2D material with outstanding electronic properties, a tunable bandgap, and strong in-plane anisotropy, highlighting their suitability as a material for constructing heterostructures. In this study, recent progress in the construction of BPNS-based heterostructures ranging from 2D hybrid structures to 3D networks is discussed, emphasizing the different types of interactions (covalent or noncovalent) between individual layers. The preparation methods, optical and electronic properties, and various applications of these heterostructures-including electronic and optoelectronic devices, energy storage devices, photocatalysis and electrocatalysis, and biological applications-are discussed. Finally, critical challenges and prospective research aspects in BPNS-based heterostructures are also highlighted., (© 2020 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

Here, we present an ab initio study of ways for engineering electronic and optical properties of bilayered graphene nanomeshes with various stacking types via mechanical deformations. Strong evolution of the electronic structure and absorption spectra during deformation is studied and analyzed. The obtained results are of significant importance and open up new prospects for using such nanomeshes as materials with easily controlled properties in electronic and optoelectronic nanodevices.

A finite-difference approach with non-uniform meshes was presented for simulating magnetotelluric responses in 2D structures. We presented the calculation formula of this scheme from the boundary value problem of electric field and magnetic field, and compared finite-difference solutions with finite-element numerical results and analytical solutions of a 1D model. First, a homogeneous half-space model was tested and the finite-difference approach can provide very good accuracy for 2D magnetotelluric modeling. Then we compared them to the analytical solutions for the two-layered geo-electric model; the relative errors of the apparent resistivity and the impedance phase were both increased when the frequency was increased. To conclude, we compare our finite-difference simulation results with COMMEMI 2D-0 model with the finite-element solutions. Both results are in close agreement to each other. These comparisons can confirm the validity and reliability of our finite-difference algorithm. Moreover, a future project will extend the 2D structures to 3D, where non-uniform meshes should perform especially well. [ABSTRACT FROM AUTHOR]