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The controlled creation and manipulation of defects in 2D materials has become increasingly popular as a means to design and tune new material functionalities. However, defect characterization by direct atomic-scale imaging is often severely limited by surface contamination due to a blanket of hydrocarbons. Thus, analysis techniques that can characterize atomic-scale defects despite the contamination layer are advantageous. In this work, we take inspiration from X-ray absorption spectroscopy and use broad-beam electron energy loss spectroscopy (EELS) to characterize defect structures in 2D hexagonal boron nitride (hBN) based on averaged fine structure in the boron K-edge. Since EELS is performed in a transmission electron microscope (TEM), imaging can be performed in-situ to assess contamination levels and other factors such as tears in the fragile 2D sheets, which can affect the spectroscopic analysis. We demonstrate the TEM-EELS technique for 2D hBN samples irradiated with different ion types and doses, finding spectral signatures indicative of boron-oxygen bonding that can be used as a measure of sample defectiveness depending on the ion beam treatment. We propose that even in cases where surface contamination has been mitigated, the averaging-based TEM-EELS technique can be useful for efficient sample surveys to support atomically resolved EELS experiments.

The exploration of 1D magnetism, frequently portrayed as spin chains, constitutes an actively pursued research field that illuminates fundamental principles in many-body problems and applications in magnonics and spintronics. The inherent reduction in dimensionality often leads to robust spin fluctuations, impacting magnetic ordering and resulting in novel magnetic phenomena. Here, structural, magnetic, and optical properties of highly anisotropic 2D van der Waals antiferromagnets that uniquely host spin chains are explored. First-principle calculations reveal that the weakest interaction is interchain, leading to essentially 1D magnetic behavior in each layer. With the additional degree of freedom arising from its anisotropic structure, the structure is engineered by alloying, varying the 1D spin chain lengths using electron beam irradiation, or twisting for localized patterning, and spin textures are calculated, predicting robust stability of the antiferromagnetic ordering. Comparing with other spin chain magnets, these materials are anticipated to bring fresh perspectives on harvesting low-dimensional magnetism.

Current reports of thermal expansion coefficients (TEC) of two-dimensional (2D) materials show large discrepancies that span orders of magnitude. Determining the TEC of any 2D material remains difficult due to approaches involving indirect measurement of samples that are atomically thin and optically transparent. We demonstrate a methodology to address this discrepancy and directly measure TEC of nominally monolayer epitaxial WSe2 using four-dimensional scanning transmission electron microscopy (4D-STEM). Experimentally, WSe2 from metal-organic chemical vapor deposition (MOCVD) was heated through a temperature range of 18-564 °C using a barrel-style heating sample holder to observe temperature-induced structural changes without additional alterations or destruction of the sample. By combining 4D-STEM measurements with quantitative structural analysis, the thermal expansion coefficient of nominally monolayer polycrystalline epitaxial 2D WSe2 was determined to be (3.5 ± 0.9) × 10-6 K-1 and (5.7 ± 2) × 10-5 K-1 for the in- and out-of-plane TEC, respectively, and (3.6 ± 0.2) × 10-5 K-1 for the unit cell volume TEC, in good agreement with historically determined values for bulk crystals.

The electronic and optical properties of 2D transition metal dichalcogenides are dominated by strong excitonic resonances. Exciton dynamics plays a critical role in the functionality and performance of many miniaturized 2D optoelectronic devices; however, the measurement of nanoscale excitonic behaviors remains challenging. Here, a near-field transient nanoscopy is reported to probe exciton dynamics beyond the diffraction limit. Exciton recombination and exciton-exciton annihilation processes in monolayer and bilayer MoS2 are studied as the proof-of-concept demonstration. Moreover, with the capability to access local sites, intriguing exciton dynamics near the monolayer-bilayer interface and at the MoS2 nano-wrinkles are resolved. Such nanoscale resolution highlights the potential of this transient nanoscopy for fundamental investigation of exciton physics and further optimization of functional devices.

The surface oxidation of 2D transition metal dichalcogenides (TMDs) has recently gained tremendous technological and fundamental interest owing to the multi‐functional properties that the surface oxidized layer opens up. In particular, when integrated into other 2D materials in the form of van der Waals heterostructures, oxidized TMDs enable designer properties, including novel electronic states, engineered light‐matter interactions, and exceptional‐point singularities, among many others. Here, the evolving landscapes of the state‐of‐the‐art surface engineering technologies that enable controlled oxidation of TMDs down to the monolayer‐by‐monolayer limit are reviewed. Next, the use of oxidized TMDs in van der Waals heterostructures for different electronic and photonic device platforms, materials growth processes, engineering concepts, and synthesizing new condensed matter phenomena is discussed. Finally, challenges and outlook for future impact of oxidized TMDs in driving rapid advancements across various application fronts is discussed. [ABSTRACT FROM AUTHOR]

Controlling the morphology of 2D transition metal dichalcogenides (TMDs) plays a key role in their applications. Although chemical vapor deposition can achieve wafer‐scale growth of 2D TMDs, a comprehensive theoretical framework for effective growth optimization is lacking. Atomistic modeling methods offer a promising approach to delve into the intricate dynamics underlying the growth. In this study, kinetic Monte Carlo (kMC) simulations are employed to identify crucial parameters that govern the morphology of MoS2 flakes grown on diverse substrates. The simulations reveal that large adsorption rates significantly enhance growth speed, which however necessitates rapid edge migration to achieve compact triangles. Substrate etching can tune the adsorption–desorption process of adatoms and enable preferential growth within a specific substrate region, controlling the flake morphology. This study unravels the complex dynamics governing 2D TMD morphology, offering a theoretical framework for decision‐making in the design and optimization of TMD synthesis processes. [ABSTRACT FROM AUTHOR]

Exploration of high‐temperature bosonic condensation is of significant importance for the fundamental many‐body physics and applications in nanodevices, which, however, remains a huge challenge. Here, in combination of many‐body perturbation theory and first‐principles calculations, a new‐type spatially indirect exciton can be optically generated in two‐dimensional (2D) Bi2S2Te because of its unique structure feature. In particular, the spin‐singlet spatially indirect excitons in Bi2S2Te monolayer are dipole/parity allowed and reveal befitting characteristics for excitonic condensation, such as small effective mass and satisfied dilute limitation. Based on the layered Bi2S2Te, the possibility of the high‐temperature excitonic Bose–Einstein condensation (BEC) and superfluid state in two dimensions, which goes beyond the current paradigms in both experiment and theory, are proved. It should be highlighted that record‐high phase transition temperatures of 289.7 and 72.4 K can be theoretically predicted for the excitonic BEC and superfluidity in the atomic thin Bi2S2Te, respectively. It therefore can be confirmed that Bi2S2Te featuring bound bosonic states is a fascinating 2D platform for exploring the high‐temperature excitonic condensation and applications in such as quantum computing and dissipationless nanodevices. [ABSTRACT FROM AUTHOR]

Free‐standing gallium nitride has been prepared using various methods; however, the removal of the original substrate is still challenging with low success rates. In this work, 2‐inch free‐standing GaN films are obtained by direct growth on a fluoro phlogopite mica by hydride vapor‐phase epitaxy. Depending on the van der Waals (vdW) interaction between GaN and mica, the effect of the significant lattice mismatch is effectively reduced; thus, enabling the production of a high‐quality wafer‐scale GaN film on mica. The vdW‐induced cracks at GaN–mica interface are found to be initiated near the interface so that GaN can easily separate from mica during rapid cooling. Owing to the hydrophilic nature of mica, the residual GaN on the mica can be lifted off by following deionized water treatment, and the mica substrate can be repeatedly used to grow free‐standing GaN films. The self‐separated GaN films grown on both pristine and used mica substrates are single crystallinity and strain‐free. Additionally, a fully functional ultraviolet light‐emitting diode is demonstrated to show that the self‐separated GaN films are of device quality. The proposed approach achieves epitaxial growth of wafer‐scale single‐crystalline GaN on 2D materials and provides a new substrate option in the technology of III‐V materials. [ABSTRACT FROM AUTHOR]

Atom-thin SnO 2 (a-SnO 2) shows promising potential for applications in gas sensors. However, its high working temperature can cause agglomeration, leading to a decrease in the specific surface area and resulting in performance deterioration of the sensors. In this study, g-C 3 N 4 was utilized as a thermal support to address this issue and improve the gas-sensing properties of a-SnO 2. When a-SnO 2 was grown with 10 wt% g-C 3 N 4 dispersed evenly in ethylenediamine, the gas-sensing performance of the composite improved significantly, including the response value (R a / R g = 8.8–10 ppm HCHO), fast response (τ res = 1.6 s), ultralow detection limit (0.1 ppm), long-term stability and humidity-resistance properties. This work not only introduces a method to utilize a thermal support for atom-thin metal oxides, enhancing their stability at high working temperatures but also investigates the underlying mechanism. This study provides valuable insights into the application of ultrathin metal oxides. Additionally, it facilitates the development of a portable smart system for detecting HCHO contamination in practical settings. [ABSTRACT FROM AUTHOR]

Context: Among two-dimensional (2D) materials, transition metal dichalcogenides (TMDs) stand out for their remarkable electronic, optical, and chemical properties. Their atomic thinness also imparts flexibility, making them ideal for flexible and wearable devices. However, our understanding of the mechanical characteristics of molybdenum ditelluride (MoTe2), particularly with defects such as pits, remains limited. Such defects, common in grown TMDs, degrade the mechanical properties and affect electronic and magnetic behaviors. This study uses molecular dynamics (MD) simulations of uniaxial and biaxial tensile loading performed on monolayer molybdenum ditelluride sheets of 2H phase containing triangular pits of varying vertex angles to investigate their fracture properties and visualize their crack propagation. From the stress–strain relationship, Young's modulus, fracture strain, ultimate tensile strength, and toughness for comparative analysis were calculated. Method: Tensile loading simulations were performed in molecular dynamics (MD) software LAMMPS, using the Stillinger–Weber (SW) interatomic potential, under strain rate 108 s−1 at room temperature (300 K). From the stress–strain relationship obtained, we calculated Young's modulus, fracture strain, ultimate tensile strength, and toughness. Results showed that variations in pit edge length, angle, and perimeter significantly affected these properties in monolayer MoTe2. Regulated alteration of pit angle under constant simulation conditions resulted in improved uniaxial mechanical properties, while altering pit perimeters improved biaxial mechanical properties. Stress distribution was visualized using OVITO software. MoTe2 with pit defects was found to be more brittle than its pristine counterpart. This study provides foundational knowledge for advanced design strategies involving strain engineering in MoTe2 and similar TMDs. [ABSTRACT FROM AUTHOR]

Wafer‐scale deposition of high‐휅 gate dielectrics compatible with atomically thin van der Waals layered semiconductors (e.g., MoS2, WS2, WSe2) is urgently needed for practical applications of field effect transistors based on 2D materials. A study on a high‐휅 molecular crystal antimony trioxide (Sb2O3) gate dielectric examined the role of electrode material on dielectric degradation and breakdown. It is demonstrated that the thin films of Sb2O3 can be uniformly deposited on a wafer scale. The current–voltage (I–V) curves show tightly controlled distributions of both leakage current and breakdown voltage. Electrical measurements reveal that defects are generated gradually upon electrical stressing. The evaluation of degradation is based on charge trapping, stress‐induced leakage current, and dielectric breakdown measurements. The breakdown voltage distribution follows a tight monomodal Weibull distribution suggesting a high quality of the film. Comparing Ti and Au as gate electrodes, both the breakdown field and the tunnel current are affected by the choice of electrode material. Transmission electron microscopy reveals that the chemistry at the electrode/Sb2O3 interface plays an important role and that Ti scavenges oxygen from the Sb2O3, forming a defective oxide layer at the Ti/Sb2O3 interface. For the Au electrode, this interfacial reaction is completely absent, improving the dielectric performance. [ABSTRACT FROM AUTHOR]

Feedback field-effect transistors (FBFETs) have been studied to obtain near-zero subthreshold swings at 300 K with a high on/off current ratio ~1010. However, their structural complexity, such as an epitaxy process after an etch process for a Si channel with a thickness of several nanometers, has limited broader research. We demonstrated a FBFET using in-plane WSe2 p−n homojunction. The WSe2 FBFET exhibited a minimum subthreshold swing of 153 mV/dec with 30 nm gate dielectric. Our modeling-based projection indicates that the swing of this device can be reduced to 14 mV/dec with 1 nm EOT. Also, the gain of the inverter using the WSe2 FBFET can be improved by up to 1.53 times compared to a silicon CMOS inverter, and power consumption can be reduced by up to 11.9%. [ABSTRACT FROM AUTHOR]

Conductive polymer composites (CPCs) with nanocarbon fillers are at the high end of modern materials science, advancing current electronic applications. Herein, we establish the interplay between the chemistry and electrophysical properties of reduced graphene oxide (rGO), separately and as a filler for CPCs with the segregated structure conferred by the chemical composition of the initial graphene oxide (GO). A set of experimental methods, namely X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy, van der Paw and temperature-dependent sheet resistance measurements, along with dielectric spectroscopy, are employed to thoroughly examine the derived materials. The alterations in the composition of oxygen groups along with their beneficial effect on nitrogen doping upon GO reduction by hydrazine are tracked with the help of XPS. The slight defectiveness of the graphene network is found to boost the conductivity of the material due to facilitating the impact of the nitrogen lone-pair electrons in charge transport. In turn, a sharp drop in material conductivity is indicated upon further disruption of the π-conjugated network, predominantly governing the charge transport. Particularly, the transition from the Mott variable hopping transport mechanism to the Efros–Shklovsky one is signified. Finally, the impact of rGO chemistry and physics on the electrophysical properties of CPCs with the segregated structure is evaluated. Taken together, our results give a hint at how GO chemistry manifests the properties of rGO and the CPC derived from it, offering compelling opportunities for their practical applications. [ABSTRACT FROM AUTHOR]

The design of 2D metal–organic frameworks (2D MOFs) takes advantage of the combination of the diverse electronic properties of simple organic ligands with different transition metal (TM) centers. The strong directional nature of the coordinative bonds is the basis for the structural stability and the periodic arrangement of the TM cores in these architectures. Here, direct and clear evidence that 2D MOFs exhibit intriguing energy‐dispersive electronic bands with a hybrid character and distinct magnetic properties in the metal cores, resulting from the interactions between the TM electronic levels and the organic ligand π‐molecular orbitals, is reported. Importantly, a method to effectively tune both the electronic structure of 2D MOFs and the magnetic properties of the metal cores by exploiting the electronic structure of distinct TMs is presented. Consequently, the ionization potential characteristic of selected TMs, particularly the relative energy position and symmetry of the 3d states, can be used to strategically engineer bands within specific metal–organic frameworks. These findings not only provide a rationale for band structure engineering in 2D MOFs but also offer promising opportunities for advanced material design. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) antiferromagnetic (AFM) semiconductors are promising components of opto‐spintronic devices due to terahertz operation frequencies and minimal interactions with stray fields. However, the lack of net magnetization significantly limits the number of experimental techniques available to study the relationship between magnetic order and semiconducting properties. Here, they demonstrate conditions under which photocurrent spectroscopy can be employed to study many‐body magnetic excitons in the 2D AFM semiconductor NiI2. The use of photocurrent spectroscopy enables the detection of optically dark magnetic excitons down to bilayer thickness, revealing a high degree of linear polarization that is coupled to the underlying helical AFM order of NiI2. In addition to probing the coupling between magnetic order and dark excitons, this work provides strong evidence for the multiferroicity of NiI2 down to bilayer thickness, thus demonstrating the utility of photocurrent spectroscopy for revealing subtle opto‐spintronic phenomena in the atomically thin limit. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) antiferromagnetic (AFM) semiconductors are promising components of opto‐spintronic devices due to terahertz operation frequencies and minimal interactions with stray fields. However, the lack of net magnetization significantly limits the number of experimental techniques available to study the relationship between magnetic order and semiconducting properties. Here, they demonstrate conditions under which photocurrent spectroscopy can be employed to study many‐body magnetic excitons in the 2D AFM semiconductor NiI2. The use of photocurrent spectroscopy enables the detection of optically dark magnetic excitons down to bilayer thickness, revealing a high degree of linear polarization that is coupled to the underlying helical AFM order of NiI2. In addition to probing the coupling between magnetic order and dark excitons, this work provides strong evidence for the multiferroicity of NiI2 down to bilayer thickness, thus demonstrating the utility of photocurrent spectroscopy for revealing subtle opto‐spintronic phenomena in the atomically thin limit. [ABSTRACT FROM AUTHOR]

We investigate the structural, electronic, optical, and thermoelectric properties of three compositions of Mo2C-MXenes (Mo2CF2, Mo2C(OH)2, and Mo2CO2) from monolayer to multilayer by first principles calculation within Density Functional Theory (DFT) and Boltzmann transport theory. Firstly, the atomic structures of Mo2C-MXenes are optimized, and their respective structures are created with comparative research. Secondly, their electronic band structures and optical properties are studied in detail. The estimation of the bandgap energy of Mo2C-MXenes with its functionalization reveal that most Mo2CF2 and Mo2C(OH)2 layers are semiconductors, while Mo2CO2 behaves as a metal. The electrical and optical properties can be altered by controlling the on-surface functional groups and the number of layers. Computation of the thermoelectric (TE) properties of Mo2C-MXenes reveals that, upon heating to 600 K, Mo2CF2 and Mo2C(OH)2 exhibit a high Seebeck coefficient and a relatively high electrical conductivity. The Seebeck coefficient reaches ~400 µV K−1 at room temperature for all layers of Mo2CF2 MXenes. Our results prove that Mo2CF2 is considered a promising material for thermoelectric devices, while Mo2CO2 does not possess better thermoelectric performance. Mo2C-MXenes from monolayer to multilayer have outstanding properties, such as flexible bandgap energy and high thermal stability, making them promising candidates for many applications, including energy storage and electrode applications. [ABSTRACT FROM AUTHOR]

2D materials, such as graphene, MXenes (metal carbides and nitrides), graphdiyne (GDY), layered double hydroxides, and black phosphorus, are widely used as electrocatalyst supports for alcohol oxidation reactions (AORs) owing to their large surface area and unique 2D charge transport channels. Furthermore, the development of highly efficient electrocatalysts for AORs via tuning the structure of 2D support materials has recently become a hot area. This article provides a critical review on modification strategies to develop 2D material‐based electrocatalysts for AOR. First, the principles and influencing factors of electrocatalytic oxidation of alcohols (such as methanol and ethanol) are introduced. Second, surface molecular functionalization, heteroatom doping, and composite hybridization are deeply discussed as the modification strategies to improve 2D material catalyst supports for AORs. Finally, the challenges and perspectives of 2D material‐based electrocatalysts for AORs are outlined. This review will promote further efforts in the development of electrocatalysts for AORs. [ABSTRACT FROM AUTHOR]

The ubiquitous, rising demand for energy storage devices with ultra-high storage capacity and efficiency has drawn tremendous research interest in developing energy storage devices. Dielectric polymers are one of the most suitable materials used to fabricate electrostatic capacitive energy storage devices with thin-film geometry with high power density. In this work, we studied the dielectric properties, electric polarization, and energy density of PMMA/2D Mica nanocomposite capacitors where stratified 2D nanofillers are interfaced between the multiple layers of PMMA thin films using two heterostructure designs of the capacitors, PMMA/2D Mica/PMMA (PMP) and PMMA/2D Mica/PMMA/2D Mica/PMMA (PMPMP). The incorporation of a 2D Mica nanofiller in the low-dielectric-constant PMMA leads to an enhancement in the dielectric constant, with ∆ε ~ 15% and 53% for PMP and PMPMP heterostructures at room temperature. Additionally, a significant improvement in discharged energy density was measured for the PMPMP capacitor (Ud ~ 38 J/cm3 at 825 MV/m) compared to the pristine PMMA (Ud ~ 9.5 J/cm3 at 522 MV/m) and PMP capacitors (Ud ~ 19 J/cm3 at 740 MV/m). This excellent capacitive and energy storage performance of the PMMA/2D Mica heterostructure nanocomposite may inform the fabrication of thin-film, high-density energy storage capacitor devices for potential applications in various platforms. [ABSTRACT FROM AUTHOR]

We report a computational study of the bending deformation of two-dimensional nanoribbons by classical molecular dynamics methods. Two-dimensional double transition metal carbides, together with monometallic ones, belong to the family of novel nanomaterials, so-called MXenes. Recently, it was reported that within molecular dynamics simulations, Ti4C3 MXene nanoribbons demonstrated higher resistance to bending deformation than thinner Ti2C MXene and other two-dimensional materials, such as graphene and molybdenum disulfide. Here, we apply a similar method to that used in a previous study to investigate the behavior of Mo2Ti2C3 nanoribbon under bending deformation, in comparison to the Ti4C3 sample that has a similar structure. Our calculations show that Mo2Ti2C3 is characterized by higher bending rigidity at D Ti 2 Mo 2 C 3 ≈ 92.15 eV than monometallic Ti4C3 nanoribbon at D Ti 4 C 3 ≈ 72.01 eV, which has a similar thickness. Moreover, approximately the same magnitude of critical central deflection of the nanoribbon before fracture was observed for both Mo2Ti2C3 and Ti4C3 samples, w c ≈ 1.7 nm, while Mo2Ti2C3 MXene is characterized by almost two times higher critical value of related external force. [ABSTRACT FROM AUTHOR]

[Display omitted] The creation of three dimensional (3D) structures out of two-dimensional (2D) materials while retaining their extraordinary mechanical and transport properties after processing is one of the current great challenges in materials sciences (Ruoff, 2008; Kong et al., 2019; Lin et al., 2019). Guided by density functional theory (DFT) and molecular dynamics (MD) simulations we found a successful route for a sustainable production of 3D metallic carbon materials that are synthesized from pristine 2D graphene flakes with hydrolyzed edges. The edge hydrolysis lead to strong geometrical anisotropy and self-organization in solution before processing. After processing we obtain a 3D carbon structure where 2D graphene flakes are crosslinked by carbon chains with aromatic groups at very mild annealing temperatures (∼150 °C), eliminating the constraints for achieving the in-situ preparation of conductive carbon structures. These 3D carbon structures preserve microscopic order but are macroscopically disordered, presenting physical properties of anisotropic metallic carbon with large Young modulus (E ≈ 20 GPa), and room temperature thermal (k ≈ 180 W/mK) and electrical (σ ≈ 300 kS/m) conductivities comparable to ordinary metals. [ABSTRACT FROM AUTHOR]

In the past decade, molybdenum ditelluride (MoTe2) has received significant attention from the scientific community due to its structural features and unique properties originate from them. In the current review, the properties, various preparation approaches, and versatile applications of MoTe2 are presented. The review provides a brief update on the state of our fundamental understanding of MoTe2 material and also discusses the issues that need to be resolved. To introduce MoTe2, we briefly summarize its structural, optoelectronic, magnetic, and mechanical properties in the beginning. Then, different preparation methods of MoTe2, such as exfoliation, laser treatment, deposition, hydrothermal, microwave, and molecular beam epitaxy, are included. The excellent electrical conductivity, strong optical activity, tunable bandgap, high sensitivity, and impressive stability make it an ideal contender for different applications, including energy storage, catalysis, sensors, solar cells, photodetectors, and transistors. The performance of MoTe2 in these applications is systematically introduced along with mechanistic insights. At the end of the article, the challenges and possible future directions are highlighted to further modify MoTe2 material for the numerous functionalities. Therefore, the availability of different phases and layer structures implies a potential for MoTe2 to lead an era of two‐dimensional materials that began from the exfoliation of graphene. [ABSTRACT FROM AUTHOR]

Nociceptors are key sensory receptors that transmit warning signals to the central nervous system in response to painful stimuli. This fundamental process is emulated in an electronic device by developing a novel artificial nociceptor with an ultrathin, nonstoichiometric gallium oxide (GaOx)‐silicon oxide heterostructure. A large‐area 2D‐GaOx film is printed on a substrate through liquid metal printing to facilitate the production of conductive filaments. This nociceptive structure exhibits a unique short‐term temporal response following stimulation, enabling a facile demonstration of threshold‐switching physics. The developed heterointerface 2D‐GaOx film enables the fabrication of fast‐switching, low‐energy, and compliance‐free 2D‐GaOx nociceptors, as confirmed through experiments. The accumulation and extrusion of Ag in the oxide matrix are significant for inducing plastic changes in artificial biological sensors. High‐resolution transmission electron microscopy and electron energy loss spectroscopy demonstrate that Ag clusters in the material dispersed under electrical bias and regrouped spontaneously when the bias is removed owing to interfacial energy minimization. Moreover, 2D nociceptors are stable; thus, heterointerface engineering can enable effective control of charge transfer in 2D heterostructural devices. Furthermore, the diffusive 2D‐GaOx device and its Ag dynamics enable the direct emulation of biological nociceptors, marking an advancement in the hardware implementation of artificial human sensory systems. [ABSTRACT FROM AUTHOR]

Bulk black phosphorous (bP) exhibits excellent infrared (IR) optoelectronic properties, but most reported bP IR photodetectors are fabricated from single exfoliated flakes with lateral sizes of < 100 µm. Here, scalable thin films of bP suitable for IR photodetector arrays are realized through a tailored solution‐deposition method. The properties of the bP film and their protective capping layers are optimized to fabricate bP IR photoconductors exhibiting specific detectivities up to 4.0 × 108 cm Hz1/2 W−1 with fast 30/60 µs rise/fall times under λ = 2.2 µm illumination. The scalability of the bP thin film fabrication is demonstrated by fabricating a linear array of 25 bP photodetectors and obtaining 25 × 25 pixel IR images at ≈203 ppi with good spatial fidelity. This research demonstrates a commercially viable method of fabricating scalable bP thin films for optoelectronic devices including room temperature‐operable IR photodetector arrays. [ABSTRACT FROM AUTHOR]

The research on two-dimensional materials has gained significant traction due to their potential for thermoelectric, optical, and other properties. The development of two-dimensional (2D) nanostructured-based TE generators and photodetectors has shown promising results. Over the years, researchers have played a crucial role in advancing this field, enhancing the properties of 2D materials through techniques such as doping, alloying, and various growth methods. Among these materials, black phosphorus, transition metal dichalcogenides, graphene, and IVA-VIA compounds stand out for their remarkable electronic, mechanical, and optical properties. This study presents a comprehensive review of the progress in the field, focusing on IVA-VIA compounds and their applications in TE and photodetector technologies. We summarize recent advancements in enhancing these materials' TE and optical properties and provide an overview of various synthesis techniques for their fabrication. Additionally, we highlight their potential applications as photodetectors in the infrared spectrum. This comprehensive review aims to equip researchers with a deep understanding of the TE and optical properties of 2DMs and their potential applications and to inspire further advancements in this field of research. [ABSTRACT FROM AUTHOR]

Thermal agents (TAs) have exhibited promise in clinical tests when utilized in cancer thermal therapy (TT). While rapid degradation of TAs may address safety concerns, it limits the thermal stability required for effective treatment. TAs, which possess exceptional thermal stability, experience gradual deterioration. There are few approaches that effectively address the trade-off between improving thermal stability and simultaneously boosting material deterioration. Here, we control the thermal character of tungsten disulfide (WS2)-based 2D materials by utilizing an M13 phage through Joule heating (the M13–WS2–PEG nanostructures were generated and termed a tripartite (T) nanostructure), and developed a T nanostructure-driven TT platform (we called it T-TT) for efficient thermal ablation of clinically relevant MCF-7 cells. A relative cell viability of ~59% was achieved, as well as onset time of degradation of ~0.5 week. The T-TT platform also discloses an energy density of 5.9 J/mL. Furthermore, the phage-conjugated WS2 can be utilized to achieve ultrasound imaging for disease monitoring. Therefore, this research not only presents a thermal agent that overcomes TA limitations, but also demonstrates a practical application of WS2-type material system in ultra-energy efficient and effective cancer therapy. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) van der Waals (vdW) magnetic materials show potential for the advancement of high-density, energy-efficient electronic and spintronic applications in future memory and computation. Here, by using first-principles density functional theory (DFT) calculations, we predict a new 2D Janus nitride MXene MnCrNO2 monolayer. Our results suggest that the optimized MnCrNO2 monolayer possesses a hexagonal structure and exhibits good dynamical stability. The intrinsic monolayer MnCrNO2 exhibits semiconductive properties and adopts a ferromagnetic ground state with an out-of-plane easy axis. It can sustain strain effects within a wide range of strains from −10% to +8%, as indicated by the phonon dispersion spectra. Under the biaxial tensile strain, a remarkable decrease in the bandgap of the MnCrNO2 is induced, which is attributed to the distinct roles played by Mn and Cr in the VBM or CBM bands. Furthermore, when the compressive strain reaches approximately −8%, the magnetic anisotropy undergoes a transition from an out-of-plane easy axis to an in-plane easy axis. This change is mainly influenced by the efficient hybridization of the d orbitals, particularly in Mn atoms. Our study of the Janus MXene MnCrNO2 monolayer indicates its potential as a promising candidate for innovative electronic and spintronic devices; this potential is expected to create interest in its synthesis. [ABSTRACT FROM AUTHOR]

Context: Myocardial infarction is one of the major health challenges. It is of great significance to develop potential delivery carriers for new anti-myocardial infarction drugs. In this paper, based on first-principles calculations, monolayer WS2 with excellent photoelectric properties was verified as a carrier for the anti-myocardial infarction drug amiodarone (AMD). Studies have shown that the WS2-adsorbed AMD system (WS2@AMD) maintains structural stability and produces an adsorption energy of—2.12 eV. Mulliken charge analysis shows that electrons are transferred from WS2 atoms to AMD atoms. Among them, C, N and O obtained the maximum values of 0.51,0.37 and 0.56 e electrons, respectively, while H and I lost the maximum values of 0.32 and 0.24 e electrons, respectively. The optical response of WS2 adsorbed AMD system is similar to that of WS2. The light absorption coefficients of the two materials in the near ultraviolet region and the visible region can reach the order of 105 cm−1 and 104 cm−1, and the strain makes the light absorption peak red-shifted. The feasibility of temperature-controlled release mechanism of WS2 as AMD carrier was discussed. This theoretical work helps to improve the performance of two-dimensional nanomaterials and make them better as drug delivery carriers to improve the therapeutic effect of myocardial infarction. These results indicate that the WS2 monolayer has potential applications in the development of drug delivery carriers. Methods: In this study, based on first-principles calculations, the CASTEP simulation software package was used to study the structure and properties of materials. The interaction between electrons and ions is considered by using Ultrasoft pseudopotentials. In order to eliminate the spurious interaction between adjacent structures caused by periodic calculations, a vacuum space no less than 18 Å is placed in the vertical direction if necessary. Different functions may produce different density functional calculation results. Due to the low sensitivity of the crystal structure to the calculation details, the PBE functional under the generalized gradient approximation (GGA) was initially used for structural optimization, and the energy cutoff value was set to 500 eV. Grimme 's dispersion correction was used to make the results more accurate. The Brillouin zone (BZ) is sampled by a 7 × 7 × 1 K-point grid to ensure the reliability of the original lattice calculation. The lattice vector and atomic coordinates are relaxed, and the tolerance of each atom is less than 0.01 eV/Å. The energy tolerance at the atomic position is less than 10–7 eV/atom. When calculating the band gap, the HSE06 hybrid functional is used to modify the optimized structure of the PBE functional to obtain more accurate results. Spin-polarized DFT calculations were performed to calculate the electronic structure. [ABSTRACT FROM AUTHOR]

Nanoscale-engineered surfaces induce regulated strain in atomic layers of 2D materials that could be useful for unprecedented photonics applications and for storing and processing quantum information. Nevertheless, these strained structures need to be investigated extensively. Here, we present texture-induced strain distribution in single-layer WS2 (1L-WS2) transferred over Si/SiO2 (285 nm) substrate. The detailed nanoscale landscapes and their optical detection are carried out through Atomic Force Microscopy, Scanning Electron Microscopy, and optical spectroscopy. Remarkable differences have been observed in the WS2 sheet localized in the confined well and at the periphery of the cylindrical geometry of the capped engineered surface. Raman spectroscopy independently maps the whole landscape of the samples, and temperature-dependent helicity-resolved photoluminescence (PL) experiments (off-resonance excitation) show that suspended areas sustain circular polarization from 150 K up to 300 K, in contrast to supported (on un-patterned area of Si/SiO2) and strained 1L-WS2. Our study highlights the impact of the dielectric environment on the optical properties of two-dimensional (2D) materials, providing valuable insights into the selection of appropriate substrates for implementing atomically thin materials in advanced optoelectronic devices. [ABSTRACT FROM AUTHOR]

The scaling of bulk Si-based transistors has reached its limits, while novel architectures such as FinFETs and GAAFETs face challenges in sub-10 nm nodes due to complex fabrication processes and severe drain-induced barrier lowering (DIBL) effects. An effective strategy to avoid short-channel effects (SCEs) is the integration of low-dimensional materials into novel device architectures, leveraging the coupling between multiple gates to achieve efficient electrostatic control of the channel. We employed TCAD simulations to model multi-gate FETs based on various dimensional systems and comprehensively investigated electric fields, potentials, current densities, and electron densities within the devices. Through continuous parameter scaling and extracting the sub-threshold swing (SS) and DIBL from the electrical outputs, we offered optimal MoS2 layer numbers and single-walled carbon nanotube (SWCNT) diameters, as well as designed structures for multi-gate FETs based on monolayer MoS2, identifying dual-gate transistors as suitable for high-speed switching applications. Comparing the switching performance of two device types at the same node revealed CNT's advantages as a channel material in mitigating SCEs at sub-3 nm nodes. We validated the performance enhancement of 2D materials in the novel device architecture and reduced the complexity of the related experimental processes. Consequently, our research provides crucial insights for designing next-generation high-performance transistors based on low-dimensional materials at the scaling limit. [ABSTRACT FROM AUTHOR]

Owing to their characteristics like fast charge–discharge rate, very long life, simple geometry and eco-friendly nature, supercapacitor is an emerging technology to fulfil the present and future requirements of the energy. The performance of a supercapacitor is derived from the composition and morphology of the electrode. 2D materials possess various excellent structural properties like surface area, flexibility in the atomic scale dimension and mechanical strength with high electrical conductivity. This makes them an entrusted material to be used as an electrode material. The teaming of 2D materials and layered transition metal dichalcogenides have been of great interest for electrode materials. In this study, the reduction of graphene oxide is done by an environment-friendly synthesis method using cow urine, and then, synthesizing the reduced graphene oxide (rGO) and transition metal dichalcogenides (TMD) composite using the refluxing method. The modified pencil graphite electrode (PGE) was functionalized using the above composite and the performance is comparable to that of glassy carbon electrode. Our main motive was to develop a low-cost, sustainable and highly effective MoS2–rGO/PGE, which is completely based on an environment and eco-friendly method using natural precursors. The prepared MoS2–rGO nanocomposite was characterized by XRD, SEM and EDX, which revealed the formation as well as its morphological scenario. MoS2–rGO/PGE is explored as electrode material by electrochemical characterization with the 3-electrode system through cyclic voltammetry and electrochemical impedance spectroscopy, which exhibit maximum specific capacitance with good cycle stability. [ABSTRACT FROM AUTHOR]

This review offers insights into the recent advancements of 3D/4D printed materials for fog collection and solar vapor generation devices. It presents a comprehensive overview of various material properties, device engineering aspects, printing technologies, practical challenges, and future prospects. [Display omitted] • Exploration of additive manufacturing technology in advanced water harvesting systems. • Utilization of 3D/4D printing materials for improved fog harvesting and solar vapor generation devices. • Examination of various material properties and device design engineering to optimize water harvesting performance. • Discussion on strategies for autonomous freshwater collection. The incorporation of cutting-edge technology in developing diverse water harvesters enhances the efficiency of water harvesting systems. Fog harvesting device (FHD) and solar vapor generation device (SVGD) have emerged as environmentally friendly, cost-effective, and efficient methods for generating clean and fresh water, gaining significant attention in recent years. Additionally, there has been extensive reporting on various fog harvesters and photothermal materials, and their structural designs to enhance the efficiency of water harvesting systems. Notably, the exploration of three-dimensional (3D)/four-dimensional (4D) printed FHD and SVGD represents a crucial research avenue in this field. This comprehensive review meticulously investigates recent advancements in designing and engineering 3D/4D printed materials, specifically tailored to enhance water harvesting efficiency. We present an overview of 3D printed materials and designs featuring diverse surface properties to enhance the effectiveness of FHD and SVGDs. The working principles of both systems and key considerations for designing new FHD and SVGD are explored. We investigate a variety of 3D printed materials optimized for fog collection and vapor generation, evaluating their performance based on structural engineering and surface properties. The review also emphasizes 4D printed materials, highlighting their potential for continuous water harvesting from day to night. In conclusion, the review furnishes a comprehensive summary, providing insights into current research, accomplishments, and future challenges in the realm of 3D/4D printed materials for water harvesting. We believe that this information serves as valuable education and motivation for new researchers and the scientific community. [ABSTRACT FROM AUTHOR]

Traditional lubricants, often containing harmful chemicals and synthetic or fossil-derived oils, pose environmental risks by damaging ecosystems and threatening human health and wildlife. There is a growing demand for environmentally sustainable and cost-effective bio-based lubricants derived from renewable raw materials. These bio-based oils often possess natural lubricating properties, making them an attractive alternative to traditional synthetic lubricants. In addition to providing effective lubrication, they offer good biodegradability and minimal toxicity, which are essential for reducing environmental impact. However, the primary challenge lies in optimizing their performance to match or surpass that of conventional lubricants while ensuring they remain cost-effective and widely available. This paper reviews the general requirements for lubricants and explores how plant-based oils can be utilized to meet the diverse lubrication needs across various industries. Further, it highlights different approaches that can be used for further improvements in the area of plant-based lubrication through bio-inspired means, such as the use of estolides, wax esters, or erucic acid, as well as through additions of nanomaterials, such as nanoparticles, nanoclays, or two-dimensional films. [ABSTRACT FROM AUTHOR]

Monolayer black phosphorus (BP) holds great promise for naturally hyperbolic polaritons and correlated states in rectangular moiré superlattices. However, preparing and identifying high-quality monolayer BP are challenging due to its instability and high transparency, which limits extensive studies. In this study, we developed a method for rapidly and nondestructively identifying monolayer BP and its crystal orientation simultaneously using modified photoluminescence (PL) microscopy. The optical contrast of monolayer BP has been significantly increased by at least twenty times compared to previous reports, making it visible even on a transparent substrate. The polarization dependence of optical contrast also allows for the in situ determination of crystal orientation. Our study facilitates the identification of monolayer BP, expediting more extensive research on and potential industrial applications of this material. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) has been extensively studied for fabricating ion exchange membranes. This material is of interest due to its surface‐governed charge which, combined with the interlayer distance between the GO flakes stack, offers ion selectivity. However, obtaining high‐performing membranes with high ion selectivity and low ionic resistance remains challenging. To address this issue, Al(OH)4− anions are incorporated into graphene oxide membranes to increase their spontaneous negative surface charge. The anions are successfully formed and encapsulated through a reaction with the alumina support under alkaline conditions during the membrane fabrication. A modeling of the system proves the anchoring of the Al(OH)4− anions within the GO matrix. The incorporation of these anions significantly improves the permselectivity and reduces the ionic resistance, reaching approximately 95% and 2 Ω cm2, respectively. The GO‐modified membranes also present mono‐valent selectivity, which can boost reverse electrodialysis power densities. [ABSTRACT FROM AUTHOR]

The study of novel materials for H2 storage is essential to consolidate the hydrogen as a clean energy source. In this sense, the H2 adsorption on Pd4-nNin (n = 0–3) clusters embedded on pyridinic-type N-doped graphene (PNG) was investigated using density functional theory calculations. First, the properties of Pd4-nNin (n = 0–3) clusters embedded on PNG were analyzed in detail. Then, the H2 adsorption on these composites was computed. The Eint between the Pd4-nNin (n = 0–3) clusters and the PNG was greater than that computed in the literature for Pd-based systems embedded on pristine graphene. Consequently, it was deduced that PNG can more significantly stabilize the Pd4-nNin (n = 0–3) clusters. The analyzed composites exhibited a HOMO–LUMO gap less than 1 eV, indicating good reactivity. Based on the Eads of H2 on Pd4-nNin (n = 0–3) clusters embedded on PNG, it was observed that the analyzed systems meet the standards set by the DOE. Therefore, these composites can be viable alternatives for hydrogen storage. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) layered materials with unique physicochemical properties, such as graphene, transition metal dichalcogenides, and hexagonal boron nitride, have shown considerable potential in the electrical and electronics industries as well as society. To realize the practical applications of 2D materials, the size, shape, and edge structures must be refined. Etching is a critical processing step in the semiconducting industry and its potential as an efficient approach for fabricating diverse nanostructures of 2D materials has been demonstrated, broadening their applications in the field of nanoelectronics. In this paper, we present an overview of recent advances in anisotropic etching of various 2D materials. Anisotropic etching and the associated mechanisms are discussed in context of the synthesis, processing, and characterization of 2D materials. An overview of the applications of anisotropic etched 2D materials is provided. Finally, the challenges and future opportunities for anisotropic etching of 2D materials are discussed.

Since the discovery of graphene in 2004, the unique properties of two-dimensional materials have sparked intense research interest regarding their use as alternative materials in various photonic applications. Transition metal dichalcogenide monolayers have been proposed as transport layers in photovoltaic cells, but the promising characteristics of group IV–VI dichalcogenides are yet to be thoroughly investigated. This manuscript reports on monolayer Ge2Se2 (a group IV–VI dichalcogenide), its optoelectronic behavior, and its potential application in photovoltaics. When employed as a hole transport layer, the material fosters an astonishing device performance. We use ab initio modeling for the material prediction, while classical drift–diffusion drives the device simulations. Hybrid functionals calculate electronic and optical properties to maintain high accuracy. The structural stability has been verified using phonon spectra. The E–k dispersion reveals the investigated material’s key electronic properties. The calculations reveal a direct bandgap of 1.12 eV for monolayer Ge2Se2. We further extract critical optical parameters using the Kubo–Greenwood formalism and Kramers–Kronig relations. A significantly large absorption coefficient and a high dielectric constant inspired the design of a monolayer Ge2Se2-based solar cell, exhibiting a high open circuit voltage of Voc = 1.11 V, a fill factor of 87.66%, and more than 28% power conversion efficiency at room temperature. Our findings advocate monolayer Ge2Se2 for various optoelectronic devices, including next-generation solar cells. The hybrid quantum-to-macroscopic methodology presented here applies to broader classes of 2D and 3D materials and structures, showing a path to the computational design of future photovoltaic materials.

[Display omitted] Förster resonance energy transfer (FRET) serves as a critical mechanism to study intermolecular interactions and the formation of macromolecular assemblies. Cascade FRET is a multi-step FRET process which can overcome limitations associated with traditional single-step FRET. Herein, a novel organic–inorganic hybrid composed of a nile red derivative attached to the edge of the layered silicate clay Laponite (Lap-NR) was used to facilitate cascade FRET between Laponite sheets. Utilizing naphthalene-diimide edge-modified Laponite (Lap-NDI) as the initial donor, Rhodamine 6G on the basal surface of Laponite as the first acceptor, and Lap-NR as the second acceptor, cascade FRET was achieved. The influence of solvent composition in a DMF/water mixture on cascade FRET was investigated, revealing that a higher water content led to an enhancement of the cascade FRET process, which is attributed to increased aggregation-induced emission of Lap-NDI and the enhanced quantum yield of R6G in water. This study provides a unique approach to achieve cascade FRET by taking advantage of the anisotropic surface chemistry of a two-dimensional nanomaterial, providing a colloidally-driven alternative with improved tunability compared to macromolecular routes. The flexibility and simplicity of this approach will advance the state of the art of organic–inorganic hybrids for applications in optoelectronics, sensors, and hybrid photovoltaics. [ABSTRACT FROM AUTHOR]

In this paper, based on the first-principles calculation method of density functional theory, the PtS2/PtSe2 heterostructure with the lowest formation energy is selected from five different stacking modes. At the same time, the phonon spectrum of PtS2/PtSe2 heterostructure has no imaginary frequency, so the structure is stable. After that, the changes of photoelectric properties of heterostructures under tensile and compressive strains were studied. It is concluded that the PtS2/PtSe2 heterostructure is a semiconductor with indirect band gap and type II band arrangement. With the increase of tensile strain, the band gap value decreases from 0.927 to 0.565 eV, and the minimum value of the conduction band is transferred from the high symmetry point M point to the K point by 8% biaxial tensile strain. The biaxial tensile strain can effectively improve the dielectric constant of the PtS2/PtSe2 heterostructure. When the strain reaches 8%, the dielectric constant is nearly twice as high as the intrinsic value and reaches 11.6, which improves the charge retention ability. The light absorption of PtS2/PtSe2 heterostructure reaches 13.7 × 104 cm−1 under compressive strain, and the stability of light absorption is enhanced. The optical reflection ability of PtS2/PtSe2 heterostructure is significantly enhanced under tensile strain, indicating that the biaxial strain has a regulatory effect on the absorption and reflection ability of light. The valley values of all systems near the ultraviolet region show a linear increase trend, which changes the transmittance of the heterostructure. These findings broaden the application of PtS2/PtSe2 heterostructures in optoelectronic engineering. [ABSTRACT FROM AUTHOR]

Abstract Silicon-based two-dimensional (2D) materials have garnered significant attention due to their unique properties and potential applications in electronics, optoelectronics, and other advanced technologies. Here, we present a comprehensive investigation of a novel silicon allotrope, Popsilicene (Pop-Si), derived from the structure of Popgraphene. Using density functional theory and ab initio molecular dynamics simulations, we explore the thermal stability, mechanical and electronic properties, and optical characteristics of Pop-Si. Our results demonstrate that Pop-Si exhibits good thermal stability at 1000 K. Electronic structure calculations reveal that Pop-Si is metallic, with a high density of states at the Fermi level. Furthermore, our analysis of the optical properties indicates that Pop-Si has pronounced UV–Vis optical activity, making it a promising candidate for optoelectronic devices. Mechanical property assessments show that Pop-Si has Young’s modulus ranging from 10 to 92 GPa and a Poisson’s ratio of 0.95. These results combined suggest its potential for practical applications.

Friction and wear collectively account for nearly a quarter of the world’s energy consumption, resulting in over eight Gigatons of CO2 emissions annually. With increasing mobility and industrial activity, the adverse effects of friction and wear on energy, the environment, the global economy, and sustainability will undoubtedly intensify. Unless we reverse this unsustainable trend, our planet could face a major ecological and environmental catastrophe. Fortunately, significant strides have been made in reducing friction to almost undetectable levels, with friction coefficients below 0.001. These remarkable achievements have resulted from numerous collaborative efforts and global initiatives focused on developing novel materials, surfaces, and interfaces that exhibit minimal or near zero friction, even at macro or engineering scales. This paper provides a comprehensive overview of the factors that contribute to and hinder superlubric sliding conditions, examining the impact of both intrinsic and extrinsic factors that are integral parts of the test conditions and environments. Drawing from recent analytical, experimental, and computational findings, underlying mechanisms most responsible for superlubricity are also discussed. The paper discusses recent mechanistic studies on highly ordered 2D materials, such as graphene, MoS2, h-BN, MXene, etc., and thin solid coatings such as diamond-like carbon or DLCs, as well as liquids, and discusses their potential for the development of large-scale mechanical systems. These exciting advancements pave the way for designing and producing next-generation engineering systems that can minimize friction in practical applications, thus conserving energy, enhancing durability, and protecting the environment for a sustainable future.

Second harmonic generation is a non-linear optical phenomenon in which coherent radiation with frequency ω interacts with a non-centrosymmetric material and produces coherent radiation at frequency 2ω. Owing to the exciting physical phenomena that take place during the non-linear optical excitation at the nanoscale, there is currently extensive research in the non-linear optical responses of nanomaterials, particularly in low-dimensional materials. Here, we review recent advancements in the polarization-resolved second harmonic generation propertied from atomically thin two-dimensional (2D) crystals and present a unified theoretical framework to account for their nonlinear optical response. Two major classes of 2D materials are particularly investigated, namely metal chalcogenides and perovskites. The first attempts to tune and control the second harmonic generation properties of such materials via the application of specific nanophotonic schemes are additionally demonstrated and discussed. Besides presenting recent advances in the field, this work also delineates existing limitations and highlights emerging possibilities and future prospects in this field.

An often observed artifact in atomic force microscopy investigations of individual monolayer flakes of 2D materials is the inaccurate height derived from topography images, often attributed to capillary or electrostatic forces. Here, we show the existence of a Joule dissipative mechanism related to charge dynamics and supplementing the dissipation due to capillary forces. This particular mechanism arises from the surface conductivity and assumes significance specially in the context of 2D materials on insulating supports. In such scenarios, the oscillating tip induces in-plane charge currents that in many circumstances constitute the main dissipative contribution to amplitude reduction and, consequently, affect the measured height. To investigate this phenomenon, we conduct measurements on monolayer flakes of co-deposited graphene oxide and reduced graphene oxide. Subsequently, we introduce a general model that elucidates our observations. This approach offers valuable insights into the dynamics of surface charges and their intricate interaction with the tip.

Single-photon emitters (SPEs) hold the key to many quantum technologies including quantum computing. In particular, developing a scalable array of identical SPEs can play an important role in preparing single photons – crucial resources for computation – at a high rate, allowing to improve the computational capacity. Recently, different types of SPEs have been found in various 2D materials. Towards realizing scalable SPE arrays in 2D materials for quantum computation, it is required to develop tunable SPEs that can produce identical photons by precisely controlling emission properties. Here, we present a brief review of the recent progress on various tuning methods in different 2D materials. Firstly, we discuss the operation principle of different 2D SPEs along with their unique characteristics. Secondly, we introduce various dynamic strain engineering methods for tuning the emission wavelengths in 2D SPEs. We also present several electric field-induced wavelength tuning methods for 2D SPEs. Lastly, we discuss the outlook of dynamically tunable 2D SPEs towards scalable 2D SPE arrays for realizing practical quantum photonics applications.

Quasi-bound states in the continuum (quasi-BICs) offer unique advantages in enhancing nonlinear optical processes and advancing the development of active optical devices. Here, the tunable robust quasi-BICs resonances are experimentally achieved through the engineering of multiple-hole Si-metasurface. Notably, the quasi-BICs mode exhibits flat bands with minimal dispersion at a wide range of incident angles, as demonstrated by the angle-resolved spectroscopy measurements. Furthermore, we demonstrate a giant second-harmonic generation (SHG) enhancement by coupling a WSe2 monolayer to the quasi-BICs hosted in the metasurface. Leveraging the strong local electric field and high state density of the observed quasi-BICs, the SHG from the WSe2 monolayer can be enhanced by more than two orders of magnitude. Our work paves the way for effectively enhancing nonlinear optical processes in two dimensional (2D) materials within the framework of silicon photonics and is expected to be applied in nonlinear optical devices.

Abstract Two-dimensional (2D) materials have emerged as promising building blocks for next generation memristive devices, owing to their unique electronic, mechanical, and thermal properties, resulting in effective switching mechanisms for charge transport. Memristors are key components in a wide range of applications including neuromorphic computing, which is becoming increasingly important in artificial intelligence applications. Crossbar arrays are an important component in the development of hardware-based neural networks composed of 2D materials. In this paper, we summarize the current state of research on 2D material-based memristive devices utilizing different switching mechanisms, along with the application of these devices in neuromorphic crossbar arrays. Additionally, we discuss the challenges and future directions for the field.

Highlights A systematic overview of the latest advancements in M4X3 MXenes is dicussed. The detailed properties of MXene are summarized. M4X3 MXenes are explored as an electrode material.

2D MXenes find applications in several technology fields. Solution processing techniques can facilitate the integration of these materials within the technological supply chain. Here, a highly concentrated (up to 1.5 g L−1) and stable dispersion of 2D Ti3C2Tx MXene flakes is produced by an environmentally friendly liquid phase exfoliation process (LPE) in dihydrolevoglucosenone (Cyrene). The flakes preserve their elemental composition after 6 months, while those exfoliated in N‐Methyl‐2‐pyrrolidone (NMP), a commonly used solvent, undergo significant oxidation. The cytotoxicity of the MXene flakes in Cyrene and in NMP is investigated by assessing the cellular viability in a human keratinocyte (HaCaT) cell line, which is a relevant model for skin applications. The data show that the MXene flakes in Cyrene induce cytotoxic effects for a dose > 1 µg cm−2, as similarly observed for the MXene flakes in NMP. Efforts are made to overcome this by collecting the MXene flakes and redispersing them in a solution of bovine serum albumin (BSA). MXene in BSA does not affect cellular viability and cell morphology, possibly due to the formation of a protective protein corona around the individual MXene flakes. These findings illustrate an environmentally friendly strategy to produce biocompatible 2D MXene for biomedical applications. [ABSTRACT FROM AUTHOR]