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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.

To achieve a balance between performance and durability in electrochemical energy conversion systems, such as fuel cells (FC) and water electrolyzers (WE), proton exchange membranes (PEMs) must be optimized for minimal thickness and resistance while maximizing gas rejection and durability. 2D materials, with Angstrom‐scale pores, hold the potential to revolutionize these devices by enabling highly selective proton transport and mitigating degradation pathways. However, to date no material has been implemented that can prevent gas crossover and extend the device lifetime without compromising initial performance. In this study, it is demonstrated that polytriazine imide (PTI), a 2D graphitic carbon nitride with optimally sized and functionalized lattice pores, facilitates unimpeded proton transport. By engineering a centimeter‐scale monolayer film composed of tessellated PTI nanosheets and placing it at the cathode‐PEM interface, significant gains in performance, efficiency, and durability ‐are achieved. These results in PEMFCs show halved hydrogen crossover and over a threefold increase in lifetime. This approach promises to accelerate the adoption of economically viable FCs and WEs with enhanced output and extended service lifetimes, essential for achieving a decarbonized society. [ABSTRACT FROM AUTHOR]

Flexible and robust memristors with controllable resistance‐switching characteristics are important to neuromorphic computing. However, the nanomaterials‐based, solution‐processed resistance switching layer usually has poor reliability and tunability due to uneven morphology and invariable surface properties. Herein, phosphorylated graphene nanoflakes (phos‐GPs) are synthesized for high‐performance solution‐processed flexible memristors. In situ conductive atomic force microscopy reveals that the tightly stacked uniform nanoflakes and modified phosphorate groups jointly reduce the formation barrier of the conductive filaments. Furthermore, phosphorylation gives rise to surface silver ion coordination leading to enhanced radial growth of the conductive filaments. The memristor shows volatile characteristics in the Ag/phos‐GPs/ITO architecture and exhibits non‐volatile properties in the Ag/Ag+‐(phos‐GPs)/ITO structure. Both types of memristors display consistent I‐‐V curves during long‐term cycling and under repetitive mechanical bending, in addition to excellent synaptic plasticity. Moreover, ultrasmall nonlinearity is observed from non‐volatile long‐term synaptic potentiation and depression. By utilizing the tunable artificial synapses, the processes of memory‐forgetting and re‐recognition are simulated, and the image recognition tasks are accomplished by the artificial neural networks. [ABSTRACT FROM AUTHOR]

Polarization photodetectors (PPDs) based on 2D materials hold great promise for ultracompact polarimeters due to their ability to directly detect polarization states. However, the existing PPDs based on 2D materials tend to focus on a single metric, making it challenging to obtain both a large polarization ratio (PR) and high responsivity (R). Here, black phosphorus (BP) PPDs are proposed under a nanowire configuration that enables large PR and high R simultaneously. Benefitting from the anisotropic coupling between the BP crystal and the nanowire geometry, specific light‐field distributions are formed under orthogonally polarized light incidences, through selectively exciting the localized surface plasmon and leaky‐mode resonances. A large carrier concentration gradient inherent to this structure is formed to induce a high response contrast and a large Dember current, enabling an ultrahigh PR ≈ 118.4, R ≈ 802.42 A W−1, and ultrashort response time ≈ 636 ps. Finally, a key‐free optical encryption communication system is constructed, demonstrating one of its promising applications. [ABSTRACT FROM AUTHOR]

Silicene has recently been revisited as a 2D material with potential thermoelectric applications. Here, the thermal properties of supported silicene are determined by optothermal Raman spectroscopy. Single and multilayer silicene is grown either directly on silver (Ag) substrates or on an intermediate tin (Sn) monolayer, introduced to reduce the influence of the substrate on the physical properties of silicene. Experimental values of an effective cross‐plane thermal conductivity of 0.5 W/mK are obtained for silicene on Ag and 0.3 W/mK for silicene on stanene‐Ag. The values of the interfacial thermal conductance, on the other hand, are 0.3 and 0.5 GW/m2K, respectively. Heterostack engineering is confirmed as a versatile strategy for extracting relevant physical parameters in silicene and for modulating the thermal response in the 2D limit. [ABSTRACT FROM AUTHOR]

2D materials with unique layer‐dependent electronic structure can bring precise control to their photocarrier dynamics for optimizing and expanding optoelectronic applications, while the challenge of controlling layer stacking makes the layer dependency law still underexplored in emerging 2D ternary metal chalcogenides. Herein, 2D rhombohedral‐phase ZnIn2S4 (R‐ZIS) with controllable layer thickness is achieved by confined‐growth strategy in high yield, exhibiting continuously tunable direct bandgap (2.39–2.77 eV) with evident upshift of conduction band minimum (CBM) and Fermi level (EF), demonstrated arising from the synergistic effect of reduced interlayer interaction with inevitably increasing Zn defects. Remarkably, the carrier dynamics of R‐ZIS in photoelectrochemical (PEC) device is successfully regulated by adjusted CBM and EF, resulting in continuously tunable optical absorption band, photocarrier separation efficiency, self‐powered capability, and dark current noise. Beneficial from tailored band structure and carrier dynamics, self‐powered PEC‐type photodetector with broadband photoresponse (254–765 nm), is achieved fast response speed (12.3/5.3 ms) and high responsivity (90.29 mA W−1) in multilayer R‐ZIS, while deep‐UV photodetector with ultra‐high specific detectivity (1.62 × 1012 Jones) at 254 nm in monolayer R‐ZIS, exhibiting the record performance in both fields. This work motivates the development of tailored band structure for 2D‐materials‐based optoelectronic devices in strategy and mechanism. [ABSTRACT FROM AUTHOR]

Ferroelectricity, band topology, and superconductivity are respectively local, global, and macroscopic properties of quantum materials, and understanding their mutual couplings offers unique opportunities for exploring rich physics and enhanced functionalities. In this mini‐review, the attempt is to highlight some of the latest advances in this vibrant area, focusing in particular on ferroelectricity‐tuned superconductivity and band topology in 2D materials and related heterostructures. First, results from predictive studies of the delicate couplings between ferroelectricity and topology or superconductivity based on first‐principles calculations and phenomenological modeling are presented, with ferroelectricity‐enabled topological superconductivity as an appealing objective. Next, the latest advances on experimental studies of ferroelectricity‐tuned superconductivity based on different 2D materials or van der Waals heterostructures are covered. Finally, as perspectives, schemes are outlined that may allow to materialize new types of 2D systems that simultaneously harbor ferroelectricity and superconductivity, or that may lead to enhanced ferroelectric superconductivity, ferroelectric topological superconductivity, and new types of superconducting devices such as superconducting diodes. [ABSTRACT FROM AUTHOR]

Regenerative biomedicine has emerged as a forefront area in medical research, heralding a new era of therapeutic strategies. This review delineates the integration of 2D materials (2DMs) within the area of biomedical engineering, leveraging their superior physicochemical attributes for enhance biomedical outcomes. The synergistic interaction between biomacromolecules and 2DMs is explored, demonstrating their potential to mitigate the limitations inherent to each while simultaneously augmenting their beneficial properties. In particular, incorporating 2DMs into hydrogels highlights their capability to enhance the mechanical strength of hydrogels, providing a biomimetic scaffold for tissue engineering regeneration and cancer diagnosis and therapy. An overview of the synthetic methodologies are provided for 2DMs, elucidating their interaction dynamics with biomacromolecules. The review primarily concentrates on the applications of biomacromolecule‐reinforced 2DM hydrogels across various biomedical fields, including bone tissue engineering, wound healing, neural tissue engineering, cardiac tissue engineering, as well as in the delivery of drugs and genes, cancer therapy, and biosensing technologies. Finally, the review discusses the existing challenges and future outlook for developing and using biomacromolecule‐reinforced 2DM hydrogels, underlining their transformative potential in regenerative medicine. [ABSTRACT FROM AUTHOR]

2D materials are highly regarded for their exceptional sensing application prospects, stemming from their distinctive atomic layer structure and exceptionally sensitive surfaces. Over the past decade, numerous high‐performance 2D material sensors are extensively developed; however, challenges related to sensitivity, selectivity, and stability continue to impede their industrial advancement. The interaction between light and 2D materials has introduced unique properties, including absorption and emission characteristics, photoelectric effects, nonlinear optical effects, surface‐enhanced Raman scattering, and light response enhancement. Consequently, exciting and adjusting the electronic structure and carrier concentration of 2D materials through light with specific wavelength ranges is an effective strategy for enhancing sensing performance. This strategy has yielded remarkable breakthroughs in applications such as photodetectors, semiconductor gas sensors, and fiber optic sensors. Moreover, it demonstrates extraordinary potential in emerging applications such as image sensors, flexible electronics, and biomedical sensors. However, the sensing mechanism, device structure design, and specific applications of 2D materials under light excitation remain unclear. This perspective endeavors to elucidate the intrinsic photophysical mechanisms between light‐excited 2D materials and their target sensing analytes. Furthermore, it aims to explain the evolutionary pattern of sensing applications and provide novel insights and inspiration to advance this burgeoning field. [ABSTRACT FROM AUTHOR]

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]

2D materials like transition metal dichalcogenides (TMDCs) have been widely studied and are a gateway to modern technologies. While research today is mostly carried out on a laboratory scale, there is an intensive need for reliable processes on a wafer‐scale, starting with monolayer‐precise deposition of high‐quality films. In this work, a plasma‐enhanced atomic layer deposition (PEALD) process is developed on a 200 mm SiO2/Si substrate. The layers are investigated regarding crystallinity, composition, homogeneity, microstructure, topography, and electrical properties. The process is then applied on 200 mm alkali‐free glass wafers aiming toward flexible electronics and compatibility with Si processes. A complete coverage of the wafer with a satisfying uniformity is achieved on both substrates and direct polycrystalline growth of MoS2 films is verified on the entire wafer at a substrate temperature of T = 230 °C. On glass, the deposited MoS2 films exhibit a higher crystallinity and are more planar compared to the SiO2/Si substrate. Furthermore, application relevant few‐nanometer thick layers are investigated in detail. This low‐temperature process inspires optimism for future direct integration of 2D‐materials in an economical bottom‐up approach on a wide variety of substrates, thus paving the way for industrial mass production. [ABSTRACT FROM AUTHOR]

Hydrogen energy is characterized as environmentally friendly and resourceful. The hydrogen evolution reaction (HER) is a crucial process for hydrogen production and is essential for achieving a transition to sustainable and clean energy. In this work, we conducted a systematic investigation into the hydrogen catalytic activity of two-dimensional WSn 2 N 4 materials. The transition metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) were substituted at the N and Sn sites in WSn 2 N 4 , respectively. The catalyst's performance was evaluated to verify its catalytic activity for the HER. The results indicate that the Gibbs free energy changes (ΔG H∗) of Ti@W–WSn 2 N 4 , V@W–WSn 2 N 4 , Fe@W–WSn 2 N 4 , Co@W–WSn 2 N 4 , and Ni@W–WSn 2 N 4 are close to zero. Among the structures examined, Ti@W–WSn 2 N 4 exhibited the lowest Gibbs free energy change (ΔG H∗ = −0.01 eV), indicating a high degree of catalytic activity. Through machine learning analysis, key features affecting catalytic activity could be directly identified, and a framework for rapid screening was established. This study lays a solid foundation for the design and development of potential HER catalysts in the future. • 2D WSn 2 N 4 Catalysts: Comprehensive analysis of WSn 2 N 4 materials for hydrogen evolution reaction (HER). • Transition Metal Doping: Effects of (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) doping at N and Sn sites in WSn 2 N 4 on catalysis. • Best Catalyst: Ti@W–WSn 2 N 4 shows optimal catalytic activity (ΔG H∗ = −0.004 eV). • Machine Learning Screening: Machine learning identified key features and enabled rapid catalyst evaluation. [ABSTRACT FROM AUTHOR]

We theoretically examine the hydrogen storage capabilities of a newly synthesized carbon allotrope known as holey graphyne (HGY). HGY exhibits weak interaction with H 2 , making it unsuitable for storage, thus prompting surface modification. Ca binds to HGY with a binding energy of −2.03 eV and experiences a diffusion energy barrier of 1.49 eV. The supercell of HGY accommodates six Ca atoms, and each Ca atom binds five H 2 with an average binding energy of −0.27 eV, resulting in an uptake capacity of 12.07 wt% and desorption temperature of 331K at 5 bar. AIMD simulation and positive phonon frequencies confirms thermal and dynamic stability of Ca-decorated HGY. RDG analysis reveals electrostatic interactions between Ca and HGY, and van der Waals interactions between H 2 and Ca. Thus, Ca-decorated HGY shows exceptional uptake capacity, desirable adsorption energy and desorption temperature, making it a suitable material for on-board reversible hydrogen storage in light vehicles. [Display omitted] • Ca bonds strongly with HGY with binding energy of −2.03 eV. • Ca-decorated HGY is thermally and dynamically stable. • High diffusion energy barrier of 1.49 eV may prevent metal clustering. • Ca-decorated HGY shows high hydrogen uptake capacity of 12.07 wt%. • Desorption temperature of 331K at 5 bar ensures feasibility in fuel cell application. [ABSTRACT FROM AUTHOR]

Graphene has emerged as one of the most promising materials for next‐generation gas sensor platforms due to its high flexibility, transparency, and hydrophobicity. However, graphene shows inherent low selectivity in gas sensing. This has led to extensive development of noble‐metal decoration on graphene to modulate its surface chemistry for enhanced selectivity. While noble metals such as Pt, Pd, and Au have widely been employed to functionalize graphene surface, non‐noble metal decoration of graphene has remained underexplored. Here, an unprecedented room‐temperature self‐activated graphene gas sensor functionalized by NiO nanoparticles and its application to wearable devices monitoring ammonia gas in daily life are demonstrated. NiO‐functionalized graphene micropatterns show ultra‐high selectivity to ammonia with a low detection limit of 2.547 ppt. Density functional theory (DFT) calculations reveal that the strong attraction between NiO and NH3 induced by charge depletion and the vertex region of NiO accelerate the adsorption of NH3 molecules. Furthermore, a wearable graphene device demonstrates the capability to detect ammonia emissions from beef, triggering an alarm call when a specific threshold is exceeded. This work proposes the functionalization of graphene with transition metal oxides, extending beyond the conventional noble metal decoration, and the potential utilization of the graphene for wearable devices. [ABSTRACT FROM AUTHOR]

Efficient heat management and control in optical devices, facilitated by advanced thermo‐optic materials, are critical for many applications such as photovoltaics, thermal emitters, mode‐locked lasers, and optical switches. Here, a range of thermo‐optic properties of 2D graphene oxide (GO) films are investigated by precisely integrating them onto microring resonators (MRRs) with control over the film thicknesses and lengths. The refractive index, extinction coefficient, thermo‐optic coefficient, and thermal conductivity for the GO films with different layer numbers and degrees of reduction, as well as reversible reduction and enhanced optical bistability induced by the photo‐thermal effects, are comprehensively characterized. Experimental results show that the thermo‐optic properties of 2D GO films vary widely with the degree of reduction. In addition, significant anisotropy is observed for the thermo‐optic response, enabling efficient polarization‐sensitive devices. The versatile thermo‐optic response of 2D GO substantially expands the scope of functionalities and devices that can be engineered, making it promising for a diverse range of thermo‐optic applications. [ABSTRACT FROM AUTHOR]

Solution‐processed memristor devices hold significant potential for advancing synaptic applications, offering scalable, cost‐effective, and efficient solutions for next‐generation neuromorphic systems. These devices replicate the behavior of biological synapses with their gradual and continuous changes in resistance, making them promising for neuromorphic computing and artificial neural networks. However, understanding the temporal characteristics and cumulative effect of successive pulses on the devices is essential for emulating the dynamics of biological synapses. This study proposes a hybrid materials‐based conductive islands‐assisted resistive switching (CIARS) in a solution‐processed active layer consisting of thermally exfoliated graphitic carbon nitride (g‐C3N4 abbreviated as CN) nanosheets embedded with silver nanoparticles (Ag NPs). The fabricated devices demonstrate repeatable and bipolar memory features with a lower operating voltage (≤0.5 V), emulating the frequency and amplitude‐dependent synaptic plasticities. The threshold switching occurs due to the formation of conduction filaments (CFs) of silver ion (Ag+), whereas the analog behavior results from the voltage pulse‐dependent modulation of Schottky barrier height combined with metallic CFs formation. The experimental findings demonstrate the efficacy of the CIARS mechanism within the material platform, highlighting its potential for applications in associative learning, Morse code detection, and image recognition. [ABSTRACT FROM AUTHOR]

Hydrogen‐terminated 2D–Germanane (2D–GeH), a germanium‐based 2D material akin to graphene, is receiving enormous attention owing to its predicted optoelectronic characteristics. However, experimental research of 2D–GeH is still in an early stage, and therefore its real implementation for task‐specific applications will depend on the correct development of suitable chemical functionalization methods. Herein, a general and straightforward organometallic (OM) approach is provided for the robust functionalization of 2D–GeH with different 0D noble metal nanoparticles (M–NPs), resulting in 0D/2D M@GeH nanoarchitectonics. As a proof‐of‐principle, 0D/2D Pt@GeH and Au@GeH nanoarchitectonics have been successfully synthesized, characterized, and explored as unconventional electrocatalysts for boosting energy conversion reactions. While the hydrogen evolution reaction activity was evaluated for Pt@GeH, the oxygen reduction reaction was interrogated for Au@GeH. Interestingly, the implanted catalytic features of M–NPs yielded to 0D/2D M@GeH nanoarchitectonics with enhanced energy conversion activity comparing to pristine 2D–GeH counterpart. This work proves the suitability of 2D–GeH as unconventional substrates to stabilize nobleM−NPs, and the versatility of the OM approach for the custom design of a new family of 0D/2D M@GeH nanoarchitectonics to expand the implementation of monoelemental 2D materials as promising electrocatalysts in energy conversion field and beyond. [ABSTRACT FROM AUTHOR]

Following the rapid development of information technology, modern polarized light, which is a critical component for display and data transmission, has been in demand for miniaturization and high efficiency, rendering two‐dimensional (2D) semiconductors potential candidates. The traditional polarized light is usually generated by external optical structures or polarizers that influence the scaling and bring up losses. Previous works have reported polarized light emission from inversion‐asymmetric 2D semiconductors such as black phosphorus (BP), black arsenide phosphorus (AsP), and rhenium disulfide (ReS2), however, their emission wavelengths are not in the visible range. Here, a direct emission of linearly polarized light is demonstrated from van der Waals light–emitting diodes (vdWLEDs) via the flexoelectric effects by inducing the non‐uniform strain in monolayer (ML) transition metal dichalcogenides (TMDCs). In this work, the effects of strain including excitonic binding energy and exciton dipole moment distribution is analyzed by the density functional theory (DFT) then we show that linearly polarized photoluminescence (PL) with a degree of linear polarization (DOLP) of ≈17% can be realized at room temperature (RT), and the polarization angle is perpendicular to the direction of the strain‐gradient. By incorporating the strained ML TMDCs into vdWLEDs, electroluminescence (EL) with DOLP of ≈19% can be observed at RT. This work puts forward a direct and universal strategy for fabricating polarized LEDs based on inversion‐symmetric semiconductors. [ABSTRACT FROM AUTHOR]

2D carbon allotropes with moderated electronic bandgaps are highly desirable for next‐generation carbon‐based nanoelectronics beyond graphene. Herein, the structural and electronic properties of bilayer α‐graphyne have been systematically investigated by using first‐principles calculations. Consequently, in addition to typical van der Waals (vdW) stacks of single‐layer α‐graphyne, new 2D carbon allotropes with purely sp2 or sp3 hybridizations can be achieved, arising from the absence of intralayer acetylene linkages during structural relaxation. Compared to the Dirac semimetallic behavior of monolayer α‐graphyne, the electronic structure of vdW bilayer α‐graphyne can be further modulated by stacking patterns, yet retains metallic characteristics. In contrast, intrinsic semiconducting characteristics can be observed in the proposed new 2D carbon allotropes with tunable bandgaps dependent on the in‐plane biaxial strain. Correspondingly, a pristine 2D carbon sheet with only sp2 hybridization exhibits a promising direct bandgap of 1.062 eV, while the sp3‐hybridized carbon network possesses an indirect bandgap of 1.708 eV, which can be further converted to the direct type under small compressive strains, implying great potential in future carbon‐based nanoelectronic applications beyond graphene. Also, this work provides a new approach for developing novel carbon allotropes via the vertical stacking of graphyne with acetylenic linkages. [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]

Polar 2D materials hold the emerging functionalities such as ferro‐, piezo‐, and pyro‐electric properties. On account of infrared‐active low bandgap and polar nature at reduced dimensionality, they served as an ideal choice of pyroelectric material. It can cover up a diverse range of applications, such as waste thermal energy harvesting, IR imaging, photodetector, temperature sensors, and several catalytic processes due to the abundance of dynamic thermal fluxes. Recently, 2D pyroelectric materials have manifested a substantial role in thermal energy harvesting. Consequently, it is realized that there are plenty of scopes available to diversify its applicability. Thus, the challenges are spotlighted in this perspective to envision the desired 2D pyroelectric materials to achieve the effective thermal energy harvesting, sensing, and catalytic efficacy. Particularly, the emphasis is given to elucidate the role of spontaneous polarization in 2D materials to ascertain the giant pyroelectricity. [ABSTRACT FROM AUTHOR]

With the theoretical high power conversion efficiency (PCE) exceeding the thermodynamic Schockley–Queisser (S–Q) limit, the bulk photovoltaic (BPV) effect, which is manifested in acentric crystals across the entire visual spectrum, holds great potential for next‐generation light‐harvesting devices. Here the abnormally giant second harmonic generation (SHG) activity and BPV response in 2D AgBiP2Se6 crystals with broken inversion symmetry is demonstrated, which can be remarkably enhanced with the thickness downscaling. Based on the vertical device sandwiched with graphene electrodes, the wideband light absorption of 2D AgBiP2Se6 crystals with Eg of 1.49 eV enables giant BPV response in the entire visible spectrum, and efficient utilization of solar energy contributes to large short‐current (≈330 mA cm−2), high PCE (≈0.13%) and EQE (≈12.5%) under 532 nm light illumination. Furthermore, benefitting from the local ion redistribution driven by an in‐plane electric field, the BPV photocurrent generation is effectively enhanced 3 times, yielding an extremely high PCE of 0.18%, according high among the reported 2D acentric crystals. The study reintroduces AgBiP2Se6 to the 2D acentric crystal family and lays the groundwork to develop BPV devices for light‐harvesting applications. [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]

Highlights Two‐dimensional (2D) MXene (MX) and silane coupling agents are increasingly used to modify carbon materials for the fabrication of composite functional materials, which exhibit enhanced electrical, optical, and mechanical properties due to the synergistic effects of both MX and silane. We demonstrate the modification of carbon fibers (CFs) with MX and three different kinds of silane coupling agents, including 3‐aminopropyltriethoxysilane, 3‐glycidyloxypropyldimethoxymethylsilane, and 3‐mercaptopropyltriethoxysilane, which are named as CF‐MX@N, CF‐MX@O, and CF‐MX@S, respectively, and further prepare the CF‐MX@silane/epoxy (EP) composites. The utilized silane coupling agents serve as bridges between MX and CFs, forming CF‐MX@silane composites. Through comparative analysis, it is found that the CF‐MX@S composites form a strong interface phase through covalent bonds, significantly enhancing the interface compatibility and revealing strong interface adhesion. The interfacial shear strength of the molded CF‐MX@S/EP composites increases to 119.7 MPa, with an 173.9% enhancement comparing to unmodified composites. This work can offer useful guidance and reference for selecting appropriate silane coupling agent to modify CFs with 2D materials to form high‐performance composite materials. Silane coupling agents are used as bridges to graft MXene‐modified CFs The surface modification of CFs is achieved by a simple one‐step approach Excellent interfacial phase is constructed through forming strong covalent bonds Microstructure and failure interface are responsible to interface strengthen. [ABSTRACT FROM AUTHOR]

3D printing, a rapidly expanding domain of additive manufacturing, enables the fabrication of intricate 3D structures with adjustable fabrication parameters and scalability. Nonetheless, post‐fabrication, 3D‐printed materials often require an activation step to eliminate non‐conductive polymers, a process traditionally achieved through chemical, thermal, or electrochemical methods. These conventional activation techniques, however, suffer from inefficiency and inconsistent results. In this study, a novel chemical‐free activation method employing laser treatment is introduced. This innovative technique effectively activates 3D‐printed electrodes, which are then evaluated for their photo and electrochemical performance against traditional solvent‐activated counterparts. The method not only precisely ablates surplus non‐conductive polymers but also exposes and activates the underlying electroactive materials. The 3D‐printed electrodes, processed with this single‐step laser approach, exhibit a notably low overpotential of ≈505 mV at a current density of −10 mA cm−2 under an illumination wavelength of 365 nm. These electrodes also demonstrate exceptional durability, maintaining stability through >100 000 cycles in energy storage applications. By amalgamating 3D printing with laser processing, the creation of electrodes with complex structures and customizable properties is enabled. This synergy paves the way for streamlined production of such devices in the field of energy conversion and storage. [ABSTRACT FROM AUTHOR]

2D materials have garnered considerable interest in various applications from catalysis to energy storage. However, the self‐stacking and poor air stability of 2D materials (e.g., MXene) leads to serious performance degradation, in particular, of micro‐supercapacitors (MSCs) with narrow working voltage and low energy density. Here, a universal confined interfacial assembly strategy is demonstrated for controllably synthesizing a series of 2D mesoporous heterostructures for high‐voltage and high‐energy ionogel‐based MSCs. This assembly process reveals accurate controllability and extraordinary versatility, endowing the 2D mesoporous heterostructures with highly adjustable mesopore size (7–22 nm), tunable thickness (15–29 nm), variable carbon precursors (including oligochitosan, glucose, and sucrose), and replaceable 2D substrates (e.g., MXene, graphene, BN, and MoS2). As a proof of concept, the 2D mesoporous carbon@MXene based MSCs with ionic liquid ionogel electrolyte deliver ultrahigh voltage of 3.7 V, superior areal energy density of 181.3 µWh cm−2, excellent flexibility with 99% of capacitance retention at 180°, and excellent modular self‐integration for variable voltage/capacitance output, surpassing most reported MXene based MSCs. Therefore, this work will open a novel available paradigm for scalable fabrication of 2D mesoporous materials to target high‐performance and functional microscale power source. [ABSTRACT FROM AUTHOR]

Understanding the nature, density, and distribution of structural defects is crucial for tailoring the properties of atomically thin two‐dimensional (2D) materials, which is paramount for advances in nanotechnology. Ion irradiation emerges as a promising technique for defect engineering of single‐atom‐thick materials, due to its high controllability, repeatability, and accuracy. The objective is to provide a comprehensive review elucidating the impact of various irradiation parameters, such as ion mass, energy, fluence, and incident angle, on defect formation in 2D materials. However, the presence of the substrate can significantly influence defect yield and the mechanism of formation due to backscattered ions and sputtered substrate atoms. Hence, a thorough comparison of ion beam‐induced defects in both freestanding (suspended) and supported (on a substrate) 2D materials, with a focus on substrate effects is conducted. Moreover, a detailed analysis of characterization techniques suitable for each scenario will be provided. This work not only contributes to advancing the current understanding of defect formation and evolution in 2D materials during ion beam irradiation but also offers insights into selecting specific parameters for this process to create desired defects in these materials. Consequently, it has the potential to facilitate the design of nanoscale devices with tailored functionality. [ABSTRACT FROM AUTHOR]

In this paper, detailed models of GaTe/XSe heterojunctions are constructed and geometrically optimised. The GaTe/InSe(X = Zn, In) heterojunction is calculated to be a Type-II direct bandgap semiconductor with a forbidden bandwidth of 1.26 eV based on the DFT study, while the GaTe/ZnSe heterojunction behaves as a Type-II indirect bandgap semiconductor with a forbidden bandwidth of 0.899 eV. The forbidden bandwidth reaches its maximum value at 2% of tensile strain. When the compressive strain reaches −8%, the forbidden bandwidth is 0 and the heterojunction is converted from a semiconductor to a conductor. The analysis of the absorption spectra of GaTe/InSe and GaTe/ZnSe heterojunctions shows that both heterojunctions increase the absorption in the visible region as well as broaden the absorption range of the spectrum. Therefore, GaTe/InSe heterojunctions are useful in the field of optoelectronic devices. • The band gap width of the GaTe/InSe heterojunction is calculated to be 1.254 eV, and this heterojunction is a direct band gap semiconductor. The band gap width of the GaTe/ZnSe heterojunction is 0.899 eV, and this material is an indirect band gap semiconductor. • GaTe/ZnSe and GaTe/InSe heterojunctions have good optoelectronic properties with smaller bandgap widths and a wider range of light absorption. [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]

2D materials are intriguing due to their remarkably thin and flat structure. This unique configuration allows the majority of their constituent atoms to be accessible on the surface, facilitating easier electron tunneling while generating weak surface forces. To decipher the subtle signals inherent in these materials, the application of techniques that offer atomic resolution (horizontal) and sub‐Angstrom (z‐height vertical) sensitivity is crucial. Scanning probe microscopy (SPM) emerges as the quintessential tool in this regard, owing to its atomic‐level spatial precision, ability to detect unitary charges, responsiveness to pico‐newton‐scale forces, and capability to discern pico‐ampere currents. Furthermore, the versatility of SPM to operate under varying environmental conditions, such as different temperatures and in the presence of various gases or liquids, opens up the possibility of studying the stability and reactivity of 2D materials in situ. The characteristic flatness, surface accessibility, ultra‐thinness, and weak signal strengths of 2D materials align perfectly with the capabilities of SPM technologies, enabling researchers to uncover the nuanced behaviors and properties of these advanced materials at the nanoscale and even the atomic scale. [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]

The burgeoning advancement of information technology has engendered a discernible surge in the examination of neuromorphic devices, notably drawing broader attention to artificial vision systems endowed with sensory recognition capabilities. Current photoelectric synapse devices employed in artificial vision systems are generally well‐suited for well‐illuminated conditions, yet exhibit diminished sensitivity in weak‐light scenarios, resulting in a pronounced deterioration of recognition accuracy. Here, an ultrasensitive photoelectric synaptic transistor based on negative quantum capacitance effect resulted from the 2D semi‐metallic graphene layer that partially enclosed within the gate dielectric layer, which manifests a noteworthy reduction in device control voltage and exhibits perception and storage capabilities for weak light of 39.4 nW cm−2 with detectivity above 1016 cm Hz1/2 W−1 is demonstrated. The voltage amplification effect and the concomitant formation of an equivalent local electrostatic field induced by the negative quantum capacitance effect engenders a robust programmable synaptic plasticity for extremely weak light by modifying the control gate. These results represent the inaugural integration of the negative quantum capacitance effect into optoelectronic devices and furnish a robust hardware foundation for developing vision systems in weak‐light environments. [ABSTRACT FROM AUTHOR]

Two‐dimensional Molybdenum diselenide is a versatile and promising material used for a wide range of applications and its synthesis in high quality and yield is currently the subject of intense research. Low temperature solution phase synthesis of nanomaterials using designed molecular precursors enjoys tremendous advantages over traditional high‐temperature solid‐state synthesis. However, molecular precursor chemistry of molybdenum selenide nanomaterials is almost non‐existent. We report here synthesis and structural characterization of new molybdenum molecular precursors with selenoether and selenourea ligands, which due to their easy synthesis, desired Mo/Se composition and moderate processing properties, are highly promising as single source precursors for the scale‐up production of 2D molybdenum diselenide materials. This is demonstrated by the solution‐phase decomposition of the Mo‐selenourea precursor which produced Mo‐rich MoSe2‐x ultrathin nanosheets (NSs) in good yield. These NSs were characterized by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP‐OES), Powder X‐ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FT‐IR), Thermogravimetric analysis (TGA), Transmission electron microscopy (TEM) and X‐ray photoelectron spectroscopy (XPS) studies. [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]

Among the two‐dimensional (2D) materials, layered hydroxides (LHs) stand out due to their chemical versatility, allowing the modulation of physicochemical properties on demand. Specifically, LHs based on earth‐abundant elements represent promising phases as electrode materials for energy storage and conversion. However, these materials exhibit significant drawbacks, such as low conductivity and in‐plane packing that limits electrolyte diffusion. In this work, we explore the synthetic flexibility of α‐CoII hydroxides (Simonkolleite‐like structures) to overcome these limitations. We elucidate the growth mechanism of 3D flower‐like α‐CoII hydroxyhalides by using in situ SAXS experiments combined with thorough physicochemical, structural, and electrochemical characterization. Furthermore, we compared these findings with the most commonly employed Co‐based LHs: β‐Co(OH)₂ and CoAl layered double hydroxides. While α‐CoII LH phases inherently grow as 2D materials, the use of ethanol (EtOH) triggers the formation of 3D arrangements of these layers, which surpass their 2D analogues in capacitive behavior. Additionally, by taking advantage of their anion‐dependent bandgap, we demonstrate that substituting halides from chloride to iodide enhances capacitive behavior by more than 40 %. This finding confirms the role of halides in modulating the electronic properties of layered hydroxides, as supported by DFT+U calculations. Hence, this work provides fundamental insights into the 3D growth of α‐CoII LH and the critical influence of morphology and halide substitution on their electrochemical performance for energy storage applications. [ABSTRACT FROM AUTHOR]

Topochemical transformation has emerged as a promising method for fabricating two-dimensional (2D) materials with precise control over their composition and morphology. However, the large-scale synthesis of ultrathin 2D materials with controllable thickness remains a tremendous challenge. Herein, we adopt an efficient topochemical synthesis strategy, employing a confined reaction space to fabricate ultrathin 2D Sn4P3 nanosheets in large-scale. By carefully adjusting the rolling number during the processing of Sn/Al foils, we have successfully fabricated Sn4P3 nanosheets with varied layer thicknesses, achieving a remarkable minimum thickness of two layers (~ 2.2 nm). Remarkably, the bilayer Sn4P3 nanosheets display an exceptional initial capacity of 1088 mAh·g−1, nearing the theoretical value of 1230 mAh·g−1. Furthermore, we reveal their high-rate property as well as outstanding cyclic stability, maintaining capacity without fading more than 3000 cycles. By precisely controlling the layer thickness and ensuring nanoscale uniformity, we enhance the lithium cycling performance of Sn4P3, marking a significant advancement in developing high-performance energy storage systems. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are excellent candidates for electronic applications because of their high carrier mobility, tunable bandgap energy depending on the number of layers, monolayer thickness, and the absence of dangling bonds on their surfaces. Despite these advantages, the crystalline structures of TMDs contain intrinsic defects such as vacancies, adatoms, grain boundaries, and substitutional impurities, which can cause large contact resistance at the source/drain interface. Customized engineering of interfaces and defects, which provides a method to modulate the properties of TMDs, is crucial as it can significantly enhance device performance. Herein, we explored a novel electrode to enhance the interface between electrode and semiconductor materials. we report the synthesis of high-quality atomically thin MoO2 using atmospheric pressure chemical vapor deposition (APCVD) and its application to field-effect transistors. To improve crystallinity of MoO2, we investigated the influence of hydrogen concentration, a key parameter in the reduction process, on the synthesis of high-crystallinity MoO₂. By adding NaCl to MoO₃ powder, we optimized the synthesis of high-crystallinity MoO₂. Utilizing the optimized MoO₂, we fabricated transistors that exhibited a mobility of 29.1 cm²/V∙s and an on/off ratio of 1.78 × 10⁴, demonstrating excellent performance. Our findings confirm that single-crystal MoO2 can be effectively applied as a contact electrode in high-performance two-dimensional semiconductor devices. [ABSTRACT FROM AUTHOR]

AbstractAn effective approach for early diagnosis of lung cancer involves detecting its biomarkers in the patient’s exhaled breath. Acetone was identified as a vital biomarker, showing significant elevation in lung cancer. Two-dimensional boron carbide materials offer benefits such as resistance to high temperatures, stability, and excellent sensitivity toward toxic gas molecules. Here, we explore acetone adsorption on the pristine and transition metal (TM)-doped (Sc, Ti, V, Cr, and Mn) boron carbide monolayers (BCMs) with density functional theory calculations. Our results revealed that the V-, Cr-, and Mn-doped BCM show larger adsorption energy values as compared to the pristine BCM surface. The change of band gap energy of surfaces after acetone adsorption is obtained between 55 and 275%. The work function variation of studied monolayers upon acetone adsorption has been also investigated and results show that V-, Cr-, and Mn-doped BCM systems are sensitive to acetone gas molecules. This work suggests that BCM-based layers can be used as a biosensor to identify VOC biomarkers such as acetone. [ABSTRACT FROM AUTHOR]

Janus transition metal dichalcogenides (TMDs) are a novel class of 2D materials with unique mirror asymmetry. Plasma‐assisted synthesis at room temperature is favored for producing Janus TMDs due to its energy efficiency and prevention of alloying. However, current methods require stringent control over growth conditions, risking defects or unintended materials. A robust plasma‐assisted (RPA) synthesis strategy is introduced, incorporating a built‐in tube with a suitable inner diameter into the plasma‐assisted system. This innovation creates a mild, uniform plasma atmosphere, allowing for broader variations in growth parameters without significantly affecting Janus MoSSe's morphology and characteristics. This approach simplifies the synthesis process and enhances the success rate of Janus TMD production. Additionally, methods are explored to enhance the photoluminescence (PL) of Janus MoSSe. Releasing MoSSe from the growth substrate and annealing it removes strain and unintentional doping, improving PL performance. MoSSe on hexagonal boron nitride (h‐BN) flakes after annealing shows a 32‐fold increase in PL intensity. Bis(trifluoromethane) sulfonimide (TFSI) treatment of MoSSe results in a remarkable 70‐fold increase in PL intensity, a 2.5‐fold extension in exciton lifetime, and quantum yield (QY) reaching up to ≈31.2%. These findings provide critical insights for optimizing the luminescence properties of 2D Janus materials, advancing Janus optoelectronics. [ABSTRACT FROM AUTHOR]

Self‐powered photodetection devices, which meet the requirement of environmental sustainability, are widely designed by PN heterojunctions. The design of the semiconductor/metal interface is vital in PN‐junction devices. In particular, the elevated potential barrier at the metal/semiconductor interface impedes efficient carrier transport. Therefore, optimizing the semiconductor/metal interface for the PN junction, either by reducing the interface barrier or leveraging the built‐in electric field within the Schottky junction, holds significant importance in enhancing the performance of PN‐junction devices. In this study, an InSe/MoTe2 Type‐II PN heterojunction photodetector is constructed, with graphene (Gr) and gold (Au) serving as electrodes in contact with InSe and MoTe2, respectively. Benefiting from the reduced barrier in Au/InSe interfaces and the built‐in electric field formed at the InSe/MoTe2 and MoTe2/Au interfaces in the same direction, the device achieves an ultra‐fast photoresponse speed of 14 µs and an ultra‐low dark current of 8.5 × 10⁻¹⁴ A at zero bias. Furthermore, the device exhibits a remarkable light on/off ratio up to 105 and achieves broad‐spectrum photodetection ranging from the visible to infrared wavelength. This research highlights the enormous potential of the Gr/InSe/MoTe2 van der Waals heterostructure in the realms of self‐powered photodetection, imaging, and optical communication. [ABSTRACT FROM AUTHOR]

Confining light in nanoscale air voids can enable new photonic applications by eliminating the requirement of low loss in traditional dielectric resonators. Van der Waals materials are uniquely suited for this purpose as they offer a tailored assembly of different materials and the ability to fully enclose air voids through transfer techniques. Here, highly lossy van der Waals materials are leveraged to demonstrate optical resonances that confine light in encapsulated air voids. Void resonances are theoretically designed in the visible spectrum and resonant modes supported by void arrays are identified. Experimentally, void arrays are fabricated in tungsten diselenide and the confined resonances are characterized using far‐field reflectance measurements and scanning near‐field optical microscopy. Using van der Waals heterostructure assembly, the voids are encapsulated with hexagonal boron nitride and tungsten diselenide, which substantially reduces the void volume causing a large spectral blue shift of the void resonance exceeding 150 nm. The work demonstrates a versatile optical platform for lossy materials, opening a new regime of material space for photonic devices. [ABSTRACT FROM AUTHOR]

Herein, the electronic and piezoelectric properties of different types of (chair form and boat form) H/F‐functionalized boron phosphide (BP) sheets are examined by density‐functional theory calculations. After H/F atoms adsorb on both sides of pristine hexagonal boron phosphide (h‐BP) cell, the functionalized BP structure undergoes significant flatness distortion. The H/F‐functionalized BP sheets are predicted to be thermodynamically and dynamically stable. According to the calculations, it is demonstrated that chemical functionalization is an effective method to modulate the bandgap of h‐BP in a wide range (0.80–3.63 eV). The chair form F–BP–H shows large e31 (−0.7 × 10−10 C m−1) and d31 (−0.68 pm V−1). The d11 of boat form F–BP–H is 4.32 pm V−1, which is 95.5% higher than the pristine h‐BP monolayer (2.21 pm V−1). The study provides a possible way to modulate the intrinsic characteristics of the pristine h‐BP sheet, which would broaden its potential applications in the future for wider range of applications. [ABSTRACT FROM AUTHOR]

The in‐plane anisotropic properties of 2D group IV monochalcogenides offer an additional degree of freedom which can be advantageous in optoelectronic applications. Here, it is demonstrated that the third harmonic generation (THG) produced by ultrathin tin (II) sulfide (SnS) is in‐plane anisotropic with respect to the direction of the excitation linear polarization. The polarization‐resolved THG (P‐THG) measurements are described with a nonlinear optics model, which accounts for the orthorhombic crystal structure of the 2D SnS. The relative magnitudes of the χ(3) tensor components are calculated by recording and simultaneously fitting two orthogonal polarization components of the P‐THG signals. Furthermore, the "THG anisotropy ratio" is introduced, which compares the THG intensity produced when the excitation linear polarization is along the armchair crystallographic direction, with the case when it is along the zigzag direction. The experimental findings provide quantitative information on the anisotropic nature of the THG process in various SnS flakes. Nonlinear anisotropic 2D materials can be used in future optoelectronic devices, where anisotropic polarization sensitivity is required. Having an optical tool that quantitatively probes the effect of the in‐plane anisotropy among different 2D materials, could be of considerable importance for evaluating the performance of such materials and devices. [ABSTRACT FROM AUTHOR]

A detailed analysis of the Surface Plasmon Resonance (SPR) sensor for the detection of gaseous analytes within the detection range (1 - 1.04) RIU was carried out. The proposed sensor is composed of a multilayer structure of prism, plasmonic metal, and 2D materials. The impact of different prisms (KF, LiF, SF-11, BK-7), metals (silver, copper, gold, aluminum), and a heterostructured layer of graphene, black phosphorous, M o S 2 demonstrated to achieve high-performance gas sensor. To achieve minimum reflectance and large shift, thickness optimization of each layer was carried out. A transfer matrix method for the N-Layer model with an angular interrogation method was used for the simulation at 633 nm wavelength. Field intensity demonstrates that the addition of each 2D layer plays an important role in the enhancement of the performance of the sensor. The sensitivity (S) and Figure of Merit (FOM) of the proposed sensor were obtained at 236.64°/RIU, and 24.5 R I U - 1 respectively. [ABSTRACT FROM AUTHOR]