Construction of 3D Electronic/Ionic Conduction Networks for All‐Solid‐State Lithium Batteries

High and balanced electronic and ionic transportation networks with nanoscale distribution in solid‐state cathodes are crucial to realize high‐performance all‐solid‐state lithium batteries. Using Cu₂SnS₃ as a model active material, such a kind of solid‐state Cu₂SnS₃@graphene‐Li₇P₃S₁₁ nanocomposite cathodes are synthesized, where 5–10 nm Cu₂SnS₃ nanoparticles homogenously anchor on the graphene nanosheets, while the Li₇P₃S₁₁ electrolytes uniformly coat on the surface of Cu₂SnS₃@graphene composite forming nanoscaled electron/ion transportation networks. The large amount of nanoscaled triple‐phase boundary in cathode ensures high power density due to high ionic/electronic conductions and long cycle life due to uniform and reduced volume change of nano‐Cu₂SnS_3. The Cu₂SnS₃@graphene‐Li₇P₃S₁₁ cathode layer with 2.0 mg cm^?2 loading in all‐solid‐state lithium batteries demonstrates a high reversible discharge specific capacity of 813.2 mAh g^?1 at 100 mA g^?1 and retains 732.0 mAh g^?1 after 60 cycles, corresponding to a high energy density of 410.4 Wh kg^?1 based on the total mass of Cu₂SnS₃@graphene‐Li₇P₃S₁₁ composite based cathode. Moreover, it exhibits excellent rate capability and high‐rate cycling stability, showing reversible capacity of 363.5 mAh g^?1 at 500 mA g^?1 after 200 cycles. The study provides a new insight into constructing both electronic and ionic conduction networks for all‐solid‐state lithium batteries.     

A Flexible Film with SnS2 Nanoparticles Chemically Anchored on 3D‐Graphene Framework for High Areal Density and High Rate Sodium Storage

The design and construction of flexible electrodes that can function at high rates and high areal capacities are essential regarding the practical application of flexible sodium‐ion batteries (SIBs) and other energy storage devices, which remains significantly challenging by far. Herein, a flexible and 3D porous graphene nanosheet/SnS₂ (3D‐GNS/SnS₂) film is reported as a high‐performance SIB electrode. In this hybrid film, the GNS/SnS₂ microblocks serve as pillars to assemble into a 3D porous and interconnected framework, enabling fast electron/ion transport; while the GNS bridges the GNS/SnS₂ microblocks into a flexible framework to provide satisfactorily mechanical strength and long‐range conductivity. Moreover, the SnS₂ nanocrystals, which chemically bond with GNS, provide sufficient active sites for Na storage and ensure the cycling stability. Consequently, this flexible 3D‐GNS/SnS₂ film exhibits excellent Na‐storage performances, especially in terms of high areal capacity (2.45 mAh cm^?2) and high rates with superior stability (385 mAh g^?1 at 1.0 A g^?1 over 1000 cycles with ≈100% retention). A flexible SIB full cell using this anode exhibits high and stable performance under various bending situations. Thus, this work provide a feasible route to prepare flexible electrodes with high practical viability for not only SIBs but also other energy storage devices.     

Low‐Temperature Wafer‐Scale Deposition of Continuous 2D SnS2 Films

Semiconducting 2D materials, such as SnS₂, hold immense potential for many applications ranging from electronics to catalysis. However, deposition of few‐layer SnS₂ films has remained a great challenge. Herein, continuous wafer‐scale 2D SnS₂ films with accurately controlled thickness (2 to 10 monolayers) are realized by combining a new atomic layer deposition process with low‐temperature (250 °C) postdeposition annealing. Uniform coating of large‐area and 3D substrates is demonstrated owing to the unique self‐limiting growth mechanism of atomic layer deposition. Detailed characterization confirms the 1T‐type crystal structure and composition, smoothness, and continuity of the SnS₂ films. A two‐stage deposition process is also introduced to improve the texture of the films. Successful deposition of continuous, high‐quality SnS₂ films at low temperatures constitutes a crucial step toward various applications of 2D semiconductors.     

Chemical Vapor Deposition of High‐Quality and Atomically Layered ReS2

Recently, anisotropic 2D materials, such as black phosphorus and rhenium disulfides (ReS₂), have attracted a lot attention because of their unique applications on electronics and optoelectronics. In this work, the direct growth of high‐quality ReS₂ atomic layers and nanoribbons has been demonstrated by using chemical vapor deposition (CVD) method. A possible growth mechanism is proposed according to the controlled experiments. The CVD ReS₂‐based filed‐effect transistors (FETs) show n‐type semiconducting behavior with a current on/off ratio of ≈10⁶ and a charge carrier mobility of ≈9.3 cm² Vs⁻¹. These results suggested that the quality of CVD grown ReS₂ is comparable to mechanically exfoliated ReS₂, which is also further supported by atomic force microscopy imaging, high‐resolution transmission electron microscopy imaging and thickness‐dependent Raman spectra. The study here indicates that CVD grown ReS₂ may pave the way for the large‐scale fabrication of ReS₂‐based high‐performance optoelectronic devices, such as anisotropic FETs and polarization detection.     

Few‐Layered Tin Sulfide Nanosheets Supported on Reduced Graphene Oxide as a High‐Performance Anode for Potassium‐Ion Batteries

Anodes involving conversion and alloying reaction mechanisms are attractive for potassium‐ion batteries (PIBs) due to their high theoretical capacities. However, serious volume change and metal aggregation upon potassiation/depotassiation usually cause poor electrochemical performance. Herein, few‐layered SnS₂ nanosheets supported on reduced graphene oxide (SnS₂@rGO) are fabricated and investigated as anode material for PIBs, showing high specific capacity (448 mAh g^?1 at 0.05 A g^?1), high rate capability (247 mAh g^?1 at 1 A g^?1), and improved cycle performance (73% capacity retention after 300 cycles). In this composite electrode, SnS₂ nanosheets undergo sequential conversion (SnS₂ to Sn) and alloying (Sn to K₄Sn₂₃, KSn) reactions during potassiation/depotassiation, giving rise to a high specific capacity. Meanwhile, the hybrid ultrathin nanosheets enable fast K storage kinetics and excellent structure integrity because of fast electron/ionic transportation, surface capacitive‐dominated charge storage mechanism, and effective accommodation for volume variation. This work demonstrates that K storage performance of alloy and conversion‐based anodes can be remarkably promoted by subtle structure engineering.     

High Mobility 2D Palladium Diselenide Field‐Effect Transistors with Tunable Ambipolar Characteristics

Due to the intriguing optical and electronic properties, 2D materials have attracted a lot of interest for the electronic and optoelectronic applications. Identifying new promising 2D materials will be rewarding toward the development of next generation 2D electronics. Here, palladium diselenide (PdSe₂), a noble‐transition metal dichalcogenide (TMDC), is introduced as a promising high mobility 2D material into the fast growing 2D community. Field‐effect transistors (FETs) based on ultrathin PdSe₂ show intrinsic ambipolar characteristic. The polarity of the FET can be tuned. After vacuum annealing, the authors find PdSe₂ to exhibit electron‐dominated transport with high mobility (µ _{e (max)} = 216 cm² V^?1 s^?1) and on/off ratio up to 10³. Hole‐dominated‐transport PdSe₂ can be obtained by molecular doping using F₄‐TCNQ. This pioneer work on PdSe₂ will spark interests in the less explored regime of noble‐TMDCs.     

Phase‐Controlled Synthesis of Monolayer W1−xRexS2 Alloy with Improved Photoresponse Performance

Tuning bandgap and phases in the ternary 2D transition metal dichalcogenides (TMDs) alloys has opened up unexpected opportunities to engineer optoelectronic properties and explore potential applications. In this work, a salt‐assisted chemical deposition vapor (CVD) growth strategy is reported for the creation of high‐quality monolayer W_1?xRe_xS₂ alloys to fulfill a readily phase control from 1H to DT by changing the ratio of Re and W precursors. The structures and chemical compositions of doping alloys are confirmed by combining atomic resolution scanning transmission electron microscopy‐annular dark field imaging with energy dispersive X‐ray spectroscopy (EDS) and X‐ray photoelectron spectroscopy, matching well with the calculated results. The field‐effect transistors (FETs) devices fabricated based on 1H‐W_0.9Re_0.1S₂ monolayer exhibit a n‐type semiconducting behavior with the mobility of 0.4 cm² V^?1 s^?1. More importantly, the FETs show high‐performance responsivity with a value of 17 µA W^?1 in air, which is superior to that of monolayer CVD‐grown WS₂. This work paves the way toward synthesizing monolayer ternary alloys with controlled phases for potential optoelectronic applications.     

Ultrahigh‐Sensitive Broadband Photodetectors Based on Dielectric Shielded MoTe2/Graphene/SnS2 p–g–n Junctions

2D atomic sheets of transition metal dichalcogenides (TMDs) have a tremendous potential for next‐generation optoelectronics since they can be stacked layer‐by‐layer to form van der Waals (vdW) heterostructures. This allows not only bypassing difficulties in heteroepitaxy of lattice‐mismatched semiconductors of desired functionalities but also providing a scheme to design new optoelectronics that can surpass the fundamental limitations on their conventional semiconductor counterparts. Herein, a novel 2D h‐BN/p‐MoTe₂/graphene/n‐SnS₂/h‐BN p–g–n junction, fabricated by a layer‐by‐layer dry transfer, demonstrates high‐sensitivity, broadband photodetection at room temperature. The combination of the MoTe₂ and SnS₂ of complementary bandgaps, and the graphene interlayer provides a unique vdW heterostructure with a vertical built‐in electric field for high‐efficiency broadband light absorption, exciton dissociation, and carrier transfer. The graphene interlayer plays a critical role in enhancing sensitivity and broadening the spectral range. An optimized device containing 5?7‐layer graphene has been achieved and shows an extraordinary responsivity exceeding 2600 A W^?1 with fast photoresponse and specific detectivity up to ≈10¹³ Jones in the ultraviolet–visible–near‐infrared spectrum. This result suggests that the vdW p–g–n junctions containing multiple photoactive TMDs can provide a viable approach toward future ultrahigh‐sensitivity and broadband photonic detectors.     

Threshold Voltage Control of Multilayered MoS2 Field‐Effect Transistors via Octadecyltrichlorosilane and their Applications to Active Matrixed Quantum Dot Displays Driven by Enhancement‐Mode Logic Gates

In recent past, for next‐generation device opportunities such as sub‐10 nm channel field‐effect transistors (FETs), tunneling FETs, and high‐end display backplanes, tremendous research on multilayered molybdenum disulfide (MoS₂) among transition metal dichalcogenides has been actively performed. However, nonavailability on a matured threshold voltage control scheme, like a substitutional doping in Si technology, has been plagued for the prosperity of 2D materials in electronics. Herein, an adjustment scheme for threshold voltage of MoS₂ FETs by using self‐assembled monolayer treatment via octadecyltrichlorosilane is proposed and demonstrated to show MoS₂ FETs in an enhancement mode with preservation of electrical parameters such as field‐effect mobility, subthreshold swing, and current on–off ratio. Furthermore, the mechanisms for threshold voltage adjustment are systematically studied by using atomic force microscopy, Raman, temperature‐dependent electrical characterization, etc. For validation of effects of threshold voltage engineering on MoS₂ FETs, full swing inverters, comprising enhancement mode drivers and depletion mode loads are perfectly demonstrated with a maximum gain of 18.2 and a noise margin of ≈45% of 1/2 V_DD. More impressively, quantum dot light‐emitting diodes, driven by enhancement mode MoS₂ FETs, stably demonstrate 120 cd m^?2 at the gate‐to‐source voltage of 5 V, exhibiting promising opportunities for future display application.     

An All‐Solution‐Based Hybrid CMOS‐Like Quantum Dot/Carbon Nanotube Inverter

The development of low‐cost, flexible electronic devices is subordinated to the advancement in solution‐based and low‐temperature‐processable semiconducting materials, such as colloidal quantum dots (QDs) and single‐walled carbon nanotubes (SWCNTs). Here, excellent compatibility of QDs and SWCNTs as a complementary pair of semiconducting materials for fabrication of high‐performance complementary metal‐oxide‐semiconductor (CMOS)‐like inverters is demonstrated. The n‐type field effect transistors (FETs) based on I^? capped PbS QDs (V _th = 0.2 V, on/off = 10⁵, S _S‐th = 114 mV dec^?1, µ _e = 0.22 cm² V^?1 s^?1) and the p‐type FETs with tailored parameters based on low‐density random network of SWCNTs (V _th = ?0.2 V, on/off > 10⁵, S _S‐th = 63 mV dec^?1, µ _h = 0.04 cm² V^?1 s^?1) are integrated on the same substrate in order to obtain high‐performance hybrid inverters. The inverters operate in the sub‐1 V range (0.9 V) and have high gain (76 V/V), large maximum‐equal‐criteria noise margins (80%), and peak power consumption of 3 nW, in combination with low hysteresis (10 mV).     

A Fermi‐Level‐Pinning‐Free 1D Electrical Contact at the Intrinsic 2D MoS2–Metal Junction

Currently 2D crystals are being studied intensively for use in future nanoelectronics, as conventional semiconductor devices face challenges in high power consumption and short channel effects when scaled to the quantum limit. Toward this end, achieving barrier‐free contact to 2D semiconductors has emerged as a major roadblock. In conventional contacts to bulk metals, the 2D semiconductor Fermi levels become pinned inside the bandgap, deviating from the ideal Schottky–Mott rule and resulting in significant suppression of carrier transport in the device. Here, MoS₂ polarity control is realized without extrinsic doping by employing a 1D elemental metal contact scheme. The use of high‐work‐function palladium (Pd) or gold (Au) enables a high‐quality p‐type dominant contact to intrinsic MoS₂, realizing Fermi level depinning. Field‐effect transistors (FETs) with Pd edge contact and Au edge contact show high performance with the highest hole mobility reaching 330 and 432 cm² V^?1 s^?1 at 300 K, respectively. The ideal Fermi level alignment allows creation of p‐ and n‐type FETs on the same intrinsic MoS₂ flake using Pd and low‐work‐function molybdenum (Mo) contacts, respectively. This device acts as an efficient inverter, a basic building block for semiconductor integrated circuits, with gain reaching 15 at V_D = 5 V.     

Liquid‐Alloy‐Assisted Growth of 2D Ternary Ga2In4S9 toward High‐Performance UV Photodetection

2D ternary systems provide another degree of freedom of tuning physical properties through stoichiometry variation. However, the controllable growth of 2D ternary materials remains a huge challenge that hinders their practical applications. Here, for the first time, by using a gallium/indium liquid alloy as the precursor, the synthesis of high‐quality 2D ternary Ga₂In₄S₉ flakes of only a few atomic layers thick (≈2.4 nm for the thinnest samples) through chemical vapor deposition is realized. Their UV‐light‐sensing applications are explored systematically. Photodetectors based on the Ga₂In₄S₉ flakes display outstanding UV detection ability (R _λ = 111.9 A W^?1, external quantum efficiency = 3.85 × 10⁴%, and D* = 2.25 × 10¹¹ Jones@360 nm) with a fast response speed (τ_ring ≈ 40 ms and τ_decay ≈ 50 ms). In addition, Ga₂In₄S₉‐based phototransistors exhibit a responsivity of ≈10⁴ A W^?1@360 nm above the critical back‐gate bias of ≈0 V. The use of the liquid alloy for synthesizing ultrathin 2D Ga₂In₄S₉ nanostructures may offer great opportunities for designing novel 2D optoelectronic materials to achieve optimal device performance.     

Controllable P‐ and N‐Type Conversion of MoTe2 via Oxide Interfacial Layer for Logic Circuits

To realize basic electronic units such as complementary metal‐oxide‐semiconductor (CMOS) inverters and other logic circuits, the selective and controllable fabrication of p‐ and n‐type transistors with a low Schottky barrier height is highly desirable. Herein, an efficient and nondestructive technique of electron‐charge transfer doping by depositing a thin Al₂O₃ layer on chemical vapor deposition (CVD)‐grown 2H‐MoTe₂ is utilized to tune the doping from p‐ to n‐type. Moreover, a type‐controllable MoTe₂ transistor with a low Schottky barrier height is prepared. The selectively converted n‐type MoTe₂ transistor from the p‐channel exhibits a maximum on‐state current of 10 µA, with a higher electron mobility of 8.9 cm² V^?1 s^?1 at a drain voltage (V_ds) of 1 V with a low Schottky barrier height of 28.4 meV. To validate the aforementioned approach, a prototype homogeneous CMOS inverter is fabricated on a CVD‐grown 2H‐MoTe₂ single crystal. The proposed inverter exhibits a high DC voltage gain of 9.2 with good dynamic behavior up to a modulation frequency of 1 kHz. The proposed approach may have potential for realizing future 2D transition metal dichalcogenide‐based efficient and ultrafast electronic units with high‐density circuit components under a low‐dimensional regime.     

Micro‐Blooming: Hierarchically Porous Nitrogen‐Doped Carbon Flowers Derived from Metal‐Organic Mesocrystals

Synthesis of 3D flower‐like zinc‐nitrilotriacetic acid (ZnNTA) mesocrystals and their conformal transformation to hierarchically porous N‐doped carbon superstructures is reported. During the solvothermal reaction, 2D nanosheet primary building blocks undergo oriented attachment and mesoscale assembly forming stacked layers. The secondary nucleation and growth preferentially occurs at the edges and defects of the layers, leading to formation of 3D flower‐like mesocrystals comprised of interconnected 2D micropetals. By simply varying the pyrolysis temperature (550–1000 °C) and the removal method of in the situ‐generated Zn species, nonporous parent mesocrystals are transformed to hierarchically porous carbon flowers with controllable surface area (970–1605 m² g^?1), nitrogen content (3.4–14.1 at%), pore volume (0.95–2.19 cm³ g^?1), as well as pore diameter and structures. The carbon flowers prepared at 550 °C show high CO₂/N₂ selectivity due to the high nitrogen content and the large fraction of (ultra)micropores, which can greatly increase the CO₂ affinity. The results show that the physicochemical properties of carbons are highly dependent on the thermal transformation and associated pore formation process, rather than directly inherited from parent precursors. The present strategy demonstrates metal‐organic mesocrystals as a facile and versatile means toward 3D hierarchical carbon superstructures that are attractive for a number of potential applications.     

Homogeneous 2D MoTe2 p–n Junctions and CMOS Inverters formed by Atomic‐Layer‐Deposition‐Induced Doping

Recently, α‐MoTe₂, a 2D transition‐metal dichalcogenide (TMD), has shown outstanding properties, aiming at future electronic devices. Such TMD structures without surface dangling bonds make the 2D α‐MoTe₂ a more favorable candidate than conventional 3D Si on the scale of a few nanometers. The bandgap of thin α‐MoTe₂ appears close to that of Si and is quite smaller than those of other typical TMD semiconductors. Even though there have been a few attempts to control the charge‐carrier polarity of MoTe₂, functional devices such as p–n junction or complementary metal–oxide–semiconductor (CMOS) inverters have not been reported. Here, we demonstrate a 2D CMOS inverter and p–n junction diode in a single α‐MoTe₂ nanosheet by a straightforward selective doping technique. In a single α‐MoTe₂ flake, an initially p‐doped channel is selectively converted to an n‐doped region with high electron mobility of 18 cm² V^?1 s^?1 by atomic‐layer‐deposition‐induced H‐doping. The ultrathin CMOS inverter exhibits a high DC voltage gain of 29, an AC gain of 18 at 1 kHz, and a low static power consumption of a few nanowatts. The results show a great potential of α‐MoTe₂ for future electronic devices based on 2D semiconducting materials.     

Roll‐to‐Roll Production of Layer‐Controlled Molybdenum Disulfide: A Platform for 2D Semiconductor‐Based Industrial Applications

A facile methodology for the large‐scale production of layer‐controlled MoS₂ layers on an inexpensive substrate involving a simple coating of single source precursor with subsequent roll‐to‐roll‐based thermal decomposition is developed. The resulting 50 cm long MoS₂ layers synthesized on Ni foils possess excellent long‐range uniformity and optimum stoichiometry. Moreover, this methodology is promising because it enables simple control of the number of MoS₂ layers by simply adjusting the concentration of (NH₄)₂MoS₄. Additionally, the capability of the MoS₂ for practical applications in electronic/optoelectronic devices and catalysts for hydrogen evolution reaction is verified. The MoS₂‐based field effect transistors exhibit unipolar n‐channel transistor behavior with electron mobility of 0.6 cm² V^?1 s^?1 and an on‐off ratio of ≈10³. The MoS₂‐based visible‐light photodetectors are fabricated in order to evaluate their photoelectrical properties, obtaining an 100% yield for active devices with significant photocurrents and extracted photoresponsivity of ≈22 mA W^?1. Moreover, the MoS₂ layers on Ni foils exhibit applicable catalytic activity with observed overpotential of ≈165 mV and a Tafel slope of 133 mV dec^?1. Based on these results, it is envisaged that the cost‐effective methodology will trigger actual industrial applications, as well as novel research related to 2D semiconductor‐based multifaceted applications.     

Remarkable Improvement in Photocatalytic Performance for Tannery Wastewater Processing via SnS2 Modified with N‐Doped Carbon Quantum Dots: Synthesis,Characterization, and 4‐Nitrophenol‐Aided Cr(VI) Photoreduction

Photocatalytic pathways are proved crucial for the sustainable production of chemicals and fuels required for a pollution‐free planet. Electron–hole recombination is a critical problem that has, so far, limited the efficiency of the most promising photocatalytic materials. Here, the efficacy of the 0D N doped carbon quantum dots (N‐CQDs) is demonstrated in accelerating the charge separation and transfer and thereby boosting the activity of a narrow‐bandgap SnS₂ photocatalytic system. N‐CQDs are in situ loaded onto SnS₂ nanosheets in forming N‐CQDs/SnS₂ composite via an electrostatic interaction under hydrothermal conditions. Cr(VI) photoreduction rate of N‐CQDs/SnS₂ is highly enhanced by engineering the loading contents of N‐CQDs, in which the optimal N‐CQDs/SnS₂ with 40 mol% N‐CQDs exhibits a remarkable Cr(VI) photoreduction rate of 0.148 min^?1, about 5‐time and 148‐time higher than that of SnS₂ and N‐CQDs, respectively. Examining the photoexcited charges via zeta potential, X‐ray photoelectron spectroscopy (XPS), surface photovoltage, and electrochemical impedance spectra indicate that the improved Cr(VI) photodegradation rate is linked to the strong electrostatic attraction between N‐CQDs and SnS₂ nanosheets in composite, which favors efficient carrier utilization. To further boost the carrier utilization, 4‐nitrophenol is introduced in this photocatalytic system and the efficiency of Cr(VI) photoreduction is further promoted.     

SnS2/Co3S4 Hollow Nanocubes Anchored on S‐Doped Graphene for Ultrafast and Stable Na‐Ion Storage

SnS₂ has been widely studied as an anode material for sodium‐ion batteries (SIBs) based on the high theoretical capacity and layered structure. Unfortunately, rapid capacity decay associated with volume variation during cycling limits practical application. Herein, SnS₂/Co₃S₄ hollow nanocubes anchored on S‐doped graphene are synthesized for the first time via coprecipitation and hydrothermal methods. When applied as the anode for SIBs, the sample delivers a distinguished charge specific capacity of 1141.8 mAh g^?1 and there is no significant capacity decay (0.1 A g^?1 for 50 cycles). When the rate is increased to 0.5 A g^?1, it presents 845.7 mAh g^?1 after cycling 100 times. Furthermore, the composite also exhibits an ultrafast sodium storage capability where 392.9 mAh g^?1 can be obtained at 10 A g^?1 and the charging time is less than 3 min. The outstanding electrochemical properties can be ascribed to the enhancement of conductivity for the addition of S‐doped graphene and the existence of p–n junctions in the SnS₂/Co₃S₄ heterostructure. Moreover, the presence of mesopores between nanosheets can alleviate volume expansion during cycling as well as being beneficial for the migration of Na⁺.     

Synthesis of Large‐Area InSe Monolayers by Chemical Vapor Deposition

Recently, 2D materials of indium selenide (InSe) layers have attracted much attention from the scientific community due to their high mobility transport and fascinating physical properties. To date, reports on the synthesis of high‐quality and scalable InSe atomic films are limited. Here, a synthesis of InSe atomic layers by vapor phase selenization of In₂O₃ in a chemical vapor deposition (CVD) system, resulting in large‐area monolayer flakes or thin films, is reported. The atomic films are continuous and uniform over a large area of 1 × 1 cm², comprising of primarily InSe monolayers. Spectroscopic and microscopic measurements reveal the highly crystalline nature of the synthesized InSe monolayers. The ion‐gel‐gated field‐effect transistors based on CVD InSe monolayers exhibit n‐type channel behaviors, where the field effect electron mobility values can be up to ≈30 cm² V^?1 s^?1 along with an on/off current ratio, of >10⁴ at room temperature. In addition, the graphene can serve as a protection layer to prevent the oxidation between InSe and the ambient environment. Meanwhile, the synthesized InSe films can be transferred to arbitrary substrates, enabling the possibility of reassembly of various 2D materials into vertically stacked heterostructures, prompting research efforts to probe its characteristics and applications.     

Metallic Porous Iron Nitride and Tantalum Nitride Single Crystals with Enhanced Electrocatalysis Performance

Altering a material's catalytic properties would require identifying structural features that deliver electrochemically active surfaces. Single‐crystalline porous materials, combining the advantages of long‐range ordering of bulk crystals and large surface areas of porous materials, would create sufficient active surfaces by stabilizing 2D active moieties confined in lattice and may provide an alternative way to create high‐energy surfaces for electrocatalysis that are kinetically trapped. Here, a radical concept of building active metal–nitrogen moieties with unsaturated nitrogen coordination on a porous surface by directly growing metallic porous metal nitride (Fe₃N and Ta₅N₆) single crystals at unprecedented 2 cm scale is reported. These porous single crystals demonstrate exceptionally high conductivity of 0.1–1.0 × 10⁵ S cm^?1, while the atomic surface layers of the porous crystals are confirmed to be an Fe termination layer for Fe₃N and a Ta termination layer for Ta₅N₆. The unsaturated metal–nitrogen moieties (Fe₆–N and Ta₅–N₃) with unique electronic structures demonstrate enhanced electrocatalysis performance and durability.