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2D ferroelectrics open a new realm of nonvolatile memory and computing devices, while metal–organic frameworks (MOF) offer tremendous possibilities to design and optimize ferroelectric performance. Integrating a MOF ferroelectric gate with a semiconducting channel provides new strategy toward ultralow power ferroelectric field effect transistors (FeFETs), yet no 2D MOF is experimentally demonstrated to be ferroelectric yet. Here, the study successfully develops 2D ferroelectric MOF nanosheets, {CuL2(H2O)2(NO3)2(H2O)1.5·(CH3OH)}∞ wherein L denotes PhPO(NH4Py)2, abbreviated as {CuIIL2}n‐MOF, and confirm its ferroelectricity down to 7 nm thickness. A large polarization of ≈14.2 µC cm−2, small coercive field of ≈33.3 V µm−1, and excellent endurability >106 cycles are found in 2D {CuIIL2}n‐MOF nanosheets. This enables to fabricate FeFETs using 2D {CuIIL2}n‐MOF as the gate and MoS2 as the channel, achieving an on/off ratio of 107 with ultralow off‐state current of 100 fA and tunable memory window, making it exceptional among known FeFETs and very promising for next‐generation ultralow power memories and computing devices [ABSTRACT FROM AUTHOR]

In recent years, 2D/3D heterojunction electronic devices have attracted considerable attention. As the size decreases, enhancing the speed of MOSFETs, reducing the subthreshold swing (SS), and lowering the power consumption (P) have become challenging. Therefore, in the post‐Moore era, in response to the continuation of Moore's law, junction field‐effect transistors (JFETs) based on mixed‐dimensional MoS2/GaN heterojunctions are proposed via thickness engineering. Accordingly, flat hetero interface and large potential barrier height of 5 eV across the heterojunction, an ultra‐low SS of 60.9 mV dec−1 (The Boltzmann limit is 60 mV dec−1) is achieved at Vds = 0.1 V when the MoS2 thickness is 10 nm. Additionally, a high Ion/Ioff ratio of 107 and a saturation current density (Jds) of 0.16 µA µm−1 is achieved. As the thickness of MoS2 increased from 6 to 16 nm, the working mode transitioned from enhancement mode to depletion mode. The depletion region across the channel is verified using computer‐aided design technology. Finally, an N‐type load inverter with a maximum voltage gain of 4 and a minimum static P of 25 nW is applied. Overall, the work provides a universal strategy for constructing a series of high‐performance transition metal dichalcogenide/GaN JFETs. [ABSTRACT FROM AUTHOR]

Absorbing near‐infrared (NIR) photons, with longer wavelengths, in atomically thin monolayer MoS2 presents a significant challenge due to its weak optical absorption and narrow absorption bands. Consequently, MoS2‐based photodetector devices often experience low responsivity and a limited detection window. Herein, a novel InAs@ZnSe core@shell/1L‐MoS2 heterostructure, leveraging InAs@ZnSe as the primary infrared‐absorbing material and exploiting the formation of a type‐II heterostructure is showcased. Steady‐state and time‐resolved spectroscopy, along with optoelectronic characterization, are employed to investigate photo‐induced charge transfer dynamics. The results show efficient hole transfer to InAs@ZnSe upon excitation of both materials. Instead, with selective excitation of InAs@ZnSe, electron transfer is observed from InAs@ZnSe to the 1L‐MoS2. The heterostructure demonstrates a broadband photoresponse spanning the wavelength range of 300 to 850 nm, exhibiting a Responsivity of ≈103 A/W and Detectivity of ≈1011 Jones. The signal‐to‐noise ratio substantially increases by 3 to 4 orders of magnitude for 700 and 850 nm excitation compared to pristine 1L‐MoS2. The enhancement in photoresponse and signal‐to‐noise ratio is attributed to increased absorption, which helps eliminate defect and trap states, thereby promoting the photogating effect. [ABSTRACT FROM AUTHOR]

Despite the promising potential of piezo‐catalysis in environmental remediation applications, the performance of various piezoelectric materials still suffer from low carrier concentrations, limited carrier mobility, and rapid recombination of electron‐hole pairs, and the reported modification strategies are quite intricate and challenging to implement. Herein, MoS2 with varying degrees of crystallinity is synthesized through drying and thermal treatment processes, and the effect of crystal engineering on the performance of the piezo‐activated peroxomonosulfate (PAP) system is investigated. The MoS2 annealed at 700 °C (M‐700) with a crystallization of 60.4% exhibited superior performance in the PAP system, which can degrade 99.6% of bisphenol A within 30 min with a mineralization rate of 57.0%. The positive correlation among the crystallinity of piezoelectric catalysts, the parameters of piezoelectric performance (d33) and piezo‐catalytic performance within a certain range is proposed. From the density functional perturbation theory (DFPT), the crystalline‐amorphous hybrid of M‐700 provided an appropriate charge transfer rate, electron concentration, and mechanical strength, which is more conducive to stimulate the active species chain reaction of PMS. This study provides a novel method for improving the piezo‐catalytic activities and holds great promise for water pollution treatment. [ABSTRACT FROM AUTHOR]

MoS2 is widely reported as anode material for sodium‐ion batteries (SIBs). However, its ability to operate effectively across a wide temperature range and at high rates continues to pose fundamental challenges, limiting its further development. Herein, a monolayer Fe‐doped MoS2/N,O‐codoped C overlapping structure is designed and employed as an anode for wide‐temperature‐range SIBs. Fe doping imparts MoS2 electrode with zero bandgap characteristics, an increased interlayer spacing, and low sodium‐ion diffusion energy barriers across wide operation temperatures. Impressively, Fe atoms doped into the MoS2 lattice can be reduced to superparamagnetic Fe0 nanocrystals of ≈2 nm during conversion reactions. In situ magnetometry reveals that these Fe0 nanocrystals can be used as electron acceptor in the formation of space charge zones with Na+, thereby triggering strong spin‐polarized surface capacitance that facilitates fast sodium‐ion storage over a wide temperature range. Consequently, the designed MoS2 electrode demonstrates exceptional fast‐charging capability in half/full cells operating at −40–60 °C. This study provides novel perspectives on the utilization of heteroatom doping strategies in conversion‐type electrode material design and proves the effectiveness of spin‐polarized surface capacitance effect on enhancing sodium‐ion storage over a wide temperature range. [ABSTRACT FROM AUTHOR]

With the rise of on‐device artificial intelligence (AI) technology, the demand for in‐memory comptuing has surged for data‐intensive tasks on edge devices. However, on‐device AI requires high‐density, low‐power memory‐based computing to efficiently handle large data volumes. Here, this study proposes a reliable multilevel, high gate‐coupling ratio memory device with MoS2 channel tailored for high‐density 3D NAND Flash‐based in‐memory computing. The MoS2 channel, featured by its small bandgap and high‐mobility, facilitates reliable memory window of approximately 8 V thanks to erase operation through hole injection. This not only suppresses vertical charge loss but also alleviates the burden on voltage generator circuits, indicating the suitability of MoS2 as channel material for 3D NAND Flash architecture. Additionally, a low‐k (≈2.2) tunneling layer deposited via initiated chemical vapor deposition increases the gate‐coupling ratio, thereby reducing the operating voltage. Utilizing Au nanoparticles as the charge storage layer, MoS2 memory devices show synaptic plasticity with 6‐bit, endurance (104 cycles), read disturbance (105 cycles), and retention times (105 s). Furthermore, device‐to‐system simulations for neural networks based on MoS2‐memory devices have successfully achieved a fingerprint recognition of 95.8%. These results provide the foundation to develop multi‐bit MoS2‐memory devices for AI accelerators and 3D NAND Flash memory. [ABSTRACT FROM AUTHOR]

Detection and discrimination of volatile organic compounds (VOCs) is important to provide a more realistic assessment of their potential implication in complex environments and medical diagnostics based on volatile biomarkers. Herein, chemiresistive sensors are fabricated using stacked MoS2 nanoflakes with defects and exposed‐edge sites. The sensor is found to be extremely selective to triethylamine (TEA) over polar, non‐polar VOCs and atmospheric gases. The sensor exhibits a sensitivity of 1.72% ppm−1, fast response/recovery (19 s/39 s) to 100 ppm TEA at room temperature, low limit of detection (64 ppb), device reproducibility, humidity tolerance (RH 90%) and stability tested up to 60 days. The kinetic analysis of sensing curves reveals two discrete adsorption sites corresponding to edge and basal sites of interaction, with a higher rate constant of association and dissociation for TEA. The Density Functional Theory (DFT) studies support higher adsorption energy of TEA on MoS2 surface with respect to other volatile amines. The sensor demonstrates TEA recognition and composition estimation capability in a binary mixture of a similar class of VOCs using Machine Learning driven analysis with 95% accuracy. The ability to discriminate amines in binary mixture of other volatile amines paves the way for the advancement of next‐generation devices in the field of disease diagnosis. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2), a two‐dimensional (2D) semiconducting material harbors intrinsic defects that can be harnessed to achieve tuneable electronic, optoelectronic, and electrochemical devices. However, achieving precise control over defect formation within monolayer MoS2, remains a notable challenge. Here, an in‐situ defect engineering approach for monolayer MoS2 using a pressure‐dependent chemical vapor deposition (CVD) process is presented. Monolayer MoS2 grown in a low pressure CVD conditions (LP‐MoS2) produces sulfur vacancy (Vs) induced defect‐rich crystals primarily attributed to the oxygen‐deficient growth conditions. Conversely, atmospheric pressure CVD‐grown MoS2 (AP‐MoS2) passivates these defects with oxygen from ambient conditions. This disparity in defect profiles profoundly impacts crucial functional properties and device performance. AP‐MoS2 shows a drastically enhanced photoluminescence, which is significantly quenched in LP‐MoS2 attributed to in‐gap electron donor states induced by the Vs defects. However, the n‐doping induced in LP‐MoS2 generates enhanced photoresponsivity and detectivity in fabricated photodetectors compared to the AP‐MoS2‐based devices. Defect‐rich LP‐MoS2 outperforms AP‐MoS2 as channel layers of field‐effect transistors (FETs), as well as electrocatalytic material for hydrogen evolution reaction (HER). This work presents a single‐step CVD approach for in situ defect engineering in monolayer MoS2 and presents a pathway to control defects in other monolayer 2D materials. [ABSTRACT FROM AUTHOR]

Ferroelectric field effect transistors (FeFETs), characterized by their low power consumption and polarization effect, can be employed in photodetectors based on 2D materials. In this paper, a MoS2 phototransistor with epitaxial ferroelectric (Hf0.5Zr0.5)O2 (HZO) is reported as a gate dielectric layer. Gate‐dielectric‐polarization‐dependent ambipolar behavior is observed in the FET, and relatively low power consumption and hysteresis‐free loop are achieved in the FeFET. The anomalous negative photoconductivity (NPC) is observed as well. Possible reasons for such phenomenon are clarified including the photogating effect originating from the interface traps and the polarization‐dependent electric‐field control through ferroelectric gating. The high responsivity of −8.44 × 103 A W−1 in the negative photoconductivity as well as the response time of 500 ms are reported. The demonstrated Molybdenum disulfide (MoS2) FeFET photodetectors show great potential in the on‐chip complementary metal‐oxide semiconductor (CMOS)‐compatible circuits for multifunctional devices. [ABSTRACT FROM AUTHOR]

It is crucial to develop advanced optoelectronic devices that incorporate multiple functions, including sensing, storage, and computing, which is considered at the forefront of semiconductor optoelectronics to meet emerging functional diversification. In this study, by stacking the n‐type Ga2O3 with the n‐type MoS2 flakes, a Ga2O3/MoS2 heterostructure optoelectronic device with high rectification ratio of ≈105 and on/off ratio of ≈108 is fabricated, which achieves high detectivity of 1.34 × 109 Jones and high responsivity of 28.92 mA/W. More importantly, the Ga2O3/MoS2 heterostructure device shows potential ability to integrate sensing and memorizing, simultaneously, which can be used as artificial neuromorphic synaptic. The device exhibits excellent photo‐induced synaptic functions including short‐term plasticity, long‐term plasticity, and paired‐pulse facilitation, realizing the ability to couple light and electrical signals by Pavlovian associative learning. At last, the device also demonstrates the information processing ability to act as optoelectronic logic gate AND by synergistically regulating the light on/off states and gate voltage. The research introduces an innovative strategy for the development of next‐generation optoelectronic devices which are highly integrated with sensing, memory, and logic processing functions, demonstrating great application prospects in constructing an efficient artificial neuromorphic visual and logic systems. [ABSTRACT FROM AUTHOR]

2D semiconductors have emerged as candidates for next‐generation electronics. However, previously reported 2D transistors which typically employ the gate‐first process to fabricate a back‐gate (BG) configuration while neglecting the thorough impact on the dielectric capping layer, are severely constrained in large‐scale manufacturing and compatibility with complementary metal–oxide–semiconductor (CMOS) technology. In this study, dual‐gate (DG) field‐effect transistors have been realized based on wafer‐scale monolayer MoS2 and the gate‐last processing, which avoids the transfer process and utilizes an optimized top‐gate (TG) dielectric stack, rendering it highly compatible with CMOS technology. Subsequently, the physical mechanism of TG dielectric deposition and the corresponding controllable threshold voltage (VTH) shift is investigated. Then the fabricated TG‐devices with a large on/off ratio up to 1.7 × 109, negligible hysteresis (≈14 mV), and favorable stability. Additionally, encapsulated TG structured photodetectors have been demonstrated which exhibit photo responsivity (R) up to 9.39 × 103 A W−1 and detectivity (D*) ≈2.13 × 1013 Jones. The result paves the way for future CMOS‐compatible integration of 2D semiconductors for complex multifunctional IC applications. [ABSTRACT FROM AUTHOR]

2D materials are solid microscopic flakes with a‐few‐Angstrom thickness possessing some of the largest surface‐to‐volume ratios known. Altering their conformation state from a flat flake to a scroll or fiber offers a synergistic association of properties arising from 2D and 1D nanomaterials. However, a combination of the long‐range electrostatic and short‐range solvation forces produces an interlayer repulsion that has to be overcome, making scrolling 2D materials without disrupting the pristine structure a challenging task. Herein, a facile method is presented to alter the 2D materials' inter‐layer interactions by confining organic salts onto their basal area, forming 2D‐confined electrolytes. The confined electrolytes produce local charge inhomogeneities, which can conjugate across the interlayer gap, binding the two surfaces. This allows the 2D‐confined electrolytes to behave as polyelectrolytes within a higher dimensional order (2D → 1D) and form robust nanofibers with distinct electronic properties. The method is not material‐specific and the resulting fibers are tightly bound even though the crystal structure of the basal plane remains unaltered. [ABSTRACT FROM AUTHOR]

Organic–inorganic 2D heterostructures combine the high optical absorption of organic molecules with exciton‐dominated optical properties in layered transition metal dichalcogenides (TMDs) such as MoS2. Critical to the interaction and the optical response in such hybrid systems is the electronic band alignment at the interface between the two species. Here, the coupling of monolayers of perylene derivatives is investigated with bilayer MoS2. In particular, variation in the perylene orientation on the MoS2 surface is identified using Raman spectroscopy and scanning probe microscopy. Low‐temperature optical spectroscopy reveals orientation‐dependent interlayer exciton formation. Furthermore, power‐dependent photoluminescence measurements provide insight into the modified interlayer charge transfer in these heterostructures. A saturation of interlayer states is found under high excitation power when the perylene molecules are in a perpendicular orientation to the surface that leads to electron accumulation in the MoS2, whereas parallel alignment of the perylene molecules leads to enhanced populations of organic–inorganic interlayer excitons. This work provides insights into the optimization of organic–inorganic heterostructures, with particular relevance to applications for optoelectronic and excitonic devices. [ABSTRACT FROM AUTHOR]

Artificial synaptic devices (ASDs) are attracting widespread attention as highly promising components for use in complex neuromorphic systems, playing crucial roles in addressing the challenges posed by the conventional von Neumann architecture. However, the instabilities of ASDs in high‐temperature environments diminish the reliabilities of the device performances, significantly inhibiting their practical application. Herein, a highly reliable 2D MoS2/GaPS4 ASD that maintains its functionality even after exposure to 400 °C is proposed. Moreover, due to the enhanced charge‐trapping effect of the GaPS4 layer, the memory window expands from an initial 42 to 55 V, accompanied by a substantial on/off ratio of 105, low off‐leakage current of 10−11 A, and high number of endurance cycles (103). The device effectively simulates various biological synaptic functions via electric and light stimulation. Notably, the high electric and light paired‐pulse facilitation indices suggest an exceptional synaptic performance. The findings introduce a novel approach to high‐temperature neuromorphic applications via defect engineering. [ABSTRACT FROM AUTHOR]

Unveiled as a unique feature of polymer ferroelectric crystals, oriented coalescence within monolayers of poly(vinylidenefluoride‐co‐trifluoroethylene)(PVDF‐TrFE) ferroelectric crystals has been found regulable upon monolayer roughness, which is accompanied by the adjustment of piezoelectric responses, and thus phase polarity. Simply with the deposition of poly(3‐hexylthiophene (P3HT)‐wrapped molybdenum disulfide (MoS2) sheets, piezoelectric responses of polymer ferroelectric crystals are surprisingly enhanced further. Also dependent on the degrees of phase polarity, the binding energy of P3HT excitons declines to a level comparable to that of inorganic excitons, together with the alteration of work functions. These results suggest mutual polarization between ferroelectric lamellar crystals and originally nonpolar P3HT‐wrapped MoS2 sheets as a result of dipole‐induced dipole phase interactions. As the Fermi levels and driving forces of interfacial electron transition are also adjustable upon involved phase interactions, P3HT‐wrapped MoS2 sheets can photocatalyze hydrogen evolution with an average production rate reaching 4.474 mmol g−1 h−1, which is 1.6 times higher than the results without the aid of phase interactions. Accordingly, amplifying phase interactions has been elucidated feasible, and able to serve as a promising approach to generally promote photocatalytic reactions. [ABSTRACT FROM AUTHOR]

Advancements in display technology have primarily focused on discovering new materials to develop thin‐film transistors (TFTs) that complement mainstream technologies. The emerging 2D semiconductors are one of the most promising candidates due to their ultra‐thin thickness, exceptional electrical qualities, and large‐scale availability. However, these atomically thin materials are delicate and typically prepared through standard gate‐first fabrication processes, necessitating their transfer onto specific substrates. In this study, a demonstration of an in situ gate‐last process for 2D semiconductor‐based TFTs technology is presented. This approach bypasses the yield‐limiting transfer process, enabling large‐scale display applications. The as‐fabricated MoS2 TFTs retains their intrinsic properties with a current density reaching ≈≈10 µA µm−1. Additionally, it is successfully showcased that the two transistor‐one capacitor active‐matrix display driving circuits with a high pixel yield. The patterned matrix exhibits no crosstalk and can be driven by either the pulse amplitude modulation or pulse width modulation scheme, offering flexible applications. [ABSTRACT FROM AUTHOR]

Optoelectronic performance of 2D transition metal dichalcogenides (TMDs)‐based solar cells and self‐powered photodetectors remain limited due to fabrication challenges, such as difficulty in doping TMDs to form p–n junctions. Herein, MoS2 diodes based on geometrically asymmetric contact areas are shown to achieve a high current rectification ratio of ≈105, facilitating efficient photovoltaic charge collection. Under solar illumination, the device demonstrates a high open‐circuit voltage (Voc) of 430 mV and a short‐circuit current density (Jsc) of −13.42 mA cm−2, resulting in a high photovoltaic power conversion efficiency (PCE) of 3.16%, the highest reported for a lateral 2D solar cell. The diodes also show a high photoresponsivity of 490.3 mA W−1, and a large photo detectivity of 4.05 × 1010 Jones, along with a fast response time of 0.8 ms under 450 nm wavelength at zero bias for self‐powered photodetection applications. The device transferred on a flexible substrate shows a high photocurrent and PCE retentions of 94.4%, and 88.2% after 5000 bending cycles at a bending radius of 1.5 cm, respectively, demonstrating robustness for flexible optoelectronic applications. The simple fabrication process, superior photovoltaic properties, and high flexibility suggests that the geometrically asymmetric MoS2 device architecture is an excellent candidate for flexible photovoltaic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) is a promising non‐precious material for hydrogen evolution reaction (HER) electrocatalysts and surface‐enhanced Raman scattering (SERS) substrates. However, its inert basal plane, poor active sites, and limited stability hamper their commercial prospects. Herein, Ru, O co‐doped MoS2 (MSORx) for accelerating the charge transfer and building more active sites using one‐step hydrothermal method is designed to address these obstacles. The outstanding HER performances of the MSOR1 with low overpotentials at 10 mA cm−2 in both acidic (197 mV) and alkaline solution (43 mV), which even rivals that of commercial Pt/C. Meanwhile, this MSOR1 is also used as SERS substrate that has excellent sensitivity with the enhancement factor of 1.7 × 106. Additionally, label‐free detection of bilirubin using MSOR1 with a detection limit of 10−10 m has been demonstrated, also better than that of most previously reported semiconductors. Superior HER and SERS activity, universality in wide PH range and long‐term stability are achieved based on the introduction of Ru and O. This study provides guidance for the synthesis of highly active catalysts and SERS substrate, and holds considerable promise for low‐cost HER over the whole pH and clinical translation in accurate diagnosis of jaundice. [ABSTRACT FROM AUTHOR]

Owing to the low-cost, dendrite-free formation, and high volumetric capacity, rechargeable Li+/Mg2+ hybrid-ion batteries (LMIBs) have attracted great attention and are regarded as promising energy storage devices. However, due to the strong Coulombic interaction ofMg2+ with host materials, the traditional "Daniell Type" LMIBs with only Li+ intercalation usually cannot ensure a satisfactory energy density. Herein, graphene monolayers are arranged intercalating into MoS2 interlamination to construct van der Waals heterostructures (MoS2/G VH). This operation transforms the construction ofion channels from pristine interlamination of two MoS2 monolayers to the interlamination ofMoS2 monolayer with graphene monolayer, thereby greatly reducing ion diffusion energy barriers. Compared with pristine MoS2, the MoS2/G VH can obviously reduce the migration energy barriers ofLi+ (from 0.67 to 0.09 eV) and Mg2+ (from 1.01 to 0.21 eV). Moreover, it is also demonstrated that MoS2/G VHs realize Li+/Mg2+ co-intercalation even at a rate current of1000 mA g-1. As expected, the MoS2/G VH exhibits superior electrochemical performance with a reversible capacity of 145.8 mAh g-1 at 1000 mA g-1 after 2200 cycles, suggesting the feasibility of potential applications for high-performance energy storage devices. [ABSTRACT FROM AUTHOR]

Molecular doping is a powerful, tuneable, and versatile method to modify the electronic properties of 2D transition metal dichalcogenides (TMDCs). While electron transfer is an isotropic process, dipole‐induced doping is a collective phenomenon in which the orientation of the molecular dipoles interfaced to the 2D material is key to modulate and boost this electronic effect, despite it is not yet demonstrated. A novel method toward the molecular functionalization of monolayer MoS2 relying on the molecular self‐assembly of metal phthalocyanine and the orientation‐controlled coordination chemistry of axial ligands is reported here. It is demonstrated that the subtle variation of position and type of functional groups exposed on the pyridinic ligand, yields a molecular dipole with programed magnitude and orientation which is capable to strongly influence the opto‐electronic properties of monolayer MoS2. In particular, experimental results revealed that both p‐ and n‐type doping can be achieved by modulating the charge carrier density up to 4.8 1012 cm−2. Density functional theory calculations showed that the doping mechanism is primarily resulting from the effect of dipole‐induced doping rather than charge transfer. The strategy to dope TMDCs is a highly modulable and robust, and it enables to enrich the functionality of 2D materials‐based devices for high‐performance applications in optoelectronics. [ABSTRACT FROM AUTHOR]

Structure and energy band engineering of 2D materials via selective doping or phase modulation provide a significant opportunity to design them for optoelectronic devices. Here, the synthesis of high‐quality MoxRe1–xS2 alloys with tunable composition and phase structure via chemical vapor deposition growth is reported, and their novel energy band structures and optoelectronic properties are explored. The phase separation and structure reconstruction, which are found to be two serious problems in the synthesis of these alloys, are successfully suppressed through tuning their growth thermodynamics. As a result, the obtained MoxRe1–xS2 alloys have uniform composition, phase structure, and crystal orientation. Together with X‐ray photoelectron spectroscopy analysis and first‐principle calculation, the Re/Mo doping‐induced Fermi level up‐shift/down‐shift, new electronic states, and "sub‐gap" formation in MoxRe1–xS2 alloys are revealed. Especially, a strong band bowing effect is discovered in the MoxRe1–xS2 alloys with structure transition between 1T′ and 2H phases. Furthermore, these alloys reveal tunable conduction behavior from n‐type to bipolar and p‐type in 1T′ phase, as well as novel "bipolar‐like" electron conduction behavior in 2H alloys. The results highlight the unique alloying effects, which do not exist in the single‐phase 2D alloys, and provide the feasibility for potential applications in building novel electronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Van der Waals p–n junctions of 2D materials present great potential for electronic devices due to the fascinating properties at the junction interface. In this work, an efficient gas sensor based on planar 2D van der Waals junctions is reported by stacking n‐type and p‐type atomically thin MoS2 films, which are synthesized by chemical vapor deposition (CVD) and soft‐chemistry route, respectively. The electrical conductivity of the van der Waals p–n junctions is found to be strongly affected by the exposure to NO2 at room temperature (RT). The MoS2 p–n junction sensor exhibits an outstanding sensitivity and selectivity to NO2 at RT, which are unavailable in sensors based on individual n‐type or p‐type MoS2. The sensitivity of 20 ppm NO2 is improved by 60 times compared to a p‐type MoS2 sensor, and an extremely low limit of detection of 8 ppb is obtained under ultraviolet irradiation. Complete and very fast sensor recovery is achieved within 30 s. These results are superior to most of the previous reports related to NO2 detection. This work establishes an entirely new sensing platform and proves the feasibility of using such materials for the high‐performance detection of gaseous molecules at RT. [ABSTRACT FROM AUTHOR]

The continuous miniaturization of field effect transistors (FETs) dictated by Moore's law has enabled continuous enhancement of their performance during the last four decades, allowing the fabrication of more powerful electronic products (e.g., computers and phones). However, as the size of FETs currently approaches interatomic distances, a general performance stagnation is expected, and new strategies to continue the performance enhancement trend are being thoroughly investigated. Among them, the use of 2D semiconducting materials as channels in FETs has raised a lot of interest in both academia and industry. However, after 15 years of intense research on 2D materials, there remain important limitations preventing their integration in solid‐state microelectronic devices. In this work, the main methods developed to fabricate FETs with 2D semiconducting channels are presented, and their scalability and compatibility with the requirements imposed by the semiconductor industry are discussed. The key factors that determine the performance of FETs with 2D semiconducting channels are carefully analyzed, and some recommendations to engineer them are proposed. This report presents a pathway for the integration of 2D semiconducting materials in FETs, and therefore, it may become a useful guide for materials scientists and engineers working in this field. [ABSTRACT FROM AUTHOR]

Wafer‐scale, single‐crystalline 2D semiconductors without grain boundaries and defects are needed for developing reliable next‐generation integrated 2D electronics. Unfortunately, few literature reports exist on the growth of 2D semiconductors with single‐crystalline structure at the wafer scale. It is shown that direct sulfurization of as‐deposited epitaxial MoO2 films (especially, with thicknesses more than ≈5 nm) produces textured MoS2 films. This texture is inherited from the high density of defects present in the as‐prepared epitaxial MoO2 film. In order to eliminate the texture of the converted MoS2 films, a new capping layer annealing process (CLAP) is introduced to improve the crystalline quality of as‐deposited MoO2 films and minimize its defects. It is demonstrated that sulfurization of the CLAP‐treated MoO2 films leads to the formation of single‐crystalline MoS2 films, instead of textured films. It is shown that the single‐crystalline MoS2 films exhibit field‐effect mobility of 6.3 cm2 V−1 s−1, which is 15 times higher than that of textured MoS2. These results can be attributed to the smaller concentration of defects in the single‐crystalline films. [ABSTRACT FROM AUTHOR]

Using synergetic effects of various sodium storage modes and materials to construct high power, high energy, and long cycling flexible sodium anode materials is significant and still challenging. Here, by advantageous functional integration of adsorption‐intercalation‐conversion sodium storage mechanisms, a 3D flexible fiber paper anode with the composition of Nb2O5@hard carbon@MoS2@soft carbon is designed and prepared. Based on the synergetic effects, it exhibits higher specific capacity than pure Nb2O5, with more excellent rate performance (245, 201, 155, 133, and 97 mAh g−1 at the current density of 0.2, 1, 5, 10, and 20 A g−1, respectively) than pure MoS2 as well as admirable long‐term cycling characteristics (≈82% capacity retention after 20 000 cycles at 5 A g−1). Relevant kinetics mechanisms are expounded in detail. This work can be helpful for preparing other types of hybrid and flexible electrodes for energy storage systems. [ABSTRACT FROM AUTHOR]

As a prerequisite for a sustainable energy economy in the future, designing earth‐abundant MoS2 catalysts with a comparable hydrogen evolution catalytic performance in both acidic and alkaline environments is still an urgent challenge. Decreasing the energy barriers could enhance the catalysts' activity but is not often a strategy for doing so. Here, the first kinetic‐oriented design of the MoS2‐based heterostructure is presented for pH‐universal hydrogen evolution catalysis by optimizing the electronic structure based on the simultaneous modulation of the 3d‐band‐offsets of Ni, Co, and Mo near the interface. Benefiting from this desirable electronic structure, the obtained MoS2/CoNi2S4 catalyst achieves an ultralow overpotential of 78 and 81 mV at 10 mA cm−2, and turnover frequency as high as 2.7 and 1.7 s−1 at the overpotential of 200 mV in alkaline and acidic media, respectively. The MoS2/CoNi2S4 catalyst represents one of the best hydrogen evolution reaction performing ones among MoS2‐based catalysts reported to date in both alkaline and acidic environments, and equally important is the remarkable long‐term stability with negligible activity loss after maintaining at 10 mA cm−2 for 48 h in both acid and base. This work highlights the potential to deeply understand and rationally design highly efficient pH‐universal electrocatalysts for future energy storage and delivery. [ABSTRACT FROM AUTHOR]

Abstract: Potassium‐ion batteries (KIBs) are new‐concept of low‐cost secondary batteries, but the sluggish kinetics and huge volume expansion during cycling, both rooted in the size of large K ions, lead to poor electrochemical behavior. Here, a bamboo‐like MoS2/N‐doped‐C hollow tubes are presented with an expanded interlayer distance of 10 Å as a high‐capacity and stable anode material for KIBs. The bamboo‐like structure provides gaps along axial direction in addition to inner cylinder hollow space to mitigate the strains in both radial and vertical directions that ultimately leads to a high structural integrity for stable long‐term cycling. Apart from being a constituent of the interstratified structure the N‐doped‐C layers weave a cage to hold the potassiation products (polysulfide and the Mo nanoparticles) together, thereby effectively hindering the continuing growth of solid electrolyte interphase in the interior of particles. The density functional theory calculations prove that the MoS2/N‐doped‐C atomic interface can provide an additional attraction toward potassium ion. As a result, it delivers a high capacity at a low current density (330 mAh g−1 at 50 mA g−1 after 50 cycles) and a high‐capacity retention at a high current density (151 mAh g−1 at 500 mA g−1 after 1000 cycles). [ABSTRACT FROM AUTHOR]

Abstract: A facile synthesis method for the heterostructures of single‐walled carbon nanotubes (SWCNTs) and few‐layer MoS2 is reported. The heterostructures are realized by in situ chemical vapor deposition of MoS2 on individual SWCNTs. Field effect transistors based on the heterostructures display different transfer characteristics depending on the formation of MoS2 conduction channels along SWCNTs. Under light illumination, negative photoresponse originating from charge transfer from MoS2 to SWCNT is observed while positive photoresponse is observed in MoS2 conduction channels, leading to ambipolar photoresponse in devices with both SWCNT and MoS2 channels. The heterostructure phototransistor, for negative photoresponse, exhibits high responsivity (100–1000 AW−1) at low bias voltages (0.1 V) in the visible spectrum (500–700 nm) by combining high mobility conduction channel (SWCNT) with efficient light absorber (MoS2). [ABSTRACT FROM AUTHOR]

Abstract: A facile synthesis method for the heterostructures of single‐walled carbon nanotubes (SWCNTs) and few‐layer MoS2 is reported. The heterostructures are realized by in situ chemical vapor deposition of MoS2 on individual SWCNTs. Field effect transistors based on the heterostructures display different transfer characteristics depending on the formation of MoS2 conduction channels along SWCNTs. Under light illumination, negative photoresponse originating from charge transfer from MoS2 to SWCNT is observed while positive photoresponse is observed in MoS2 conduction channels, leading to ambipolar photoresponse in devices with both SWCNT and MoS2 channels. The heterostructure phototransistor, for negative photoresponse, exhibits high responsivity (100–1000 AW−1) at low bias voltages (0.1 V) in the visible spectrum (500–700 nm) by combining high mobility conduction channel (SWCNT) with efficient light absorber (MoS2). [ABSTRACT FROM AUTHOR]

Abstract: Despite high‐energy density and low cost of the lithium–sulfur (Li–S) batteries, their commercial success is greatly impeded by their severe capacity decay during long‐term cycling caused by polysulfide shuttling. Herein, a new phase engineering strategy is demonstrated for making MXene/1T‐2H MoS2‐C nanohybrids for boosting the performance of Li–S batteries in terms of capacity, rate ability, and stability. It is found that the plentiful positively charged S‐vacancy defects created on MXene/1T‐2H MoS2‐C, proved by high‐resolution transmission electron microscopy and electron paramagnetic resonance, can serve as strong adsorption and activation sites for polar polysulfide intermediates, accelerate redox reactions, and prevent the dissolution of polysulfides. As a consequence, the novel MXene/1T‐2H MoS2‐C‐S cathode delivers a high initial capacity of 1194.7 mAh g−1 at 0.1 C, a high level of capacity retention of 799.3 mAh g−1 after 300 cycles at 0.5 C, and reliable operation in soft‐package batteries. The present MXene/1T‐2H MoS2‐C becomes among the best cathode materials for Li–S batteries. [ABSTRACT FROM AUTHOR]

Abstract: The design of transition‐metal chalcogenides (TMCs) photocatalysts for water splitting is highly important, in which both light absorption and interfacial engineering play vital roles in photoexcited electron generation, electron transport, and ultimately speeding up water splitting. To this end, plasmonic metal nanomaterials with surface plasmon resonances are promising candidates. However, it is very difficult to enhance the light absorption and manage the interfacial engineering simultaneously, thus, resulting in suboptimal photocatalytic performance. Here, a doped semiconductor plasmon is proposed to optically and electrically enhance TMCs hydrogen evolution. With the tunability of plasmon resonance in a doped MoO3 semiconductor via hydrogen reduction, the broadband absorption and good interfacial engineering are simultaneously demonstrated in flexible MoS2@MoO3 core–shell nanowire photocatalysts. Better energy‐band alignment with MoS2 can also be realized, thereby achieving improved photoinduced electron generation. More importantly, the defects at the interface between MoO3 and MoS2 are effectively reduced because of precise tunability of plasmon resonance, which enhances electron transport. As a proof of concept, this optimized hybrid nanostructure exhibits outstanding H2 evolution characteristics (841.4 μmol h−1 g−1), excellent stability, and good flexibility. The value is also one of the highest hydrogen evolution activity rates to date among the two dimensional‐layered visible‐light photocatalysts. [ABSTRACT FROM AUTHOR]

Abstract: A synthetic route toward hybrid MoS2‐based materials that combines the 2D bonding of MoS2 with 3D networking of aliphatic carbon chains is devised, leading to a film with enhanced electrocatalytic activity. The hybrid inorganic–organic thin films are synthesized by combining atomic layer deposition (ALD) with molecular layer deposition (MLD) using the precursors molybdenum hexacarbonyl and 1,2‐ethanedithiol and characterized by in situ Fourier transform infrared spectroscopy, and the resultant material properties are probed by X‐ray photoelectron spectroscopy, Raman spectroscopy, and grazing incidence X‐ray diffraction. The process exhibits a growth rate of 1.3 Å per cycle, with an ALD/MLD temperature window of 155–175 °C. The hybrid films are moderately stable for about a week in ambient conditions, smooth (σRMS ≈ 5 Å for films 60 Å thick) and uniform, with densities ranging from 2.2–2.5 g cm−3. The material is both optically transparent and catalytically active for the hydrogen evolution reaction (HER), with an overpotential (294 mV at −10 mA cm−2) superior to that of planar MoS2. The enhancement in catalytic activity is attributed to the incorporation of organic chains into MoS2, which induces a morphological change during electrochemical testing that increases surface area and yields high activity HER catalysts without the need for deliberate nanostructuring. [ABSTRACT FROM AUTHOR]

Abstract: Solar steam generation is achieved by localized heating system using various floating photothermal materials. However, the steam generation efficiency is hindered by the difficulty in obtaining a photothermal material with ultrathin structure yet sufficient solar spectrum absorption capability. Herein, for the first time, an ultrathin 2D porous photothermal film based on MoS2 nanosheets and single‐walled nanotube (SWNT) films is prepared. The as‐prepared SWNT–MoS2 film exhibits an absorption of more than 82% over the whole solar spectrum range even with an ultrathin thickness of ≈120 nm. Moreover, the SWNT–MoS2 film floating on the water surface can generate a sharp temperature gradient due to the localized heat confinement effect. Meanwhile, the ultrathin and porous structure effectively facilitates the fast water vapor escaping, consequently an impressively high evaporation efficiency of 91.5% is achieved. Additionally, the superior mechanical strength of the SWNT–MoS2 film enables the film to be reused for atleast 20 solar illumination cycles and maintains stable water productivity as well as high salt rejection performance. This rational designed hybrid architecture provides a novel strategy for constructing 2D‐based nanomaterials for solar energy harvesting, chemical separation, and related technologies. [ABSTRACT FROM AUTHOR]

Monolayer 2D MoS2 grown by chemical vapor deposition is nanopatterned into nanodots, nanorods, and hexagonal nanomesh using block copolymer (BCP) lithography. The detailed atomic structure and nanoscale geometry of the nanopatterned MoS2 show features down to 4 nm with nonfaceted etching profiles defined by the BCP mask. Atomic resolution annular dark field scanning transmission electron microscopy reveals the nanopatterned MoS2 has minimal large-scale crystalline defects and enables the edge density to be measured for each nanoscale pattern geometry. Photoluminescence spectroscopy of nanodots, nanorods, and nanomesh areas shows strain-dependent spectral shifts up to 15 nm, as well as reduction in the PL efficiency as the edge density increases. Raman spectroscopy shows mode stiffening, confirming the release of strain when it is nanopatterned by BCP lithography. These results show that small nanodots (≈19 nm) of MoS2 2D monolayers still exhibit strong direct band gap photoluminescence (PL), but have PL quenching compared to pristine material from the edge states. This information provides important insights into the structure-PL property correlations of sub-20 nm MoS2 structures that have potential in future applications of 2D electronics, optoelectronics, and photonics. [ABSTRACT FROM AUTHOR]

Monolayer 2D MoS2 grown by chemical vapor deposition is nanopatterned into nanodots, nanorods, and hexagonal nanomesh using block copolymer (BCP) lithography. The detailed atomic structure and nanoscale geometry of the nanopatterned MoS2 show features down to 4 nm with nonfaceted etching profiles defined by the BCP mask. Atomic resolution annular dark field scanning transmission electron microscopy reveals the nanopatterned MoS2 has minimal large-scale crystalline defects and enables the edge density to be measured for each nanoscale pattern geometry. Photoluminescence spectroscopy of nanodots, nanorods, and nanomesh areas shows strain-dependent spectral shifts up to 15 nm, as well as reduction in the PL efficiency as the edge density increases. Raman spectroscopy shows mode stiffening, confirming the release of strain when it is nanopatterned by BCP lithography. These results show that small nanodots (≈19 nm) of MoS2 2D monolayers still exhibit strong direct band gap photoluminescence (PL), but have PL quenching compared to pristine material from the edge states. This information provides important insights into the structure-PL property correlations of sub-20 nm MoS2 structures that have potential in future applications of 2D electronics, optoelectronics, and photonics. [ABSTRACT FROM AUTHOR]

Low-power, nonvolatile memory is an essential electronic component to store and process the unprecedented data flood arising from the oncoming Internet of Things era. Molybdenum disulfide (MoS2) is a 2D material that is increasingly regarded as a promising semiconductor material in electronic device applications because of its unique physical characteristics. However, dielectric formation of an ultrathin low- k tunneling on the dangling bond-free surface of MoS2 is a challenging task. Here, MoS2-based low-power nonvolatile charge storage memory devices are reported with a poly(1,3,5-trimethyl-1,3,5-trivinyl cyclotrisiloxane) (pV3D3) tunneling dielectric layer formed via a solvent-free initiated chemical vapor deposition (iCVD) process. The surface-growing polymerization and low-temperature nature of the iCVD process enable the conformal growing of low- k (≈2.2) pV3D3 insulating films on MoS2. The fabricated memory devices exhibit a tunable memory window with high on/off ratio (≈106), excellent retention times of 105 s with an extrapolated time of possibly years, and an excellent cycling endurance of more than 103 cycles, which are much higher than those reported previously for MoS2-based memory devices. By leveraging the inherent flexibility of both MoS2 and polymer dielectric films, this research presents an important milestone in the development of low-power flexible nonvolatile memory devices. [ABSTRACT FROM AUTHOR]

High overpotentials and low efficiency are two main factors that restrict the practical application for MoS2, the most promising candidate for hydrogen evolution catalysis. Here, RhMoS2 nanocomposites, the addition of a small amount of Rh (5.2 wt%), exhibit the superior electrochemical hydrogen evolution performance with low overpotentials, small Tafel slope (24 mV dec−1), and long term of stability. Experimental results reveal that 5.2 wt% RhMoS2 nanocomposite, even exceeding the commercial 20 wt% Pt/C when the potential is less than −0.18 V, exhibits an excellent mass activity of 13.87 A mgmetal−1 at −0.25 V, four times as large as that of the commercial 20 wt% Pt/C catalyst. The hydrogen yield of 5.2 wt% RhMoS2 nanocomposite is 26.3% larger than that of the commercial 20 wt% Pt/C at the potential of −0.25 V. The dramatically improved electrocatalytic performance of RhMoS2 nanocomposites may be attributed to the hydrogen spillover from Rh to MoS2. [ABSTRACT FROM AUTHOR]

Controllable creating of wafer-scale homogeneous vertical or parallel 2D heterostructures with low cost by the van der Waals stacking or covalently bonded stitching of 2D layered materials, such as graphene, hexagonal boron nitride, and transition-metal dichalcogenides, is of great challenge. In this paper, a new green growth strategy for the fabrication of high-quality large-area and low-cost vertical MoS2/graphene heterostructures has been successfully demonstrated via electrochemical deposition in water solution, followed by an annealing process in chemical vapour deposition system for the first time. The vertical MoS2/graphene heterostructures have been systematically investigated by the combined use of Raman spectroscopy, atomic force microscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. This simple, reliable, and environmentally friendly growth strategy on conducting monolayer graphene in a controlled manner opens up a new way for producing low-cost, large-area, and high-quality vertical MoS2/graphene heterostructures, which have promising applications not only in electronics and optoelectronics but also in the fields of catalysis and renewable energy. [ABSTRACT FROM AUTHOR]

Transition-metal dichalcogenides (TMDCs) are an important class of two-dimensional (2D) layered materials for electronic and optoelectronic applications, due to their ultimate body thickness, sizable and tunable bandgap, and decent theoretical room-temperature mobility. So far, however, all TMDCs show much lower mobility experimentally because of the collective effects by foreign impurities, which has become one of the most important limitations for their device applications. Here, taking MoS2 as an example, the key factors that bring down the mobility in TMDC transistors, including phonons, charged impurities, defects, and charge traps, are reviewed. A theoretical model that quantitatively captures the scaling of mobility with temperature, carrier density, and thickness is introduced. By fitting the available mobility data from literature over the past few years, one obtains the density of impurities and traps for a wide range of transistor structures. It shows that interface engineering can effectively reduce the impurities, leading to improved device performances. For few-layer TMDCs, the lopsided carrier distribution is analytically modeled to elucidate the experimental increase of mobility with the number of layers. From our analysis, it is clear that the charge transport in TMDC samples is a very complex problem that must be handled carefully. [ABSTRACT FROM AUTHOR]

In order to realize the promising potential of MoS2 as the alternative channel material, it is essential to achieve high-performance top-gated MoS2 field-effect transistors (FETs), especially since the back-gated counterparts cannot control the device individually. Although uniform high- k dielectric films, such as HfO2, can be obtained through the introduction of artificial nucleation sites on the MoS2 channel to fabricate top-gated FETs, this would inevitably degrade their channel/dielectric interface quality, induce significant charged impurity scattering and lower carrier mobility. In this work, MoS2 FETs are fabricated using a self-aligned nanowire top-gate, which can effectively reduce the charged impurity scattering on the surface of MoS2. Specifically, the fabricated short-channel devices exhibit impressive electrical performances, such as the high on/off current ratio, low interface trap density, and near-ideal subthreshold slope at room temperature. In addition, the short channel effect is systematically analyzed, which indicates that the phonon scattering can be the dominant scattering mechanism in the devices when the amount of charged impurities is effectively reduced with the self-aligned nanowire gate. All these provide an enhanced fabrication scheme to attain top-gated short-channel devices with the optimized interface and potentially to explore their corresponding performance limits. [ABSTRACT FROM AUTHOR]

Flexible 2D inorganic MoS2 and organic g-C3N4 hybrid thin film photodetectors with tunable composition and photodetection properties are developed using simple solution processing. The hybrid films fabricated on paper substrate show broadband photodetection suitable for both UV and visible light with good responsivity, detectivity, and reliable and rapid photoswitching characteristics comparable to monolayer devices. This excellent performance is retained even after the films are severely deformed at a bending radius of ≈2 mm for hundreds of cycles. The detailed charge transfer and separation processes at the interface between the 2D materials in the hybrid films are confirmed by femtosecond transient absorption spectroscopy with broadband capability. [ABSTRACT FROM AUTHOR]

Novel self-monitoring photothermal (PT) agents are developed using optothermally responsive block copolymer-MoS2 composites (BCP-MoS2), which enable simultaneous PT heating and imaging of temperature profiles. In particular, upon near-infrared light exposure, PT energy from MoS2 successfully increases local temperature and induces thermally activated conformational transitions of the BCP on MoS2. This leads to fluorescent signal changes caused by distance-dependent Förster resonance energy transfer between the BCP and MoS2. Importantly, it is demonstrated that the use of BCP-MoS2 for PT heating and optical mapping is fully reversible with excellent stability. The detailed mechanism of the responsive behavior of BCP-MoS2 is elucidated by measurements of time-resolved fluorescence and dynamic light scattering. In addition, the BCP-MoS2 system is integrated into organogel matrices to demonstrate its potential as aportable, self-monitoring PT system suitable for biological and environmental applications. [ABSTRACT FROM AUTHOR]

Two types of transition metal dichalcogenide (TMD) transistors are applied to demonstrate their possibility as switching/driving elements for the pixel of organic light-emitting diode (OLED) display. Such TMD materials are 6 nm thin WSe2 and MoS2 as a p-type and n-type channel, respectively, and the pixel is thus composed of external green OLED and nanoscale thin channel field effect transistors (FETs) for switching and driving. The maximum mobility of WSe2-FETs either as switch or as driver is ≈30 cm2 V−1 s−1, in linear regime of the gate voltage sweep range. Digital (ON/OFF-switching) and gray-scale analogue operations of OLED pixel are nicely demonstrated. MoS2 nanosheet FET-based pixel is also demonstrated, although limited to alternating gray scale operation of OLED. Device stability issue is still remaining for future study but TMD channel FETs are very promising and novel for their applications to OLED pixel because of their high mobility and ID ON/OFF ratio. [ABSTRACT FROM AUTHOR]

In recent years, 2D layered materials have been considered as promising photon absorption channel media for next-generation phototransistors due to their atomic thickness, easily tailored single-crystal van der Waals heterostructures, ultrafast optoelectronic characteristics, and broadband photon absorption. However, the photosensitivity obtained from such devices, even under a large bias voltage, is still unsatisfactory until now. In this paper, high-sensitivity phototransistors based on WS2 and MoS2 are proposed, designed, and fabricated with gold nanoparticles (AuNPs) embedded in the gate dielectric. These AuNPs, located between the tunneling and blocking dielectric, are found to enable efficient electron trapping in order to strongly suppress dark current. Ultralow dark current (10−11 A), high photoresponsivity (1090 A W−1), and high detectivity (3.5 × 1011 Jones) are obtained for the WS2 devices under a low source/drain and a zero gate voltage at a wavelength of 520 nm. These results demonstrate that the floating-gate memory structure is an effective configuration to achieve high-performance 2D electronic/optoelectronic devices. [ABSTRACT FROM AUTHOR]

In recent years, 2D layered materials have been considered as promising photon absorption channel media for next-generation phototransistors due to their atomic thickness, easily tailored single-crystal van der Waals heterostructures, ultrafast optoelectronic characteristics, and broadband photon absorption. However, the photosensitivity obtained from such devices, even under a large bias voltage, is still unsatisfactory until now. In this paper, high-sensitivity phototransistors based on WS2 and MoS2 are proposed, designed, and fabricated with gold nanoparticles (AuNPs) embedded in the gate dielectric. These AuNPs, located between the tunneling and blocking dielectric, are found to enable efficient electron trapping in order to strongly suppress dark current. Ultralow dark current (10−11 A), high photoresponsivity (1090 A W−1), and high detectivity (3.5 × 1011 Jones) are obtained for the WS2 devices under a low source/drain and a zero gate voltage at a wavelength of 520 nm. These results demonstrate that the floating-gate memory structure is an effective configuration to achieve high-performance 2D electronic/optoelectronic devices. [ABSTRACT FROM AUTHOR]

Van der Waals heterostructures (vdWHs), obtained by artificially stacking 2D layered material (2DLM) plains upon each other, are brand new structures that have exhibited novel electronic and optoelectronic properties and attracted a great deal of attention. So far, the results are only based on devices with symmetrical configurations: devices predominated by vdWH parts, or cross-like configurations combined with both vdWHs and extra individual 2DLM layers. Quite different gate tunable phenomena have been observed for these two configurations even though 2DLMs with similar band alignments were used, which may be due to the different device configurations utilized. For a deeper understanding, rational investigation on configuration-dependent properties of vdWHs is needed. Here, using MoTe2/MoS2 as an example, vdWH device is artificially designed with two asymmetrical configurations. Through comparing the respective results, it is found that the properties that stem only from the vdWH, i.e., the rectification behavior and open voltage in photovoltaic effect, are independent of the device structures. However, other properties, i.e., drain currents, short circuit currents, and photoreponse performances, strongly depend on the configuration used. These results give a guideline on studying the intrinsic properties of vdWHs and optimizing the device structures for better performances. [ABSTRACT FROM AUTHOR]

Van der Waals heterostructures (vdWHs), obtained by artificially stacking 2D layered material (2DLM) plains upon each other, are brand new structures that have exhibited novel electronic and optoelectronic properties and attracted a great deal of attention. So far, the results are only based on devices with symmetrical configurations: devices predominated by vdWH parts, or cross-like configurations combined with both vdWHs and extra individual 2DLM layers. Quite different gate tunable phenomena have been observed for these two configurations even though 2DLMs with similar band alignments were used, which may be due to the different device configurations utilized. For a deeper understanding, rational investigation on configuration-dependent properties of vdWHs is needed. Here, using MoTe2/MoS2 as an example, vdWH device is artificially designed with two asymmetrical configurations. Through comparing the respective results, it is found that the properties that stem only from the vdWH, i.e., the rectification behavior and open voltage in photovoltaic effect, are independent of the device structures. However, other properties, i.e., drain currents, short circuit currents, and photoreponse performances, strongly depend on the configuration used. These results give a guideline on studying the intrinsic properties of vdWHs and optimizing the device structures for better performances. [ABSTRACT FROM AUTHOR]

Rational nanoscale surface engineering of electroactive nanoarchitecture is highly desirable, since it can both secure high surface-controlled energy storage and sustain the structural integrity for long-time and high-rate cycling. Herein, ultrasmall MoS2 quantum dots (QDs) are exploited as surface sensitizers to boost the electrochemical properties of Li4Ti5O12 (LTO). The LTO/MoS2 composite is prepared by anchoring 2D LTO nanosheets with ultrasmall MoS2 QDs using a simple and effective assembly technique. Impressively, such 0D/2D heterostructure composites possess enhanced surface-controlled Li/Na storage behavior. This unprecedented Li/Na storage process provides a LTO/MoS2 composite with outstanding Li/Na storage properties, such as high capacity and high-rate capability as well as long-term cycling stability. As anodes in Li-ion batteries, the materials have a stable specific capacity of 170 mAhg−1 after 20 cycles and are able to retain 94.1% of this capacity after 1000 cycles, i.e., 160 mAhg−1, at a high rate of 10 C. Due to these impressice performance, the presented 0D/2D heterostructure has great potential in high-performance LIBs and sodium-ion batteries. [ABSTRACT FROM AUTHOR]

MoS2/montmorillonite (MoS2/MMT) composite nanosheets have been successfully synthesized by a facile hydrothermal method, and the catalytic activities of composites are evaluated by reduction reaction of methyl orange in aqueous phase. A preparation strategy demonstrates that MoS2 can be in situ formed on the surface of MMT from Na2MoO4· and H2NCSNH2. The microstructures and morphologies characterization indicates that few-layered MoS2 nanosheets are uniformly grown on the surface of montmorillonite, and the hydrogen bonds are formed at the interfaces. The catalytic activity of MoS2/MMT is enhanced by support of montmorillonite, which can be attribu­ted to the large surface area, more reactive sites, dispersibility of MoS2/MMT, and the synergistic adsorption property of montmorillonite. Based on density functional theory calculations, the preferred adsorption configurations of MoS2 cluster on MMT are studied. The supporting effect of MMT on MoS2 nanoparticles will lead to the anchoring of these reactive MoS2 nanoparticles on clay surface and enhance the absorption ability of MoS2 to the organics and meanwhile improving the catalytic properties of the MoS2/MMT composite. The MoS2/MMT composite nanosheets show prospective application to treat effectively wastewater of dyes. [ABSTRACT FROM AUTHOR]