MoS2 Research Articles

Back-End-of-Line-Compatible Passivation of Sulfur Vacancies in MoS2 Transistors Using Electron-Withdrawing Benzenethiol.

Atomically thin two-dimensional semiconductor molybdenum disulfide (MoS2) is considered an ideal n-type channel material for field-effect transistors (FETs) due to its immunity to short-channel effects by dangling bond-free surface. However, sulfur atom dissociation or nonideal film deposition can easily lead to sulfur vacancies (SVs) in the MoS2 film. These crystal imperfections create defects in the electronic structure, thereby limiting the utility of this promising material. We introduce an electron-withdrawing benzenethiol (BT) to repair the vacancies with the exact missing atoms at 200°C─marking the lowest process temperature for complete SV repair. These thiol groups actively and selectively bond with the vacant sites due to their self-assembly nature. Notably, we found that the fluorination of BT weakens the S-C bond as the BT withdraws electrons from the sulfur side. This enables a low-temperature annealing process to detach the headgroups from the MoS2 surface. The atomic ratio of MoS2 was recovered from 1.68 to 1.98, leading to an ideal subthreshold swing of MoS2 FETs 62.5 mV·dec-1. The proposed SV repair process, repeatedly applicable between fabrication steps for its low process temperature, unveils the potential of the BEOL MoS2 FETs with a nearly ideal atomic ratio adhering to their thermal budget.

Dielectric Regulation in Quasi-vdW Europium Oxysulfur Compounds by Compositional Engineering for 2D Electronics.

Advancing next-generation electronics necessitates precise control of dielectric properties in 2D materials. Here, the first synthesis of novel 2D quasi-van der Waals (vdW) europium oxysulfur (Eu2SOx) compounds, comprising hexagonal Eu₂SO₂ and tetragonal Eu₂SO₆ phases, with composition-tunable dielectric properties, is presented. Using a homodiffusive-controlled epitaxial growth method, materials are achieved with complementary characteristics: the hexagonal Eu₂SO₂ phase exhibits a high dielectric constant (≈30) paired with a moderate bandgap (≈4.56 eV), while the tetragonal Eu₂SO₆ phase offers a wider bandgap (≈5.62 eV) but a lower dielectric constant (≈20). The potential of these materials is demonstrated by integrating ultrathin Eu₂SO₂ nanoplates with molybdenum disulfide (MoS₂) field-effect transistors (FETs) via vdW forces. The resulting devices achieve a near-ideal Ion/Ioff ratio (≈10⁸), minimal hysteresis (≈5.3 mV), a low subthreshold slope (≈63.5 mV dec⁻¹), and ultralow leakage current (≈10⁻¹⁴ A). These results highlight the capacity of europium oxysulfur compounds to address the trade-off between dielectric constant and bandgap, offering tailored solutions for diverse 2D electronic applications. This work underscores the potential of composition engineering to expand the family of rare-earth oxysulfur compounds for nanoelectronics, paving the way for innovative gate dielectrics in next-generation devices.

The Experimental Study on the Thermoelectric Properties of Sputtered Amorphous Molybdenum Disulfide Films

ABSTRACT Molybdenum disulfide (MoS2), a promising two-dimensional material, has attracted significant attention due to its unique electronic and thermal properties, making it a potential thermoelectric material Extensive research is underway to improve the thermoelectric properties of MoS2 by enhancing the figure of merit (ZT). However, there is currently limited research on the effects of thickness and temperature on the thermoelectric properties of MoS2 films prepared by magnetron sputtering. In this paper, amorphous MoS2 films with different thicknesses were first deposited using magnetron sputtering, ranging from 43nm to 231nm. The Frequency Domain Thermoreflectance (FDTR) system was established to measure the thermal conductivity of MoS2 film. The experimental results indicate a thermal conductivity range of 0.49 to 0.53W/m·K, with thickness showing minimal impact. The thermal boundary conductance between the sputter-deposited MoS2 film and the SiO2 substrate is measured at 12±5MW/m2 ·K. The electrical conductivity and Seebeck coefficient were measured in the temperature range of 300 K to 450 K using LSR-3 equipment. The results indicate that the MoS2 films prepared in this study were all p-type semiconductors, with electrical properties increasing with temperature. Within the temperature range of 300–430 K, the power factor of all films increases with the rise in temperature, reaching a maximum value of 0.36 µW/cm·K2

Inter-overlapped 1 T-rich phase MoS2/C anode with large-interlayer-spacing to enhance lithium storage performance

Molybdenum disulfide (MoS2), a classical graphene-like layered transition metal disulfide (TMD), shows great potential as an excellent Li+ storage and transport channel for lithium-ion batteries (LIBs) due to its high theoretical capacity. Nevertheless, the narrow interlayer spacing, slow Li+ diffusion kinetics and low intrinsic conductivity of stable 2H-MoS2 limit its application. In this work, 1 T-MoS2/C with expanded layer spacing and carbon molecular layers alternately stacked into nanosheet structures were constructed by a one-step hydrothermal method using an interlayer carbon strategy. This layered heterogeneous structure aims to stack the alternating MoS2 and carbon layers, thereby maximizing the specific contact area between the active substance and the cushioning layer. The effective mitigation of active material loss caused by crushed MoS2 or low intrinsic conductivity. The prepared 1 T-MoS2/C electrode has a high specific capacity of 1191 mAh/g at 0.1 A/g. The specific capacity of the electrode was 1185 mAh/g after 700 cycles at 0.5 A/g, stabilized at 2000 mAh/g after 1000 cycles at 1 A/g, and remained at 630 mAh/g after 2000 cycles at 2 A/g. This layered design electrode material has great potential to be generalised to other types of layered materials.

Machine learning interatomic potential for friction study in silicon and molybdenum disulfide

Machine learning interatomic potential for friction study in silicon and molybdenum disulfide

Improvement of MoS2 film quality using sputtering processes controlling particle- and energy-flux followed by sulfur-vapor annealing

Abstract Molybdenum disulfide (MoS2) deposited by sputtering holds promise for applications in areas such as three-dimensional (3D)-stacked field-effect transistors (FETs) and human-interface devices. The quality of the MoS2 film is enhanced by maintaining a low particle flux with sufficient energy flux during sputtering. Furthermore, the sulfur defects in the MoS2 films were suppressed by annealing in a sulfur-vapor atmosphere, leading to an improvement in the film quality. This technology has great potential for the development of high-performance FETs based on MoS2 channels using sputtering.

Structure Modulation and Self-Lubricating Properties of Porous TiN–MoS2 Composite Coating Under Humidity–Fluctuating Conditions

To improve the friction performance and service life of protective coatings in humidity-fluctuating environments, porous hard titanium nitride (TiN)–molybdenum disulfide (MoS2) composite coatings were prepared by using direct current magnetron sputtering (DCMS) with the mode of oblique angle deposition (OAD) and chemical vapor deposition (CVD) technologies. The structure and chemical component were characterized by field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), grazing incidence X-ray diffraction (GIXRD), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The tribological properties of these TiN–MoS2 composite coatings were investigated. The results indicate that the porous TiN–MoS2 composite coating exhibited outstanding friction performance and long service life under humidity-fluctuating environments. At the initial 20% relative humidity (RH) stage, the MoS2 on the porous TiN–MoS2 composite coating surface worked as an effective lubricant; thus, the coating demonstrated excellent lubrication performance, and the friction coefficient (COF) was about 0.05. As the humidity was alternated to 70% RH, the lubrication effect diminished due to the production of molybdenum oxide (MoO3), and the COF was about 0.2, which was attributed to the degradation of MoS2 on the wear track and the release of fresh MoS2 from the porous TiN matrix. After the environmental conditions shifted from 70% to 20% RH, the MoO3 was removed, and the lubrication effect was restored. In summary, TiN–MoS2 porous composite coating offers a promising approach for lubrication in humidity-fluctuating environments.

Degradation of molybdenum disulfide through cascade reactions with hydrogen peroxide in aqueous system

Transformation is a crucial process determining the lifespan and risk of MoS2 nanomaterial during usage and after disposal. This study revealed the degradation of MoS2 in the presence of H2O2 using experimental and computational methods. Experimental results showed that MoS2 nanosheets were degraded by 45.1% after 72-h incubation with H2O2. MoS2 decomposed H2O2 into various reactive oxygen species, among which ·O2- played a dominant role breaking MoS2 into fragments with defects and holes. Mo (Ⅳ) in MoS2 catalyzed ·O2- formation through electron transfer towards H2O2. Additionally, electrons generated from cleavage of O-O in H2O2 initiated the O2 reduction to generate ·O2-. The interaction of MoS2 with ·O2- yielded soluble MoO42– and SO42–, and 22.4% of Mo on residual MoS2 was in the form of Mo (Ⅵ) after 72-h incubation. Density function theory calculations elucidated that·O2- is more potent than ·OH in adsorbing on MoS2 ( -2.25eV vs. -0.14eV) to initiate reaction. The reaction occurred preferentially from Mo and adjacent S atoms, which transferred 1.07 electrons toward ·O2- to induce O-O cleavage and formation of O-M and O-S bonds. The obtained finding on MoS2 degradation is fundamental for promoting sustainable applications and risk assessment of MoS2-based nanomaterials.

Molybdenum disulfide nanosheets hybridized with lysine molecules for highly efficient near-infrared photothermal energy conversion

The paper reports a facile way for noncovalent functionalization of 1T-MoS2 with L-lysine (Lys) monolayers. The structure of the resultant hybrid compound was revealed by the powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, absorption spectroscopy and density functional theory (DFT) calculations study. A significant strength of the in-layer organic and organic-inorganic hydrogen bonding amounting to 24.6 and 29.9 kcal per mole of Lys, respectively, was found to hold the hydrated Lys molecules arranged in 2D chains and keep these chains tightly bound to the MoS2 sheets. The MoS2 hybridization with Lys significantly rises the upper temperature stability limit of 1T-MoS2 polymorph, which possesses the remarkable photothermal properties in near infra-red (NIR) region. The hybrid structure demonstrates excellent photothermal light-to-heat conversion efficiency reaching 49.5% upon 808 nm laser irradiation and higher thermal durability than unmodified 1T-MoS2.

Unraveling the fracture and failure mechanisms of molybdenum disulfide with various crystalline structures

Unraveling the fracture and failure mechanisms of molybdenum disulfide with various crystalline structures

Design and screening of DNA/RNA sequencing materials based on non-metallic substituted molybdenum sulfide: A density functional theory study

Design and screening of DNA/RNA sequencing materials based on non-metallic substituted molybdenum sulfide: A density functional theory study

Iron-Molybdenum Sulfide Electrocatalysts for the Hydrogen Evolution Reaction: An Operando XAS study

The comprehensive characterization of the structure-electrocatalytic activity relationships is of great interest to support the development of efficient catalysts for hydrogen evolution reaction (HER) in proton-exchange membrane (PEM) electrolyzers. The successful implementation of a bimetallic iron-molybdenum sulfide electrocatalyst for HER into a PEM electrolyzer has been reported. However, the precise nature of their active sites is still elusive. In this study, we employed X-ray absorption spectroscopy (XAS) to study iron-molybdenum and molybdenum sulfides obtained by a microwave irradiation synthetic approach. Operando XAS measurements in an acidic environment revealed sulfur-defective amorphous MoSx and FeS phases. Although the amount of dopant Fe is 10 times lower than that of Mo, the synergy between the two phases promotes the HER performance of iron-molybdenum sulfides.

A tumor microenvironment-responsive multifunctional MoS2-Ru nanocatalyst with photothermally enhanced chemodynamic activity.

Targeting the unique characteristics of the tumor microenvironment (TME) has emerged as a highly promising strategy for cancer therapy. Chemodynamic therapy (CDT), which leverages the TME's intrinsic properties to convert H2O2 into cytotoxic hydroxyl radicals (˙OH), has attracted significant attention. However, the effectiveness of CDT is often limited by the catalytic efficiency of the materials used. Although Molybdenum disulfide (MoS2) exhibits remarkable chemodynamic and photothermal properties, its limited efficiency in catalyzing the conversion of endogenous H2O2 into ˙OH radicals remains a significant challenge. To overcome this, we developed a nanocomposite of MoS2 and ruthenium (MoS2-Ru), by incorporating Ru into MoS2 nanosheets. The MoS2-Ru nanocomposite demonstrated significantly enhanced catalytic activity at a low concentration (500 ng mL-1), whereas the same effect was achieved only with 20 μg mL-1 of MoS2. The low Michaelis-Menten constant (Km) of 4.69 mM further confirmed the superior catalytic activity of the nanocomposite, indicative of the enhanced enzyme-like activity. Additionally, the integration of Ru in MoS2 reduced the bandgap to 1.18 eV, facilitating near-infrared (NIR) absorption with a high conversion efficiency of 41%. Electron paramagnetic resonance (EPR) analysis confirmed robust ˙OH radical generation driven by the combined chemodynamic and photothermal effects. In vitro studies using triple-negative breast cancer (TNBC) cells validated the synergistic activity of CDT and PTT, demonstrating significant ˙OH radical production under TME conditions, leading to effective cancer cell death. This study underscores the potential of MoS2-Ru nanocomposites as a versatile and powerful platform for multimodal cancer therapy, seamlessly integrating CDT and PTT to achieve synergistic, precise, and highly effective treatment outcomes.

Microwave synthesis of molybdenum disulfide quantum dots and the application in bilirubin sensing

Molybdenum disulfide quantum dots (MoS2QDs) is a new type of graphite like nanomaterial, which exhibited well chemical stability, unique fluorescence characteristics, and excellent biocompatibility. The conventional hydrothermal synthesis of MoS2generally requires a long-term reaction at high temperature and high pressure. Herein, we have developed a simple and fast MoS2QDs synthesis scheme using microwave heating, and further modified the surface of MoS2QDs using 3-aminophenylboronic acid. The 3- aminophenylboronic acid modified MoS2QDs (B-MoS2QDs) were further coated by a zinc-based metal-organic backbone (ZIF-8) in a solution containing zinc ions and 2-methylimidazolium. The constructed nanohybrid B-MoS2@ZIF-8 were successfully applied to the visualization and rapid detection of bilirubin based on the ratiometric fluorescence changes. The linear range for bilirubin detection is 0.2-75 μmol·l-1, and detection limit is 0.017 μmol·l-1.

Self-Foldable Three-Dimensional Biointerfaces by Strain Engineering of Two-Dimensional Layered Materials on Polymers.

Two-dimensional layered materials (2DLMs) have received increasing attention for their potential in bioelectronics due to their favorable electrical, optical, and mechanical properties. The transformation of the planar structures of 2DLMs into complex 3D shapes is a key strategic step toward creating conformal biointerfaces with cells and applying them as scaffolds to simultaneously guide their growth to tissues and enable integrated bioelectronic monitoring. Using a strain-engineered self-foldable bilayer, we demonstrate the facile formation of predetermined 3D microstructures of 2DLMs with controllable curvatures, called microrolls. Three types of 2DLM microrolls─graphene, hexagonal boron nitride, and molybdenum disulfide─provide scaffolds to encapsulate and organize human-induced pluripotent stem cell-derived cardiomyocytes into tubular aggregates. Encapsulating cardiomyocytes in porous 2DLMs-laden microrolls allows for real-time microscopic observation and construction of precisely shaped cardiac tissues interacting with their surroundings. The ability to combine 2DLMs of diverse properties in the same structure further demonstrates the potential of this self-folding strategy for creating flexible, ultrathin bioelectronic devices that integrate seamlessly with complex biological environments, offering real-time, noninvasive monitoring of engineered tissues and organoids.

Surface Engineered MoS2-Based Novel Vertical Triboelectric Nanogenerator (V-TENG) for Wireless Information Processing.

Self-sustaining mechanical energy harvesting devices are pivotal for developing durable energy-efficient systems, providing scalable and adaptable solutions to wearable technology. Triboelectric nanogenerators (TENGs) efficaciously convert ambient mechanical energy into usable electrical power to sustainably drive modern electronics. Surface and structural engineering is an avenue to boost TENGs' energy harvesting through modulating contact interfaces and charge transfer interactions between the constituent layers. This study explores dielectric engineering incorporating an additional transition layer, such as Polyethylene Terephthalate (PET), alongside kapton to store accumulated charges. The surface of molybdenum sulfide (MoS2) is modified with different aromatic carboxylic acids to boost the vertical TENG's performance. The anchoring of aromatic carboxylic acid [4,4'-Oxybis (Benzoic acid)] modifies the work function and surface charge density of MoS2-based TENG and enhances the output performance. The output open-circuit voltage (VOC) and short-circuit current (ISC) for "PET-Kapton@4,4'-MoS2" TENG increase from 6 to 30V and 65 to 202nA, respectively. The maximum power density obtained after inserting the transition layer and modifying the MoS2 surface is 399mWm- 2. The "PET-Kapton@4,4'-MoS2" TENG can power up to 6 LEDs, run a calculator, and generate International Morse code. A microcontroller unit successfully decodes the Morse code and transmits it wirelessly to a smartphone via Wi-Fi.

Effects of Substrate Biasing and Sulfur Annealing on the Surface of MoS2 Thin Films and TFT

In this work, we report the properties of molybdenum disulfide (MoS2) thin films deposited on the p-type silicon substrate using RF magnetron sputtering. The structural, vibrational and morphological properties of MoS2 thin films were investigated using the Raman spectroscopy, X-ray diffraction technique (XRD), atomic force microscope (AFM) and scanning electron microscope (SEM). Raman spectroscopy result showed the appearance of broad E12g and A1g Raman peaks even without DC biasing the substrate and becomes sharp and distinct when the substrate is DC biased at 60 V. Post-deposition annealing in sulfur ambient resulted in sharp and distinct Raman E12g and A1g peaks confirming the formation of MoS2 thin film and improved Mo-S bonding on the top surface. X-ray diffraction spectra of the samples validates the formation of MoS2 thin film with the appearance of [002] XRD peak, when the substrates are biased. Improved morphological effects with the reduction in nano-sized defects, advent of continuous film and low surface rms roughness value of 0.872 nm, were observed on samples deposited with substrate biasing and post sulfur annealing. A back-gated thin film transistor was fabricated with Al as source-drain contacts and MoS2 as the semiconducting channel. The fabricated transistor exhibited p-type transfer characteristics with threshold voltage of −3.8 V. As a result of annealing and ambient exposure, MoO3 fragments on the top of thinned MoS2 layer resulted in extraction of hole from MoS2, resulting in the p-type behavior in the fabricated thin film transistor. The combination of XRD analysis, Raman measurements and EDS data of the film confirmed MoO3 inclusions in the MoS2 thin film.

Molybdenum sulphide incorporated flexible poly(vinylidene fluoride) nanocomposites for energy harvesting and water remediation by dye degradation via piezocatalysis

AbstractMolybdenum sulphide (MoS2) was incorporated into poly(vinylidene difluoride) (PVDF) matrix via melt‐mixing followed by solution casting, to prepare PVDF/MoS2 nanocomposite films with varying MoS2 concentration. Piezoelectric properties of PVDF/MoS2 nanocomposites were significantly boosted by incorporation of MoS2 in PVDF by aiding in the formation of polar phase in the PVDF/MoS2 nanocomposites. Formation of electroactive phases in PVDF/MoS2 nanocomposites was analyzed through Fourier transform infrared and Raman spectroscopic analyses, which also highlighted the interactions between MoS2 and PVDF dipoles. A remarkable polar phase content of ~97% was achieved in the PVDF/3 MoS2 nanocomposite (containing 3 wt% MoS2). Dielectric and ferroelectric investigations further supported the enhancement of interfacial polarization in PVDF/MoS2 nanocomposite films. Piezoelectric response of the fabricated devices was subsequently assessed, demonstrating an output voltage of ~96 V generated through human‐hand actuation on the PVDF/3 MoS2 nanocomposite film. Additionally, the fabricated device exhibited a substantial volumetric power density of ~150 μW/cm2 and a current density of ~7.2 μA/cm2. Notably, the optimized PVDF/MoS2 nanocomposite film exhibited significant degradation efficiencies of ~69.7% and ~67.4% in case of Methylene Blue and Rhodamine B dye, respectively. The successful fabrication of a piezocatalytic PVDF/MoS2 nanocomposite film provided valuable insights into the piezoelectric response for the degradation of various dyes.Highlights Self‐polarized PVDF/MoS2 nanocomposite with high polar phase content (∼97%) has been achieved via melt‐mixing followed by solution casting. High d33 value of ~72 pm/V was achieved in the PVDF/3 MoS2 nanocomposite. PVDF/3 MoS2 nanocomposite based piezoelectric nanogenerator can generate an output voltage of ~96 V under 3 N with sensitivity of ~26 V/N. Power density of ~150 μW/cm2 and current density of ~7.2 μA/cm2 were obtained. PVDF/3 MoS2 nanocomposite film acted as an effective piezocatalysts for the degradation of organic dye with >69% efficiency.

Volatile MoS2 Memristors with Lateral Silver Ion Migration for Artificial Neuron Applications

Layered 2D semiconductors have shown enhanced ion migration capabilities along their van der Waals (vdW) gaps and on their surfaces. This effect can be employed for resistive switching (RS) in devices for emerging memories, selectors, and neuromorphic computing. To date, all lateral molybdenum disulfide (MoS2)‐based volatile RS devices with silver (Ag) ion migration have been demonstrated using exfoliated, single‐crystal MoS2 flakes requiring a forming step to enable RS. Herein, present volatile RS with multilayer MoS2 grown by metal‐organic chemical vapor deposition (MOCVD) with repeatable forming‐free operation is presented. The devices show highly reproducible volatile RS with low operating voltages of ≈2 V and fast‐switching times down to 130 ns considering their micrometer‐scale dimensions. The switching mechanism is investigated based on Ag ion surface migration through transmission electron microscopy, electronic transport modeling, and density functional theory. Finally, a physics‐based compact model is developed and the implementation of the volatile memristors as artificial neurons in neuromorphic systems is exploredd.

Recent Developments in Synthesis Techniques and Microwave Absorption Performance of Materials Based on Molybdenum Disulfide (MoS<sub>2</sub>) with Metal Oxides: A Review

The widespread usage of various wireless equipment in many facets of life has significantly contributed to the serious pollution caused by electromagnetic radiation. Thankfully, scientists have created materials that can absorb microwave radiation and convert dangerous electromagnetic waves into other forms of energy, including heat energy. Many investigations regarding the development of materials that absorb microwaves with different constituents, morphologies, and architectures have been published recently. Microwave-absorbing materials (MAMs) are becoming more and more popular for use in a variety of aviation applications, including EMI prevention, information security, and reducing the risks of electromagnetic radiation to human health. Molybdenum di-sulphide (MoS2) is a transition metal sulphide extensively employed as a microwave absorption material (MAM) owing to its superior structural and physicochemical qualities. Because of its many flaws, huge specific surface area, and semiconductor qualities, MoS2 exhibits exceptional microwave loss properties. Using a number of various designs, MoS2 may efficiently boost the absorption and dispersion of microwaves inside the absorber. This study introduces the structure, characteristics, and synthesis method based on MoS2 material. The effectiveness of MoS2-based MAMs has been evaluated and analyzed in detail at the moment. Furthermore, the key problems and development challenges are examined, and the most recent advancements in MoS2-based MAMs are impartially assessed and discussed. As a result, it is anticipated that MoS2-based composites would provide excellent choices for very thin and light MAMs.