Metallic MoS2 Research Articles

Photoelectrochemical response of tin iodide phosphide (SnIP) composites with MoSe2, MoS2, and h‐BN

For a future world fuelled by green energy it is invaluable to develop, test and maximise the catalytic efficiency of new effective water‐splitting materials. In this paper, we further explore the catalytic activity of double‐helical tin iodide phosphide (SnIP), as it features bandgaps in the ideal region for this process. We found that its photoelectrochemical response can be multiplied by forming composites of SnIP with selected 2D materials, focusing on hexagonal boron nitride and the transition metal dichalcogenides (TMDs) MoSe2 and MoS2. These nanocomposites were analysed with Powder‐X‐ray diffraction (P‐XRD), Raman, and UV/VIS bandgap determination. Their photo activity was assessed under simulated solar light through chrono amperometry and linear sweep voltammetry (CA, LSV). The high anisotropy of the involved materials enables efficient charge separation at the 1D/2D interfaces, increasing photoelectrochemical response four‐fold.

High-yield preparation of 1T-MoS2 with excellent piezo-catalytic activity via W6+ doping for antibiotics degradation and Cr(VI) reduction: Mechanistic insights from characterizations to DFT calculations

Molybdenum disulfide (MoS2) is a promising piezoelectric material. Herein, a simple method is reported for the high-yield production of metallic (1 T) phase MoS2 which exhibits excellent piezo-catalytic activity by in-situ doping of trace amounts of W6+. At 1 wt% W6+ doping, the 1 T phase of the obtained MoS2 reaches a concentration as high as 85.56 % and the piezoelectric coefficient and piezoelectric response current increase by 1.67 and 1.18 times, respectively, as compared to pristine MoS2. Consequently, W1.0-MoS2 can remove more than 99.8 % of tetracycline and 97.3 % of Cr(VI) in 10 min. Experimental characterization and theoretical calculations indicate that the enhanced piezoelectric catalytic activity is attributed to the strong synergistic effect between 1T-MoS2 and W6+ doping, which facilitates the rapid generation of hydroxyl radicals and superoxide radicals. This new strategy of doping 1 T/2H-MoS2 with W6+ can significantly enhance the piezoelectric catalytic performance, providing important insights for the removal of pollutants.

Growth and stabilization of high-concentration metallic 1T-phase MoS2 as a high-performance l-cysteine electrochemical sensor by electron injection engineering

MoS2 is an attractive electrochemical sensing electrode material for the detection of biomolecule because of its adjustable band gap, large surface area, and unique electrochemical characteristics. However, the poor catalytic and electrical conductivity of the semiconductor 2H-phase MoS2 and the phenomenon of restacking during electrochemical use hinder its sensing application. Herein, electron injection engineering is employed for the formation and stabilization of high-concentration metal 1T-phase MoS2 nanosheets on ionic liquid-functionalized carbon nanotubes (CNTs-IL). The increase of MoS2 concentration in the metal 1T phase significantly accelerates electron transfer kinetics. The in-situ growth method results in a tightly interfaced coupling effect, thereby substantially shortening the electron transport pathway and decreasing interfacial transmission impedance. In addition, the sulfur defects on the surface of MoS2 as the anchoring point of sulfhydryl groups promote the enrichment of thiols on the surface of the material and reduce the reaction barrier for sulfhydryl oxidation, thereby improving the catalytic performance. The prepared CNTs-IL-MoS2/SPE biosensor shows excellent l-cysteine sensing performance by electrochemical detection.

Heteroelectrocatalyst MoS2@CoS2 modified separator for Li-S battery: Unveiling superior polysulfides conversion and reaction kinetics

Mitigating the shuttle effect of polysulfides and enhancing their conversion efficiency are critical challenges for the practical application of Li-S batteries. Herein, we present a novel MoS2@CoS2 heteroelectrocatalyst synthesized via a hydrothermal method, used to modify the separator for Li-S batteries. This innovative heterostructure combines the exceptional properties of metallic CoS2 and semiconductor MoS2, creating a synergistic effect that significantly improves electrochemical performance. The built-in electric field at the heterointerface promotes rapid charge transport and enhances surface reaction kinetics, effectively addressing polysulfide shuttle and sluggish redox kinetics. The Li-S battery with MoS2@CoS2 separator exhibits an impressive initial capacity of 1480 mAh g−1 at 0.1 C and maintains 811 mAh g−1 at 3 C, with long-term cycling stability showing a minimal decay rate of 0.05 % per cycle at 1 C. Even with high sulfur loading (6 mg cm−2) and a low electrolyte/sulfur ratio, the cell achieves a high reversible capacity of 4.5 mAh cm−2 at 0.2 C. The innovative approach of integrating semimetal-semiconductor heterointerfaces opens new avenues for the development of high-performance Li-S batteries, addressing critical challenges and paving the way for future technological advancements in the field.

Metallic MoS2 grown on CNT as high performance anodes for lithium-ion batteries

To mitigate the structural collapse of MoS2 during charging and discharging, MoS2-CNT composites were fabricated as anodes for lithium-ion batteries (LIBs). Hydroxylation CNT was incorporated to provide growth sites for MoS2 nanosheets, thereby enhancing their overall dispersion. This structure effectively improves the stability during cycling compared to MoS2/CNT, and to some extent improves the structural collapse of MoS2. As a result, the initial discharge capacity of the MoS2-CNT anode was 1194 mAh g−1 and the sustained capacity was 774 mAh g−1 after 200 cycles at 0.5 A g−1.

Molybdenum sulfide modified with nickel or platinum nanoparticles as an effective catalyst for hydrogen evolution reaction

In this study, we investigate the catalytic performance of molybdenum sulfide (MoS2) modified with either nickel (Ni) or platinum (Pt) nanoparticles as catalysts for the hydrogen evolution reaction (HER). The MoS2 was prepared on the TiO2 nanotube substrates via a facile hydrothermal method, followed by the deposition by magnetron sputtering of Ni or Pt nanoparticles on the MoS2 surface. Structural and morphological characterization confirmed the successful incorporation of Ni or Pt nanoparticles onto the MoS2 support. Electrochemical measurements revealed that Ni- and Pt-modified MoS2 catalysts exhibited enhanced HER activity compared to pristine MoS2. Obtained catalysts demonstrated a low onset potential, reduced overpotential, and increased current density, indicating efficient electrocatalytic performance. Furthermore, the Ni or Pt-modified MoS2 catalyst exhibited remarkable stability during prolonged HER operation. The improved catalytic activity can be attributed to the synergistic effect between metal nanoparticles and MoS2, facilitating charge transfer kinetics and promoting hydrogen adsorption and desorption. Incorporating Ni and Pt nanoparticles also provided additional active sites on the MoS2 surface, enhancing the catalytic activity.

Large-scale growth of MoS2 hybrid layer by chemical vapor deposition with nanosheet promoter

Molybdenum disulfide (MoS2) serves as the representative transition metal dichalcogenide material, showing promise for diverse applications owing to its outstanding properties. Extensive research has been conducted on the growth of large-scale MoS2 films using chemical vapor deposition (CVD) with seeding accelerators for various device applications. In this study, we investigated the growth of large-scale MoS2 films for potential applications, in which our approach utilized CVD with a homogeneous nanosheet promoter (MoS2 flakes) and effectively minimized residue creation. Optical and structural analyses confirmed the successful synthesis of a large-scale MoS2 layer. Moreover, the decoration of metallic nanoparticles on the MoS2 surface was employed to enhance the functionalities of application devices such as optical sensors and gas sensors. The capability of MoS2 to act as a nucleation site for nanoparticles during synthesis offered an intriguing pathway for augmenting the attachment and performance of nanoparticles on the MoS2 surface. The photodetector, integrating a hybrid MoS2 layer and Cu nanoparticles, exhibited superior photodetection properties, attributed to the increased excitons at the interface between the metal electrodes and MoS2 films. Furthermore, in order to enhance the characteristics of the gas sensor, Pd nanoparticles were incorporated during the synthesis of MoS2 layers. This dynamic interface between Pd particles and MoS2 films presents an opportunity to explore novel materials with enhanced catalytic properties.

Ultrafast 2D Nanosheet Assembly via Spontaneous Spreading Phenomenon.

In 2D materials, a key engineering challenge is the mass production of large-area thin films without sacrificing their uniform 2D nature and unique properties. Here, it is demonstrated that a simple fluid phenomenon of water/alcohol solvents can become a sophisticated tool for self-assembly and designing organized structures of 2D nanosheets on a water surface. In situ, surface characterizations show that water/alcohol droplets of 2D nanosheets with cationic surfactants exhibit spontaneous spreading of large uniform monolayers within 10s. Facile transfer of the monolayers onto solid or flexible substrates results in high-quality mono- and multilayer films with high coverages (>95%) and homogeneous electronic/optical properties. This spontaneous spreading is quite general and can be applied to various 2D nanosheets, including metal oxides, graphene oxide, h-BN, MoS2, and transition metal carbides, enabling on-demand smart manufacture of large-size (>4 inchϕ) 2D nanofilms and free-standing membranes.

Cold Spray Deposition of MoS2- and WS2-Based Solid Lubricant Coatings

The cold spray deposition technique has been used to produce a new class of solid lubricant coatings using powder feedstocks of the metal disulfides WS2 or MoS2, either pure or mixed with Cu and Ni metal powders. Friction and cycle lives were obtained using ball-on-flat reciprocating tribometry of coated 304 SS flats in dry nitrogen and vacuum at higher Hertzian contact stresses (Smax = 1386 MPa (201 ksi)). The measured friction and thickness of the coatings were much lower than for previous studies (COF = 0.03 ± 0.01 and ≤1 µm, respectively), which is due to their high metal disulfide:metal ratios. Cu-containing metal sulfide coatings exhibited somewhat higher cycle lifetimes than the pure metal sulfide coatings, even though the Cu content was only ~1 wt%. Profiling of wear tracks for coatings tested to 3000 cycles (i.e., pre-failure) yielded specific wear rates in the range 3–7 × 10−6 mm3N−1m−1, similar to other solid lubricant coatings. When compared to other coating techniques, the cold spray method represents a niche that has heretofore been vacant. In particular, it will be useful in many precision ball-bearing applications that require higher throughput and lower costs than sputter-deposited MoS2-based coatings.

Quasi-Solid-State Electrolyte Induced by Metallic MoS2 for Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are a promising high-energy-density technology for next-generation energy storage but suffer from an inadequate lifespan. The poor cycle life of Li-S batteries stems from their commonly adopted catholyte-mediated operating mechanism, where the shuttling of dissolved polysulfides results in active material loss on the sulfur cathode and surface corrosion on the lithium anode. Here, we report in situ formation of a quasi-solid-state electrolyte (QSSE) on the metallic 1T phase molybdenum disulfide (MoS2) host that extends the lifetime of Li-S batteries. We find that the metallic 1T phase MoS2 host is able to initiate the ring-opening polymerization of 1,3-dioxolane (DOL), forming an integrated QSSE inside batteries. Nuclear magnetic resonance analysis reveals that the QSSE consists of ∼13% liquid DOL in a solid polymer matrix. The QSSE efficiently mediates sulfur redox reactions through dissolution-conversion chemistry while simultaneously suppressing polysulfide shuttling. Therefore, while ensuring high sulfur utilization, it avoids degradation of both electrodes, as well as the concomitant electrolyte consumption, leading to enhanced cycling stability. Under a practical lean electrolyte condition (electrolyte-to-sulfur ratio = 2 μL mg-1), Li-S pouch cell batteries with the QSSE demonstrate a capacity retention of 80.7% after 200 cycles, much superior to conventional liquid electrolyte cells that fail within 70 cycles. The QSSE also enables Li-S pouch cell batteries to operate across a wider temperature range (5 to 45 °C), together with improved safety under mechanical damage.

1T-rich MoS2 nanosheets anchored on conductive porous carbon as effective polysulfide promoters for lithium–sulfur batteries

The practical applications of lithium-sulfur (Li-S) batteries have severely been hindered by notorious shuttle effect and sluggish redox kinetics of lithium polysulfide intermediates (LiPSs), which bring about rapid capacity degradation, low coulombic efficiency and poor cycling stability. In this work, 1T-rich MoS2 nanosheets are in-situ developed onto the conductive porous carbon matrix (1T-rich MoS2@PC) as efficient polysulfide promotors for high-performance Li-S batteries. The porous carbon skeleton tightly anchors MoS2 nanosheets to prevent their reaggregation and ensures accessible electrical channels, and at the same time provides a favorable confined space that promotes the generation of 1T-rich MoS2 structure. More importantly, the uniformly distributed metallic 1T-rich MoS2 nanosheets not only affords rich sulfphilic sites and high binding energy for immobilizing LiPSs, but also favors rapid electron transfer and LiPSs conversation kinetics, substantially regulating sulfur chemistry in working cells. Consequently, the Li-S cell assembled with 1T-rich MoS2@PC modified separator delivers a remarkable cycling stability with ultralow capacity decay rate of 0.067% over 500 cycles at 1C. Encouragingly, under harsh conditions (high sulfur loading of 4.78 mg cm−2 and low E/S ratio of 8 μL mg−1), a favorable electrochemical performance can still be demonstrated. This study highlights the profitable design of 1T-rich MoS2/carbon based electrocatalyst for suppressing shuttle effect and promoting catalytic conversation of LiPSs, and has the potential to be applied to in other energy storage systems.

Wear and friction characteristics of ZA-27/MoS2 metal matrix nanocomposites by using response surface methodology

Wear and friction characteristics of ZA-27/MoS2 metal matrix nanocomposites by using response surface methodology

One-step hydrothermal synthesis of few-layered metallic phase MoS2 for high-performance supercapacitors

In recent years, molybdenum disulfide (MoS2) has gained significant attention in the scientific community. Few-layered MoS2 demonstrates unique properties and potential applications. However, the synthesis of few-layered and high-purity 1T-MoS2 is still a challenge. In this study, we successfully employed a hydrothermal method to synthesize few-layered and high-purity 1T-MoS2. The purity of the material is controlled by a combination of sodium borohydride and ethanol. Notably, the few-layered 1T-MoS2 exhibits exceptional performance as a supercapacitor, including the high specific capacitance (250.3 ​F ​g−1 at a current density of 1 ​A ​g−1) and excellent long-trem cycling stability (90.7 ​% after 5000 cycles). Meanwhile, the asymmetric device assembled by 6-FL-1T-MoS2 and active carbon on carbon cloths exhibits excellent flexibility and high energy and power density (23.1 ​μWh cm−2 at 600 ​μW ​cm−2, 55 ​μWh cm−2 at 12000 ​μW ​cm−2). This work provides valuable insights into the synthesis of few-layered and high-purity 1T-MoS2, opening up new avenues for further research and applications.

Bio-surfactant mediated sustainable exfoliation of MoS2 and in-situ preparation of Ag@MoS2 nanocomposites for photocatalysis under sunlight in aqueous medium

Exfoliation of MoS2 has been performed in the aqueous solution of bio-based surfactant choline deoxycholate, ([Cho][Doc]), employing low-energy bath sonication. The ability of [Cho]+ to reduce the Ag+ under sunlight accompanied by the templating effect of [Doc]− has been exploited to decorate the exfoliated MoS2 in a single step. The dimensions as well as the extent of adherence of Ag NPs to MoS2 in Ag@MoS2 nanocomposites (NCs) have been controlled by adjusting the concentration of [Cho][Doc]. The prepared NCs have been characterized by UV–vis spectroscopy, atomic force microscopy (AFM), dynamic light scattering (DLS), zeta-potential measurements (ζ-potential), X-ray diffraction (XRD), Raman spectroscopy, X-ray photon spectroscopy (XPS), transmission (TEM) and high-resolution transmission electron microscopy (HR-TEM). The NCs have shown enhancement in photocatalytic activity compared to bare Ag NPs under sunlight in an aqueous medium. It has been observed that the Schottky junction between metallic Ag NPs and semiconductor MoS2 in NCs shows efficient charge separation by generating a continuum-charged region resulting in increased catalytic activity of NCs. The present work is expected to serve as a platform for preparing photocatalytic NCs sustainably employing various other 2D materials.

MoS2/graphdiyne nanotube/MXene 3D-interconnected ternary aerogel: A high-performance electrocatalyst for hydrogen evolution reaction

MoS2 is a promising challenger to Pt for the HER, but we must make it more durable before it can take over the hydrogen production scene. This work fabricated and evaluated a hybrid structure of MXene-graphydine nanotube-MoS2 (MGMX) aerogel toward HER. It showed efficient and stable activity H2 evolution with ƞ10 = 109 mV vs RHE and a Tafel slope of 55 mVdec−1. The catalytic performance results from a synergistic interplay between increased exposed active sites and improved charge transfer within the catalyst. The two-dimensional (2D) islands of double-phase MoS2 are directly deposited onto graphdiyne nanotubes (GDNTs) surface, creating a structurally interesting material with interconnected components. The unique combination of sp and sp2 carbon atoms in the graphdiyne (GDY) makes it an ideal support for catalyst material. The combination of high edge density in metallic MoS2, a conducting MXene framework, and the bridging structure of GDNT significantly enhance the overall HER performance of the ternary aerogel structure.

Low-power MoS2 metal–semiconductor field effect transistors (MESFETs) based on standard metal–semiconductor contact

With the popularization of electronic devices and the demand for portability, low-power consumption has become crucial for integrated circuit chips. Two-dimensional (2D) semiconductors offer significant potential in constructing low-power devices due to their ultrathin thickness, enabling fully depletion operation. However, fabricating these 2D low-power devices, such as negative-capacitance transistors or tunneling transistors, often requires multiple layers of gate dielectrics or channel band engineering, adding complexity to the manufacturing process and posing challenges for their integration with silicon technology. In this work, we have developed low-power MoS2 metal–semiconductor field effect transistors utilizing a standard metal–semiconductor contact, which eliminates the need for gate dielectrics and semiconductor heterojunctions. It demonstrates a sharp subthreshold slope (SS ∼ 64 mV/dec), a minimum operating gate voltage range (−0.5 ∼ 1 V), a minimum current hysteresis (3.69 mV), and a stable threshold voltage close to 0 V (Vth ∼ −0.27 V). Moreover, we implemented an inverter circuit with a high voltage gain of 47.

Highly conductive riboflavin-based carbon quantum dot–embedded SiO2@MoS2 nanocomposite for enhancing bioelectricity generation through synergistic direct and indirect electron transport

A microbial fuel cell (MFC) is an advanced green battery that has limited application because of its low current density. In the present study, Shewanella oneidensis MR-1, which is an electricity-producing bacterium, was used in an electrochemical reactor as a bacterial model. Mesoporous spherical silica nanoparticles (NPs) loaded with riboflavin (RF) were prepared as the starting material, following which surface modification was conducted to expose the thiol group, which considerably increased the affinity of the NPs to MoS2 and resulted in the formation of a dense MoS2 shell on the surface after calcination. Moreover, the loaded RFs were successfully transformed into RF-based carbon quantum dots (CQDs), which resulted in a substantial increase in conductivity. The CQD-embedded SiO2@MoS2 NPs, which contained redox-active N-doped CQDs and had a metallic MoS2 shell, were able to receive electrons from exoelectrogenic bacteria (charging) and transfer electrons to an indium tin oxide electrode (discharging). Thus, these NPs could act as an electron nanoshuttle and a conductive medium in biofilms for enhancing systematic extracellular electron transport. A 10-fold increase in bioelectricity production than no NPs addition was achieved, which confirmed the applicability of the aforementioned NPs in advanced MFC applications. The NPs prepared in this study, which mimic biological electron shuttles (e.g., RF) in long-distance conduction, can usher in a new era in the development of advanced MFCs.

Characterization of band alignment at a metal–MoS2 interface by Kelvin probe force microscopy

Transition metal dichalcogenides, such as MoS2, have garnered considerable attention because of their significant potential in device applications. A limiting factor in their development is the formation of a Schottky barrier with strong Fermi-level pinning at the metal–MoS2 interface. Herein, we report Kelvin probe force microscopy (KPFM) measurements of the work function (WF) modulation at this interface. We found an increase in the WF at the metal–MoS2 interface, depending on the layer number and the contact metal used, indicating the formation of a Schottky barrier. These variations potentially arise from the layer-number-dependent strength of Fermi-level pinning in MoS2. Visualization and calculation of WF modulation at metal–MoS2 interfaces using the KPFM method can help understand the structure and properties of such interfaces.

Vertical Phase-Engineering MoS2 Nanosheet-Enhanced Textiles for Efficient Moisture-Based Energy Generation.

Flexible moisture-electric generators (MEGs) capture chemical energy from atmospheric moisture for sustainable electricity, gaining attention in wearable electronics. However, challenges persist in the large-scale integration and miniaturization of MEGs for long-term, high-power output. Herein, a vertical heterogeneous phase-engineering MoS2 nanosheet structure based silk and cotton were rationally designed and successfully applied to construct wearable MEGs for moisture-energy conversion. The prepared METs exhibit ∼0.8 V open-circuit voltage, ∼0.27 mA/cm2 current density for >10 h, and >36.12 μW/cm2 peak output power density, 3 orders higher than current standards. And the large-scale device realizes a current output of 0.145 A. An internal phase gradient between the 2H semiconductor MoS2 in carbonized silks and 1T metallic MoS2 in cotton fibers enables a phase-engineering-based heterogeneous electric double layer functioning as an equivalent parallel circuit, leading to enhanced high-power output. Owing to their facile customization for seamless adaptation to the human body, we envision exciting possibilities for these wearable METs as integrated self-power sources, enabling real-time monitoring of physiological parameters in wearable electronics.

Transition metal (Mn, Fe, Co, Ni) and nitrogen co-doping for improving the photocatalytic activity of monolayer MoS2

Exploring efficient photocatalyst is important for environmental protection. In this work, we systematically investigate the doping configuration, formation energy, band structures, density of state, recombination rate, catalytic active site, work function, redox potential, and optical absorption properties of transition metal and nitrogen co-doped monolayer MoS2. In transition doped MoS2, transition metal atoms replace Mo. Transition metal and nitrogen atoms substitute Mo and S atoms in transition metal and nitrogen co-doped MoS2, respectively. Compared with undoped MoS2, transition metal and nitrogen co-doped MoS2 have low photogenerated carrier recombination rate, abundant catalytic active sites, small work function, suitable redox potentials, and strong light absorption, especially Mn-N and Ni-N co-doped MoS2.