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Pd-doped MoS2 monolayer: A promising candidate for DGA in transformer oil based on DFT method
摘要： Density functional theory (DFT) method was carried out to simulate the adsorption of three dissolved gases on Pd-doped MOS2 (Pd-MoS2) monolayer. We initially studied the possible structures of Pd-MoS2 monolayer and found that the Pd dopant preferred to be adsorbed onto the surface by TMo site. The adsorption and desorption performance, along with the sensing principle of Pd-MoS2 towards three typical gases, including H2, CH4 and C2H2, were analyzed. These analysis indicated that Pd-MoS2 could be a satis?ed material for C2H2 and H2 sensing at speci?c condition; while it is unsuitable for detection of CH4 due to the weak interaction and extremely short recovery time. All these give a ?rst insight into the application of Pd-MoS2 for DGA, evaluating the working operation of the transformer through sensitive detection of H2 and C2H2. We are hopeful that this work would support informative knowledge for experimentalists to realize the potential of Pd-MoS2 in the ?eld of electrical engineering in the near future.
关键词： DGA,Transformer oil,DFT,Pd-MoS2 monolayer
更新于2025-09-10 09:29:36
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Low-Temperature Wafer-Scale Growth of MoS2-Graphene Heterostructures
摘要： In this study, we successfully demonstrate the fabrication of a MoS2-graphene heterostructure (MGH) on a 4-inch wafer at 300 oC by depositing a thin Mo film seed layer on graphene followed by sulfurization using H2S plasma. By utilizing Raman spectroscopy and high-resolution transmission electron microscopy, we have confirmed that 5–6 MoS2 layers with a large density of sulfur vacancies are grown uniformly on the entire substrate. The chemical composition of MoS2 on graphene was evaluated by X-ray photoelectron spectroscopy, which confirmed the atomic ratio of Mo to S to be 1:1.78, which is much lower than the stoichiometric value of 2 from standard MoS2. To exploit the properties of the nanocrystalline and defective MGH film obtained in our process, we have utilized it as a catalyst for hydrodesulfurization and as an electrocatalyst for the hydrogen evolution reaction. Compared to MoS2 grown on an amorphous SiO2 substrate, the MGH has smaller onset potential and Tafel slope, indicating its enhanced catalytic performance. Our practical growth approach can be applied to other two-dimensional crystals, which are potentially used in a wide range of applications such as electronic devices and catalysis.
关键词： PECVD,graphene,large-scale,heterostructure,hydrogen evolution reaction,MoS2
更新于2025-09-10 09:29:36
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Two-dimensional Dy doped MoS2 ferromagnetic sheets
摘要： Magnetic two-dimensional materials have attracted immense consideration as spintronic devices. However, design and synthesis of the magnetic two-dimensional MoS2 crystals with more controllable electronic structure and better conductivity are still great challenges. Here, we make a breakthrough to synthesize the MoS2:Dy sheets with robust adjustable room-temperature ferromagnetic properties by a gas-liquid chemical deposition method. The as-synthesized samples are characterized by XRD, Raman, TEM, HRTEM and XPS. Furthermore, the magnetic properties of the samples are also investigated by VSM and Squid. The maximum observed saturation magnetization is 0.023 emu/g. The origin of ferromagnetism in the samples is investigated by using the ?rst-principles calculations based on the density functional theory. The ferromagnetism is mainly related to the exchange interactions among the S 3p, Mo 4d and Dy 5d orbits. The results indicate that the transformation of the localized charges can e?ectively engineer and manipulate the magnetic properties of 2D materials, making MoS2 a potential candidate for spintronics and electronic applications and providing a new perspective on other 2D layered materials in spintronics application.
关键词： High pressure,2D materials,MoS2,First principles calculations,Ferromagnetism,Dy doping
更新于2025-09-10 09:29:36
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Temperature dependence of the dielectric function of monolayer MoS2
摘要： An analytic expression of the dielectric function of monolayer molybdenum disulfide (MoS2) ε = ε1 + iε2 is presented for energies from 1.4 to 6.0 eV and temperatures from 35 to 350 K. The dielectric function parametric model is used to express ε as a sum of polynomials, which naturally includes asymmetry of critical-point lineshapes. The temperature dependence is achieved by fitting model parameters. In this way the dielectric function of MoS2 for arbitrary temperature can be calculated. We observed the fundamental absorption peak, which occurs at the K point of the Brillouin zone. These results are expected to be useful in designing and understanding applied-device technologies based on monolayer MoS2.
关键词： Monolayer MoS2,Ellipsometry,Dielectric function parametric model,Dielectric function
更新于2025-09-10 09:29:36
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Defect Engineering in Single-Layer MoS2 Using Heavy Ion Irradiation
摘要： Transition metal dichalcogenides (TMDs) have attracted much attention due to their promising optical, electronic, magnetic, and catalytic properties. Engineering the defects in TMDs represents an effective way to achieve novel functionalities and superior performance of TMD devices. However, it remains a significant challenge to create defects in TMDs in a controllable manner or to correlate the nature of defects with their functionalities. In this work, taking single-layer MoS2 as a model system, defects with controlled densities are generated by 500 keV Au irradiation with different ion fluences, and the generated defects are mostly S vacancies. We further show that the defects introduced by ion irradiation can significantly affect the properties of the single-layer MoS2, leading to considerable changes in its photoluminescence characteristics and electrocatalytic behavior. As the defect density increases, the characteristic photoluminescence peak of MoS2 first blueshifts and then redshifts, which is due to the electron transfer from MoS2 to the absorbed O2 at the defect sites. The generation of the defects can also strongly improve the hydrogen evolution reaction activity of MoS2, attributed to the modified adsorption of atomic hydrogen at the defects.
关键词： PL,defect engineering,Raman,ion beam,MoS2
更新于2025-09-10 09:29:36
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Biological interactions of biocompatible and water-dispersed MoS2 nanosheets with bacteria and human cells
摘要： Two dimensional materials beyond graphene such as MoS2 and WS2 are novel and interesting class of materials whose unique physico-chemical properties can be exploited in applications ranging from leading edge nanoelectronics to the frontiers between biomedicine and biotechnology. To unravel the potential of TMD crystals in biomedicine, control over their production through green and scalable routes in biocompatible solvents is critically important. Furthermore, considering multiple applications of eco-friendly 2D dispersions and their potential impact onto live matter, their toxicity and antimicrobial activity still remain an open issue. Herein, we focus on the current demands of 2D TMDs and produce high-quality, few-layered and defect-free MoS2 nanosheets, exfoliated and dispersed in pure water, stabilized up to three weeks. Hence, we studied the impact of this material on human cells by investigating its interactions with three cell lines: two tumoral, MCF7 (breast cancer) and U937 (leukemia), and one normal, HaCaT (epithelium). We observed novel and intriguing results, exhibiting evident cytotoxic effect induced in the tumor cell lines, absent in the normal cells in the tested conditions. The antibacterial action of MoS2 nanosheets is then investigated against a very dangerous gram negative bacterium, such as two types of Salmonellas: ATCC 14028 and wild-type Salmonella typhimurium. Additionally, concentration and layer-dependent modulation of cytotoxic effect is found both on human cells and Salmonellas.
关键词： antibacterial activity,biocompatibility,MoS2 nanosheets,two-dimensional materials,cytotoxicity
更新于2025-09-10 09:29:36
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Bi-layer high-<i>k</i> dielectrics of Al<sub>2</sub>O<sub>3</sub>/ZrO<sub>2</sub> to reduce damage to MoS<sub>2</sub> channel layers during atomic layer deposition
摘要： To implement Two-dimensional (2D) transition metal dichalcogenides (TMDCs) in electric devices, a top-gated device structure is desired. However, there has been possibility of the channel layer being damaged during the upper dielectric deposition process. Because several layers of 2D TMDCs are atomically thin, the damage may significantly degrade the overall electrical performance. In this study, we investigated the damage to molybdenum disulfide (MoS2) during the atomic layer deposition (ALD) of single dielectrics of Al2O3 and ZrO2. We observed the MoS2 layers were damaged, depending on the ALD process conditions; the kind of oxidant and the growth temperature. To reduce the damage, we formed a bi-layered Al2O3/ZrO2 dielectric structure by developing a two-step ALD process. It is notable that the electrical performance of the device was significantly improved compared to those using the single dielectrics, indicating this two-step process is a promising candidate to satisfy the requirements of future 2D TMDCs-based electronics.
关键词： 2D TMDC,high-k dielectric,Atomic layer deposition,MoS2
更新于2025-09-10 09:29:36
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Nanoscratch on Single-layer MoS2 Crystal by Atomic Force Microscopy: Semi-circular to Periodical Zigzag Cracks
摘要： The fracture behaviors of single-layer molybdenum disulfide (MoS2) grown on SiO2/Si wafer by chemical vapor deposition (CVD) were systematically investigated here via a technique that combining AFM-based nanoscratch tests with friction force microscopy (FFM). To get a complete cognition of fracture behavior and deepen the understanding of mesoscopic anisotropy of the mechanical failure of 2D materials, the gradual process of fracture behavior on nanoscale layered films and confirmed the different fracture stages in the process, nanoscratch with progressive and constant force was done step by step. The radius of AFM tip we used is ~10 nm which is relatively blunt to produce a tensile fracture rather than pierce the film at the initial stage. As a result, there were novel crack modes with specific normal load in the surface of CVD-grown MoS2: semi-circular and periodical zigzag cracks, and both crack modes exhibit anisotropy during the generation and propagation.
关键词： nanoscratch,periodical zigzag crack,Single-layer,semi-circular crack,MoS2
更新于2025-09-10 09:29:36
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Preparation and electromagnetic attenuation properties of MoS2–PANI composites: a promising broadband absorbing material
摘要： As an ideal electromagnetic (EM) wave absorber, it is prone to possess lightweight, thin matching thickness, broad absorption bandwidth and strong absorption performance. In this work, MoS2–PANI composites were prepared by situ chemical oxidative polymerization method, and the crystal structure, morphology, composition and EM properties were characterized. The microwave absorption properties of MoS2–PANI composites could be tuned by changing the PANI content to reach the best impedance match. The minimum reflection loss (RL) value of MoS2–PANI was ? 40.79 dB at 14.01 GHz with the thickness of 2.0 mm, and the maximum effective absorption bandwidth was 5.02 GHz ranging from 11.88 to 16.90 GHz with a thickness of 2.0 mm. Moreover, the RL value of MoS2–PANI composites could reach under ? 10 dB in a wide frequency range of 4.74–18 GHz with a thickness of 1.5–4.5 mm. In particular, the 3 mm wave attenuation properties of MoS2–PANI composites were investigated for the first time, and the maximum attenuation value reached 15.45 dB. As a result, MoS2–PANI composites are promising to be excellent EM wave absorption materials in broadband.
关键词： Electromagnetic wave absorption,Broadband absorbing material,MoS2–PANI composites,Chemical oxidative polymerization,Impedance match
更新于2025-09-10 09:29:36
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Increased yield of MoS <sub/>2</sub> monolayer exfoliation through the bimetallic corrosion of aluminum
摘要： In this paper, we propose a corrosion assisted exfoliation method as an improvement to the traditional tape exfoliation to obtain transition-metal dichalcogenide monolayers. Our method primarily relies on the electrochemical potential difference between transition metals and aluminum. The assistance of bubbles resulting from the bimetallic corrosion increases the yield of the exfoliation process for monolayers by 30-fold while boosting the probability of obtaining isolated monolayers. We use Raman measurements and a statistical comparison of the improved method with tape exfoliation to lay the evidence for our findings.
关键词： transition-metal dichalcogenides,MoS2,bimetallic corrosion,monolayer exfoliation,aluminum
更新于2025-09-10 09:29:36