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Liquid exfoliation of g-C3N4 nanosheets to construct 2D-2D MoS2/g-C3N4 photocatalyst for enhanced photocatalytic H2 production activity
摘要： Although graphitic carbon nitride (g-C3N4) is an attractive photocatalyst for solar H2 generation, the preparation of g-C3N4 nanosheets via a “green” and simple method as well as the construction of highly-efficient g-C3N4-based photocatalysts are still challenges. In this study, g-C3N4 nanosheets prepared by a simple probe sonication assisted liquid exfoliation method were used to construct 2D-2D MoS2/g-C3N4 photocatalyst for photocatalytic H2 production. The 2D-2D MoS2/g-C3N4 photocatalyst containing 0.75% MoS2 showed the highest H2 evolution rate of 1155 μmol·h-1·g-1 with an apparent quantum yield of 6.8% at 420 nm monochromatic light, which is much higher than that of the optimized 0D-2D Pt/g-C3N4 photocatalyst. The high photocatalytic H2 production activity of 2D-2D MoS2/g-C3N4 photocatalyst can be attributed to the large surface area and the formed 2D interfaces between MoS2 and g-C3N4 nanosheets. As demonstrated by photoluminescence quenching and time-resolved fluorescence decay studies, the 2D interfaces can accelerate the photoinduced charge transfer, resulting in the high photocatalytic H2 production performance. This study provides a new strategy in developing highly-efficient g-C3N4-based photocatalysts for H2 production via using 2D nanojunction as a bridge to promote the photoinduced charge separation and transfer.
关键词： Hydrogen generation,Molybdenum disulfide,Graphitic carbon nitride,Photocatalysis,2D photocatalyst
更新于2025-09-23 15:22:29
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Perforating Freestanding Molybdenum Disulfide Monolayers with Highly Charged Ions
摘要： Porous single layer molybdenum disulfide (MoS2) is a promising material for applications such as DNA sequencing and water desalination. In this work, we introduce irradiation with highly charged ions (HCIs) as a new technique to fabricate well-defined pores in MoS2. Surprisingly, we find a linear increase of the pore creation efficiency over a broad range of potential energies. Comparison to atomistic simulations reveals the critical role of energy deposition from the ion to the material through electronic excitation in the defect creation process, and suggests an enrichment in molybdenum in the vicinity of the pore edges at least for ions with low potential energies. Analysis of the irradiated samples with atomic resolution scanning transmission electron microscopy reveals a clear dependence of the pore size on the potential energy of the projectiles, establishing irradiation with highly charged ions as an effective method to create pores with narrow size distributions and radii between ca. 0.3 and 3 nm.
关键词： 2D material,perforation,ion irradiation,MD simulation,molybdenum disulfide,highly charged ions,STEM
更新于2025-09-23 15:22:29
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Nanostructuring Strategies To Increase the Photoelectrochemical Water Splitting Activity of Silicon Photocathodes
摘要： Photoelectrochemical water splitting is a promising route for sustainable hydrogen production. Herein, we demonstrate a photoelectrode motif that enables a nanostructured large-surface area electrocatalyst without requiring a nanostructured semiconductor surface with the goal of promoting electrocatalysis while minimizing surface recombination. We compare the photoelectrochemical H2 evolution activity of two silicon photocathode nanostructuring strategies: (1) direct nanostructuring of the silicon surface and (2) incorporation of nanostructured zinc oxide to increase the electrocatalyst surface area on planar silicon. We observed that silicon photocathodes that utilized nanostructured ZnO supports outperformed nanostructured silicon electrodes by ～50 mV at open circuit under 1 sun illumination and demonstrated comparable electrocatalytic activity.
关键词： photocathodes,silicon nanowires,hydrogen evolution,molybdenum disulfide,zinc oxide nanowires,photoelectrochemical water splitting
更新于2025-09-23 15:22:29
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DNA origami deposition on native and passivated molybdenum disulfide substrates
摘要： Maintaining the structural fidelity of DNA origami structures on substrates is a prerequisite for the successful fabrication of hybrid DNA origami/semiconductor-based biomedical sensor devices. Molybdenum disulfide (MoS2) is an ideal substrate for such future sensors due to its exceptional electrical, mechanical and structural properties. In this work, we performed the first investigations into the interaction of DNA origami with the MoS2 surface. In contrast to the structure-preserving interaction of DNA origami with mica, another atomically flat surface, it was observed that DNA origami structures rapidly lose their structural integrity upon interaction with MoS2. In a further series of studies, pyrene and 1-pyrenemethylamine, were evaluated as surface modifications which might mitigate this effect. While both species were found to form adsorption layers on MoS2 via physisorption, 1-pyrenemethylamine serves as a better protective agent and preserves the structures for significantly longer times. These findings will be beneficial for the fabrication of future DNA origami/MoS2 hybrid electronic structures.
关键词： atomic force microscopy (AFM),molybdenum disulfide (MoS2),1-pyrenemethylamine,pyrene,DNA origami,surface modification
更新于2025-09-23 15:22:29
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Selective Transfer of Rotationally Commensurate MoS <sub/>2</sub> from an Epitaxially Grown van der Waals Heterostructure
摘要： Large-scale synthesis of high quality two-dimensional (2D) semiconductors are critical for their incorporation in emerging electronic and optoelectronic technologies. In particular, chemical vapor deposition (CVD) of transition metal dichalcogenides (TMDs) via van der Waals epitaxy on epitaxial graphene (EG) leads to rotationally commensurate TMDs in contrast to randomly aligned TMDs grown on amorphous oxide substrates. However, the interlayer coupling between TMDs and EG hinders the investigation and utilization of the intrinsic electronic properties of the resulting TMDs, thus requiring their isolation from the EG growth substrate. To address this issue, we report here a technique for selectively transferring monolayer molybdenum disulfide (MoS2) from CVD-grown MoS2-EG van der Waals heterojunctions using copper (Cu) adhesion layers. The choice of Cu as the adhesion layer is motivated by density functional theory calculations that predict the preferential binding of monolayer MoS2 to Cu in contrast to graphene. Atomic force microscopy and optical spectroscopy confirm the large-scale transfer of rotationally commensurate MoS2 onto SiO2/Si substrates without cracks, wrinkles, or residues. Furthermore, the transferred MoS2 shows high performance in field-effect transistors with mobilities up to 30 cm2/Vs and on/off ratios up to 106 at room temperature. This transfer technique can likely be generalized to other TMDs and related 2D materials grown on EG, thus offering a broad range of benefits in nanoelectronic, optoelectronic, and photonic applications.
关键词： molybdenum disulfide,van der Waals epitaxy,two-dimensional semiconductors,field-effect transistors,copper adhesion layers,transition metal dichalcogenides,chemical vapor deposition
更新于2025-09-23 15:21:21
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Sputter-Deposited-MoS2 nMISFETs with Top-Gate and Al2O3 Passivation under Low Thermal Budget for Large Area Integration
摘要： We have fabricated large area integrated top-gate nMISFETs with sputter-deposited-MoS2 film having n-type operation. A sputtering method enables us to form a large-area MoS2 thin film followed by H2S annealing to compensate sulfur vacancies. Two passivation films of ALD-Al2O3 enhance the process endurance of MoS2 channel. Therefore, we demonstrate TiN-top-gate nMISFET, which is a substantial first step to realize industrial chip-level LSIs with MoS2-channel FETs.
关键词： Top gate,MISFET,Transition metal di-chalcogenide,Sputtering,Passivation,Molybdenum disulfide,Large area integration
更新于2025-09-23 15:21:21
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Catalytic growth of large area monolayer molybdenum disulfide film by chemical vapor deposition
摘要： Large area monolayer molybdenum disulfide (MoS2) film grown on silica/silicon substrate was synthesized using a catalyst perylene-3, 4, 9, 10-tetracarboxylic acid tetrapotassium salt (PTAS) by the method of chemical vapor deposition. The properties of the monolayer MoS2 film were characterized using a number of techniques. The optical microscope images show the film is uniform and continuous on a large scale. The 0.7 nm film thickness measured by atomic force microscope, as well as the difference of 20 cm-1 between the two characteristic Raman peaks, all prove that the film is single layer. The strong photoluminescence spectrum and image as well as the x-ray diffraction indicate that the monolayer MoS2 film has a good quality. The MoS2 film synthesized under the same conditions without PTAS was also characterized as a comparison. The results show that the MoS2 film tends to thicker without using PTAS, suggesting that PTAS can not only promote the formation of the MoS2 seeding, but also induce horizontal growth of the MoS2 film on the substrate.
关键词： Molybdenum disulfide,Chemical vapor deposition,Monolayer
更新于2025-09-23 15:21:21
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Frictional Characteristics of Suspended MoS <sub/>2</sub>
摘要： Molybdenum disulfide (MoS2), a booming layered two-dimensional (2D) nanomaterial, has gain intensive interests for its remarkable physical properties. In this work, the friction characteristics of suspended MoS2 are systematically investigated with atomic force microscopy (AFM). The friction on the suspended MoS2 is much larger than that on the supported MoS2 because of the softening bending rigidity and easier formation of puckering at the AFM tip-MoS2 contact interface, and the difference would increases with the applied load. Similar to the supported MoS2, the friction on the suspended MoS2 also decreases with the increasing layers because of the enhanced bending rigidity. The friction on the suspended MoS2 is relatively insensitive to the shapes of holes below but sensitive to the dimensions. This work can provide beneficial guidance for the diverse design requirements of MoS2-based nanoelectromechanical devices.
关键词： friction,suspended,Molybdenum disulfide,puckering effect,bending rigidity,AFM,atomic force microscopy,MoS2,supported
更新于2025-09-23 15:21:21
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The Reaction Mechanism for the Hydrogen Evolution Reaction on the Basal Plane Sulfur Vacancy Site of MoS2 Using Grand Canonical Potential Kinetics
摘要： We develop the grand canonical potential kinetics (GCP-K) formulation based on thermodynamics from quantum mechanics calculations to provide a fundamental basis for understanding heterogeneous electrochemical reactions. Our GCP-K formulation arises naturally from minimizing the free energy using a Legendre transform relating the net charge of the system and the applied voltage. Performing this macroscopic transformation explicitly allows us to make the connection of GCP-K to the traditional Butler-Volmer kinetics. Using this GCP-K based free energy, we show how to predict both the potential and pH dependent chemistry for a specific example, the hydrogen evolution reaction (HER) at a sulfur vacancy on the basal plane of MoS2. We find that the rate determining steps in both acidic and basic conditions are the Volmer reaction in which the second hydrogen atom is adsorbed from the solution. Using the our GCP-K formulation, we show that the stretched bond distances change continuously as a function of the applied potential. This shows that the main reason for the higher activity in basic conditions is that the transition state is closer to the product, which leads to a more favorable Tafel slope of 60mV/dec. In contrast if the transition state were closer to the reactant, where the transfer coefficient is less than 0.5 we would obtain a Tafel slope of almost 150mV/dec. Based on this detailed understanding of the reaction mechanism, we conclude that the second hydrogen at the chalcogenide vacant site is the most active towards the hydrogen evolution reaction. Using this as a descriptor, we compare to the other 2H group VI metal dichalcogenides and predict that vacancies on MoTe2 will have the best performance towards HER.
关键词： Grand Canonical Potential,Hydrogen Evolution Reaction,Molybdenum Disulfide,Electrochemistry
更新于2025-09-23 15:21:21
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Synthesis of Tungsten Disulfide and Molybdenum Disulfide Quantum Dots and their Applications
摘要： With fascinating optical, electronic, and mechanical properties, tungsten disulfide (WS2) and molybdenum disulfide (MoS2) quantum dots (QDs) are promising for related applications. Their bandgap energy, photoluminescence and electrochemical properties are closely related to their size, morphology, dimensionality, crystal phase and structure. In this review, we introduce the crystal phases and structures of WS2 and MoS2 QDs followed by a summary of their physical and chemical synthetic methods and their applications in light-emitting devices (LEDs), supercapacitors and others. Additionally, the advantages and limitations of different synthetic strategies and challenges in these promising fields are discussed on the basis of current development.
关键词： Synthesis methods,Applications,Quantum dots,Molybdenum disulfide,Tungsten disulfide
更新于2025-09-23 15:21:01