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Ruifeng Qi, Shanling Wang, Minxiang Wang, Wentao Liu, Zhihui Yan, Xiaofeng Bi, Qingsong Huang
High quality molybdenum dioxide plates are engineered as templates for epitaxial growth of well-defined MoS2 nanoribbons (MNRs). The obtained MNRs possess prominent ferromagnetism, suggesting edge zigzag topologies. Our findings have opened an alternative route to large-scale synthesis of well-defined 1D materials.
August 16, 2017: Chemical Communications: Chem Comm
Yuzhu Zhang, Jianping Xu, Shaobo Shi, Yanyan Gao, Xiangguo Zhao, Chengtai Wei, Xiaosong Zhang, Lan Li
MoS2 with layered structure and distinct physical properties has attracted attention for electronic or optoelectronic devices. The photoelectric response properties of MoS2/ZnO heterojunctions based devices fabricated by spin-coating MoS2 nanosheets solutions on ZnO nanorod arrays (NRs) were investigated. The results revealed that MoS2 nanosheets were vertically aligned on the surface of ZnO NRs and the devices exhibit good photoresponse stability and reproducibility under UV and red light illuminations. The vertically aligned MoS2 nanosheets facilitate the fast photogenerated carrier separation and transport...
August 16, 2017: Nanotechnology
Shenghao Xu, Xiuying Feng, Teng Gao, Gufan Liu, Yaning Mao, Jiehua Lin, Xijuan Yu, Xiliang Luo
An aptamer induced "switch on" fluorescence resonance energy transfer (FRET) biosensor for the simultaneous detection of multiple tumor markers (e.g., AFP and CEA) combining molybdenum disulfide (MoS2) nanosheets with multicolored Au NCs by a single excitation was developed for the first time. Here, AFP aptamer functionalized green colored Au NCs (510 nm) and CEA aptamer functionalized red colored Au NCs (650 nm) are used as energy donors, while MoS2 is used as energy receptor. On the basis of recording the change of the recovered fluorescence intensity at 510 nm and 650 nm upon the addition of targets CEA and AFP, these two tumor markers can be simultaneously quantitatively detected, with detection limits of 0...
August 29, 2017: Analytica Chimica Acta
Feng Zhou, Wei Ji
We develop a theoretical model to quantify the two-photon absorption (2 PA) coefficients of monolayer MoS2. Based on two-dimensional excitons, our model reveals the 2 PA coefficient spectrum on the order of 0.01-0.1 cm/MW in the near-infrared for monolayer MoS2. As compared to the band theory for bulk semiconductors, these coefficients are enhanced by at least one order of magnitude. Our model is in agreement with light-intensity-dependent photocurrent measurements on a monolayer MoS2, subband photodetector with femtosecond laser pulses...
August 15, 2017: Optics Letters
Ming Chen, Juan Xia, Jiadong Zhou, Qingsheng Zeng, Kaiwei Li, Kazunori Fujisawa, Wei Fu, Ting Zhang, Jing Zhang, Zhe Wang, Zhixun Wang, Xiaoting Jia, Mauricio Terrones, Ze Xiang Shen, Zheng Liu, Lei Wei
Thermoplastic polymers subjected to a continuous tensile stress experience a state of mechanical instabilities, resulting in neck formation and propagation. The necking process with strong localized strain enables the transformation of initially brittle polymeric materials into robust, flexible, and oriented forms. Here we harness the polymer-based mechanical instabilities to control the fragmentation of atomically thin transition metal dichalcogenides (TMDs). We develop a simple and versatile nanofabrication tool to precisely fragment atom-thin TMDs sandwiched between thermoplastic polymers into ordered and atomically perfect TMD nanoribbons in arbitrary directions regardless of the crystal structures, defect content, and original geometries...
August 15, 2017: ACS Nano
Cijun Shuai, Hang Sun, Chengde Gao, Pei Feng, Wang Guo, Youwen Yang, Mingchun Zhao, Sheng Yang, Fulai Yuan, Shuping Peng
The inherent brittleness of bioceramics restricts their applications in load bearing implant, although they possess good biocompatibility and bioactivity. In this study, molybdenum disulfide nanoplatelets (MSNPs) were used to reinforce bioceramics (Mg2SiO4/CaSiO3) scaffolds fabricated by selective laser sintering (SLS). The fracture mode of scaffolds was transformed from transgranular to mixed trans- and intergranular. It could be explained that MSNPs could slide easily due to their weak interlayer van der Waals interactions and provide elastic deformation due to their high elastic modulus...
July 20, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Shanshan Wang, Hidetaka Sawada, Qu Chen, Grace G D Han, Christopher Allen, Angus I Kirkland, Jamie H Warner
Pt-nanocrystal:MoS2 hybrid materials have promising catalytic properties for hydrogen evolution, and understanding their detailed structures at the atomic scale is crucial to further development. Here, we use an in situ heating holder in an aberration-corrected transmission electron microscope to study the formation of Pt nanocrystals directly on the surface of monolayer MoS2 from a precursor on heating to 800 °C. Isolated single Pt atoms and small nanoclusters are observed after in situ heating, with two types of preferential alignment between the Pt nanocrystals and the underlying monolayer MoS2...
August 14, 2017: ACS Nano
Peng Zhang, Furong Qin, Lei Zou, Mengran Wang, Kai Zhang, Yanqing Lai, Jie Li
Sodium-ion batteries (SIBs) show great potential as alternative energy storage devices for next generation energy storage systems due to the deficiency of lithium resources. MoS2 is a promising anode material for SIBs due to its high theoretical sodium storage capability and large interspace for accommodating sodium ions with a larger ionic radius than lithium ions. However, bulk MoS2 exhibits a sluggish kinetics for the intercalation-deintercalation of sodium ions and large volume expansion, which result in poor cyclability and rate performance...
August 14, 2017: Nanoscale
Chundong Wang, Jianjun Jiang, Yunjun Ruan, Xiang Ao, Kostya Ken Ostrikov, WenJun Zhang, Jian Lu, Yang Yang Li
Herein, MoO2 quantum dots (QDs, <5 nm) are synthesized through one-step solvothermal process. MoO2 QDs-bonded graphene sheets (MoO2-QDs@RGO) are facilely produced, which can be further converted through sulfidation into MoS2 nanoparticles-bonded graphene sheets (MoS2-NPs@RGO). The novel MoO2-QDs@RGO electrodes demonstrate exceptionally attractive lithium storage capability (e.g., 1257 mAh g-1 at 100 mA g-1, being close to the highest values ever reported for MoO2-based LIB electrode), rate capability, and cycle stability...
August 14, 2017: ACS Applied Materials & Interfaces
Jun Hong Park, Suresh Vishwanath, Steven F Wolf, Kehao Zhang, Iljo Kwak, Mary Edmonds, Michael Breeden, Xinyu Liu, Margaret Dobrowolska, Jacek Furdyna, Joshua A Robinson, Huili Grace Xing, Andrew C Kummel
To fabricate practical devices based on semiconducting two-dimensional (2D) materials, the source, channel, and drain materials are exposed to ambient air. However, the response of layered 2D materials to air has not been fully elucidated at the molecular level. In the present report, the effects of air exposure on transition metal dichalcogenides (TMD) and metal dichalcogenides (MD) are studied using ultra-high vacuum scanning tunneling microscopy (STM). The effects of a one-day ambient air exposure on MBE grown WSe2, powder vaporization (PV) grown MoS2, and MBE SnSe2, are compared...
August 14, 2017: ACS Applied Materials & Interfaces
Hongmei Li, Xing Qian, Chong Xu, Shaowei Huang, Changli Zhu, Xiancai Jiang, Li Shao, Linxi Hou
The development of highly active and stable earth-abundant electrocatalysts to reduce or eliminate the reliance on noble-metal based ones for hydrogen evolution reaction (HER) over a broad pH range remains a great challenge. Herein, hierarchical porous Co9S8/N-doped carbon@MoS2 (Co9S8/NC@MoS2) polyhedrons have been synthesized by a facile hydrothermal approach using highly conductive Co/NC polyhedrons composed of cobalt nanoparticles embedded in N-doped carbon matrices as both the structural support and cobalt source...
August 14, 2017: ACS Applied Materials & Interfaces
Ruxing Wang, Shu Gao, Kangli Wang, Min Zhou, Shijie Cheng, Kai Jiang
A simple one-pot hydrothermal method is developed for fabrication of MoS2@rGO nanoflakes using the economical MoO3 as the molybdenum source. Benefiting from the unique nanoarchitecture, high MoS2 loading (90.3 wt%) and the expanded interlayer spacing, the as-prepared MoS2@rGO nanoflakes exhibit greatly enhanced sodium storage performances including a high reversible specific capacity of 441 mAh g(-1) at a current density of 0.2 A g(-1), high rate capability, and excellent capacity retention of 93.2% after 300 cycles...
August 11, 2017: Scientific Reports
Qu Chen, Huashan Li, Wenshuo Xu, Shanshan Wang, Hidetaka Sawada, Christopher S Allen, Angus I Kirkland, Jeffrey C Grossman, Jamie H Warner
The edges of 2D materials show novel electronic, magnetic, and optical properties, especially when reduced to nanoribbon widths. Therefore, methods to create atomically flat edges in 2D materials are essential for future exploitation. Atomically flat edges in 2D materials are found after brittle fracture or when electrically biasing, but a simple scalable approach for creating atomically flat periodic edges in monolayer 2D transition metal dichalcogenides has yet to be realized. Here, we show how heating monolayer MoS2 to 800 °C in vacuum produces atomically flat Mo terminated zigzag edges in nanoribbons...
August 11, 2017: Nano Letters
Mengxi Liu, Jianping Shi, Yuanchang Li, Xiebo Zhou, Donglin Ma, Yue Qi, Yanfeng Zhang, Zhongfan Liu
The existence of defects in 2D semiconductors has been predicted to generate unique physical properties and markedly influence their electronic and optoelectronic properties. In this work, it is found that the monolayer MoS2 prepared by chemical vapor deposition is nearly defect-free after annealing under ultrahigh vacuum conditions at ≈400 K, as evidenced by scanning tunneling microscopy observations. However, after thermal annealing process at ≈900 K, the existence of dominant single sulfur vacancies and relatively rare vacancy chains (2S, 3S, and 4S) is convinced in monolayer MoS2 as-grown on Au foils...
August 11, 2017: Small
Namasivayam Dhenadhayalan, Kanchan Yadav, Muthu Irulappan Sriram, Hsin-Lung Lee, King-Chuen Lin
Herein, we report ultra-sensitive sensing of a prostate-specific antigen (PSA), which is used as a biomarker to detect prostate cancer, using a molybdenum series (MoO3, MoS2, and MoSe2) of two-dimensional nanosheets (2D NSs). Moreover, the design of a 2D NS-based PSA aptamer sensor system was demonstrated based on a fluorescence turn-on mechanism in the presence of a target. The 2D NSs acted as an excellent sensing platform in which the PSA aptamer was adsorbed on the NSs and subsequent energy transfer between them led to fluorescence quenching of the aptamer...
August 11, 2017: Nanoscale
Tsachi Livneh, Juan S Reparaz, Alejandro R Goni
We report on the combined effect of temperature (6-300 K) and high pressure (up to 6 GPa) on the resonant Raman scattering by A1g phonons in bulk 2H-MoS2, as the energy of the A exciton is tuned into resonance with an exciting laser at EL=1.96 eV. As expected, with decreasing temperature the pressure to be applied for attaining resonant conditions also decreases. A striking result concerns the combined effect of temperature and pressure on the strength of the incoming relative to the outgoing resonance of the A1g phonon...
August 11, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Yuanzheng Li, Xinshu Li, Heyu Chen, Jia Shi, Qiuyu Shang, Shuai Zhang, Xiaohui Qiu, Zheng Liu, Qing Zhang, Haiyang Xu, Weizhen Liu, Xinfeng Liu, Yichun Liu
MoS2 as atomically thin semiconductor is highly sensitive to ambient atmosphere (e.g., oxygen, moisture etc.) in optical and electrical properties. Here we report a controlled gas molecules doping of monolayer MoS2 via atomic layer deposited Al2O3 films. The deposited Al2O3 films, in the shape of nanospheres, can effectively control the contact areas between ambient atmosphere and MoS2 that allows precise modulation of gas-molecules doping. By analyzing photoluminescence (PL) emission spectra of MoS2 with different thickness of Al2O3, the doped carrier concentration is estimated at ~2...
August 10, 2017: ACS Applied Materials & Interfaces
Parikshit Sahatiya, Sushmee Badhulika
Electronic structure and carrier behavior in semiconductor junctions can be effectively modulated on application of strain. This work represents the first demonstration of large area, flexible, paper based Gr/MoS2 broadband photodetector using low-cost solution processed hydrothermal method and enhancement in photodetection through strain modulation by assembling the device on PDMS. Optimization in terms of process parameters were done to obtain trilayer MoS2 over Gr-cellulose paper. Under strain, potential barrier variation and piezopotential induced in MoS2 leads to 79...
August 10, 2017: Nanotechnology
Jiwook Shim, Shouvik Banerjee, Hu Qiu, Kirby K H Smithe, David Estrada, Julian Bello, Eric Pop, Klaus Schulten, Rashid Bashir
Methylation at the 5-carbon position of the cytosine nucleotide base in DNA has been shown to be a reliable diagnostic biomarker for carcinogenesis. Early detection of methylation and intervention could drastically increase the effectiveness of therapy and reduce the cancer mortality rate. Current methods for detecting methylation involve bisulfite genomic sequencing, which are cumbersome and demand a large sample size of bodily fluids to yield accurate results. Hence, more efficient and cost effective methods are desired...
August 10, 2017: Nanoscale
C N R Rao, K Pramoda, Ram Kumar
Covalent linking of 2D structures such as graphene, MoS2 and C3N4 by employing coupling reactions provides a strategy to generate a variety of materials with new or improved properties. These materials in a way provide the counter point based on covalent bonds to the van der Waals heterostructures. In this article, we describe materials obtained by linking graphene, MoS2 and BN with other layered structures and also with one-dimensional nanotubes and zero-dimensional MOFs and MOPs. Novel properties of the materials relate not only to porosity, surface area and gas adsorption, but also to supercapacitor characterstics, mechanical properties and the hydrogen evolution reaction...
August 10, 2017: Chemical Communications: Chem Comm
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