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Jinhua Hong, Yuhao Pan, Zhixin Hu, Danhui Lv, Chuanhong Jin, Wei Ji, Jun Yuan, Ze Zhang
Direct observation of atomic migration both on and below surfaces is a long-standing but important challenge in materials science as diffusion is one of the most elementary processes essential to many vital material behaviors. Probing the kinetic pathways, including metastable or even transition states involved down to atomic scale, holds the key to the underlying physical mechanisms. Here, we applied aberration-corrected transmission electron microscopy (TEM) to demon-strate direct atomic-scale imaging and quasi-real-time tracking of diffusion of Mo adatoms and vacancies in monolayer MoS2, an important 2D transition metal dichalcogenide (TMD) system...
May 26, 2017: Nano Letters
Ruina Dai, Yangyang Wang, Jie Wang, Xianyu Deng
MoS2 as a graphene-like 2D material shows a large potential to replace even overcome graphene in various important applications due to its perfect properties of electrical, optical, frictional, and tunable band gap. However, low solubility in the most of common solvents makes it difficult to prepare via a simple solution process. Here we introduce a metalorganic compound to modify MoS2. Phenyl acetylene silver (PAS) functionalized MoS2 compound is easily dispersed in the solvent of DMF and water. A conductive polymer PEDOT: PSS blend with the MoS2 leads to a significant enhancement of the performance of planar heterojunction perovskite solar cells...
May 25, 2017: ChemSusChem
Ranjith Bose, Zhenyu Jin, Seokhee Shin, Sungjoon Kim, Sun Young Lee, Yo-Sep Min
MoS2 is a promising material to replace Pt catalyst for electrochemical hydrogen evolution reaction (HER). It is well known that the activity of the MoS2 catalyst in the HER is significantly promoted by doping cobalt atoms. Recently, the Co-Mo-S phase, in which cobalt atoms decorate the edge positions of the MoS2 slabs, has been identified as a co-catalytic phase in the Co-doped MoS2 (Co-MoSx) with a low Co content. Here, we report the effect of the incorporation of cobalt atoms on the chemical state of Co-MoSx catalyst which gives rise to the co-catalytic effect...
May 25, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Chi Chen, Xiao Ji, Kui Xu, Bao Zhang, Ling Miao, Jianjun Jiang
The discovery of various two-dimensional (2D) nanomaterials with different phases is fundamentally and technologically intriguing, leading to diverse physical and chemical properties for expanded applications. Herein, we performed systematic first-principles calculations to explore a series of single-layer MXenes (M2 X: M=Sc, Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta; X=C, N). The new H-phase MXenes are firstly predicted, which are compared with the usually synthesized MXenes named as T-phase MXenes on their structure and electronic properties...
May 24, 2017: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Shinichiro Mouri, Wenjin Zhang, Daichi Kozawa, Yuhei Miyauchi, Goki Eda, Kazunari Matsuda
Correction for 'Thermal dissociation of inter-layer excitons in MoS2/MoSe2 hetero-bilayers' by Shinichiro Mouri et al., Nanoscale, 2017, DOI: 10.1039/c7nr01598d.
May 25, 2017: Nanoscale
Lili Cai, Connor J McClellan, Ai Leen Koh, Hong Li, Eilam Yalon, Eric Pop, Xiaolin Zheng
Two-dimensional (2D) molybdenum trioxide (MoO3) with mono- or few-layer thickness can potentially advance many applications, ranging from optoelectronics, catalysis, sensors, and batteries to electrochromic devices. Such ultrathin MoO3 sheets can also be integrated with other 2D materials (e.g., as dopants) to realize new or improved electronic devices. However, there is lack of a rapid and scalable method to controllably grow mono- or few-layer MoO3. Here, we report the first demonstration of using a rapid (<2 minutes) flame synthesis method to deposit mono- and few-layer MoO3 sheets (several microns in lateral dimension) on a wide variety of layered materials, including mica, MoS2, graphene and WSe2, based on van der Waals epitaxy...
May 24, 2017: Nano Letters
Juan Xia, Jin Wang, Dongliang Chao, Zhen Chen, Zheng Liu, Jer-Lai Kuo, Jiaxu Yan, Ze Xiang Shen
Due to the easy intralayer gliding and weak interlayer van der Waals interaction in transition metal dichalcogenides (TMDs), ion (particularly Li(+)) intercalation has been used to modify and tune their atomic structures to obtain the desired optical, electronic and chemical properties for future optoelectronics and energy storage applications. A good understanding of the transformative structures during intercalation is critical. In this paper, we investigate the structural transformation dynamics of 2H-MoS2 using electrochemical Li(+) intercalation for 2H-MoS2...
May 23, 2017: Nanoscale
Ji Dong, Fengjing Liu, Feng Wang, Jiawei Wang, Molin Li, Yao Wen, Liang Wang, Gongtang Wang, Jun He, Chao Jiang
Recently, van der Waals heterostructures (vdWHs) have trigged intensive interest due to their novel electronic and optoelectronic properties. The vdWHs could be achieved by stacking two dimensional layered materials (2DLMs) on top of another and vertically kept by van der Waals forces. Furthermore, organic semiconductors are also known to interact via van der Waals forces, which offer an alternative for the fabrication of organic-inorganic p-n vdWHs. However, the performances of organic-inorganic p-n vdWHs produced so far are rather poor, owing to the unmatched electrical property between the 2DLMs and organic polycrystalline films...
May 23, 2017: Nanoscale
Youngsin Park, Sang Wook Han, Christopher C S Chan, Benjamin P L Reid, Robert A Taylor, Nammee Kim, Yongcheol Jo, Hyunsik Im, Kwang S Kim
Due to its unique layer-number dependent electronic band structure and strong excitonic features, atomically thin MoS2 is an ideal 2D system where intriguing photoexcited-carrier-induced phenomena can be detected in excitonic luminescence. We perform micro-photoluminescence (PL) measurements and observe that the PL peak redshifts nonlinearly in mono- and bi-layer MoS2 as the excitation power is increased. The excited carrier-induced optical bandgap shrinkage is found to be proportional to n(4/3), where n is the optically-induced free carrier density...
May 23, 2017: Nanoscale
Peng Chen, Jin-Yu Zou, Bang-Gui Liu
The electronic, magnetic, and topological properties of a CoBr2 monolayer are studied in the framework of density-functional theory (DFT) combined with tight-binding (TB) modeling in terms of the Wannier basis. Our DFT investigation and Monte Carlo simulation show that there exists intrinsic two-dimensional ferromagnetism in the CoBr2 monolayer, thanks to the large out-of-plane magnetocrystalline anisotropic energy. Our further study indicates that the spin-orbit coupling makes it become a topologically nontrivial insulator with a quantum anomalous Hall effect and topological Chern number [script C] = 4 and its edge states can be manipulated by changing the width of its nanoribbons and applying strains...
May 23, 2017: Physical Chemistry Chemical Physics: PCCP
Yunqiu Kelly Luo, Jinsong Xu, Tiancong Zhu, Guanzhong Wu, Elizabeth Joan McCormick, Wenbo Zhan, Mahesh R Neupane, Roland K Kawakami
Two dimensional (2D) materials provide a unique platform for spintronics and valleytronics due to the ability to combine vastly different functionalities into one vertically-stacked heterostructure, where the strengths of each of the constituent materials can compensate for the weaknesses of the others. Graphene has been demonstrated to be an exceptional material for spin transport at room temperature, however it lacks a coupling of the spin and optical degrees of freedom. In contrast, spin/valley polarization can be efficiently generated in monolayer transition metal dichalcogenides (TMD) such as MoS2 via absorption of circularly-polarized photons, but lateral spin or valley transport has not been realized at room temperature...
May 23, 2017: Nano Letters
Takashi Komesu, Duy Le, Iori Tanabe, Eike Schwier, Yohei Kojima, Mingtian Zheng, Kazuaki Taguchi, Miyamoto Koji, Taichi Okuda, Hideaki Iwasawa, Kenya Shimada, Talat Rahman, Peter Dowben
We have investigated the influence of metal adsorbates (sodium and cobalt) on the occupied and unoccupied electronic structure of MoS2(0001) and WSe2(0001), through a combination of both photoemission and inverse photoemission. The electronic structure is rigidly shifted in both the WSe2 and MoS2 systems, with either Na or Co adsorption, generally as predicted by accompanying density functional theory based calculations. Na adsorption is found to behave as an electron donor (n-type) in MoS2, while Co adsorption acts as an electron acceptor (p-type) in WSe2...
May 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Ji Hyun An, Jyongsik Jang
Arsenic (As) contamination in drinking water is problematic due to its threat to human health. Highly stable, sensitive and selective sensors are needed for As(iii), which is the most toxic of the various forms of arsenic. Herein, we describe the fabrication of field-effect transistor (FET)-type aptasensors for As(iii) detection that is based on carboxylic polypyrrole (CPPy)-coated flower-like MoS2 nanospheres (CFMNSs). Arsenic-binding aptamer-conjugated CFMNSs were integrated into a liquid-ion gated FET system, leading to extraordinary performance with a rapid response (on a time scale of less than 1 s)...
May 22, 2017: Nanoscale
H Khani, M Esmaeilzadeh, F Kanjouri
Generation of large currents, versatile functionality, and simple structures are of fundamental importance in the development of adiabatic quantum pump devices with nanoscale dimensions. In the present study, we propose an adiabatic quantum pump with a simple structure based on molybdenum disulfide, MoS2, to generate large spin and valley resolved currents. We show that pure and fully polarized spin and valley currents can be easily generated by employing two potential gates and using an exchange magnetic field...
May 22, 2017: Physical Chemistry Chemical Physics: PCCP
Jie Su, Liping Feng, Wei Zeng, Zhengtang Liu
Metal/insertion-MoS2 sandwich interfaces are designed to reduce the Schottky barriers at metal-MoS2 interfaces. The effects of geometric and electronic structures of two-dimensional (2D) insertion materials on the contact properties of metal/insertion-MoS2 interfaces are comparatively studied by first-principles calculations. Regardless of the geometric and electronic structures of 2D insertion materials, Fermi level pinning effects and charge scattering at the metal/insertion-MoS2 interface are weakened due to weak interactions between the insertion and MoS2 layers, no gap states and negligible structural deformations for MoS2 layers...
May 22, 2017: Nanoscale
Tao Liang, Shuang Xie, Weifei Fu, Yu Cai, Chinnathambi Shanmugavel, Hideo Iwai, Daisuke Fujita, Nobutaka Hanagata, Hongzheng Chen, Mingsheng Xu
Atomically thin, two-dimensional materials ranging from superconductors, metals, semiconductors to insulators are emerging as potential candidates for the next-generation digital electronics and optoelectronic applications. Their synthesis on a commonly used substrate and fast transfer to a plenty of desired substrates need to be addressed to meet the industrialization criteria for practical applications. In this study, fused silica, which is amorphous, transparent, and inexpensive, was examined as a substrate for MoS2 synthesis...
May 22, 2017: Nanoscale
Changbin Nie, Leyong Yu, Xingzhan Wei, Jun Shun, Wenqiang Lu, Weimin Chen, Shuanglong Feng, Haofei Shi
Two-dimensional molybdenum disulfide (MoS2) is a promising material for ultrasensitive photodetector owing to its tunable band gap and high absorption coefficient. However, controlled synthesis of high quality, large area monolayer molybdenum disulfide (MoS2) is still a challenge in practical application. In this work, we report a gold foil assistant chemical vapor deposition (CVD) method of large size (>400 μm) single crystal MoS2 film on silicon dioxide (SiO2) substrate. The influence of Au foil in enlarging the size of single crystal MoS2 were investigated systemically using thermal simulation in Ansys workbench 16...
May 22, 2017: Nanotechnology
Cao Yang, Jianhua Cheng, Yuancai Chen, Yongyou Hu
A MoS2 nanosheet-coated chromium terephthalate MIL-101 octahedron hybrid (denoted as MoS2/MIL-101) was prepared via a simple hydrothermal reaction. The obtained MoS2/MIL-101 hybrid exhibited a significantly enhanced adsorption ability toward rhodamine B (RhB) as compared with pure MoS2, MIL-101, and the physical mixture of the two. The results demonstrate that the MoS2/MIL-101 hybrid had a high uptake capacity (Qm ≈ 344.8mgg(-1)) and fast adsorption rate for the removal of aqueous RhB. The excellent adsorption performance is likely related to the synergism of hydrogen bonding, π-π stacking interactions, and direct coordination between the MIL-101 substrate and RhB, as well as electrostatic interactions between MoS2 nanosheets and RhB...
May 10, 2017: Journal of Colloid and Interface Science
Ting Xiang, Qi Fang, Hui Xie, Chuanqiang Wu, Changda Wang, Yu Zhou, Daobin Liu, Shuangming Chen, Adnan Khalil, Shi Tao, Qin Liu, Li Song
Vertical 1T-MoS2 nanosheets with an expanded interlayer spacing of 9.8 Å were successfully grown on a graphene surface via a one-step solvothermal method. Such unique hybridized structures provided strong electrical and chemical coupling between the vertical nanosheets and graphene layers by means of C-O-Mo bonding. The merits are very beneficial for a high-efficiency electron/ion transport pathway and structural stability. As a proof of concept, the lithium ion battery with the as-obtained hybrid's electrode exhibited excellent rate performance with a 666 mA h g(-1) capacity at a high current density of 3500 mA g(-1)...
May 19, 2017: Nanoscale
Kuangzhou Du, Lirong Zheng, Tanyuan Wang, Junqiao Zhuo, Zhiwei Zhu, Yuanhua Shao, Meixian Li
Molybdenum sulfides are considered to be one kind of the promising candidates as cheap and efficient electrocatalysts for hydrogen evolution reaction (HER). But this is still a gap on electrocatalytic performance toward Pt. In order to further enhance electrocatalytic activity of molybdenum sulfides, in this work, Mo3S13 films with high ratio of sulfur to molybdenum were prepared by electrodeposition. The Mo3S13 films exhibit highly efficient electrocatalytic activity for HER and achieve a current density of 10 mA/cm2 at an overpotential of 200 mV with an onset potential of 130 mV vs...
May 19, 2017: ACS Applied Materials & Interfaces
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