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Qingyong Tian, Wei Wu, Shuanglei Yang, Jun Liu, Weijing Yao, Feng Ren, Changzhong Jiang
Flower-like MoS2 nanoparticles (NPs) consist of ultra-thin MoS2 nanosheets are synthesized via a facile one-pot hydrothermal method. The MoS2/ZnO p-n heterostructure is formed by coating n-type ZnO on the surface of flower-like MoS2 NPs through the seed-mediate route and post-annealing treatment. The effects for the dye removal and photocatalytic performances after ZnO coating are systematically investigated. The results demonstrated that the coating of ZnO nanoparticles has a positive promotion to the photodegrading properties while negative effect on the adsorption capacity of the MoS2/ZnO heterostructures...
December 2017: Nanoscale Research Letters
Xiaoxue Song, Fei Hui, Keith Gilmore, Bingru Wang, Guangyin Jing, Zhongchao Fan, Enric Grustan-Gutierrez, Yuanyuan Shi, Lucia Lombardi, Stephen A Hodge, Andrea C Ferrari, Mario Lanza
The development of piezoelectric layered materials may be one of the key elements enabling expansion of nanotechnology, as they offer a solution for the construction of efficient transducers for a wide range of applications, including self-powered devices. Here, we investigate the piezoelectric effect in multilayer (ML) stepped MoS2 flakes obtained by liquid-phase exfoliation, which is especially interesting because it may allow the scalable fabrication of electronic devices using large area deposition techniques (e...
March 24, 2017: Nanoscale
César González, Blanca Biel, Yannick J Dappe
We present a theoretical study of molecular adsorption on defects on a MoS2 monolayer. Based on Density Functional Theory, our calculations confirm that small inorganic molecules, such as CO2, CO, H2O, NO, NO2, H2 and N2, remain bonded to the pristine monolayer through weak van der Waals interactions, suggesting that the molecules may easily diffuse over the clean monolayer. On the other hand, the introduction of defects can lead to three different situations, depending on the defect and the molecule considered: physisorption, chemical (strong) bonding to the metallic defects, namely the Mo substitutional atoms on the S vacancies, and dissociation, that can take place spontaneously at 0 K in some specific cases or by the effect of thermal agitation in molecules such as CO2 or NO2 on the S vacancy...
March 24, 2017: Physical Chemistry Chemical Physics: PCCP
Juwon Lee, Sangyeon Pak, Young-Woo Lee, Yuljae Cho, John Hong, Paul Giraud, Hyeon Suk Shin, Stephen M Morris, Jung Inn Sohn, SeungNam Cha, Jong Min Kim
Monolayer transition metal dichalcogenides are considered to be promising candidates for flexible and transparent optoelectronics applications due to their direct bandgap and strong light-matter interactions. Although several monolayer-based photodetectors have been demonstrated, single-layered optical memory devices suitable for high-quality image sensing have received little attention. Here we report a concept for monolayer MoS2 optoelectronic memory devices using artificially-structured charge trap layers through the functionalization of the monolayer/dielectric interfaces, leading to localized electronic states that serve as a basis for electrically-induced charge trapping and optically-mediated charge release...
March 24, 2017: Nature Communications
Ding Jiang, Xiaojiao Du, Lei Zhou, Henan Li, Kun Wang
Deeply understanding the internal mechanism of photoelectrohemical (PEC) process is conducive to fabricate high-performances PEC biosensors. In this work, we proposed a new insight towards efficient charge separation mechanism in high-performances PEC biosensors. Specifically, we disclosed that the lifetimes of photogenerated charge carriers of ultrathin MoS2 nanosheets could be prolonged by approximately millisecond timescales after a proper mole ratio of NGQDs were coupled, leading to the promoted charge separation, and giant photocurrent signal-magnify...
March 24, 2017: Analytical Chemistry
Mitsuhiro Okada, Yuhei Miyauchi, Kazunari Matsuda, Takashi Taniguchi, Kenji Watanabe, Hisanori Shinohara, Ryo Kitaura
Monolayer transition metal dichalcogenides (TMDCs) including WS2, MoS2, WSe2 and WS2, are two-dimensional semiconductors with direct bandgap, providing an excellent field for exploration of many-body effects in 2-dimensions (2D) through optical measurements. To fully explore the physics of TMDCs, the prerequisite is preparation of high-quality samples to observe their intrinsic properties. For this purpose, we have focused on high-quality samples, WS2 grown by chemical vapor deposition method with hexagonal boron nitride as substrates...
March 23, 2017: Scientific Reports
Wenqi Xiong, Congxin Xia, Juan Du, Tianxing Wang, Yuting Peng, Zhongming Wei, Jingbo Li
As a fast developing field, van der Waals (vdW) heterostructure can overcome the weakness of single two-dimensional (2D) layered material and extend its electronic and optoelectronic applications. Through first-principles methods, the studied MoS2/stanene heterostructure preserves high-speed carrier characteristics and opens the direct band gap. Meanwhile, the band alignment shows that the electrons transfer from stanene to MoS2, which forms an internal electric field. As an effective strategy, the out-of-plane strain remarkably change the band gaps of heterostructure and enhances its carrier concentration...
March 23, 2017: Nanotechnology
Ming-Lin Li, Haili Huang, Liping Tu, Weidong Wang, Peifeng Li, Yang Lu
The nonlocal scale parameter of the nonlocal Euler-Bernoulli beam theory is evaluated for the static bending of single layer molybdenum disulfide (SLMoS2) without the predetermined bending rigidity. The evaluation activity is performed by matching the fitted curve between the maximum deflection and the beam length obtained from molecular mechanics simulations. It was observed that the fitted curves have an abnormal sign in the second order term of the maximum deflection for SLMoS2, opposite to that for graphene and regardless of the used interatomic interaction potentials...
March 23, 2017: Nanotechnology
Zhepeng Zhang, Xujing Ji, Jianping Shi, Xiebo Zhou, Shuai Zhang, Yue Hou, Yue Qi, Qiyi Fang, Qingqing Ji, Yu Zhang, Min Hong, Pengfei Yang, Xinfeng Liu, Qing Zhang, Lei Liao, Chuanhong Jin, Zhongfan Liu, Yanfeng Zhang
Stacked transition-metal dichalcogenides on hexagonal boron nitride (h-BN) are platforms for high-performance electronic devices. However, such vertical stacks are usually constructed by the layer-by-layer polymer-assisted transfer of mechanically exfoliated layers. This inevitably causes interfacial contamination and device performance degradation. Herein, we develop a two-step, low-pressure chemical vapor deposition synthetic strategy incorporating the direct growth of monolayer h-BN on Au foil with the subsequent growth of MoS2...
March 23, 2017: ACS Nano
Qi Ding, Kyle J Czech, Yuzhou Zhao, Jianyuan Zhai, Robert J Hamers, John C Wright, Song Jin
Molybdenum disulfide (MoS2) is a two-dimensional material promising for electronic, optical, and catalytic applications. To fully harness its potential, functionalization is essential to control its properties. However, MoS2 functionalization has been mostly limited to either 1T-phase MoS2 or the edges of 2H-phase MoS2, and the chemistry of covalent functionalization on the basal plane of 2H-MoS2 is poorly understood. Here we report a facile approach to covalently functionalize chemical vapor deposition (CVD) grown 2H-MoS2 monolayers (MLs), as well as mechanically exfoliated MoS2, via thiol conjugation at sulfur vacancies on the basal plane...
March 23, 2017: ACS Applied Materials & Interfaces
Xi Liu, Yang Chai, Zhaojun Liu
With the development of portable electronics, higher performance transistors are required to reduce the form factor and improve the performance of the devices. The key issue relies on developing transistors with outstanding electrical properties and low energy consumption at small scale. Here we demonstrate chemical vapor deposition (CVD) grown MoS2 transistors with a high on/off ratio using ZrO2 as a gate dielectric. Using 10 nm thick ZrO2, the transistor has an on/off ratio of 10(8), a sub-threshold swing of 0...
March 23, 2017: Nanotechnology
Zhen Cao, Moussab Harb, Sheikha Lardhi, Luigi Cavallo
We explored the impact of interfacial defects on the stability and optoelectronic properties of monolayer transition metal dichalcogenides lateral heterojunction using a DFT approach. As prototype, we focused on MoS2-WSe2, and we found that even a random alloy-like interface, within a width of 1 nm, has minimal impact on the band gap and alignment compared to defect-less interfaces. The largest impact is on the evolution of the total local potential energy across the monolayer. Similarly to defect-less interfaces, small amount of defects results in a potential energy profile with a sharp change at the interface, which facilitates exciton dissociation...
March 23, 2017: Journal of Physical Chemistry Letters
Hao Zhang, Feirong Ran, Xiaotong Shi, Xiangru Fang, Shiyu Wu, Yue Liu, Xianqiang Zheng, Peng Yang, Yang Liu, Lin Wang, Xiao Huang, Hai Li, Wei Huang
Transparent and flexible devices based on two-dimensional (2D) materials hold great potential for many electronic/optoelectronic applications. The direct and fast thickness identification of 2D materials on transparent substrates is therefore an essential step in such applications, but remains challenging. Here, we present a simple, rapid and reliable optical method to identify the thickness of 2D nanosheets on transparent substrates, such as polydimethylsiloxane, glass, and coverslip. Under reflection and transmission light, 1-20L MoS2 and 1-14L WSe2 nanosheets can be reliably identified by measuring the optical contrast difference between the 2D nanosheets and substrates in color, red, green or blue channels...
March 22, 2017: Nanotechnology
Zexing Wu, Wen Lei, Jie Wang, Rong Liu, Kedong Xia, Cuijuan Xuan, Deli Wang
A facile and scalable solvothermal high-temperature treatment strategy was developed to construct few-layered ultra-small MoS2 with less than three layers. These are embedded in carbon spheres (MoS2-C) and can be used as advanced anode material for lithium ion batteries (LIBs). In the resulting architecture, the intimate contact between MoS2 surface and carbon spheres can effectively avert aggregation and volume expansion of MoS2 during the lithiation-delithiation process. Moreover, it improves the structural integrity of the electrode remarkably, while the conductive carbon spheres provide quick transport of both electrons and ions within the electrode...
March 22, 2017: ACS Applied Materials & Interfaces
Aurora Piazza, Filippo Giannazzo, Gianpiero Buscarino, Gabriele Fisichella, Antonino La Magna, Fabrizio Roccaforte, Marco Cannas, Franco Mario Gelardi, Simonpietro Agnello
The effects of temperature and atmosphere (air and O2) on the doping of monolayers of graphene (Gr) on SiO2 and Si substrates, and on the doping of MoS2 multilayer flakes transferred on the same substrates have been investigated. The investigations were carried out by in situ micro-Raman spectroscopy during thermal treatments up to 430 °C, and by atomic force microscopy (AFM). The spectral positions of the G and 2D Raman bands of Gr undergo only minor changes during treatment, while their amplitude and full width at half maximum (FWHM) vary as a function of the temperature and the used atmosphere...
2017: Beilstein Journal of Nanotechnology
Shao Su, Xiaoyan Han, Zaiwei Lu, Wei Liu, Dan Zhu, Jie Chao, Chunhai Fan, Lihua Wang, Shiping Song, Lixing Weng, Lianhui Wang
Herein, an electrochemical detection platform was designed based on Prussian blue nanocubes-decorated molybdenum disulfide nanocomposite (MoS2-PBNCs). Shape-controlled and high-dispersion PBNCs were supported on MoS2 nanosheets' surface, which would be simply controlled by varying experimental conditions. Expectedly, such obtained MoS2-based nanocomposite possessed excellent electrocatalytic ability, which could be employed to construct an electrochemical sensor for nonenzymatic hydrogen peroxide (H2O2) detection...
March 22, 2017: ACS Applied Materials & Interfaces
W P Cathie Lee, Fhu-Hin Wong, Nicole K Attenborough, Xin Ying Kong, Lling-Lling Tan, S Sumathi, Siang-Piao Chai
In the present work, two-dimensional bismuth oxybromide (BiOBr) was synthesized and coupled with co-catalyst molybdenum disulphide (MoS2) via a simple hydrothermal process. The photoactivity of the resulting hybrid photocatalyst (MoS2/BiOBr) was evaluated under the irradiation of 15 W energy-saving light bulb at ambient condition using Reactive Black 5 (RB5) as model dye solution. The photo-degradation of RB5 by BiOBr loaded with 0.2 wt% MoS2 (MoBi-2) exhibited more than 1.4 and 5.0 folds of enhancement over pristine BiOBr and titanium dioxide (Degussa, P25), respectively...
March 18, 2017: Journal of Environmental Management
Lei Liu, Yazhou Huang, Jingjie Sha, Yunfei Chen
Monolayer and/or atomically thin transition metal dichalcogenides cover a wide range of two-dimensional (2-D) materials, whose fascinating semiconducting and optical properties have made them being promising candidate materials for optoelectronic device. Controllable growth of these materials is critical for their device applications. By using MoCl5 and H2S as precursors, monolayer and ultrathin molybdenum disulfide (MoS2) films with controlled lamellar structure have been directly built layer by layer on SiO2 substrates without followed high-temperature annealing...
March 21, 2017: Nanotechnology
Fu-Yu Shih, Yueh-Chun Wu, Yi-Siang Shih, Ming-Chiuan Shih, Tsuei-Shin Wu, Po-Hsun Ho, Chun-Wei Chen, Yang-Fang Chen, Ya-Ping Chiu, Wei-Hua Wang
Two-dimensional (2D) materials are composed of atomically thin crystals with an enormous surface-to-volume ratio, and their physical properties can be easily subjected to the change of the chemical environment. Encapsulation with other layered materials, such as hexagonal boron nitride, is a common practice; however, this approach often requires inextricable fabrication processes. Alternatively, it is intriguing to explore methods to control transport properties in the circumstance of no encapsulated layer...
March 21, 2017: Scientific Reports
Qingfeng Liu, Brent Cook, Maogang Gong, Youpin Gong, Ewing Dan, Matthew Casper, Alex Stramel, Judy Z Wu
Two-dimensional (2D) MoS2/graphene van der Waals heterostructures integrate the superior light-solid interaction in MoS2 and charge mobility in graphene for high-performance optoelectronic devices. Key to the device performance lies in a clean MoS2/graphene interface to facilitate efficient transfer of photo-generated charges. Here we report a printable and transfer-free process for fabrication of wafer-size MoS2/graphene van der Waals heterostructures obtained using a metal-free-grown graphene, followed by low-temperature growth of MoS2 from the printed thin film of ammonium thiomolybdate on graphene...
March 21, 2017: ACS Applied Materials & Interfaces
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