MoS2

/Tag: MoS2

High‐Performance Photoinduced Memory with Ultrafast Charge Transfer Based on MoS2/SWCNTs Network Van Der Waals Heterostructure

2018-12-16T00:33:38+00:00December 15th, 2018|Categories: Publications|Tags: , |

A high‐speed photoinduced memory device is achieved based on the MoS2/single‐walled carbon nanotube network mixed‐dimensional van der Waals heterostructure. It demonstrates the multibit storage capacity, and meets all needs of an ideal photoinduced memory simultaneously—a record fast program/erase operation of 32/0.4 ms, a high program/erase ratio (106), appropriate storage time (103 s), and simple program/erase operation at room temperature. Abstract Photoinduced memory devices with fast program/erase operations are crucial for modern communication technology, especially for high‐throughput data storage and transfer. Although some photoinduced memories based on 2D materials have already demonstrated desirable performance, the program/erase speed is still limited to hundreds of micro‐seconds. A high‐speed photoinduced memory based on MoS2/single‐walled carbon nanotubes (SWCNTs) network mixed‐dimensional van der Waals heterostructure is demonstrated here. An intrinsic ultrafast charge transfer occurs at the heterostructure interface between MoS2 and SWCNTs (below 50 fs), therefore enabling a record program/erase speed of ≈32/0.4 ms, which is faster than that of the previous reports. Furthermore, benefiting from the unique device structure and material properties, while achieving high‐speed program/erase operation, the device can simultaneously obtain high program/erase ratio (≈106), appropriate storage time (≈103 s), record‐breaking detectivity (≈1016 Jones) and multibit storage capacity with a simple program/erase operation. It even has a potential application as a flexible optoelectronic device. Therefore, the designed concept here opens an avenue for high‐throughput fast data communications.

Published in: "Small".

Molecule‐Driven Nanoenergy Generator

2018-12-16T00:33:33+00:00December 15th, 2018|Categories: Publications|Tags: , |

A nanoenergy generator that comprises half‐sealed single‐crystalline ZnO nanowires (NWs) can generate electricity from various organic molecules including gaseous species from human breath. The magnitude of the voltage generated by ZnO NWs is about one‐order of magnitude larger than the typical streaming or piezoelectric potentials, and is powerful enough to directly drive a single carbon nanotube field‐effect transistor. Abstract A large potential can be generated when one end of 1D and/or 2D semiconducting nanostructures such as zinc oxide (ZnO) and molybdenum disulfide is exposed to a wide spectrum of chemical molecules. A nanoenergy generator that comprises vertically aligned ZnO nanowires and poly(vinyl chloride‐co‐vinyl‐co‐2‐hydroxypropyl acrylate) is fabricated, and it can generate electricity from various molecules including gaseous species exhaled from human breath. The generated voltage, which depends sensitively on the molecular dipole moment of adsorbed chemical species and surface coverage, is significantly larger than the streaming or piezoelectric potentials and is powerful enough to directly drive a single carbon nanotube field‐effect transistor. It is demonstrated that the notion of voltage generation through molecule‐surface interactions bears general implications to other semiconducting materials, and has the advantages of simplicity, cost‐effectiveness, fast response to a wide range of molecules, and high power output, making our approach a promising tool for energy conversion and sensing applications.

Published in: "Small".

2D MoS2‐Based Nanomaterials for Therapeutic, Bioimaging, and Biosensing Applications

2018-12-16T00:33:18+00:00December 15th, 2018|Categories: Publications|Tags: |

2D MoS2‐based nanomaterials have emerged as a new class of material for biomedical applications. This review article discusses the growth of MoS2 as a nanomaterial in the field of biomedicine by highlighting its diverse applications in drug/gene delivery, phototherapy, imaging, sensing, and theranostics, which demonstrates the potential of this 2D material to evolve as a new class of nanomedicine. Abstract Molybdenum disulfide (MoS2), a typical layered 2D transition metal dichalcogenide, has received colossal interest in the past few years due to its unique structural, physicochemical, optical, and biological properties. While MoS2 is mostly applied in traditional industries such as dry lubricants, intercalation agents, and negative electrode material in lithium‐ion batteries, its 2D and 0D forms have led to diverse applications in sensing, catalysis, therapy, and imaging. Herein, a systematic overview of the progress that is made in the field of MoS2 research with an emphasis on its different biomedical applications is presented. This article provides a general discussion on the basic structure and property of MoS2 and gives a detailed description of its different morphologies that are synthesized so far, namely, nanosheets, nanotubes, and quantum dots along with synthesis strategies. The biomedical applications of MoS2‐based nanocomposites are also described in detail and categorically, such as in varied therapeutic and diagnostic modalities like drug delivery, gene delivery, phototherapy, combined therapy, bioimaging, theranostics, and biosensing. Finally, a brief commentary on the current challenges and limitations being faced is provided, along with a discussion of some future perspectives for the overall improvement of

Published in: "Small".

MoS2/NiS Yolk–Shell Microsphere‐Based Electrodes for Overall Water Splitting and Asymmetric Supercapacitor

2018-12-16T00:33:16+00:00December 15th, 2018|Categories: Publications|Tags: , |

MoS2/NiS yolk–shell microspheres exhibit prominent electrochemical performance for both overall water splitting and asymmetric supercapacitors, which can be attributed to the advanced structural features of the interface effect and hollow structure. Abstract Rational designing of the composition and structure of electrode material is of great significance for achieving highly efficient energy storage and conversion in electrochemical energy devices. Herein, MoS2/NiS yolk–shell microspheres are successfully synthesized via a facile ionic liquid‐assisted one‐step hydrothermal method. With the favorable interface effect and hollow structure, the electrodes assembled with MoS2/NiS hybrid microspheres present remarkably enhanced electrochemical performance for both overall water splitting and asymmetric supercapacitors. In particular, to deliver a current density of 10 mA cm−2, the MoS2/NiS‐based electrolysis cell for overall water splitting only needs an output voltage of 1.64 V in the alkaline medium, lower than that of Pt/C–IrO2‐based electrolysis cells (1.70 V). As an electrode for supercapacitors, the MoS2/NiS hybrid microspheres exhibit a specific capacitance of 1493 F g−1 at current density of 0.2 A g−1, and remain 1165 F g−1 even at a large current density of 2 A g−1, implying outstanding charge storage capacity and excellent rate performance. The MoS2/NiS‐ and active carbon‐based asymmetric supercapacitor manifests a maximum energy density of 31 Wh kg−1 at a power density of 155.7 W kg−1, and remarkable cycling stability with a capacitance retention of approximately 100% after 10 000 cycles.

Published in: "Small".

Micro‐Nano Fabrication: Fabrication of Sub‐Micrometer‐Sized MoS2 Thin‐Film Transistor by Phase Mode AFM Lithography (Small 49/2018)

2018-12-16T00:33:09+00:00December 15th, 2018|Categories: Publications|Tags: |

In article number 1803273, Lianqing Liu and co‐workers propose a unique mask‐free and marker‐free lithography technique to fabricate a sub‐micrometer‐sized 2D material thin‐film transistor using the phase mode of atomic force microscopy. This method does not change the chemical, physical, and electrical properties of 2D materials. It offers a flexible, easy, effective, and low‐cost way to fabricate prototypes of sub‐micrometer‐sized devices, and provides the opportunity to explore the potential performance of 2D materials.

Published in: "Small".

Room‐Temperature Ultrabroadband Photodetection with MoS2 by Electronic‐Structure Engineering Strategy

2018-12-15T22:34:14+00:00December 15th, 2018|Categories: Publications|Tags: , |

Based on a proposed novel electronicstructure strategy, layered MoS2 is designed, which realizes ultrabroadband photodetection at room temperature. By introducing defect energy levels, the bandgap and electronic state density are modulated suitably. The prototype photodetector is investigated from 445 nm (blue) to 9536 nm (far‐IR) and offers a record high photoresponsivity of 21.8 mA W−1 (7.79 µm). Abstract Photodetection using semiconductors is critical for capture, identification, and processing of optical information. Nowadays, broadband photodetection is limited by the underdeveloped mid‐IR photodetection at room temperature (RT), primarily as a result of the large dark currents unavoidably generated by the Fermi–Dirac distribution in narrow‐bandgap semiconductors, which constrains the development of some modern technologies and systems. Here, an electronic‐structure strategy is proposed for designing ultrabroadband covering mid‐ and even far‐IR photodetection materials operating at RT and a layered MoS2 is manifested with an engineered bandgap of 0.13 eV and modulated electronic state density. The sample is designed by introducing defect energy levels into layered MoS2 and its RT photodetection is demonstrated for wavelengths from 445 nm to 9.5 µm with an electronic state density‐dependent peak photoresponsivity of 21.8 mA W−1 in the mid‐IR region, the highest value among all known photodetectors. This material should be a promising candidate for modern optoelectronic devices and offers inspiration for the design of other optoelectronic materials.

Published in: "Advanced Materials".

Photonic Memory: Infrared‐Sensitive Memory Based on Direct‐Grown MoS2–Upconversion‐Nanoparticle Heterostructure (Adv. Mater. 49/2018)

2018-12-15T22:33:45+00:00December 15th, 2018|Categories: Publications|Tags: , |

In article number 1803563, Feng Wang, Ye Zhou, Su‐Ting Han, and co‐workers develop an NIR photonic memristor based on a MoS2–upconversion nanoparticle heterostructure. The heterostructure, acting as exciton generation/separation centers, remarkably improves NIR‐light‐controlled memory performance. Meanwhile, the as‐fabricated photonic memory array also displays high integration with photodetectors, and can be used to make a core component of a bioinspired vision system.

Published in: "Advanced Materials".

Infrared‐Sensitive Memory Based on Direct‐Grown MoS2–Upconversion‐Nanoparticle Heterostructure

2018-12-15T22:33:43+00:00December 15th, 2018|Categories: Publications|Tags: , |

A MoS2–upconversion‐nanoparticle (UCNP) nanocomposite is used to fabricate near‐infrared (NIR) modulated photonic resistive‐switching memory. The heterostructure between the MoS2 and the UCNPs acting as excitons generation/separation centers remarkably improves the NIR‐light‐controlled memory performance. Meanwhile, the as‐fabricated photonic memory array also displays high integration with photodetectors, and can thus be used to make a core component of bioinspired vision systems. Abstract Photonic memories as an emerging optoelectronic technology have attracted tremendous attention in the past few years due to their great potential to overcome the von Neumann bottleneck and to improve the performance of serial computers. Nowadays, the decryption technology for visible light is mature in photonic memories. Nevertheless, near‐infrared (NIR) photonic memristors are less progressed. Herein, an NIR photonic memristor based on MoS2–NaYF4:Yb3+, Er3+ upconversion nanoparticles (UCNPs) nanocomposites is designed. Under excitation by 980 nm NIR light, the UCNPs show emissions well overlapping with the absorption band of the MoS2 nanosheets. The heterostructure between the MoS2 and the UCNPs acting as excitons generation/separation centers remarkably improves the NIR‐light‐controlled memristor performance. Furthermore, in situ conductive atomic force microscopy is employed to elucidate the photo‐modulated memristor mechanism. This work provides novel opportunities for NIR photonic memory that holds promise in future multifunctional robotics and electronic eyes.

Published in: "Advanced Materials".

Molecule‐Driven Nanoenergy Generator

2018-12-15T10:33:42+00:00December 15th, 2018|Categories: Publications|Tags: , |

A nanoenergy generator that comprises half‐sealed single‐crystalline ZnO nanowires (NWs) can generate electricity from various organic molecules including gaseous species from human breath. The magnitude of the voltage generated by ZnO NWs is about one‐order of magnitude larger than the typical streaming or piezoelectric potentials, and is powerful enough to directly drive a single carbon nanotube field‐effect transistor. Abstract A large potential can be generated when one end of 1D and/or 2D semiconducting nanostructures such as zinc oxide (ZnO) and molybdenum disulfide is exposed to a wide spectrum of chemical molecules. A nanoenergy generator that comprises vertically aligned ZnO nanowires and poly(vinyl chloride‐co‐vinyl‐co‐2‐hydroxypropyl acrylate) is fabricated, and it can generate electricity from various molecules including gaseous species exhaled from human breath. The generated voltage, which depends sensitively on the molecular dipole moment of adsorbed chemical species and surface coverage, is significantly larger than the streaming or piezoelectric potentials and is powerful enough to directly drive a single carbon nanotube field‐effect transistor. It is demonstrated that the notion of voltage generation through molecule‐surface interactions bears general implications to other semiconducting materials, and has the advantages of simplicity, cost‐effectiveness, fast response to a wide range of molecules, and high power output, making our approach a promising tool for energy conversion and sensing applications.

Published in: "Small".

Discovering the forbidden Raman modes at the edges of layered materials

2018-12-14T20:36:54+00:00December 14th, 2018|Categories: Publications|Tags: , , , , |

The edges of layered materials have unique properties that substantially differ from the body regions. In this work, we perform a systematic Raman study of the edges of various layered materials (MoS2, WS2, WSe2, PtS2, and black phosphorus). The Raman spectra of the edges feature newly observed forbidden Raman modes,

Published in: "Science Advances".

Suppression of the Shear Raman Mode in Defective Bilayer MoS2. (arXiv:1812.05543v1 [cond-mat.mtrl-sci])

2018-12-14T02:29:15+00:00December 14th, 2018|Categories: Publications|Tags: |

We investigate the effects of lattice disorders on the low frequency Raman spectra of bilayer MoS2. The bilayer MoS2 was subjected to defect engineering by irradiation with a 30 keV He+ ion beam and the induced morphology change was characterized by transmission electron microscopy. With increasing ion dose the shear mode is observed to redshift and it is also suppressed sharply compared to other Raman peaks. We use the linear chain model to describe the changes to the Raman spectra. Our observations suggest that crystallite size and orientation are the dominant factors behind the changes to the Raman spectra.

Published in: "arXiv Material Science".

High‐Performance Photoinduced Memory with Ultrafast Charge Transfer Based on MoS2/SWCNTs Network Van Der Waals Heterostructure

2018-12-13T22:34:42+00:00December 13th, 2018|Categories: Publications|Tags: , |

A high‐speed photoinduced memory device is achieved based on the MoS2/single‐walled carbon nanotube network mixed‐dimensional van der Waals heterostructure. It demonstrates the multibit storage capacity, and meets all needs of an ideal photoinduced memory simultaneously—a record fast program/erase operation of 32/0.4 ms, a high program/erase ratio (106), appropriate storage time (103 s), and simple program/erase operation at room temperature. Abstract Photoinduced memory devices with fast program/erase operations are crucial for modern communication technology, especially for high‐throughput data storage and transfer. Although some photoinduced memories based on 2D materials have already demonstrated desirable performance, the program/erase speed is still limited to hundreds of micro‐seconds. A high‐speed photoinduced memory based on MoS2/single‐walled carbon nanotubes (SWCNTs) network mixed‐dimensional van der Waals heterostructure is demonstrated here. An intrinsic ultrafast charge transfer occurs at the heterostructure interface between MoS2 and SWCNTs (below 50 fs), therefore enabling a record program/erase speed of ≈32/0.4 ms, which is faster than that of the previous reports. Furthermore, benefiting from the unique device structure and material properties, while achieving high‐speed program/erase operation, the device can simultaneously obtain high program/erase ratio (≈106), appropriate storage time (≈103 s), record‐breaking detectivity (≈1016 Jones) and multibit storage capacity with a simple program/erase operation. It even has a potential application as a flexible optoelectronic device. Therefore, the designed concept here opens an avenue for high‐throughput fast data communications.

Published in: "Small".

Micro‐Nano Fabrication: Fabrication of Sub‐Micrometer‐Sized MoS2 Thin‐Film Transistor by Phase Mode AFM Lithography (Small 49/2018)

2018-12-13T04:36:41+00:00December 13th, 2018|Categories: Publications|Tags: |

In article number 1803273, Lianqing Liu and co‐workers propose a unique mask‐free and marker‐free lithography technique to fabricate a sub‐micrometer‐sized 2D material thin‐film transistor using the phase mode of atomic force microscopy. This method does not change the chemical, physical, and electrical properties of 2D materials. It offers a flexible, easy, effective, and low‐cost way to fabricate prototypes of sub‐micrometer‐sized devices, and provides the opportunity to explore the potential performance of 2D materials.

Published in: "Small".

Room‐Temperature Ultrabroadband Photodetection with MoS2 by Electronic‐Structure Engineering Strategy

2018-12-13T00:34:08+00:00December 12th, 2018|Categories: Publications|Tags: , |

Based on a proposed novel electronicstructure strategy, layered MoS2 is designed, which realizes ultrabroadband photodetection at room temperature. By introducing defect energy levels, the bandgap and electronic state density are modulated suitably. The prototype photodetector is investigated from 445 nm (blue) to 9536 nm (far‐IR) and offers a record high photoresponsivity of 21.8 mA W−1 (7.79 µm). Abstract Photodetection using semiconductors is critical for capture, identification, and processing of optical information. Nowadays, broadband photodetection is limited by the underdeveloped mid‐IR photodetection at room temperature (RT), primarily as a result of the large dark currents unavoidably generated by the Fermi–Dirac distribution in narrow‐bandgap semiconductors, which constrains the development of some modern technologies and systems. Here, an electronic‐structure strategy is proposed for designing ultrabroadband covering mid‐ and even far‐IR photodetection materials operating at RT and a layered MoS2 is manifested with an engineered bandgap of 0.13 eV and modulated electronic state density. The sample is designed by introducing defect energy levels into layered MoS2 and its RT photodetection is demonstrated for wavelengths from 445 nm to 9.5 µm with an electronic state density‐dependent peak photoresponsivity of 21.8 mA W−1 in the mid‐IR region, the highest value among all known photodetectors. This material should be a promising candidate for modern optoelectronic devices and offers inspiration for the design of other optoelectronic materials.

Published in: "Advanced Materials".

Infrared‐Sensitive Memory Based on Direct‐Grown MoS2–Upconversion‐Nanoparticle Heterostructure

2018-12-13T00:33:53+00:00December 12th, 2018|Categories: Publications|Tags: , |

A MoS2–upconversion‐nanoparticle (UCNP) nanocomposite is used to fabricate near‐infrared (NIR) modulated photonic resistive‐switching memory. The heterostructure between the MoS2 and the UCNPs acting as excitons generation/separation centers remarkably improves the NIR‐light‐controlled memory performance. Meanwhile, the as‐fabricated photonic memory array also displays high integration with photodetectors, and can thus be used to make a core component of bioinspired vision systems. Abstract Photonic memories as an emerging optoelectronic technology have attracted tremendous attention in the past few years due to their great potential to overcome the von Neumann bottleneck and to improve the performance of serial computers. Nowadays, the decryption technology for visible light is mature in photonic memories. Nevertheless, near‐infrared (NIR) photonic memristors are less progressed. Herein, an NIR photonic memristor based on MoS2–NaYF4:Yb3+, Er3+ upconversion nanoparticles (UCNPs) nanocomposites is designed. Under excitation by 980 nm NIR light, the UCNPs show emissions well overlapping with the absorption band of the MoS2 nanosheets. The heterostructure between the MoS2 and the UCNPs acting as excitons generation/separation centers remarkably improves the NIR‐light‐controlled memristor performance. Furthermore, in situ conductive atomic force microscopy is employed to elucidate the photo‐modulated memristor mechanism. This work provides novel opportunities for NIR photonic memory that holds promise in future multifunctional robotics and electronic eyes.

Published in: "Advanced Materials".

A MoS2/PTCDA Hybrid Heterojunction Synapse with Efficient Photoelectric Dual Modulation and Versatility

2018-12-13T00:33:48+00:00December 12th, 2018|Categories: Publications|Tags: , , |

A multifunctional artificial synapse based on a molybdenum disulfide/perylene‐3,4,9,10‐tetracarboxylic dianhydride hybrid heterojunction with remarkable short/long‐term plasticity and photoelectric dual modulation is demonstrated by exploiting the band alignment between two‐dimensional inorganic and organic semiconductors. Robust inhibition/excitation can be obtained in a single device. Excellent performance, including 3% inhibition, 500% facilitation, and synaptic weight change of up to 60, is demonstrated, which is far superior to previous work. Abstract Just as biological synapses provide basic functions for the nervous system, artificial synaptic devices serve as the fundamental building blocks of neuromorphic networks; thus, developing novel artificial synapses is essential for neuromorphic computing. By exploiting the band alignment between 2D inorganic and organic semiconductors, the first multi‐functional synaptic transistor based on a molybdenum disulfide (MoS2)/perylene‐3,4,9,10‐tetracarboxylic dianhydride (PTCDA) hybrid heterojunction, with remarkable short‐term plasticity (STP) and long‐term plasticity (LTP), is reported. Owing to the elaborate design of the energy band structure, both robust electrical and optical modulation are achieved through carriers transfer at the interface of the heterostructure, which is still a challenging task to this day. In electrical modulation, synaptic inhibition and excitation can be achieved simultaneously in the same device by gate voltage tuning. Notably, a minimum inhibition of 3% and maximum facilitation of 500% can be obtained by increasing the electrical number, and the response to different frequency signals indicates a dynamic filtering characteristic. It exhibits flexible tunability of both STP and LTP and synaptic weight changes of up to 60, far superior to previous work in optical modulation. The fully

Published in: "Advanced Materials".

Photonic Memory: Infrared‐Sensitive Memory Based on Direct‐Grown MoS2–Upconversion‐Nanoparticle Heterostructure (Adv. Mater. 49/2018)

2018-12-13T00:33:44+00:00December 12th, 2018|Categories: Publications|Tags: , |

In article number 1803563, Feng Wang, Ye Zhou, Su‐Ting Han, and co‐workers develop an NIR photonic memristor based on a MoS2–upconversion nanoparticle heterostructure. The heterostructure, acting as exciton generation/separation centers, remarkably improves NIR‐light‐controlled memory performance. Meanwhile, the as‐fabricated photonic memory array also displays high integration with photodetectors, and can be used to make a core component of a bioinspired vision system.

Published in: "Advanced Materials".

Reversible and selective ion intercalation through the top surface of few-layer MoS<sub>2</sub>

2018-12-11T10:36:06+00:00December 11th, 2018|Categories: Publications|Tags: |

Reversible and selective ion intercalation through the top surface of few-layer MoS2Reversible and selective ion intercalation through the top surface of few-layer MoS<sub>2</sub>, Published online: 11 December 2018; doi:10.1038/s41467-018-07710-zElectrochemical ion intercalation in 2D layered materials is known to occur through the material’s edges, accompanied by frequent structural deformations. Here the authors show that in MoS2 flakes where the edges have been sealed, a reversible and ion-selective intercalation occurs through the top surface via the intrinsic defects.

Published in: "Nature Communications".

A Novel Route to Manufacture [email protected] p-n Heterostructure Hollow Tubes with Enhanced Photocatalytic Activity

2018-12-11T04:36:42+00:00December 11th, 2018|Categories: Publications|Tags: , |

Chem. Commun., 2018, Accepted ManuscriptDOI: 10.1039/C8CC08614A, CommunicationYing Zeng, Na Guo, Haiyan Li, Quanying Wang, Xingjian Xu, Yong Yu, Xuerong Han, Hongwen [email protected] n-p heterostructure hollow tubes ([email protected] tubes) with large surface area have been prepared for the first time by a facile one-pot hydrothermal method. Notabely, the [email protected] tubes present the…The content of this RSS Feed (c) The Royal Society of Chemistry

Published in: "Chemical Communications".

Exchange-driven intravalley mixing of excitons in monolayer transition metal dichalcogenides

2018-12-10T16:34:40+00:00December 10th, 2018|Categories: Publications|Tags: |

Exchange-driven intravalley mixing of excitons in monolayer transition metal dichalcogenidesExchange-driven intravalley mixing of excitons in monolayer transition metal dichalcogenides, Published online: 10 December 2018; doi:10.1038/s41567-018-0362-yTwo-dimensional electronic spectroscopy experiments and first-principles many-electron calculations demonstrate the quantum mixing of different exciton states in monolayer MoS2. This reveals the many-body effects and dynamics of exciton formation in 2D materials.

Published in: "Nature Physics".

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