MoS2

/Tag: MoS2

Multivalent Glycosheets for Double Light–Driven Therapy of Multidrug‐Resistant Bacteria on Wounds

2019-02-10T14:34:28+00:00February 10th, 2019|Categories: Publications|Tags: |

A multivalent, double light–driven glycosheet is developed for the effective killing of multidrug‐resistant, clinically isolated P. Aeruginosa on wounds. Abstract With the evergrowing threat posed by multidrug resistance of bacteria, the development of effective antibacterial agents remains a global challenge. Infection with multidrug‐resistant bacteria in hospitals significantly impairs the healing of wounds caused by deep‐burn injuries or diabetic foot ulceration, leading to a high mortality rate among these patients. A multivalent glycosheet for the double light–driven therapy against multidrug‐resistant Pseudomonas aeruginosa (P. aeruginosa) infection on wounds is developed here. Galactose‐ and fucose‐based ligands are self‐assembled to form a glyco‐layer on the surface of thin‐layer molybdenum disulfide, producing the glycosheets capable of selectively localizing P. aeruginosa through multivalent carbohydrate–lectin interactions. The glycosheets loaded with antibiotics have proven applicable for: 1) near‐infrared‐light driven, in situ thermal release of antibiotics, increasing bacterial membrane permeability, and 2) white light–driven reactive‐oxygen‐species production to more thoroughly kill the bacteria. The targetability, together with the light sensibility, of the glycosheets enables a highly effective and optically controlled therapeutic regime for the healing of wounds infected by multidrug‐resistant as well as clinically isolated P. aeruginosa.

Published in: "Advanced Functional Materials".

Van der Waals Bipolar Junction Transistor Using Vertically Stacked Two‐Dimensional Atomic Crystals

2019-02-10T14:34:14+00:00February 10th, 2019|Categories: Publications|Tags: , , |

Van der Waals bipolar junction transistors based on vertically stacked 2D materials (V2D‐BJT) are proposed, and experimental studies are conducted on the V2D‐BJT using an MoS2/WSe2/MoS2 heterostructure in an n‐p‐n configuration. The V2D‐BJT shows excellent gas sensing performance with a low power dissipation (≈2 nW), a fast response (9 s), and a fast recovery (35 s) time. Abstract The majority of microelectronic devices rely on a p‐n junction. The process of making such a junction is complicated, and it is difficult to make layers that form a junction with an atomic thickness. In this study, bipolar junctions are made by using 2D atomic crystalline layers and even a single layer in which 2D layers adhere together to form a heterostructure via van der Waals forces. A vertical 2D bipolar junction transistor (V2D‐BJT) is studied for the first time. It uses an MoS2/WSe2/MoS2 heterostructure and has an n‐p‐n configuration that exhibits a maximum common‐base current gain of ≈0.97 and a stable common‐emitter current gain (β) of 12 with a nanowatt power consumption. In the first attempt at gas sensing, it shows outstanding performance, exhibiting a very fast response and recovery time (9 and 35 s, respectively) with a power dissipation of only 2 nW. This study demonstrates the potential application of the V2D‐BJT in nanowatt power amplifiers as well as fast‐response and low‐power gas sensors.

Published in: "Advanced Functional Materials".

Multivalent Glycosheets for Double Light–Driven Therapy of Multidrug‐Resistant Bacteria on Wounds

2019-02-09T10:32:58+00:00February 9th, 2019|Categories: Publications|Tags: |

A multivalent, double light–driven glycosheet is developed for the effective killing of multidrug‐resistant, clinically isolated P. Aeruginosa on wounds. Abstract With the evergrowing threat posed by multidrug resistance of bacteria, the development of effective antibacterial agents remains a global challenge. Infection with multidrug‐resistant bacteria in hospitals significantly impairs the healing of wounds caused by deep‐burn injuries or diabetic foot ulceration, leading to a high mortality rate among these patients. A multivalent glycosheet for the double light–driven therapy against multidrug‐resistant Pseudomonas aeruginosa (P. aeruginosa) infection on wounds is developed here. Galactose‐ and fucose‐based ligands are self‐assembled to form a glyco‐layer on the surface of thin‐layer molybdenum disulfide, producing the glycosheets capable of selectively localizing P. aeruginosa through multivalent carbohydrate–lectin interactions. The glycosheets loaded with antibiotics have proven applicable for: 1) near‐infrared‐light driven, in situ thermal release of antibiotics, increasing bacterial membrane permeability, and 2) white light–driven reactive‐oxygen‐species production to more thoroughly kill the bacteria. The targetability, together with the light sensibility, of the glycosheets enables a highly effective and optically controlled therapeutic regime for the healing of wounds infected by multidrug‐resistant as well as clinically isolated P. aeruginosa.

Published in: "Advanced Functional Materials".

Vertical, electrolyte-gated organic transistors: continuous operation in the MA/cm$^2$ regime and use as low-power artificial synapses. (arXiv:1902.01854v1 [physics.app-ph] CROSS LISTED)

2019-02-07T04:30:31+00:00February 7th, 2019|Categories: Publications|Tags: , |

Organic semiconductors are usually not thought to show outstanding performance in highly-integrated, sub 100 nm transistors. Consequently, single-crystalline materials such as SWCNTs, MoS2 or inorganic semiconductors are the material of choice at these nanoscopic dimensions. Here, we show that using a novel vertical field-effect transistor design with a channel length of only 40 nm and a footprint of 2 x 80 x 80 nm$^2$, high electrical performance with organic polymers can be realized when using electrolyte gating. Our organic transistors combine high on-state current densities of above 3 MA/cm$^2$, on/off current modulation ratios of up to 108 and large transconductances of up to 5000 S/m. Given the high on-state currents at yet large on/off ratios, our novel structures also show promise for use in artificial neural networks, where they could operate as memristive devices with sub 100 fJ energy usage.

Published : "arXiv Mesoscale and Nanoscale Physics".

Fabrication of interlayer β-CD/[email protected] for highly enhanced photodegradation of glyphosate under simulated sunlight irradiation

2019-02-06T10:37:50+00:00February 6th, 2019|Categories: Publications|Tags: |

RSC Adv., 2019, 9,4635-4643DOI: 10.1039/C8RA10190F, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Xiufang He, Zhansheng Wu, Yongtao Xue, Zhenzhen Gao, Xia YangThe fabrication of an interlayer β-CD/[email protected] composite photocatalyst for highly enhanced photodegradation of glyphosate

Published in: "RSC Advances".

Van der Waals Bipolar Junction Transistor Using Vertically Stacked Two‐Dimensional Atomic Crystals

2019-02-04T12:37:39+00:00February 4th, 2019|Categories: Publications|Tags: , , |

Van der Waals bipolar junction transistors based on vertically stacked 2D materials (V2D‐BJT) are proposed, and experimental studies are conducted on the V2D‐BJT using an MoS2/WSe2/MoS2 heterostructure in an n‐p‐n configuration. The V2D‐BJT shows excellent gas sensing performance with a low power dissipation (≈2 nW), a fast response (9 s), and a fast recovery (35 s) time. Abstract The majority of microelectronic devices rely on a p‐n junction. The process of making such a junction is complicated, and it is difficult to make layers that form a junction with an atomic thickness. In this study, bipolar junctions are made by using 2D atomic crystalline layers and even a single layer in which 2D layers adhere together to form a heterostructure via van der Waals forces. A vertical 2D bipolar junction transistor (V2D‐BJT) is studied for the first time. It uses an MoS2/WSe2/MoS2 heterostructure and has an n‐p‐n configuration that exhibits a maximum common‐base current gain of ≈0.97 and a stable common‐emitter current gain (β) of 12 with a nanowatt power consumption. In the first attempt at gas sensing, it shows outstanding performance, exhibiting a very fast response and recovery time (9 and 35 s, respectively) with a power dissipation of only 2 nW. This study demonstrates the potential application of the V2D‐BJT in nanowatt power amplifiers as well as fast‐response and low‐power gas sensors.

Published in: "Advanced Functional Materials".

Aligned Heterointerface‐Induced 1T‐MoS2 Monolayer with Near‐Ideal Gibbs Free for Stable Hydrogen Evolution Reaction

2019-02-04T02:37:33+00:00February 4th, 2019|Categories: Publications|Tags: , , , |

The hydrogen evolution reaction from 1T‐MoS2 exhibits high efficiency but suffers from durability problems. The 1T‐MoS2 monolayer at the edge‐aligned 2H‐MoS2 and N‐RGO interface shows stable and highly efficient electrochemical properties for the hydrogen evolution reaction (HER) in acidic electrolyte. Abstract 1T‐phase molybdenum disulfide (1T‐MoS2) exhibits superior hydrogen evolution reaction (HER) over 2H‐phase MoS2 (2H‐MoS2). However, its thermodynamic instability is the main drawback impeding its practical application. In this work, a stable 1T‐MoS2 monolayer formed at edge‐aligned 2H‐MoS2 and a reduced graphene oxide heterointerface (EA‐2H/1T/RGO) using a precursor‐in‐solvent synthesis strategy are reported. Theoretical prediction indicates that the edge‐aligned layer stacking can induce heterointerfacial charge transfer, which results in a phase transition of the interfacial monolayer from 2H to 1T that realizes thermodynamic stability based on the adhesion energy between MoS2 and graphene. As an electrocatalyst for HER, EA‐2H/1T/RGO displays an onset potential of −103 mV versus RHE, a Tafel slope of 46 mV dec−1 and 10 h stability in acidic electrolyte. The unexpected activity of EA‐2H/1T/RGO beyond 1T‐MoS2 is due to an inherent defect caused by the gliding of S atoms during the phase transition from 2H to 1T, leading the Gibbs free energy of hydrogen adsorption (ΔGH*) to decrease from 0.13 to 0.07 eV, which is closest to the ideal value (0.06 eV) of 2H‐MoS2. The presented work provides fundamental insights into the impressive electrochemical properties of HER and opens new avenues for phase transitions at 2D/2D hybrid interfaces.

Published in: "Small".

[email protected]‐Doped [email protected] Nanosheets: An Efficient Electrocatalyst for Hydrogen Evolution Reaction

2019-02-04T02:37:12+00:00February 4th, 2019|Categories: Publications|Tags: |

[email protected]‐doped [email protected] nanosheets ([email protected]@MoS2) hierarchical sub‐microspheres are prepared by a simple hydrothermal process. The [email protected]@MoS2 displays excellent electrocatalytic activity for the hydrogen evolution reaction due to the synergistic effect of dense catalytic sites on MoS2 nanosheets with exposed edges, expanded interlayer spacings and rich defects, and the rapid electron transfer from [email protected] substrate to MoS2 nanosheets. Abstract Developing cheap, abundant, and easily available electrocatalysts to drive the hydrogen evolution reaction (HER) at small overpotentials is an urgent demand of hydrogen production from water splitting. Molybdenum disulfide (MoS2) based composites have emerged as competitive electrocatalysts for HER in recent years. Herein, [email protected]‐doped [email protected] nanosheets ([email protected]@MoS2) hybrid sub‐microspheres are presented as HER catalyst. MoS2 nanosheets with expanded interlayer spacings are vertically grown on [email protected]‐doped carbon ([email protected]) substrate to form [email protected]@MoS2 hierarchical sub‐microspheres by a simple hydrothermal process. The formed [email protected]@MoS2 composites display excellent electrocatalytic activity for HER with an onset overpotential of 18 mV, a low overpotential of 82 mV at 10 mA cm−2, a small Tafel slope of 47.5 mV dec−1, and high durability in 0.5 H2SO4 solution. The outstanding HER performance of the [email protected]@MoS2 catalyst can be ascribed to the synergistic effect of dense catalytic sites on MoS2 nanosheets with exposed edges and expanded interlayer spacings, and the rapid electron transfer from [email protected] substrate to MoS2 nanosheets. The excellent [email protected]@MoS2 electrocatalyst promises potential application in practical hydrogen production, and the strategy reported here can also be extended to grow MoS2 on other nitrogen‐doped carbon encapsulated metal species for various applications.

Published in: "Small".

Probing the origin of lateral heterogeneities in synthetic monolayer molybdenum disulfide

2019-02-01T12:55:33+00:00February 1st, 2019|Categories: Publications|Tags: |

Synthetic two-dimensional (2D) materials provide an opportunity to realize large-scale applications in next generation electronic and optoelectronic devices. One of the biggest challenges of synthetic 2D materials is the lateral heterogeneity such as non-uniform strain, composition and defect density. The electronic and optical properties are found to be not uniform in many cases, even within a single crystalline domain, potentially limiting synthetic 2D materials in advanced devices. In this work, we probe the origin of the widely observed lateral heterogeneities in synthetic monolayer MoS 2 . Epitaxial single crystalline domains (~10 µ m) are optically homogeneous and uniform with 0.3%–0.4% tensile strain, while misoriented domains (>20 µ m) exhibit distinct photoluminescence (PL) emissions from the center to the edge, along with released strain at the center. Temperature-dependent Raman and PL mapping reveals that the center of non-epitaxial domains ex…

Published in: "2DMaterials".

MoS2 nanosheet mediated ZnO–g-C3N4 nanocomposite as a peroxidase mimic: catalytic activity and application in the colorimetric determination of Hg(II)

2019-02-01T12:39:44+00:00February 1st, 2019|Categories: Publications|Tags: |

RSC Adv., 2019, 9,4268-4276DOI: 10.1039/C8RA09814J, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.A. Anand Babu Christus, P. Panneerselvam, A. Ravikumar, M. Marieeswaran, S. SivanesanA novel colorimetric sensing platform using the peroxidase mimicking activity of ternary

Published in: "RSC Advances".

Interlayer excitons in bilayer ${mathrm{MoS}}_{2}$ with strong oscillator strength up to room temperature

2019-01-31T14:43:08+00:00January 31st, 2019|Categories: Publications|Tags: , |

Author(s): Iann C. Gerber, Emmanuel Courtade, Shivangi Shree, Cedric Robert, Takashi Taniguchi, Kenji Watanabe, Andrea Balocchi, Pierre Renucci, Delphine Lagarde, Xavier Marie, and Bernhard UrbaszekTransition metal dichalcogenides are semiconducting materials in which optical properties are governed by Coulomb-bound electron-hole pairs, called excitons. Here, the authors investigate the different excitonic properties of monolayer, bilayer, and trilayer MoS2, revealing the existence of interlayer excitons in the last two cases. The paper presents both theoretical and experimental studies. DFT calculations of absorption are underpinned by reflectivity measurements, at temperatures from 4 to 300 K, on high-quality samples encapsulated in hexagonal boron nitride (hBN).[Phys. Rev. B 99, 035443] Published Thu Jan 31, 2019

Published in: "Physical Review B".

Highly Efficient Solar‐Driven Carbon Dioxide Reduction on Molybdenum Disulfide Catalyst Using Choline Chloride‐Based Electrolyte

2019-01-30T20:34:14+00:00January 30th, 2019|Categories: Publications|Tags: , |

An efficient and scalable solar‐driven CO2 reduction process is reported based on an MoS2 catalyst and an inexpensive hybrid electrolyte of choline chloride and KOH. A maximum solar to fuel and catalytic conversion efficiencies of 23% and 83% are obtained, respectively. This demonstration of solar‐driven CO2 conversion process is a key step toward the industrialization of this technology. Abstract Conversion of CO2 to energy‐rich chemicals using renewable energy is of much interest to close the anthropogenic carbon cycle. However, the current photoelectrochemical systems are still far from being practically feasible. Here the successful demonstration of a continuous, energy efficient, and scalable solar‐driven CO2 reduction process based on earth‐abundant molybdenum disulfide (MoS2) catalyst, which works in synergy with an inexpensive hybrid electrolyte of choline chloride (a common food additive for livestock) and potassium hydroxide (KOH) is reported. The CO2 saturated hybrid electrolyte utilized in this study also acts as a buffer solution (pH ≈ 7.6) to adjust pH during the reactions. This study reveals that this system can efficiently convert CO2 to CO with solar‐to‐fuel and catalytic conversion efficiencies of 23% and 83%, respectively. Using density functional theory calculations, a new reaction mechanism in which the water molecules near the MoS2 cathode act as proton donors to facilitate the CO2 reduction process by MoS2 catalyst is proposed. This demonstration of a continuous, cost‐effective, and energy efficient solar driven CO2 conversion process is a key step toward the industrialization of this technology.

Published in: "Advanced Energy Materials".

Aligned Heterointerface‐Induced 1T‐MoS2 Monolayer with Near‐Ideal Gibbs Free for Stable Hydrogen Evolution Reaction

2019-01-30T10:37:11+00:00January 30th, 2019|Categories: Publications|Tags: , , , |

The hydrogen evolution reaction from 1T‐MoS2 exhibits high efficiency but suffers from durability problems. The 1T‐MoS2 monolayer at the edge‐aligned 2H‐MoS2 and N‐RGO interface shows stable and highly efficient electrochemical properties for the hydrogen evolution reaction (HER) in acidic electrolyte. Abstract 1T‐phase molybdenum disulfide (1T‐MoS2) exhibits superior hydrogen evolution reaction (HER) over 2H‐phase MoS2 (2H‐MoS2). However, its thermodynamic instability is the main drawback impeding its practical application. In this work, a stable 1T‐MoS2 monolayer formed at edge‐aligned 2H‐MoS2 and a reduced graphene oxide heterointerface (EA‐2H/1T/RGO) using a precursor‐in‐solvent synthesis strategy are reported. Theoretical prediction indicates that the edge‐aligned layer stacking can induce heterointerfacial charge transfer, which results in a phase transition of the interfacial monolayer from 2H to 1T that realizes thermodynamic stability based on the adhesion energy between MoS2 and graphene. As an electrocatalyst for HER, EA‐2H/1T/RGO displays an onset potential of −103 mV versus RHE, a Tafel slope of 46 mV dec−1 and 10 h stability in acidic electrolyte. The unexpected activity of EA‐2H/1T/RGO beyond 1T‐MoS2 is due to an inherent defect caused by the gliding of S atoms during the phase transition from 2H to 1T, leading the Gibbs free energy of hydrogen adsorption (ΔGH*) to decrease from 0.13 to 0.07 eV, which is closest to the ideal value (0.06 eV) of 2H‐MoS2. The presented work provides fundamental insights into the impressive electrochemical properties of HER and opens new avenues for phase transitions at 2D/2D hybrid interfaces.

Published in: "Small".

Strained bubbles in van der Waals heterostructures as local emitters of photoluminescence with adjustable wavelength. (arXiv:1901.09727v1 [cond-mat.mes-hall])

2019-01-29T04:30:31+00:00January 29th, 2019|Categories: Publications|Tags: , , , , |

The possibility to tailor photoluminescence (PL) of monolayer transition metal dichalcogenides (TMDCs) using external factors such as strain, doping and external environment is of significant interest for optoelectronic applications. Strain in particular can be exploited as a means to continuously vary the bandgap. Micrometer-scale strain gradients were proposed for creating ‘artificial atoms’ that can utilize the so-called exciton funneling effect and work, for example, as exciton condensers. Here we describe room-temperature PL emitters that naturally occur whenever monolayer TMDC is deposited on an atomically flat substrate. These are hydrocarbon-filled bubbles which provide predictable, localized PL from well-separated submicron areas. Their emission energy is determined by the built-in strain controlled only by the substrate material, such that both the maximum strain and the strain profile are universal for all bubbles on a given substrate, i.e., independent of the bubble size. We show that for bubbles formed by monolayer MoS2, PL can be tuned between 1.72 to 1.81 eV by choosing bulk PtSe2, WS2, MoS2 or graphite as a substrate and its intensity is strongly enhanced by the funneling effect. Strong substrate-dependent quenching of the PL in areas of good contact between MoS2 and the substrate ensures localization of the luminescence to bubbles only; by employing optical reflectivity measurements we identify the mechanisms responsible for the quenching. Given the variety of available monolayer TMDCs and atomically flat substrates and the ease of creating such bubbles, our findings open a venue for making and studying the discussed light-emitting ‘artificial atoms’ that could be

Published : "arXiv Mesoscale and Nanoscale Physics".

Simultaneous Production and Functionalization of Boron Nitride Nanosheets by Sugar‐Assisted Mechanochemical Exfoliation

2019-01-26T22:34:46+00:00January 26th, 2019|Categories: Publications|Tags: , , |

Sucrose‐grafted BN nanosheets (sucrose‐g‐BNNSs) are produced by a simple yet efficient sucrose‐assisted mechanochemical exfoliation process, and easily dispersed in polar liquids. Compared to pure poly(vinyl alcohol) (PVA), the sucrose‐g‐BNNS/PVA composites show remarkably improved tensile strength, thermal dissipation and flame‐retardancy. This method also works for the simultaneous exfoliation and functionalization of many other two‐dimensional (2D) materials. Abstract Due to their extraordinary properties, boron nitride nanosheets (BNNSs) have great promise for many applications. However, the difficulty of their efficient preparation and their poor dispersibility in liquids are the current factors that limit this. A simple yet efficient sugar‐assisted mechanochemical exfoliation (SAMCE) method is developed here to simultaneously achieve their exfoliation and functionalization. This method has a high actual exfoliation yield of 87.3%, and the resultant BNNSs are covalently grafted with sugar (sucrose) molecules, and are well dispersed in both water and organic liquids. A new mechanical force–induced exfoliation and chemical grafting mechanism is proposed based on experimental and density functional theory investigations. Thanks to the good dispersibility of the nanosheets, flexible and transparent BNNS/poly(vinyl alcohol) (PVA) composite films with multifunctionality is fabricated. Compared to pure PVA films, the composite films have a remarkably improved tensile strength and thermal dissipation capability. Noteworthy, they are flame retardant and can effectively block light from the deep blue to the UV region. This SAMCE production method has proven to be highly efficient, green, low cost, and scalable, and is extended to the exfoliation and functionalization of other two‐dimensional (2D) materials including MoS2, WS2, and graphite.

Published in: "Advanced Materials".

Enhanced Photocarrier Generation with Selectable Wavelengths by M‐Decorated‐CuInS2 Nanocrystals (M = Au and Pt) Synthesized in a Single Surfactant Process on MoS2 Bilayers

2019-01-26T22:34:46+00:00January 26th, 2019|Categories: Publications|Tags: , |

Au‐ and Pt‐decorated CuInS2 nanocrystals (CIS NCs) are synthesized through a facile approach and demonstrated as sensitizer materials on bilayered MoS2‐based photodetectors. The enhancement of the responsivity is ≈22 times for the Pt‐CIS/MoS2 photodetector under the illumination of 405 nm and ≈40 times for Au‐CIS/MoS2 under the light of 532 nm due to efficient carrier generation and transportation compared with the pristine MoS2 device. Abstract A facile approach for the synthesis of Au‐ and Pt‐decorated CuInS2 nanocrystals (CIS NCs) as sensitizer materials on the top of MoS2 bilayers is demonstrated. A single surfactant (oleylamine) is used to prepare such heterostructured noble metal decorated CIS NCs from the pristine CIS. Such a feasible way to synthesize heterostructured noble metal decorated CIS NCs from the single surfactant can stimulate the development of the functionalized heterostructured NCs in large scale for practical applications such as solar cells and photodetectors. Photodetectors based on MoS2 bilayers with the synthesized nanocrystals display enhanced photocurrent, almost 20–40 times higher responsivity and the On/Off ratio is enlarged one order of magnitude compared with the pristine MoS2 bilayers‐based photodetectors. Remarkably, by using Pt‐ or Au‐decorated CIS NCs, the photocurrent enhancement of MoS2 photodetectors can be tuned between blue (405 nm) to green (532 nm). The strategy described here acts as a perspective to significantly improve the performance of MoS2‐based photodetectors with the controllable absorption wavelengths in the visible light range, showing the feasibility of the possible color detection.

Published in: "Small".

[email protected]‐Doped [email protected] Nanosheets: An Efficient Electrocatalyst for Hydrogen Evolution Reaction

2019-01-26T22:34:27+00:00January 26th, 2019|Categories: Publications|Tags: |

[email protected]‐doped [email protected] nanosheets ([email protected]@MoS2) hierarchical sub‐microspheres are prepared by a simple hydrothermal process. The [email protected]@MoS2 displays excellent electrocatalytic activity for the hydrogen evolution reaction due to the synergistic effect of dense catalytic sites on MoS2 nanosheets with exposed edges, expanded interlayer spacings and rich defects, and the rapid electron transfer from [email protected] substrate to MoS2 nanosheets. Abstract Developing cheap, abundant, and easily available electrocatalysts to drive the hydrogen evolution reaction (HER) at small overpotentials is an urgent demand of hydrogen production from water splitting. Molybdenum disulfide (MoS2) based composites have emerged as competitive electrocatalysts for HER in recent years. Herein, [email protected]‐doped [email protected] nanosheets ([email protected]@MoS2) hybrid sub‐microspheres are presented as HER catalyst. MoS2 nanosheets with expanded interlayer spacings are vertically grown on [email protected]‐doped carbon ([email protected]) substrate to form [email protected]@MoS2 hierarchical sub‐microspheres by a simple hydrothermal process. The formed [email protected]@MoS2 composites display excellent electrocatalytic activity for HER with an onset overpotential of 18 mV, a low overpotential of 82 mV at 10 mA cm−2, a small Tafel slope of 47.5 mV dec−1, and high durability in 0.5 H2SO4 solution. The outstanding HER performance of the [email protected]@MoS2 catalyst can be ascribed to the synergistic effect of dense catalytic sites on MoS2 nanosheets with exposed edges and expanded interlayer spacings, and the rapid electron transfer from [email protected] substrate to MoS2 nanosheets. The excellent [email protected]@MoS2 electrocatalyst promises potential application in practical hydrogen production, and the strategy reported here can also be extended to grow MoS2 on other nitrogen‐doped carbon encapsulated metal species for various applications.

Published in: "Small".

Phosphorus‐Mediated MoS2: Phosphorus‐Mediated MoS2 Nanowires as a High‐Performance Electrode Material for Quasi‐Solid‐State Sodium‐Ion Intercalation Supercapacitors (Small 4/2019)

2019-01-26T22:34:22+00:00January 26th, 2019|Categories: Publications|Tags: , |

In article number 1803984, Kwun Nam Hui, Chu‐Ying Ouyang, Seong Chan Jun, and co‐workers propose an efficient P‐anion doping strategy to enhance the electrochemical performance of MoS2 nanowires by increasing the number of electrochemically active sites, improving the electrical conductivity, and decreasing the energy barrier of Na+ ion diffusion. The resultant P‐doped MoS2 shows significantly high intercalation pseudocapacitance, indicating new opportunities to develop advanced electrode materials for supercapacitors.

Published in: "Small".

Threshold Voltage Control of Multilayered MoS2 Field‐Effect Transistors via Octadecyltrichlorosilane and their Applications to Active Matrixed Quantum Dot Displays Driven by Enhancement‐Mode Logic Gates

2019-01-26T22:34:15+00:00January 26th, 2019|Categories: Publications|Tags: |

Threshold voltage adjustment as a control manner for molybdenum disulfide (MoS2) field‐effect transistors (FETs) is demonstrated by back‐channel modification. Octadecyltrichlorosilane treatment on a back channel of MoS2 FETs induces a negative dipole at the interface, leading to depopulation of electrons. As representative applications, active control for one‐pixel quantum dot light‐emitting diode and full‐swing logic gates are successfully demonstrated. Abstract In recent past, for next‐generation device opportunities such as sub‐10 nm channel field‐effect transistors (FETs), tunneling FETs, and high‐end display backplanes, tremendous research on multilayered molybdenum disulfide (MoS2) among transition metal dichalcogenides has been actively performed. However, nonavailability on a matured threshold voltage control scheme, like a substitutional doping in Si technology, has been plagued for the prosperity of 2D materials in electronics. Herein, an adjustment scheme for threshold voltage of MoS2 FETs by using self‐assembled monolayer treatment via octadecyltrichlorosilane is proposed and demonstrated to show MoS2 FETs in an enhancement mode with preservation of electrical parameters such as field‐effect mobility, subthreshold swing, and current on–off ratio. Furthermore, the mechanisms for threshold voltage adjustment are systematically studied by using atomic force microscopy, Raman, temperature‐dependent electrical characterization, etc. For validation of effects of threshold voltage engineering on MoS2 FETs, full swing inverters, comprising enhancement mode drivers and depletion mode loads are perfectly demonstrated with a maximum gain of 18.2 and a noise margin of ≈45% of 1/2 V DD. More impressively, quantum dot light‐emitting diodes, driven by enhancement mode MoS2 FETs, stably demonstrate 120 cd m−2 at the gate‐to‐source voltage of 5

Published in: "Small".

Unique 1D Cd1−[email protected]‐MoS2/NiOx Nanohybrids: Highly Efficient Visible‐Light‐Driven Photocatalytic Hydrogen Evolution via Integrated Structural Regulation

2019-01-26T22:34:12+00:00January 26th, 2019|Categories: Publications|Tags: , |

Unique 1D Cd1 − xZn [email protected]‐MoS2/NiO x nanohybrids are prepared which demonstrate a superior visible‐light‐driven photocatalytic H2 evolution activity of 223.17 mmol h−1 g−1, a high apparent quantum yield of 64.1% at 420 nm, and a good stability under long‐time illumination, owing to the optimized band alignments, increased exposure of active sites, and facilitated interfacial charge separation. Abstract Development of noble‐metal‐free photocatalysts for highly efficient sunlight‐driven water splitting is of great interest. Nevertheless, for the photocatalytic H2 evolution reaction (HER), the integrated regulation study on morphology, electronic band structures, and surface active sites of catalyst is still minimal up to now. Herein, well‐defined 1D Cd1− xZn [email protected]‐MoS2/NiO x hybrid nanostructures with enhanced activity and stability for photocatalytic HER are prepared. Interestingly, the band alignments, exposure of active sites, and interfacial charge separation of Cd1− xZn [email protected]‐MoS2/NiO x are optimized by tuning the Zn‐doping content as well as the growth of defect‐rich O‐MoS2 layer and NiO x nanoparticles, which endow the hybrids with excellent HER performances. Specifically, the visible‐light‐driven (>420 nm) HER activity of Cd1− xZn [email protected]‐MoS2/NiO x with 15% Zn‐doping and 0.2 wt% O‐MoS2 (CZ0.15S‐0.2M‐NiO x) in lactic acid solution (66.08 mmol h−1 g−1) is about 25 times that of Pt loaded CZ0.15S, which is further increased to 223.17 mmol h−1 g−1 when using Na2S/Na2SO3 as the sacrificial agent. Meanwhile, in Na2S/Na2SO3 solution, the CZ0.15S‐0.2M‐NiO x sample demonstrates an apparent quantum yield of 64.1% at 420 nm and a good stability for HER under long‐time illumination. The results presented in

Published in: "Small".

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