scholarly journals Single-atom doping of MoS2 with manganese enables ultrasensitive detection of dopamine: Experimental and computational approach

2020 ◽  
Vol 6 (32) ◽  
pp. eabc4250 ◽  
Author(s):  
Yu Lei ◽  
Derrick Butler ◽  
Michael C. Lucking ◽  
Fu Zhang ◽  
Tunan Xia ◽  
...  
Keyword(s):  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Density Functional Theory Calculations ◽  
Single Atom ◽  
Buffer Solution ◽  
Dopamine Detection ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Metal Dichalcogenides ◽  
Metal Doped

Two-dimensional transition metal dichalcogenides (TMDs) emerged as a promising platform to construct sensitive biosensors. We report an ultrasensitive electrochemical dopamine sensor based on manganese-doped MoS2 synthesized via a scalable two-step approach (with Mn ~2.15 atomic %). Selective dopamine detection is achieved with a detection limit of 50 pM in buffer solution, 5 nM in 10% serum, and 50 nM in artificial sweat. Density functional theory calculations and scanning transmission electron microscopy show that two types of Mn defects are dominant: Mn on top of a Mo atom (MntopMo) and Mn substituting a Mo atom (MnMo). At low dopamine concentrations, physisorption on MnMo dominates. At higher concentrations, dopamine chemisorbs on MntopMo, which is consistent with calculations of the dopamine binding energy (2.91 eV for MntopMo versus 0.65 eV for MnMo). Our results demonstrate that metal-doped layered materials, such as TMDs, constitute an emergent platform to construct ultrasensitive and tunable biosensors.

Pristine edge structures of T′′-phase transition metal dichalcogenides (ReSe2, ReS2) atomic layers

Nanoscale ◽  
2020 ◽  
Vol 12 (32) ◽  
pp. 17005-17012
Author(s):  
Xiya Chen ◽  
Bao Lei ◽  
Yong Zhu ◽  
Jiadong Zhou ◽  
Zheng Liu ◽  
...  
Keyword(s):  
Scanning Transmission Electron Microscopy ◽  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Density Functional Theory Calculations ◽  
Microscopy Imaging ◽  
Functional Theory ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Metal Dichalcogenides ◽  
T Phase

Atomically sharp pristine edges of ReSe2 atomic layers were identified with scanning transmission electron microscopy imaging and density functional theory calculations.

scholarly journals Rolling the WSSe Bilayer into Double-Walled Nanotube for the Enhanced Photocatalytic Water-Splitting Performance

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 705
Author(s):  
Lin Ju ◽  
Jingzhou Qin ◽  
Liran Shi ◽  
Gui Yang ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Water Splitting ◽  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Density Functional Theory Calculations ◽  
Stable Configuration ◽  
Photocatalytic Water Splitting ◽  
Stacking Pattern ◽  
Metal Dichalcogenides ◽  
Photocatalytic Performances ◽  
Carrier Separation

For the emerging Janus transition metal dichalcogenides (TMD) layered water-splitting photocatalysts, stacking the monolayers to form bilayers has been predicted to be an effective way to improve their photocatalytic performances. To achieve this, the stacking pattern plays an important role. In this work, by means of the density functional theory calculations, we comprehensively estimate energetical stability, light absorption and redox capacity of Janus WSSe bilayer with different stacking patterns. Unfortunately, the Janus WSSe bilayer with the most stable configuration recover the out-of-plane symmetry, which is not in favor of the photocatalytic reactions. However, rolling the Janus WSSe bilayer into double-walled nanotube could stabilize the appropriate stacking pattern with an enhanced instinct dipole moment. Moreover, the suitable band edge positions, high visible light absorbance, outstanding solar-to-hydrogen efficiency (up to 28.48%), and superior carrier separation promise the Janus WSSe double-walled nanotube the potential for the photocatalytic water-splitting application. Our studies not only predict an ideal water-splitting photocatalyst, but also propose an effective way to improve the photocatalytic performances of Janus layered materials.

scholarly journals Atomic origin of spin-valve magnetoresistance at the SrRuO3 grain boundary

2020 ◽  
Vol 7 (4) ◽  
pp. 755-762 ◽  
Author(s):  
Xujing Li ◽  
Li Yin ◽  
Zhengxun Lai ◽  
Mei Wu ◽  
Yu Sheng ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Density Functional ◽  
Magnetic Moments ◽  
Spin Valve ◽  
Density Functional Theory Calculations ◽  
Precise Knowledge ◽  
Transmission Electron ◽  
Defect Control ◽  
Scanning Transmission ◽  
Low Dimensional

Abstract Defects exist ubiquitously in crystal materials, and usually exhibit a very different nature from the bulk matrix. Hence, their presence can have significant impacts on the properties of devices. Although it is well accepted that the properties of defects are determined by their unique atomic environments, the precise knowledge of such relationships is far from clear for most oxides because of the complexity of defects and difficulties in characterization. Here, we fabricate a 36.8° SrRuO3 grain boundary of which the transport measurements show a spin-valve magnetoresistance. We identify its atomic arrangement, including oxygen, using scanning transmission electron microscopy and spectroscopy. Based on the as-obtained atomic structure, the density functional theory calculations suggest that the spin-valve magnetoresistance occurs because of dramatically reduced magnetic moments at the boundary. The ability to manipulate magnetic properties at the nanometer scale via defect control allows new strategies to design magnetic/electronic devices with low-dimensional magnetic order.

scholarly journals Vibronic response of a spin-1/2 state from a carbon impurity in two-dimensional WS2

2020 ◽  
Author(s):  
Katherine Cochrane ◽  
Jun-Ho Lee ◽  
Christoph Kastl ◽  
Jonah Haber ◽  
Tianyi Zhang ◽  
...  
Keyword(s):  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Single Atom ◽  
Chemical Doping ◽  
Two Dimensional ◽  
Radical Ions ◽  
Defect States ◽  
Carbon Impurity ◽  
Carbon Impurities ◽  
Metal Dichalcogenides

Abstract We demonstrate the creation of a spin-1/2 state via the atomically controlled generation of magnetic carbon radical ions (CRIs) in synthetic two-dimensional transition metal dichalcogenides. Hydrogenated carbon impurities located at chalcogen sites introduced by chemical doping are activated with atomic precision by hydrogen depassivation using a scanning probe tip. In its anionic state, the carbon impurity exhibits a magnetic moment of 1 μB resulting from an unpaired electron populating a spin-polarized in-gap orbital. By inelastic tunneling spectroscopy and density functional theory we show that the CRI defect states couple to a small number of vibrational modes, including a local, breathing-type mode. The electron-phonon coupling strength critically depends on the spin state and differs for monolayer and bilayer WS2. These carbon radical ions in TMDs comprise a new class of surface-bound, single-atom spin-qubits that can be selectively introduced, are spatially precise, feature a well-understood vibronic spectrum, and are charge state controlled.

scholarly journals High-Throughput Screening Single-Atom Alloy for Electroreduction of Dinitrogen to Ammonia

2021 ◽  
Author(s):  
Guokui Zheng ◽  
Ziqi Tian ◽  
Xingwang Zhang ◽  
Liang Chen ◽  
Xu Qian ◽  
...  
Keyword(s):  
High Throughput Screening ◽  
Density Functional ◽  
Ammonia Synthesis ◽  
Density Functional Theory Calculations ◽  
Reduction Reaction ◽  
Single Atom ◽  
Functional Theory ◽  
Metal Doped ◽  
Single Atom Alloy ◽  
Single Atom Alloys

<p></p><p>Exploring electrocatalyst with high activity, selectivity and stability is essential for development of applicable electrocatalytic ammonia synthesis technology. By performing density functional theory calculations, we systematically investigated a series of transition-metal doped Au-based single atom alloys (SAAs) as promising electrocatalysts for nitrogen reduction reaction (NRR). For Au-based electrocatalyst, the first hydrogenation step (*N<sub>2</sub>→*NNH) normally determines the limiting potential of the overall reaction process. Compared with pristine Au(111) surface, introducing single atom can significantly enhance the binding strength of N<sub>2</sub>, leading to decreased energy barrier of the key step, i.e., ΔG(*N<sub>2</sub>→*NNH). According to simulation results, three descriptors were proposed to describe ΔG(*N<sub>2</sub>→*NNH), including ΔG(*NNH), <i>d</i>-band center, and . Eight doped elements (Ti, V, Nb, Ru, Ta, Os, W, and Mo) were initially screened out with limiting potential ranging from -0.75V to -0.30 V. Particularly, Mo- and W-doped systems possess the best activity with limiting potentials of -0.30 V, respectively. Then the intrinsic relationship between structure and the potential performance was further analyzed by using machine-learning. The selectivity, feasibility, stability of these candidates were also evaluated, confirming that SAA containing Mo, Ru ,Ta, and W could be outstanding NRR electrocatalysts. This work not only broadens the understating of SAA application in electrocatalysis, but also devotes to the discovery of novel NRR electrocatalysts.</p><br><p></p>

scholarly journals One-step synthesis of single-site vanadium substitution in 1T-WS2 monolayers for enhanced hydrogen evolution catalysis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ali Han ◽  
Xiaofeng Zhou ◽  
Xijun Wang ◽  
Sheng Liu ◽  
Qihua Xiong ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Active Sites ◽  
Density Functional ◽  
Chemical Vapor ◽  
Single Atom ◽  
High Concentration ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Vanadium Substitution ◽  
One Step

AbstractMetallic tungsten disulfide (WS2) monolayers have been demonstrated as promising electrocatalysts for hydrogen evolution reaction (HER) induced by the high intrinsic conductivity, however, the key challenges to maximize the catalytic activity are achieving the metallic WS2 with high concentration and increasing the density of the active sites. In this work, single-atom-V catalysts (V SACs) substitutions in 1T-WS2 monolayers (91% phase purity) are fabricated to significantly enhance the HER performance via a one-step chemical vapor deposition strategy. Atomic-resolution scanning transmission electron microscopy (STEM) imaging together with Raman spectroscopy confirm the atomic dispersion of V species on the 1T-WS2 monolayers instead of energetically favorable 2H-WS2 monolayers. The growth mechanism of V SACs@1T-WS2 monolayers is experimentally and theoretically demonstrated. Density functional theory (DFT) calculations demonstrate that the activated V-atom sites play vital important role in enhancing the HER activity. In this work, it opens a novel path to directly synthesize atomically dispersed single-metal catalysts on metastable materials as efficient and robust electrocatalysts.

scholarly journals Ultra-small rhenium clusters supported on graphene

2015 ◽  
Vol 17 (12) ◽  
pp. 7898-7906 ◽  
Author(s):  
Orlando Miramontes ◽  
Franco Bonafé ◽  
Ulises Santiago ◽  
Eduardo Larios-Rodriguez ◽  
Jesús J. Velázquez-Salazar ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Dark Field ◽  
High Angle ◽  
Functional Theory ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field

In this work, the adsorption of very small rhenium clusters (2–13 atoms) supported on graphene was studied by high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) in combination with density functional theory calculations.

scholarly journals Uniaxial strain-induced phase transition in the 2D topological semimetal IrTe2

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Christopher W. Nicholson ◽  
Maxime Rumo ◽  
Aki Pulkkinen ◽  
Geoffroy Kremer ◽  
Björn Salzmann ◽  
...  
Keyword(s):  
Density Functional ◽  
Transition Metal Dichalcogenides ◽  
Gain Control ◽  
Density Functional Theory Calculations ◽  
Uniaxial Strain ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Topological Semimetal ◽  
Topological States ◽  
Metal Dichalcogenides

AbstractStrain is ubiquitous in solid-state materials, but despite its fundamental importance and technological relevance, leveraging externally applied strain to gain control over material properties is still in its infancy. In particular, strain control over the diverse phase transitions and topological states in two-dimensional transition metal dichalcogenides remains an open challenge. Here, we exploit uniaxial strain to stabilize the long-debated structural ground state of the 2D topological semimetal IrTe2, which is hidden in unstrained samples. Combined angle-resolved photoemission spectroscopy and scanning tunneling microscopy data reveal the strain-stabilized phase has a 6 × 1 periodicity and undergoes a Lifshitz transition, granting unprecedented spectroscopic access to previously inaccessible type-II topological Dirac states that dominate the modified inter-layer hopping. Supported by density functional theory calculations, we show that strain induces an Ir to Te charge transfer resulting in strongly weakened inter-layer Te bonds and a reshaped energetic landscape favoring the 6×1 phase. Our results highlight the potential to exploit strain-engineered properties in layered materials, particularly in the context of tuning inter-layer behavior.

scholarly journals Tunable Single-Atomic Charge/Spin States of Intercalant Co Ions in a Transition Metal Dichalcogenide

2021 ◽  
Author(s):  
Seongjoon Lim ◽  
Shangke Pan ◽  
Kefeng Wang ◽  
Alexey Ushakov ◽  
Ekaterina Sukhanova ◽  
...  
Keyword(s):  
Transition Metal ◽  
Scanning Probe Microscopy ◽  
Density Functional ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Atomic Charge ◽  
Single Atom ◽  
Transition Metal Dichalcogenide ◽  
Functional Theory ◽  
Metal Dichalcogenides

Abstract Intercalation raises manifold possibilities to manipulate the properties of two-dimensional (2D) materials1, and its impact on local electronic/magnetic properties has drawn much attention with the rise of nano-structured 2D materials2,3. Typically, changing an ionic state in a solid involves a dramatic local change of energy as well as orbital/spin magnetic moment from its ground state. However, the atomic investigation of the charging process of an intercalant ion in 2D material has never been explored while such subject has been studied in artificially deposited atoms on thin insulating 2D layers using scanning probe microscopy4–7. Herein, we demonstrate an atomical manipulation of the charge and spin state of Co ions on a metallic NbS2, obtained by cleaving of Co-intercalated NbS2. Density functional theory investigation of various Co configurations reveals that the charging is possible due to a change in the crystal field at the surface and a significant coupling between NbS2 and intercalants occurs via orbitals of the a1g symmetry. The results can be generalized to numerous other combinations of intercalants and base matrixes, suggesting that intercalated transition metal dichalcogenides can be a new platform to introduce single-atom operation 2D electronics/spintronics.

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