Our Publications

  • Layer Identification of Colorful Black Phosphorus. Small. 2017

    A quick method for estimating the layer number of black phosphorus is demonstrated by simple color-comparison using optical microscope in this paper. A thickness-dependent reflection model of black phosphorus/SiO2/Si is constructed and a colorbar confirmed by experiments is obtained for quick identifying layer number. The enhanced visibility affected by substrates or wavelength of light is further verified by calculating the contrast.

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  • Insertion of Neurotransmitters into a Lipid Bilayer Membrane and Its Implication on Membrane Stability: A Molecular Dynamics Study. ChemPhysChem. 2017

    The signaling molecules in neurons, called neurotransmitters, play an essential role in the transportation of neural signals, during which the neurotransmitters interact with not only specific receptors, but also cytomembranes, such as synaptic vesicle
    membranes and postsynaptic membranes. Through extensive molecular dynamics simulations, the atomic-scale insertion dynamics of typical neurotransmitters, including methionine enkephalin (ME), leucine enkephalin (LE), dopamine (DA), acetylcholine (ACh), and aspartic acid (ASP), into lipid bilayers is investigated. The results show that the first three neurotransmitters (ME, LE, and DA) are able to diffuse freely into both 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) membranes, and are guided by the aromatic residues Tyr and Phe. Only a limited number of these neurotransmitters are allowed to penetrate into the membrane, which suggests an intrinsic mechanism by which the membrane is protected from being destroyed by excessive inserted neurotransmitters. After spontaneous insertion, the neurotransmitters disturb the surrounding phospholipids in the membrane, as indicated by the altered distribution of components in lipid leaflets and the disordered lipid tails. In contrast, the last two neurotransmitters (ACh and ASP) cannot enter the membrane, but instead always diffuse freely in solution. These findings provide an understanding at the atomic level of how neurotransmitters interact with the surrounding cytomembrane, as well as their impact on membrane behavior.

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  • Tunable Rashba spin splitting in quantum-spin Hall-insulator AsF bilayers. Nano Research. 2016

    Rashba spin splitting (RSS) in quantum-spin Hall (QSH) insulators is of special importance for fabricating spintronic devices. By changing the stacking order, a unique bilayered fluorinated arsenene (AsF) system is demonstrated to simultaneously possess RSS and non-trivial topological electronic states. We show by first-principle calculations that tunable RSS can be realized in bilayered AsF. Intrinsic RSS of 25 meV is obtained in the AA-stacked AsF bilayer by considering the spin-orbit coupling effect. The RSS can be tuned in the range of 0 to 50 meV by applying biaxial strains and can be significantly enhanced up to 186 meV in the presence of an external electric field. The AB-stacked AsF bilayer is shown to be a two-dimensional topological insulator with a sizable bulk bandgap of 140 meV (up to 240 meV), which originates from the spin-orbit coupling within the px,y–pz band inversion. Surprisingly, RSS up to 295 meV can be induced in the AB-stacked AsF bilayer by applying an external electric field, while the robust topology property without RSS can be retained under the applied strains. The AsF bilayers with tunable RSS and a nontrivial bandgap with AA- and AB-stacking orders can pave the way for designing spin field-effect transistors and new QSH devices.

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  • Oxygen-suppressed selective growth of monolayer hexagonal boron nitride on copper twin crystals. Nano Research. 2016

    Controlled growth of hexagonal boron nitride (h-BN) with desired properties is essential for its wide range of applications. Here, we systematically carried out the chemical vapor deposition of monolayer h-BN on Cu twin crystals. It was found that h-BN nucleated and grew preferentially and simultaneously on the narrow twin crystal strips present in the Cu substrates. The density functional theory calculations revealed that the introduction of oxygen could efficiently tune the selectivity. This is because of the reduction in the dehydrogenation barrier of the precursor molecules by the introduction of oxygen. Our findings throw light on the direct growth of functional h-BN nanoribbons on nano-twinned crystal strips and switching of the growth behavior of h-BN films by oxygen.

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  • Hydroelectric generator from transparent flexible zinc oxide nanofilms. Nano Energy. 2016

    Harvesting wave energy based on waving potential, a newly found electrokinetic effect, is attractive but limited mainly to monolayer graphene. Here we demonstrate that moving a transparent flexible ZnO nanofilm across the surface of ionic solutions can generate electricity. The generated electricity increases linearly with the moving velocity with an open-circuit voltage up to tens of millivolt and a short-circuit current at the order of microampere. The harvested electricity can be efficiently scaled up through series and parallel connections. Theoretical simulations show that it is the proper electrical property that endows the ZnO nanofilm with the outstanding capacity in harvesting the wave energy.

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  • Bending-induced extension in two-dimensional crystals. Acta Mech. Sin. 2017

    We find by ab initio simulations that significant overall tensile strain can be induced by pure bending in a wide range of two-dimensional crystals perpendicular to the bending moment, just like an accordion being bent to open. This bending-induced tensile strain increases in a power law with bent curvature and can be over 20% in monolayered black phosphorus and transition metal dichalcogenides at a moderate curvature of 2 nm−1 butmore than an order weaker in graphene and hexagon boron nitride. This accordion effect is found to be a quantum mechanical effect raised by the asymmetric response of chemical bonds and electron density to the bending curvature.

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  • Water-evaporation-induced electricity with nanostructured carbon materials. Nature Nanotechnology. 2017

    Water evaporation is a ubiquitous natural process that harvests thermal energy from the ambient environment. It has previously been utilized in a number of applications including the synthesis of nanostructures and the creation of energyharvesting devices. Here, we show that water evaporation from the surface of a variety of nanostructured carbon materials can be used to generate electricity. We find that evaporation from centimetre-sized carbon black sheets can reliably generate
    sustained voltages of up to 1 V under ambient conditions. The interaction between the water molecules and the carbon layers and moreover evaporation-induced water flow within the porous carbon sheets are thought to be key to the voltage generation. This approach to electricity generation is related to the traditional streaming potential, which relies on driving ionic solutions through narrow gaps, and the recently reported method of moving ionic solutions across graphene surfaces, but as it exploits the natural process of evaporation and uses cheap carbon black it could offer advantages in the development of practical devices.

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