MoSe 2 nanosheets and MoSe 2 /graphene hybrids have been prepared by a facile hydrothermal method. The number of layers of the MoSe 2 nanosheets is typically <10 as confirmed directly by transmission electron microscopy and indirectly by a red shift of the characteristic A 1g Raman peak. The hydrogen evolution reaction (HER) studies show that the onset potentials of MoSe 2 and MoSe 2 /RGO hybrids are only $0.15 V vs. RHE and $0.05 V vs. RHE, respectively, about 20-30 mV lower than those of MoS 2 and its graphene hybrids reported previously. Density functional theory calculations reveal that the Gibbs free energy for atomic hydrogen adsorption (DG 0 H ) on MoSe 2 edges is closer to thermoneutral than that on MoS 2 , with an H coverage of about 75% on the edge under operating conditions, which is also higher than that of MoS 2 reported in the literature. The consistency between the experimental and computational results indicates that MoSe 2 nanosheets have potential to be a better HER catalyst than their MoS 2 counterpart.

We use a first-principles technique to calculate the length dependence of resistance of alkanethiol wires in the metal−alkanethiol−metal configuration. The current−voltage characteristics of the wires are found to be largely linear, and the small bias resistance increases exponentially with the molecule length. We also investigate the effects of changes at the metal−molecule junction, including the contact geometry, end-groups, and junction distance. We compare theoretical results with recently reported experimental data.

We have calculated charge transport properties of molecular wires from first principles. The wires are made of oligophenylene molecules of three different lengths, in contact with atomic scale Au electrodes. The currentvoltage characteristics of the wires are found to be linear, but the small bias resistances increase exponentially with the wire length. These behaviors are in qualitative agreement with recent experimental data. Quantitatively, our calculated slope of the resistance-wire-length curve is the same as the experimental data, while values of current and resistance are at the same order of magnitude as the data.

Resonance inelastic conduction in molecular-scale electronics can be used to channel energy into a given mode of the molecular component to generate a desired motion. Dependence of the conductance properties on the molecular configuration, in turn, leads to a time-modulated current whose temporal properties are subject to control. We use an ab initio nonequilibrium formalism and the example of Au-C60-Au junctions to illustrate the strongly correlated phenomena of current-driven dynamics and time-dependent conductance in nanoelectronics, noting implications to, and potential applications in, several disciplines.

Interlayer coupling is of vital importance for manipulating physical properties, e.g. electronic bandgap, in two-dimensional materials. However, tuning magnetic properties in these materials is yet to be addressed. Here, we found the in-plane magnetic orders of CrS2 mono-and few-layers are tunable between striped antiferromagnetic (sAFM) and ferromagnetic (FM) orders by manipulating charge transfer between Cr t2g and eg orbitals. Such charge transfer is realizable through interlayer coupling, direct charge doping or substituting S with Cl atoms. In particular, the transferred charge effectively reduces a portion of Cr 4+ to Cr 3+ , which, together with delocalized S p orbitals and their resulting direct S-S interlayer hopping, enhances the double-exchange mechanism favoring the FM rather than sAFM order. An exceptional interlayer spin-exchange parameter was revealed over -10 meV, an order of magnitude stronger than available results of interlayer magnetic coupling. It addition, the charge doping could tune CrS2 between p-and n-doped magnetic semiconductors. Given these results, several prototype devices were proposed for manipulating magnetic orders using external electric fields or mechanical motion. These results manifest the role of interlayer coupling in modifying magnetic properties of layered materials and shed considerable light on manipulating magnetism in these materials.

Using first-principles calculations based on the density functional theory and the nonequilibrium Green's functions approach, we study the charge transport in Au-alkanedithiol-Au single-molecule junctions with different electrode orientations and molecular lengths. We attribute the recently measured high-/low-conductance in these heterostructures to two distinct electrode orientations, [100] and [111], which can control the electrode-molecule coupling as well as the tunneling strength by way of diverse band structures. Our detailed analysis on the transmission spectra suggests that even a single alkanedithiol junction can serve as a double quantum-dot system to yield tunable quantum interference.

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Electron stimulated desorption of cyclopentene from the Si(100)-(2 x 1) surface is studied experimentally with cryogenic UHV STM and theoretically with transport, electronic structure, and dynamical calculations. Unexpectedly for a saturated hydrocarbon on silicon, desorption is observed at bias magnitudes as low as 2.5 V, albeit the desorption yields are a factor of 500 to 1000 lower than previously reported for unsaturated molecules on silicon. The low threshold voltage for desorption is attributed to hybridization of the molecule with the silicon surface, which results in low-lying ionic resonances within 2-3 eV of the Fermi level. These resonances are long-lived, spatially localized, and displaced in equilibrium with respect to the neutral state. This study highlights the importance of nuclear dynamics in silicon-based molecular electronics and suggests new guidelines for the control of such dynamics.