Vincent Meunier

• Rensselaer Polytechnic Institute

The last decade has seen a flurry of studies related to graphene nanoribbons owing to their potential applications in the quantum realm. However, little experimental work has been reported towards nanoribbons of other 2D materials. Here, we propose a universal approach to synthesize high-quality networks of nanoribbons from arbitrary 2D materials w...

The last decade has seen a flurry of studies related to graphene nanoribbons owing to their potential applications in the quantum realm. However, little experimental work has been reported towards nanoribbons of other 2D materials due to the absence of synthesis routes. Here, we propose a universal approach to synthesize high-quality networks of na...

Spin-polarized transport through a rhombic graphene quantum dot (rGQD) attached to armchair graphene nanoribbon (AGNR) electrodes is investigated by means of the Green's function technique combined with single-band tight-binding (TB) approach including a Hubbard-like term. The Hubbard repulsion was included within the mean-field approximation. Comp...

We study the electronic structure of an ordered array of poly(para-phenylene) chains produced by surface-catalyzed dehalogenative polymerization of 1,4-dibromobenzene on copper (110). The quantization of unoccupied molecular states is measured as a function of oligomer length by scanning tunneling spectroscopy, with Fermi level crossings observed f...

As a new two-dimensional layered material, black phosphorus (BP) is a very promising material for nanoelectronics and optoelectronics. We use Raman spectroscopy and first-principles theory to characterize and understand the low-frequency (LF) interlayer breathing modes (<100 cm-1) in few-layer BP for the first time. Using laser polarization depende...

The discovery of magnetism in carbon structures containing zigzag edges has stimulated new directions in the development and design of spintronic devices. However, many of the proposed structures are designed without incorporating a key phenomenon known as topological frustration, which leads to localized non-bonding states (free radicals), increas...

By mixing pure precursor monomers and nitrogen-doped equivalents, atomically sharp wiggle-edged heterojunctions can be obtained via the combined action of Ullmann coupling followed by cyclodehydrogenation [Cai et al., Nat. Nanotechnol. 2014, 9, 896]. We used first-principles density functional theory and the many-body GW approach to establish the r...

We model the atomistic restructuring of different types of carbon nanoribbons as they are irradiated and subjected to uniaxial stress. Time scales relevant to realistic experimental conditions are achieved with an original Monte-Carlo algorithm that enacts rare events in a stochastic manner using the structure adjacency information. We use a Hubbar...

Single-layer black phosphorus (BP), or phosphorene, is a highly anisotropic two-dimensional elemental material possessing promising semiconductor properties for flexible electronics. However, the direct bandgap of single-layer black phosphorus predicted theoretically has not been directly measured, and the properties of its edges have not been cons...

http://www.nature.com/nnano/journal/vaop/ncurrent/full/nnano.2014.184.html Despite graphene's remarkable electronic properties, the lack of an electronic bandgap severely limits its potential for applications in digital electronics. In contrast to extended films, narrow strips of graphene (called graphene nanoribbons) are semiconductors through qu...

A combination of theoretical and computational methods is used to study the electronic properties of three-terminal graphitic nanowiggles (3TGNWs). 3TGNWs consisting of three GNWs connected at 120. to each other have been recently synthesized. Theory predicts that individual GNWs possess a broad set of electronic and magnetic properties. It follows...

http://pubs.acs.org/doi/abs/10.1021/nl5014597 Two-dimensional molybdenum disulfide (MoS2) is a promising material for optoelectronic devices due to its strong photoluminescence emission. In this work, the photoluminescence of twisted bilayer MoS2 is investigated, revealing a tunability of the interlayer coupling of bilayer MoS2. It is found that t...

A three-dimensional elemental carbon kagome lattice, made of only fourfold-coordinated carbon atoms, is proposed based on first-principles calculations. Despite the existence of 60° bond angles in the triangle rings, widely perceived to be energetically unfavorable, the carbon kagome lattice is found to display exceptional stability comparable to t...

We propose a graphene nanoribbon-based heterojunction, where a defect-free interface separates two zigzag graphene nanoribbons prepared in opposite antiferromagnetic spin configurations. This heterospin junction is found to allow the redirecting of low-energy electrons from one edge to the other. The basic scattering mechanisms and their relation t...

The vital importance of energy to society continues to demand a relentless pursuit of energy responsive materials that can bridge fundamental chemical structures at the molecular level and achieve improved functionality and performance. This demand can potentially be realized by harnessing the power of self-assembly, a spontaneous process where mol...

http://pubs.rsc.org/en/Content/ArticleLanding/2014/NR/C3NR06906K#!divAbstract Raman spectra of MoS2, WS2, and their heterostructures are studied by density functional theory. We quantitatively reproduce existing experimental data and present evidence that the apparent discrepancy between intensity ratios observed experimentally can be explained by...

The performance of graphene oxide framework (GOF) membranes for water desalination is assessed using classical molecular dynamics (MD) simulations. The coupling between water permeability and salt rejection of GOF membranes is studied as a function of linker concentration n, thickness h and applied pressure ΔP. The simulations reveal that water per...

Low energy electron diffraction, scanning tunneling microscopy and spectroscopy, and first-principles spin-dependent density functional theory are utilized to investigate the geometric, electronic, and magnetic structures of the stripe-ordered (1×2) surface of Ca(Fe1-xCox)2As2 (x=0, 0.075). The surface is terminated with a 50% Ca layer. Compared to...

We study the electronic properties of a series of coronene-derived graphitic nanoribbons recently synthesized in a pre-programmed, nanotube assisted, chemical route [Talyzin et al. Nano Lett., 2011, 11, 4352 and Fujihara et al. J. Phys. Chem. C, 2012, 116, 15141]. We employ a combination of density functional theory and spin-polarized tight-binding...

The electronic transport properties of three-terminal graphene-based triangular patches are investigated using a combination of semi-empirical tight-binding calculations and Green's function-based transport theory within Landauer's framework. The junctions are composed of a triangular structure based on armchair edged graphene nanoribbons. We show...

We study the electronic transport properties of graphene nanoribbon barbell systems using a combination of density functional theory and Landauer–Büttiker electronic transport theory to establish the relationship between the conduction gaps of barbell‐shaped graphitic heterojunctions and those of their constituting elements. The barbells considered...

We report electron transport measurements from gold-zinc-porphyrin-gold molecular junctions formed in an electromigrated nanogap. Asymmetric current-voltage (I-V) behaviors about the zero bias voltage were observed at room temperature and 4.2 K. These observations are in contrast to measurements from a nanogap without any molecules, which are domin...

We use quantum mechanical calculations to develop a full set of force field parameters in order to perform molecular dynamics simulations to understand and optimize the molecular storage properties inside graphene oxide frameworks (GOFs). A set of boron-related parameters for commonly used empirical force fields is determined to describe the nonbon...

We provide insight into surface-catalyzed dehalogenative polymerization, analyzing the organometallic intermediate and its evolution into planar polymeric structures. A combined study using scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), near-edge x-ray absorption fine structure (...

Nitrogen-doped graphitic nanoribbons (Nx-GNRs), synthesized by chemical vapor deposition (CVD) using pyrazine as a nitrogen precursor, are reported for the first time. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) reveal that the synthesized materials are formed by multilayered corrugated GNRs, whic...

This chapter reviews recent progress in describing electron transport in graphitic nanoribbons (GNRs) from a theoretical and computational perspective and how works reported in the literature provide unique physicochemical insight applicable to the development of novel GNR-based materials and devices. The chapter first analyses the general quantum...

We have used in situ current-voltage measurements of cup-stacked carbon nanotubes (CSCNTs) to establish reversible strain induced (compressive bending) semiconducting to metallic behavior. The corresponding electrical resistance decreases by two orders of magnitude during the process, and reaches values comparable to those of highly crystalline mul...

We model the thermal, irradiation-induced fusion of single-wall carbon nanotubes into X junctions utilizing a Metropolis Monte Carlo algorithm enacting the most commonly observed transformations in sp2 carbon. We introduce the concept of the sp2 to sp3 parallel defect to model early stages of welding. Quantum mechanical tight-binding calculations a...

Periodic repetitions of nonaligned and finite-sized graphene nanoribbon domains, known as graphene nanowiggles, can be synthesized using a surface-assisted bottom-up approach. They have been predicted to possess unusual properties such as tunable band gaps and versatile magnetic behaviors. Here, a first-principles many-body Green's function approac...

We demonstrate a controllable surface-coordinated linear polymerization of long-chain poly(phenylacetylenyl)s that are self-organized into a "circuit-board" pattern on a Cu(100) surface. Scanning tunneling microscopy/spectroscopy (STM/S) corroborated by ab initio calculations, reveals the atomistic details of the molecular structure, and provides a...

Self-Organized and Cu-Coordinated Surface Linear Polymerization

The efficient calculation of the Green's function is a central issue for assessing electronic transport at the nanoscale. In a near-to-equilibrium description, it can be obtained from a matrix inversion, combined with iterative algorithms developed in the 80s. However, this procedure becomes computationally challenging when dealing with very large...

Substitutional doping in graphene nanoribbons (GNRs) promises to enable specific tuning of their electronic properties. Recent work by Lv et al (2012 Nature Sci. Rep. 2 586) on large sheets of nitrogen-doped graphene determined that a highly predominant amount of nitrogen dopants (80%) are present in pairs of neighbouring atoms of the same sublatti...

We report a theoretical study of the electronic, thermal, and structural properties of a series of graphene oxide frameworks (GOFs) using first-principles calculations based on density functional theory. The molecular structure of GOFs is systematically studied by varying the nature and concentration of linear boronic acid pillars and the thermal s...

Graphene nanowiggles (GNWs) are one-dimensional wiggle edged graphene nanoribbons (GNRs) that have been synthesized using an atomically precise bottom-up approach. They are known to possess superior thermoelectric properties compared to straight GNRs. Here, first-principles density functional theory calculations establish that these properties can...

Recent work by Lu, et al. (Nature Scientific Reports, DOI: 10.1038) on large sheets of nitrogen-doped graphene, determined that a highly predominant amount of nitrogen dopants (80 %) form in pairs on the same sub-lattice. Graphene nanoribbons, which are essentially narrow strips of graphene, have a natural band gap and tunable electronic properties...

Highly ordered assembly of individual graphene nanoribbons (GNRs) into graphene nanowiggles (GNWs) has been recently demonstrated using a surface-assisted bottom-up chemical approach. GNWs are characterized by a periodic repetition of wiggle-like junctions where armchair- or zigzag-edged GNRs sectors alternate. We employed both density functional t...

We report a detailed theoretical study of the electronic and transport properties of a series of graphene oxide frameworks (GOFs) using first-principles calculations based on density functional theory. The pillar molecular structure of GOFs determine that with various linear boronic acid pillars and different pillar concentrations, GOF structures c...

Push-pull organic molecules include both electron donor and acceptor substituents, which upon excitation induce a charge separation with potential uses in conductive polymers and light-harvesting materials for use in solar cells. In a recent work, a new set of such molecules using fluorenone as the electron-acceptor unit have been reported [1]. Her...

The on-surface synthesis of covalent organic aggregates and networks has received considerable attention. However, most of the polymerization reactions require high temperatures to overcome the activation barrier. We demonstrate a surface-coordinated linear polymerization, which occurred at 100 K and forms long chain that are well-organized into a...

Low energy electron diffraction (LEED) and density functional theory (DFT) have been utilized to investigate the surface structure for the stripe 1x2 phase of Ca(Fe1-xCox)2As2 iron pnictides, for x = 0 and x = 0.075. Quantitative structural analysis of LEED-I(V) using the fractional spots of the 1x2 phase on both parent and doped samples gives a si...

Titanium dioxide is one of the most extensively investigated transition metal oxide. It has well-known applications in catalytically converting toxic organic and inorganic materials to benign products, as well as turning solar energy into a chemical. In these processes, it is believed that surface defects with lower coordination and/or stoichiometr...

A partially reduced TiO2 surface exhibits increasingly complex nature when forming various defects, whose stoichiometry, structure and properties are markedly different from those of bulk TiO2. Using scanning tunneling microscopy and density functional theory, we investigate different types of surface defects formed by Ti interstitials on TiO2 (110...

High-resolution transmission electron microscopy studies show the dynamics of small graphene platelets on larger graphene layers. The platelets move nearly freely to eventually lock in at well-defined positions close to the edges of the larger underlying graphene sheet. While such movement is driven by a shallow potential energy surface described b...

Here we establish a fundamental principle to open a relatively large band gap for graphene by hydrogenation. Specifically, the large band gap can be obtained when the number of nonmagnetic sp2-substructures on graphene basal plane is maximized. The principle indicates unequivocally what additive patterning should be used to attain the largest band...

Atomic vacancies in graphene are created under relatively low energy electron bombardment, but the formation of vacancies is significanlty enhanced by iron nanocatalysis. The evolution of the overall process involves nanoparticle agglomeration, interlayer migration, and confinement to nearby defects. The catalytic activation of metal nanoparticles...

The electronic properties of a number of two-dimensional covalent organic frameworks are studied using a combination of density functional theory and quasiparticle theory calculations. The effect of composition and system size on the electronic band gap is systematically considered for a series of systems, using van der Waals corrected density func...

Experimentally measured electronic band gaps of atomically sharp straight and chevronlike armchair graphene nanoribbons (GNRs) adsorbed on a gold substrate are smaller than theoretically predicted quasiparticle band gaps of their free-standing counterparts [Linden et al., Phys. Rev. Lett. 108, 216801 (2012)]. The influence of the substrate on elect...

Graphene nanowiggles (GNWs) are periodic repetitions of graphene nanoribbon (GNR) junctions resulting in quasi-one-dimensional wiggle-edged structures. They are synthesized using a surface-assisted bottom-up chemical approach and have been predicted to possess unusual electromagnetic properties. Here we show that GNWs also possess superior thermoel...

Organic materials, in particular conjugated polymers, have recently become the subject of extensive research for photovoltaic device applications. This increase of interest is primarily the result of their potentially low manufacturing cost, compatibility with flexible substrates, diverse chemical tunability, scalability, and ease of processing cur...

Ferroelectrics are multifunctional materials that reversibly change their polarization under an electric field. Recently, the search for new ferroelectrics has focused on organic and bio-organic materials, where polarization switching is used to record/retrieve information in the form of ferroelectric domains. This progress has opened a new avenue...

Using molecular dynamics simulations, we show that charge storage in subnanometer pores follows a distinct voltage-dependent behavior. Specifically, at lower voltages, charge storage is achieved by swapping co-ions in the pore with counterions in the bulk electrolyte. As voltage increases, further charge storage is due mainly to the removal of co-i...

Graphitic nanowiggles (GNWs) are 1D systems with segmented graphitic nanoribbon GNR edges of varying chiralities. They are characterized by the presence of a number of possible different spin distributions along their edges and by electronic band-gaps that are highly sensitive to the details of their geometry. These two properties promote these exp...

Recent experiments have demonstrated a viable bottom-up strategy to produce narrow and highly ordered nanoribbons, including complex segmented structures called graphitic nanowiggles (GNWs). These defect-free systems are made of successive repetitions of finite-sized graphitic nanoribbons (GNRs) regularly connected at a given angle. Theoretical cal...

Theoretical and computational chemical physics and materials science offers great opportunity toward helping solve some of the grand challenges in science and engineering, because structure and properties of molecules, solids, and liquids are direct reflections of the underlying quantum motion of their electrons. With the advent of semilocal and es...

Polycrystalline copper foils are surprisingly effective in chemical vapor deposition of graphene, although only Cu(111) facets possess the correct symmetry and low lattice mismatch. Density functional theory calculations of carbon on three copper facets show that, as the carbon cluster grows, the carbon-copper interaction weakens while the carbon-c...

The establishment of covalent junctions between carbon nanotubes (CNTs) and the modification of their straight tubular morphology are two strategies needed to successfully synthesize nanotube-based three-dimensional (3D) frameworks exhibiting superior material properties. Engineering such 3D structures in scalable synthetic processes still remains...

We used scanning tunneling microscopy and spectroscopy (STM/S) techniques to analyze the relationships between the edge shapes and the electronic structures in as-grown chemical vapor deposition (CVD) graphene nanoribbons (GNRs). A rich variety of single-layered graphene nanoribbons exhibiting a width of several to 100 nm and up to 1 μm long were s...

We report a novel physicochemical route to produce highly crystalline nitrogen-doped graphene nanoribbons. The technique consists of an abrupt N(2) gas expansion within the hollow core of nitrogen-doped multiwalled carbon nanotubes (CN(x)-MWNTs) when exposed to a fast thermal shock. The multiwalled nanotube unzipping mechanism is rationalized using...

The edge physics of graphene plays an essential role in the electronic properties of nanometer scale graphene. Studying the Joule-heating of a graphene sample supported by an integrated TEM-STM instrument is an effective way to sharpen graphene edges, and therefore produce smooth graphene nanoribbons, which will be studied in this work. Through obs...

Carbon nanotubes (CNTs) have been demonstrated to be promising nanoscale molecular sensors for detecting gas molecules such as NH3, NO2 and O2. But pristine CNTs show limitations in detection of highly toxic gases such as carbon monoxide (CO). In our work, interaction of CO molecules with both armchair and zigzag single-walled CNTs (SWCNTs) has bee...

We are reporting the fabrication of a very efficient electron source using long and crystalline carbon nanotubes. These devices start to emit electrons at fields as low as 0.10 V/μm and reach threshold emission at 0.164 V/μm. In addition, these electron sources are very stable for long operation periods up to 200 hrs and can achieve peak current de...

Graphitic nanowiggles (GNWs) are periodic repetitions of non-aligned finite-sized graphitic nanoribbon domains seamlessly stitched together without structural defects. These complex nanostructures have been recently fabricated using the self-assembly and subsequent fusion of small aromatic compound (Nature 466, 470 (2010)). The structures are predi...

Ferroelectric phase stability in ferroelectric films is critically dependent on the surface and interface phenomena, especially governed by electrostatic depolarization energy. Predictions for the minimum critical film thickness for ferroelectricity have continuously decreased down to few unit cells. We have examined surface/interface atomic struct...

Recent experiments have shown that the capacitance of subnanometer pores increases anomalously as the pore width decreases, thereby opening a new avenue for developing supercapacitors with enhanced energy density. However, this behavior is still subject to some controversy since its physical origins are not well understood. Using atomistic simulati...

http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.107.135501 Graphitic nanowiggles (GNWs) are periodic repetitions of nonaligned finite-sized graphitic nanoribbon domains seamlessly stitched together without structural defects. These complex nanostructures have been recently fabricated [Cai et al., Nature (London) 466, 470 (2010)] and are he...

Room-temperature ionic liquids (RTILs) have received significant attention as electrolytes due to a number of attractive properties such as their wide electrochemical windows. Since electrical double layers (EDLs) are the cornerstone for the applications of RTILs in electrochemical systems such as supercapacitors, it is important to develop an unde...

A theoretical modeling of scanning tunneling microscopy of the carbon nanotubes is presented. This theory is based on the standard perturbation description of elastic tunneling within a tight-binding description of the carbon ir-electrons. The tip is treated as a single atom with answavefunction. Several simulations of topographic STM images of per...

The quantum transport properties of graphene nanoribbon networks are investigated using first-principles calculations based on density functional theory. Focusing on systems that can be experimentally realized with existing techniques, both in-plane conductance in interconnected graphene nanoribbons and tunneling conductance in out-of-plane nanorib...

We are reporting the fabrication of a very efficient electron source using millimeter-long and highly crystalline carbon nanotubes. These devices start to emit electrons at fields as low as 0.17 V/μm and reach threshold emission at 0.24 V/μm. In addition, these electron sources are very stable and can achieve a peak current density of 750 mA cm(-2)...

Graphene based toroidal carbon nanostructures possess unique electronic properties induced by quantum confinement and cyclic boundary conditions imposed to the wave-functions along the circumference. We used a tight-binding approach to demonstrate that nanoribbon and nanotube based ring structures have energy-dependent selection rules for electron...

We present a study of the electronic properties of narrow zigzag and armchair nanoribbons substitutionally doped with a single boron, nitrogen, or phosphorus atom. Using density-functional calculations, we analyze the formation energy, electronic band structure, magnetic, and quantum conductance properties of these nanoribbons with doping sites ran...

Graphene nanoribbons (GNRs) are quasi one dimensional structures which have unique transport properties, and have a potential to open a bandgap at small ribbon widths. They have been extensively studied in recent years due to their high potential for future electronics applications. We have experimentally found some GNRs in our CVD grown graphene l...

Unlike single-C60-based devices, molecular assemblies based on two or more C60 can exhibit negative differential resistance (NDR). We evaluate electron transport properties of molecular devices built from two C60 connected by an alkane chain, using a non-equilibrium Green function technique implemented within the framework of linear-scaling DFT. We...

Electrodes featuring sub-nanometer pores can potentially improve the energy density of supercapacitors significantly. However, ions entering such narrow pores often need to pay an energy penalty because part of their salvation shell must be removed. This can potentially limit the charging kinetics of such nanopores. In this work, we investigate the...

Few layer graphene (FLG) can be synthesized by chemical vapor deposition methods. Considering a graphene bilayer with a small angle rotation between the layers---a stacking defect was observed by high resolution scanning tunneling microscopy. Low-energy Van Hove singularities in twisted graphene layers are identified as two sharp peaks in the densi...

With the advent of atomically thin and flat layers of conducting materials such as graphene, new designs for thin film energy storage devices with good performance have become possible. Here, we report an "in-plane" fabrication approach for ultrathin supercapacitors based on electrodes comprised of pristine graphene and multilayer reduced graphene...

We investigate the electronic transport properties of carbon nanotori covalently connected to external electrodes made up of carbon nanotubes of various chiralities. The study is based on computing ballistic transport characteristics within the framework of Green's function theory using a simple π-orbital tight-binding model. The calculations focus...

The current status of graphene edge fabrication and characterization is reviewed in detail. We first compare different fabrication methods, including the chemical vapor deposition method, various ways of unzipping carbon nanotubes, and lithographic methods. We then summarize the different edge/ribbon structures that have been produced experimentall...

Phenalenyl and its derivatives have recently attracted a great deal of interest as a result of a two-electron multicenter (2e/mc) π−π bonding between two π-stacked phenalenyl units. The 2e/mc bonded π-dimers are close in energy to the σ-dimers of phenalenyl and therefore fickle properties may emerge from bond fluctuation, yielding “smart” π-functio...

A first-principles approach is used to establish that substitutional phosphorus atoms within carbon nanotubes strongly modify the chemical properties of the surface, thus creating highly localized sites with specific affinity towards acceptor molecules. Phosphorus-nitrogen co-dopants within the tubes have a similar effect for acceptor molecules, bu...

We study molecular transistors where graphene nanoribbons act as three metallic electrodes connected to a ring-shaped 18-annulene molecule. Using the nonequilibrium Green function formalism combined with density functional theory, recently extended to multiterminal devices, we show that these nanostructures exhibit exponentially small transmission...

Room-temperature ionic liquids (ILs) are an emerging class of electrolytes for supercapacitors. We investigate the effects of ion size and electrode curvature on the electrical double layers (EDLs) in two ILs 1-butyl-3-methylimidazolium chloride [BMIM][Cl] and 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF(6)], using a combination of mol...

Unlike single-C(60)-based devices, molecular assemblies based on two or more appropriately connected C(60) molecules have the potential to exhibit negative differential resistance (NDR). In this work, we evaluate electron transport properties of molecular devices built from two C(60) molecules connected by an alkane chain, using a nonequilibrium Gr...

Electrodes featuring sub-nanometer pores can significantly enhance the capacitance and energy density of supercapacitors. However, ions must pay an energy penalty to enter sub-nanometer pores as they have to shed part of their solvation shell. The magnitude of such energy penalty plays a key role in determining the accessibility and charging/discha...

Line defects on the surface of rutile TiO(110) form in pairs separated by 1.2 nm creating a quantum well. The well is effectively closed by the presence of two charged structures at both ends separated by a distance in the 10-20 nm range. As expected for quantum confinement a long period oscillatory feature of the local density of states is observe...

The novel phenomena induced by symmetry breaking at homointerfaces between ferroic variants in ferroelectric and ferroelastic materials have attracted recently much attention. Using variable temperature scanning microwave microscopy, we demonstrate the mesoscopic strain-induced metal-insulator phase transitions in the vicinity of ferroelastic domai...

We study all-carbon-hydrogen molecular transistors where zigzag graphene nanoribbons play the role of three metallic electrodes connected to a ring-shaped 18-annulene molecule. Using the nonequilibrium Green function formalism combined with density functional theory, recently extended to multiterminal devices, we show that the proposed nanostructur...

Capacitive energy storage mechanisms in nanoporous carbon supercapacitors hinge on endohedral interactions in carbon materials with macro-, meso-, and micropores that have negative surface curvature. In this article, we show that because of the positive curvature found in zero-dimensional carbon onions or one-dimensional carbon nanotube arrays, exo...

We present a theoretical model for electrical double layers formed by ion adsorption in nanoscale carbon pores. In this work a combination of computational methods, including first-principles and classical modeling, are used to explain the onset of an anomalous increase in capacitance for small pores. The study highlights the key role played by por...

Atomically engineered oxide multilayers and superlattices display unique properties responsive to the electronic and atomic structures of the interfaces. We have followed the growth of ferroelectric BaTiO3 on SrRuO3 electrode with in situ atomic scale analysis of the surface structure at each stage. An oxygen-induced surface reconstruction of SrRuO...

Recent experimental reports indicate that Joule heating can atomically sharpen the edges of chemical vapor deposition grown graphitic nanoribbons. The absence or presence of loops between adjacent layers in the annealed materials is the topic of a growing debate that this Letter aims to put to rest. We offer a rationale explaining why loops do form...

Recent advances in theoretical methods combined with the advent of massively parallel supercomputers allow one to reliably simulate the properties of complex materials and device structures from first principles. We describe applications in two general areas: i) novel polymer composites for ultra-high-density capacitors, necessary for pulsed-power...

One of the great challenges in surface chemistry is to assemble aromatic building blocks into ordered structures that are mechanically robust and electronically interlinked--i.e., are held together by covalent bonds. We demonstrate the surface-confined growth of ordered arrays of poly(3,4-ethylenedioxythiophene) (PEDOT) chains, by using the substra...

The structure and charging kinetics of electrical double layers (EDLs) at interfaces of NaCl solutions and planar electrodes are studied by molecular dynamics (MD) and Poisson–Nernst–Planck (PNP) simulations. Based on the MD results and prior experimental data, we show that counterion packing in planar EDLs does not reach the steric limit at electr...

The organic electrolyte of tetraethylammonium tetrafluoroborate (TEABF(4)) in the aprotic solvent of acetonitrile (ACN) is widely used in electrochemical systems such as electrochemical capacitors. In this paper, we examine the solvation of TEA(+) and BF(4)(-) in ACN, and the structure, capacitance, and dynamics of the electrical double layers (EDL...

The distribution of K+ ions in electrified slit-shaped micropores with pore widths ranging from 9.36 to 14.7 A was studied using molecular dynamics simulations. We show that, in slit pores with pore widths between 10 and 14.7 A, the K+ ion distribution differs qualitatively from that described by classical electrical double-layer (EDL) theories in...

The electron transport properties of a four-terminal molecular device are computed within the framework of density functional theory and nonequilibrium Keldysh theory. The additional two terminals lead to new properties, including a pronounced negative differential resistance not present in a two-terminal setup, and a pseudogating effect. In genera...