Understanding the mechanisms which determine band offsets and Schottky barriers at semiconductor contacts engineering them for specific device applications are important theoretical technological challenges. In this review, we present a approach to band-line-up problem discuss its application prototypical systems. The emphasis is on ab initio computations models derived from first-principles numerical experiments. An based linear-response-theory concepts allows general description of...

Oxygen-containing functional groups can be present in considerable amount intentionally or unintentionally on graphene, and a complete reduction of graphene oxide is difficult to achieve. To address the origin this behavior, we have performed pseudopotential density theory calculations investigate particular adsorption hydroxyl (OH) perfect defected individually presence other coadsorbed groups. We found that weakly adsorb easily aggregate, also with epoxy groups, react each barrier about...

We demonstrate that the key step for reaction of CO 2 with hydrogen on Ni(110) is a change activated molecule coordination to metal surface. At 90 K, negatively charged and chemically bonded via carbon atom. When temperature increased H approaches, H-CO complex flips binds surface through two oxygen atoms, while atom, thus yielding formate. provide atomic-level description this process by means conventional ultrahigh vacuum science techniques combined density functional theory calculations...

Watching graphene grow The growth of on metal surfaces can be catalyzed by mobile surface atoms. Patera et al. used a high-speed scanning tunneling microscope to image the islands nickel surface. High temperatures caused carbon diffuse surface, where atoms edges islands. Molecular dynamics and density functional theory calculations provide mechanistic insights into reaction steps. Science , this issue p. 1243

Through a combined scanning tunneling microscopy (STM) and density functional theory (DFT) approach, we provide full characterization of the different chemisorbed configurations epitaxial graphene coexisting on Ni(111) single crystal surface. Top-fcc, top-hcp, top-bridge are found to be stable structures with comparable adsorption energy. By comparison experiments simulations, solve an existing debate, unambiguously distinguishing these in high-resolution STM images characterizing...

Catalytic decomposition of aromatic polluters at room temperature represents a green route for air purification but is currently challenged by the difficulty generating reactive oxygen species (ROS) on catalysts. Herein, we develop mullite catalyst YMn2O5 (YMO) with dual active sites Mn3+ and Mn4+ use ozone to produce highly O* upon YMO. Such strong oxidant YMO shows complete removal benzene from −20 >50 °C high COx selectivity (>90%) through generated surface (60 000 mL g–1 h–1). Although...

We measure electron localization in different materials by means of a ``localization tensor'', based on Berry phases and related quantities. analyze its properties, we actually compute such tensor from first principles for several tetrahedrally coordinated semiconductors. discuss the trends our calculated quantity, relate findings to recent work other authors. also address ``hermaphrodite orbitals'', which are localized (Wannier-like) given direction, delocalized (Bloch-like) two orthogonal...

The local Zn/Se relative concentration at the interface in ZnSe-GaAs(001) heterostructures synthesized by molecular beam epitaxy was found to be controlled flux ratio employed during early growth stage of ZnSe on GaAs. Correspondingly, valence band discontinuity varies from 1.20 eV (Zn-rich interface) 0.58 (Se-rich interface). Comparison with results first-principles calculations suggests that observed trend offsets is related establishment neutral interfaces different atomic configurations.

The nanoscale description of the reaction pathways and role intermediate species involved in a chemical process is crucial milestone for tailoring more active, stable, cheaper catalysts, thus providing "reaction engineering" capabilities. This level insight has not been achieved yet catalytic hydrogenation CO2 on Ni enormous environmental relevance. We present thorough atomic-scale mechanisms this reaction, studied under controlled conditions model catalyst, clarifying long-standing debate...

Band offsets can be modified at semiconductor heterojunctions or created homojunctions by depositing thin intralayers of group-IV atoms III-V/III-V polar interfaces. We present here a theoretical study Si and Ge deposited along (001) GaAs AlAs homojunctions, GaAs/AlAs heterojunctions. Our results show that the offset is very sensitive to coverage abruptness intralayer. A comparison with recent experiments for in suggests are confined over two atomic planes coverages lower than about 0.5...

We present a combined experimental and theoretical study of the $\mathrm{C}{\mathrm{O}}_{2}$ interaction with Ni(110) surface. Photoelectron spectroscopy, temperature-programmed desorption, high-resolution electron energy loss spectroscopy measurements are performed at different coverages for increasing surface temperature after adsorption $90\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ aim to competing processes dissociation desorption. Simulations within framework density functional theory using...

Abstract In Physics Education Research (PER), Hake’s learning gain is widely used to measure students’ improvements. As tries emphasise progression in learning, the same manner, we teaching trend changing practices. To define , referred teachers’ development of new habits mind and practices when they start adopt ISLE approach their classrooms. We report results from analysis case studies eight teachers involved an in-service training program, which guided them reflect on change tasks .

To improve reactivity and achieve a higher material efficiency, catalysts are often used in the form of clusters with nanometer dimensions, down to single atoms. Since corresponding properties highly structure‐dependent, suitable support is thus required ensure cluster stability during operating conditions. Herein, an efficient method stabilize cobalt nanoclusters on graphene grown nickel substrates, exploiting anchoring effect atoms incorporated carbon network presented. The anchored...

The adsorption of CO on Pt nanoclusters grown in a regular array template provided by the graphene/Ir(111) Moiré was investigated means infrared-visible sum frequency generation vibronic spectroscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy from ultrahigh vacuum to near-ambient pressure, and ab initio simulations. Both terminally bridge bonded species populate nonequivalent sites clusters, spanning first second-layer terraces borders edges, depending particle size...

Achieving control in the design of monolayer 2D functional catalysts represents a significant challenge. If that challenge is surmounted, coordinated single-metal-atom sites can offer tailored electronic configuration, ligation geometries, chemical activity and selectivity, stability. We report spectroscopic evidence formation metal-organic framework supported by single graphene sheet which coordination among tetra-pyridyl porphyrins (TPyPs) spontaneously obtained exploiting iron atoms. The...

We investigate by first-principles pseudopotential calculations the structural properties and energetics of undoped Si-doped unpassivated GaAs nanowires (NWs). On basis total energy for NWs as a function diameter we find that, in contrast to bulk phase, wurtzite (WZ) are more stable than zincblende (ZB) diameters up about 50 Angstrom. also preferential position Si dopants WZ NWs: that donors segregate surface, while acceptors prefer inner positions. formation study, stability ranges donor...

Structure and thermodynamics of CuNi nanoalloys determined by a new DFT-fitted atomistic potential.

We report the formation of dimethyl sulfoxide (DMSO) molecular complexes on Au(111) enabled by native gold adatoms unusually linking molecules via a bonding ionic nature, yielding mutual stabilization between and adatom(s). DMSO is widely used polar, aprotic solvent whose interaction with metal surfaces not fully understood. By combining X-ray photoelectron spectroscopy, low temperature scanning tunneling microscopy, density functional theory (DFT) calculations, we show that form made up to...

In the perspective of a sustainable energy economy, CO2 reduction is attracting increasing attention as key step toward synthesis fuels and valuable chemicals. A possible strategy to develop novel conversion catalysts consists in mimicking reaction centers available nature, such those enzymes which Fe, Ni, Cu play major role active metals. this respect, NiCu shows peculiar activity for both water-gas shift methanol reactions. The identification useful descriptors engineer tune reactivity...

Atomic-scale description of the structure graphene edges on Ni(111), both during and post growth, is obtained by scanning tunneling microscopy (STM) in combination with density functional theory (DFT). During at 470 °C, fast STM images (250 ms/image) evidence flakes anchored to substrate, exhibiting zigzag or Klein depending orientation. If growth frozen, flake hydrogenate detach from hydrogen reconstructing edges.

Ni adatoms incorporated in epitaxial graphene during growth on Ni(111) are identified by scanning tunneling microscopy and density functional theory calculations.

The widely investigated oxygen reduction reaction (ORR) is well-known to proceed via two competing routes, involving or four electrons, and yielding different products, respectively. Both pathways are believed share a common, elusive intermediate, namely, the hydroperoxyl radical. By exploiting cobalt single-atom biomimetic model catalyst, based on self-assembled monolayer of Co-porphyrins grown an almost free-standing graphene sheet, we identify, in situ at room temperature O2+H2O...