As a promising route for large-scale ${\mathrm{H}}_{2}$ production, the water-gas-shift reaction (WGS, $\mathrm{CO}+{\mathrm{H}}_{2}\mathrm{O}\ensuremath{\rightarrow}{\mathrm{CO}}_{2}+{\mathrm{H}}_{2}$) on ceria-supported Au catalysts is of enormous potential in efforts to move towards hydrogen economy. Recent research suggests that this fact catalyzed by cations instead conventionally regarded metallic particles. Here density functional theory calculations demonstrate presence empty...

Evidence from density functional theory calculations that the main reaction pathway for Fischer−Tropsch process on Co{0001} is not carbide mechanism but an alternative branch starting with hydrogenation of CO to oxymethylidyne species. We show path at realistic pressure using microkinetic simulations and thereby bridge gap in heterogeneous catalysis.

We review first-principles calculations relevant to the adsorption of aromatic molecules on metal surfaces. Benzene has been intensively studied a variety substrates, providing an opportunity comment upon trends from one another. Meanwhile, elucidating polycyclic are more sparse, but nevertheless yield important insights into role non-covalent interactions. Heterocyclic and substituted compounds introduce complicating possibility electronic steric effects, whose relative importance can thus...

Defects such as oxygen vacancies dominate the electronic and chemical properties of ceria. However, fundamental understanding defects, especially clusters vacancies, is sparse. In this work, we use density-functional theory with addition Hubbard $U$ term to investigate various including vacancy monomer, dimer, trimer, tetramer, in which subsurface can also be involved. We show that individual surface have very similar stabilities; dimer consisting two not reported experimentally, stable...

The catalytic properties of Au/CeO2 systems are sensitive to the nature Au clusters; however, atomic information on clusters is sparse. In this work, we use density functional theory investigate nucleation small (up Au11). By depositing atoms one by at a reduced CeO2{111} surface, present detailed patterns. Although relatively in size, nanoclusters obtained exhibit interesting characteristic features. addition face-centered cubic (fcc) geometry, reminiscent bulk Au, also find existence novel...

Common staging point: Results of DFT studies on surface-catalyzed processes indicate that oxymethylidyne species (CHO) are intermediates in both the combustion and synthesis hydrocarbons noble-metal surfaces (the picture shows CHO formation Pd). Combustion proceed by very similar pathways, but opposite directions, even though different metals used two processes.

The great promise of ceria-supported gold clusters as catalysts the future for important industrial processes, such water gas shift reaction, has prompted a flurry activity aimed at understanding molecular-level details their operation. Much this focused on experimental and theoretical studies structure perfect defective ceria surfaces, with without various sizes. complicated electronic ceria, particularly in its reduced form, means that present it is highly challenging to carry out accurate...

Within the framework of GGA+U implementation density functional theory, we investigate atomistic and electronic structures Au adsorbed on stoichiometric defective CeO(2){111} surfaces, in latter which either O or Ce vacancies are presented. We show that surface, most stable adsorption site is not top outermost atoms, as previously suggested, but a bridgelike directly binds to two atoms. suggest both sites, original empty 4f states near Fermi level facilitate oxidation Au; preference for...

Combining energetic data from density functional theory with thermodynamic calculations, we have studied in detail selective NO reduction under excess O2 conditions on Ir. We show that can readily poison the Ir catalyst for and poisoning starts a low O coverage surface. The adsorbed switches reaction selectivity (N2 production) to oxidation (NO2 production). As is built up, metal eventually be oxidized IrO2, which predicted thermodynamically possible conditions. To prevent surface, presence...

Gold atoms act as anchoring sites for gold nanoparticles in the ceria-catalyzed water−gas shift reaction; however, site of nanoparticle is a matter debate. Both oxygen and cerium vacancies have been suggested different studies. Aiming to provide insight into this issue, we utilize density functional theory ab initio thermodynamics approaches investigate formation various at CeO2{111} surface, both with without adatoms. We find that, under reaction conditions, vacancy much harder form less...

Density functional calculations are employed to study the molecular dissociation of hydrogen on graphene, diffusion chemisorbed atomic species, and electronic properties resulting graphene system. Our results show that applying stress substrate can lower barrier by a factor six, change process from endothermic exothermic. These values for heat reaction, unlike zero values, compatible with time scales observed in experiments. Diffusion, other hand, is not greatly modified stress. We analyse...

Abstract The ratio of NMR relaxation time constants provides a non‐destructive indication the relative surface affinities exhibited by adsorbates within liquid‐saturated mesoporous catalysts. In present work we provide supporting evidence for existence quantitative relationship between such measurements and adsorption energetics. As prototypical example with relevance to green chemical processes examine contrast characteristics primary alcohols cyclohexane an industrial silica catalyst...

The conversion of NO to N2 is a key issue encountered in the control emission from vehicles. selectivity reduction on two platinum group metals, Ir and Pt, including close-packed flat surface monatomic steps are extensively studied within first-principles density functional theory framework. A stepped found possess high for reduction, which attributed both electronic geometric structures steps. other surfaces considered fail combine attributes, activity selectivity. In particular, Pt has...

Understanding the oxidation of silicon has been an ongoing challenge for many decades. Ozone recently received considerable attention as alternative oxidant in low temperature, damage-free silicon. The ozone-grown oxide was also found to exhibit improved interface and electrical characteristics over a conventionally dioxygen-grown oxide. In this review article, we summarize key findings about process. We discuss different methods O3 generation, advantages Si/SiO2 interface. An understanding...

Both enantiomers of serine adsorb on the intrinsically chiral Cu{531} surface in two different adsorption geometries, depending coverage. At saturation, substrate bonds are formed through oxygen atoms carboxylate group and amino (μ3 coordination), whereas at lower coverage, an additional bond is deprotonated β-OH (μ4 coordination). The latter geometry involves three side groups center, respectively, which leads to significantly larger enantiomeric differences geometries energies compared μ3...

We discuss the results of large-scale density functional calculations for (7×7) benzene adsorption on ferromagnetic substrate Ni{111}. Adsorption at bridge site, with C–C bonds parallel to [2̄11] direction, is found be energetically preferred over [1̄10]-oriented hcp site suggested by electron diffraction experiments. roles intermolecular forces and anisotropic molecular vibrations in accounting this apparent discrepancy. Furthermore, our analysis charge spin densities clarifies relationship...

The Fischer−Tropsch and higher oxygenate syntheses by hydrogenation of CO were two the most intensively studied catalytic reactions last century, yet a complete understanding their underlying mechanisms remains elusive. Promotion alkali metal coadsorption is often regarded as being due to enhanced dissociation, but recent experimentally determined surface structure for Co{101̄0}/(K + CO) indicates that more subtle processes may also be involved. This highly unusual structure, having no...

NO reduction on the noble metal Ag has been studied using density functional theory calculations. It was found that monomeric dissociation is subject to prohibitive barriers and thus unlikely account for experimental observations over Ag-based catalysts. For first time, a mechanism via an inverted (NO)2 dimer identified, which can explain both high activity selectivity of this catalytic system. N2O major product dimer, in accord with experiment. The physical origin metallic state as good...

The synergetic effect in multicomponent catalysts is a topic of profound industrial importance and intense academic interest. On newly identified catalyst, Au/IrO(2)/TiO(2), first-principles density-functional theory analyzed to clarify the outstanding catalytic activity system for oxidative reactions at high temperatures. By comparing CO oxidation on interfaces single-component surfaces, it revealed that dispersion more active oxide (IrO2), inert (TiO2) key. It preserves sintering...

This study investigates the adsorption properties of methylidyne (CH) on Rh{111}, its partial and full oxidation as well surface mobility, by means plane-wave density functional theory (DFT) calculations. Besides investigating known pathways rhodium, such decomposition CH subsequent products, new direct reaction oxygen toward a aldyhyde-type species this are considered. The unexpected novel pathway determined here DFT is utilized for microkinetic model formation CO CO2 from methylidyne. A...