The transformation of CO2 into alcohols or other hydrocarbon compounds is challenging because the difficulties associated with chemical activation by heterogeneous catalysts. Pure metals and bimetallic systems used for this task usually have low catalytic activity. Here we present experimental theoretical evidence a completely different type site activation: copper-ceria interface that highly efficient synthesis methanol. combination metal oxide sites in affords complementary properties lead...

Where oxide and metals meet: The activation of an efficient associative mechanistic pathway for the water–gas shift reaction by oxide–metal interface leads to increase in catalytic activity nanoparticles ceria deposited on Cu(111) or Au(111) more than order magnitude (see graph). In situ experiments demonstrated that a carboxy species formed at metal–oxide is critical intermediate reaction. As service our authors readers, this journal provides supporting information supplied authors. Such...

CeO takes charge: Ceria grows forming small islands on terraces (2–5 nm, CeOx-I) and large steps of a copper substrate (30–50 CeOx-II; see scheme; 100×100 nm2). The resulting CeOx/Cu(111) systems display an extraordinary water-gas shift activity illustrate the role that oxide can play in improving performance copper-based catalysts. Detailed facts importance to specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They...

A Cu(111) surface displays a low activity for the oxidation of carbon monoxide (2CO + O(2) → 2CO(2)). Depending on temperature, background pressure O(2), and exposure time, one can get chemisorbed O or layer Cu(2)O that may be deficient in oxygen. The addition ceria nanoparticles (NPs) to substantially enhances interactions with molecule facilitates copper substrate. In images scanning tunneling microscopy, NPs exhibit two overlapping honeycomb-type moiré structures, larger ones (H(1))...

Mixed-metal oxides play a very important role in many areas of chemistry, physics, materials science, and geochemistry. Recently, there has been strong interest understanding phenomena associated with the deposition oxide nanoparticles on surface second (host) oxide. Here, scanning tunneling microscopy, photoemission, density-functional calculations are used to study behavior ceria deposited TiO(2)(110) surface. The titania substrate imposes nontypical coordination modes nanoparticles. In...

At small coverages of ceria on TiO(2)(110), the CeO(x) nanoparticles have an unusual coordination mode. Scanning tunneling microscopy and density-functional calculations point to presence Ce(2)O(3) dimers, which form diagonal arrays that specific orientations 0, 24, 42 degrees with respect [1 -1 0] direction titania substrate. high surface exhibits two types terraces. In one type, morphology is not very different from observed at low coverage. However, in second type terrace, there a compact...

The deposition of Cu and Au nanoparticles on TiO2(110) produces very good catalysts for the WGS. Although bulk metallic gold is not active as a WGS catalyst, supported have an activity comparable to that Cu/ZnO(000ı̅). Cu/TiO2(110) clearly better catalyst than Cu/ZnO(0001̅) or Au/TiO2(110). highest also lowest apparent activation energy. On Cu(111) Cu(100), aparent energies are 18.1 15.2 kcal/mol, respectively. energy decreases 12.4 kcal/mol Cu/ZnO(0001̅), 10.2 Au/TiO2(110), 8.3...

Time dependent density functional theory (TD-DFT) calculations have been carried out to study the electronic structure and optical properties of five coumarin based dyes: C343, NKX-2311, NKX-2586, NKX-2753 NKX-2593. We found that position width first band in absorption spectra, threshold LUMO energy with respect conduction edge are key parameters order establish some criteria allow evaluating efficiency derivatives as sensitizers Dye Sensitized Solar Cells (DSSC). Those predict ordering for...

The structural and electronic properties of the alizarin dye supported on TiO2 nanoclusters have been examined by means time-dependent density-functional (TD-DFT) calculations performed in time-domain framework. calculated absorption spectrum free shows a first band centered at 2.67 eV that upon adsorption features red shift 0.31 eV, agreement with both experimental previous theoretical work. This arises from relative stabilization LUMO when adsorbed. To analyze dependence dye-support couple...

We present a study concerning the effect of on site $d\text{\ensuremath{-}}d$ Coulomb interaction energy $U$ band-gap states nonstoichiometric rutile (110) $\mathrm{Ti}{\mathrm{O}}_{2}$ surface. As well known, excess electrons resulting from formation oxygen vacancies localize $\mathrm{Ti}\phantom{\rule{0.2em}{0ex}}3d$ orbitals forming states. Local density approximation (LDA) does not give correct description these states, either with or without gradient corrections. The failure LDA is...

Dye-sensitized solar cells based on organic dyes have attracted considerable attention in recent years. These present important differences geometry and electronic structure, diverse mechanisms for injection into semiconductor conduction band been reported. In this work, the structure optical response of several dyes, free bound to TiO2, analyzed compared using time-dependent density functional theory (TD-DFT) performing calculations both real time frequency domains. The aim is illustrate...

Inverse oxide/metal catalysts have shown to be excellent systems for studying the role of oxide and oxide–metal interface in catalytic reactions. These can special structural properties due strong interactions difficult attain when depositing a metal on regular support. Oxide phases that are not seen or metastable bulk become stable an system opening possibility new chemical properties. Using these systems, it has been possible explore fundamental metal–oxide (composition, structure,...

The outstanding catalytic properties of cerium oxides rely on the easy Ce(3+) ↔ Ce(4+) redox conversion, which however constitutes a challenge in density functional based theoretical chemistry due to strongly correlated nature 4f electrons present reduced materials. In this work, we report an analysis performance five exchange-correlation functionals (HH, HHLYP, PBE0, B3LYP, and B1-WC) implemented CRYSTAL06 code describe three ceria: crystal structure, band gaps, reaction energies CeO2 →...

Reduced graphene oxide exhibits high activity as Fenton catalyst with HO(.) radical generation efficiency over 82 % and turnover numbers of 4540 15023 for phenol degradation H2 O2 consumption, respectively. These values compare favorably those achieved transition metals, showing the potential carbocatalysts reaction.

Chalcopyrite-structured semiconductors have promising potential as low-cost thermoelectric materials, but their figures of merit must be increased for practical applications. Understanding thermal properties is important engineering conductivities and achieving better behavior. We present here a theoretical investigation the lattice 20 chalcopyrite with an ABX2 composition (I–III–VI2) (A = Cu or Ag; B Al, Ga, In, Tl; X S, Se, Te). To afford accurate predictions across this large family...

Thermal and electronic transport properties are the keys to many technological applications of materials. Thermoelectric, TE, materials can be considered a singular case in which not only one but three different combined describe their performance through TE figure merit, ZT. Despite availability high-throughput experimental techniques, synthesizing, characterizing, measuring samples with numerous variables affecting ZT cost- or time-efficient approach lead this strategy. The significance...

Methods for the determination of frequency dependent hyperpolarizabilities, β(−2ω;ω,ω), β(−ω;ω,0), and β(0;ω,−ω) at self-consistent field (SCF) level theory are discussed compared. Two efficient alternatives proposed; one involves appropriate response vectors which arise in first-order perturbation ω, other solving equations 0 (static), ω 2ω. Neither approach solution second-order equations. The method is illustrated with application to formaldehyde methyl fluoride using large one-particle...

The electronic properties of N-doped rutile TiO2(110) have been investigated using synchrotron-based photoemission and density-functional calculations. doping via N2+ ion bombardment leads to the implantation N atoms (∼5% saturation concentration) that coexist with O vacancies. Ti 2p core level spectra show formation Ti3+ a second partially reduced species oxidation states between +4 +3. valence region TiO2−xNy(110) systems exhibits broad peak for near Fermi N-induced features above band...

N-doping of titania makes photocatalytic activity possible for the splitting water, and other reactions, under visible light. Here, we show from both theory experiment that Au preadsorption on TiO2 surfaces significantly increases reachable amount N implanted in oxide. The stabilization embedded is due to an electron transfer 6s levels toward 2p levels, which also Au-surface adhesion energy. Theoretical calculations predict can stabilize metal oxides with activity, such as SrTiO3 ZnO,...

The interaction of Cu, Ag, and Au atoms with the regular terrace sites CeO2(111) surface has been investigated within LDA+U GGA+U density functional theory approaches using different U values periodic slab models. For Cu Ag this methods consistently predict same qualitative description stable active sites, order stability oxidized character adsorbed Ag. case is more method dependent due to nearly degeneracy between solutions cationic neutral Au, in agreement a recent study. present results...

A realistic model, consisting of six-layer slabs, and density-functional calculations were used to perform a detailed analysis the structural electronic properties N doped TiO2(110). All positions examined for adsorption atomic are unstable regarding formation further escape N2(g). The could take place only when having isolated adatoms. In this case, prefers bond O centers located either on surface or in interstitial channels oxide lattice. These adatoms probably give rise peak seen at ∼400...

In this work we report on theoretical calculations of methanol adsorption and dissociation the stoichiometric defective TiO2(110) surface. The periodic implementation density functional theory (DFT) with plane waves pseudopotentials was employed. A supercell made 4 × 1 unit cells used to represent surface, which corresponds coverage 0.25 ML. surface modeled by removing one bridging oxygen from outermost layer. Several sites were explored through both static molecular dynamics calculations....

The electronic structure and the optical response of free catechol, [Ti(cat)3]2− complex, catechol bound to TiO2 nanoclusters have been analysed using time dependent density functional theory (TD-DFT) performing calculations both in real frequency domains. Both approaches lead similar results providing basis sets functionals are similar. For all cases, simulated spectra agree well with experimental ones. adsorption systems, show a band at 4.7 eV associated intramolecular π → π* transitions,...