A5001539080- Catalytic Processes in Materials Science
- Electrocatalysts for Energy Conversion
- Catalysis and Oxidation Reactions
- Copper-based nanomaterials and applications
- Surface Chemistry and Catalysis
- Graphene research and applications
- Advanced Chemical Physics Studies
- Electronic and Structural Properties of Oxides
- Surface and Thin Film Phenomena
- Molecular Junctions and Nanostructures
- Railway Systems and Energy Efficiency
- Electron and X-Ray Spectroscopy Techniques
- Nursing education and management
- Machine Learning in Materials Science
- Railway Engineering and Dynamics
- Iron oxide chemistry and applications
- Advancements in Battery Materials
- ZnO doping and properties
- Quantum and electron transport phenomena
- Magnetic properties of thin films
- Catalysts for Methane Reforming
- Nanomaterials for catalytic reactions
- Advancements in Solid Oxide Fuel Cells
- Polyoxometalates: Synthesis and Applications
- Thermal properties of materials
Scuola Internazionale Superiore di Studi Avanzati
2015-2024
National Research Council
2015-2024
Istituto Officina dei Materiali
2015-2024
University of Udine
2011-2024
Consorzio Roma Ricerche
2019
University of Trieste
2005-2018
Henan University of Technology
2018
Qingdao Binhai University
2018
Shandong University
2018
University of Chinese Academy of Sciences
2018
QUANTUM ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, pseudopotentials (norm-conserving, ultrasoft, projector-augmented wave). The acronym stands opEn Source Package Research in Electronic Structure, Simulation, Optimization. It freely available to researchers around the world under terms GNU General Public License. builds upon newly-restructured that have been developed tested...
The high performance of ceria (CeO2) as an oxygen buffer and active support for noble metals in catalysis relies on efficient supply lattice at reaction sites governed by vacancy formation. We used high-resolution scanning tunneling microscopy density functional calculations to unravel the local structure surface subsurface vacancies (111) surface. Electrons left behind released localize cerium ions. Clusters more than two exclusively expose these reduced ions, primarily including vacancies,...
Graphene is easily produced by thermally reducing graphene oxide. However, defect formation in the C network during deoxygenation compromises charge carrier mobility reduced material. Understanding mechanisms of thermal reactions essential for defining alternative routes able to limit density defects generated carbon evolution. Here, we identify a dual path mechanism reduction oxide driven oxygen coverage: at low surface density, O atoms adsorbed as epoxy groups evolve O2 leaving unmodified....
Abstract Single-atom catalysts maximize the utilization of supported precious metals by exposing every single metal atom to reactants. To avoid sintering and deactivation at realistic reaction conditions, atoms are stabilized specific adsorption sites on catalyst substrates. Here we show combining photoelectron spectroscopy, scanning tunnelling microscopy density functional theory calculations that Pt ceria most ubiquitous defects solid surfaces—monoatomic step edges. segregation steps leads...
Modeling multiple-valence compounds using density-functional theory has long been considered a formidable task due to the role that strong electronic correlations play in these systems. We show that, case of defective ceria, main effect is produce multitude metastable low-energy states among which one displaying correct valence cerium most stable. This ground state may be difficult access practice and it fact so far escaped proper identification. The introduction Hubbard-$U$ term energy...
The atomistic and electronic structures of oxygen vacancies on the (111) (110) surfaces ceria are studied by means periodic density functional calculations. removal a neutral surface atom leaves back two excess electrons that shown to localize cerium ions neighboring defect. resulting change valency these Ce (Ce 4+ → Ce3+) originates from populating tightly bound 4f states is modeled adding Hubbard U term traditional energy functionals. calculated defect-free reduced agree with spectroscopic...
Density functional theory calculations that account for the on-site Coulomb interaction via a Hubbard term (DFT+U) reveal mechanisms oxidation of CO catalyzed by isolated Au atoms as well small clusters in Au/CeO2 catalysts. Ceria (111) surfaces containing positively charged ions, either supported Au+ adatoms or substitutional Au3+ are shown to activate molecular and catalyze its CO2. In case single adatoms, limiting rate is determined adsorbate spillover from adatom oxide support. The...
The limiting steps of CO oxidation catalyzed by ceria via the Mars−van Krevelen reaction mechanism are identified and investigated means density functional theory calculations that account for on-site Coulomb interaction a Hubbard term (DFT+U). We address adsorption on (111) (110) surfaces, its participation lattice oxygen leading to vacancy formation CO2 desorption. physisorbs surface (Ebind < 0.2 eV), while it chemisorbs more open > 2 eV) yielding carbonate reduction. DFT+U energy is...
An open superstructure: A Pd/CeO2 catalyst prepared by solution combustion synthesis is three to five times more active for CH4 than the best conventional palladium-based systems. The contains an ordered, stable Pd-O-Ce surface superstructure (see picture; cyan arrow a square-planar Pd site, red undercoordinated O atom) and example of ultra-highly dispersed, PdO within oxide carrier. Detailed facts importance specialist readers are published as ”Supporting Information”. Such documents...
Abstract The oxygen evolution reaction (OER) plays a crucial role in (photo)electrochemical devices that use renewable energy to produce synthetic fuels. Recent measurements on semiconducting oxides have found power law dependence of the OER rate surface hole density, suggesting multihole mechanism. In this study, using transient photocurrent measurements, density functional theory simulations and microkinetic modelling, we uncovered origin behaviour haematite. We show here has third-order...
The initial oxidation stages of perfect and defective graphitic surfaces exposed to atomic oxygen have been studied with a combined high-resolution photoemission spectroscopy (HR-PES) density functional theory (DFT) computational approach. resulting oxygen-containing surface groups are identified by analyzing the multicomponent C 1s O core level spectra that then interpreted on basis DFT calculations. In stage, epoxy formed graphene, whereas preferential adsorption atoms vacancies results in...
We address the issues raised in preceding Comment by discussing effects of an explicit account nonlinear core correction (NLCC) into Ce pseudopotential employed our previous calculations reduced ceria [Phys. Rev. B 71, 041102(R) (2005)]. At plain density-functional-theory (DFT) level, such brings results good agreement with all-electron ones, which do not predict insulating character ceria. $\mathrm{DFT}+U$ inclusion NLCC has no effect on previously reported electronic structure and...
The electronic structure of isolated bis(phthalocyaninato) terbium(III) molecules, a novel single-molecular-magnet (SMM), supported on the Cu(111) surface has been characterized by density functional theory and scanning tunneling spectroscopy. These studies reveal that interaction with metal preserves both molecular large spin magnetic moment center. 4f electron states are not perturbed adsorption while strong molecular/metal can induce suppression minor contribution delocalized over...
We identify mechanisms and surface precursors for the nucleation growth of extended defects on oxidized graphene. Density functional theory calculations show that formation structures capable to initiate unzipping cracking C network is strongly influenced by constraint graphitic lattice groups. Accounting this effect preferential spatial patterning O adsorbates allows us revise extend current models graphene oxidative cutting. find these processes are rate limited diffusion driven local...
Wet conditions in heterogeneous catalysis can substantially improve the rate of surface reactions by assisting diffusion reaction intermediates between sites. The atomistic mechanisms underpinning this accelerated mass transfer are, however, concealed complexity dynamic water/solid interface. Here we employ ab initio molecular dynamics simulations to disclose fast protons and hydroxide species along interface water ceria, a catalytically important, highly reducible oxide. Up 20% interfacial...
Nanomaterials coated with atomically dispersed platinum on ceria are structurally dynamic and show high potential for applications in fuel cells.
Line them up: Metal–organic chains (see scanning tunneling microscopy image) have been created in situ by self-organized growth at a metal surface under ultrahigh vacuum. These 1D arrangements of centers (Fe, Cu), regularly spaced organic linkers such as trimesitylic acid, open new possibilities for the study low-dimensional magnetism.
Reversible oxygen release makes ceria $(\mathrm{Ce}{\mathrm{O}}_{2})$ among the most efficient oxide supports for low-temperature oxidation reactions. A clear identification of species responsible this buffering is still missing since only indirect information available. We present a systematic study O adsorbates on stable surfaces based density functional theory calculations. The results rationalize experimental findings supporting interpretation that superoxide are key factors in promoting...
The adsorption of trimesic acid (TMA) on Cu(110) has been studied in the temperature range between 130 and 550 K for coverages up to one monolayer. We combine scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), reflection absorption infrared spectroscopy (RAIRS), X-ray photoemission (XPS), density functional theory (DFT) calculations produce a detailed phase diagram TMA/Cu(110) system as function molecular coverage substrate temperature. identify quite complex set...
The reduction of graphene oxide surfaces yielding molecular CO/CO2 is studied from first principles using density functional theory. We find that this reaction can proceed exothermically only surface precursors containing more oxygen atoms than strictly needed to produce in the gas phase. calculations show lowest-energy configurations multiple O adsorbates do not involve clustering epoxy groups (the stable form adatoms on graphitic surfaces) but always contain lactone either lactone−ether or...
Solar-to-fuel energy conversion relies on the invention of efficient catalysts enabling water oxidation through low-energy pathways. Our aerobic life is based this strategy, mastered by natural Photosystem II enzyme, using a tetranuclear Mn-oxo complex as oxygen evolving center. Within artificial devices, can be oxidized efficiently tailored metal-oxide surfaces such RuO2. The quest for catalyst optimization in vitro plagued elusive description active sites bulk oxides. Although molecular...
Density functional theory (DFT) calculations are used to identify correlations among reactivity, structural stability, cohesion, size, and morphology of small Au clusters supported on stoichiometric defective CeO2(111) surfaces. Molecular adsorption significantly affects the cluster in some cases induces dissociation into smaller particles deactivation. We present a thermodynamic rationalization these effects Au3 as smallest stable nanoparticle that can sustain catalytic cycles for CO...