103 research outputs found
Dinitrosyl formation as an intermediate stage of the reduction of NO in the presence of MoO_3
We present first-principles calculations in the framework of
density-functional theory and the pseudopotential approach, aiming to model the
intermediate stages of the reduction of NO in the presence of MoO(010). In
particular, we study the formation of dinitrosyl, which proves to be an
important intermediate stage in the catalytic reduction. We find that the
replacement of an oxygen of MoO by NO is energetically favorable, and that
the system lowers further its energy by the formation of (NO). Moreover,
the geometry and charge distribution for the adsorbed dinitrosyl indicates a
metal-oxide mediated coupling between the two nitrogen and the two oxygen
atoms. We discuss the mechanisms for the dinitrosyl formation and the role of
the oxide in the reaction.Comment: 6 pages, 4 figs, RevTeX. To be published in J. Chem. Phy
Thermodynamics of C incorporation on Si(100) from ab initio calculations
We study the thermodynamics of C incorporation on Si(100), a system where
strain and chemical effects are both important. Our analysis is based on
first-principles atomistic calculations to obtain the important lowest energy
structures, and a classical effective Hamiltonian which is employed to
represent the long-range strain effects and incorporate the thermodynamic
aspects. We determine the equilibrium phase diagram in temperature and C
chemical potential, which allows us to predict the mesoscopic structure of the
system that should be observed under experimentally relevant conditions.Comment: 5 pages, 3 figure
Aromaticity in a Surface Deposited Cluster: Pd on TiO (110)
We report the presence of \sigma-aromaticity in a surface deposited cluster,
Pd on TiO (110). In the gas phase, Pd adopts a tetrahedral
structure. However, surface binding promotes a flat, \sigma-aromatic cluster.
This is the first time aromaticity is found in surface deposited clusters.
Systems of this type emerge as a promising class of catalyst, and so
realization of aromaticity in them may help to rationalize their reactivity and
catalytic properties, as a function of cluster size and composition.Comment: 4 pages, 3 figure
Substrate co-doping modulates electronic metal–support interactions and significantly enhances single-atom catalysis
DFT Insight into CO Oxidation Catalyzed by Gold Nanoclusters: Charge Effect and Multi-State Reactivity
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