Atomic and molecular adsorption on Rh(111)

Mavrikakis, Manos; Rempel, Jane; Greeley, Jeffrey; Nørskov, Jens K.

doi:10.1063/1.1507104

Cited by 202 publications

(211 citation statements)

References 41 publications

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“…GGA DFT functionals, as PW91 used here, have been argued to overestimate the adsorption energies on transition metal surfaces. 38,42,43 The values for the first structure are in very good agreement with those given by Loffreda et al 7 The experimental adsorption energy reported was −1.0± 0.1 eV, 39 but this value was obtained from temperature-programmed desorption ͑TPD͒ spectra for NO decomposition at 0.25 ML NO coverage in the presence of 0.25 ML N and 0.25 ML O atoms. There are considerable lateral interactions in this adlayer, making it very difficult to determine experimentally the real adsorption energy of NO.…”

Section: ͒supporting

confidence: 77%

NO structures adsorbed on Rh(111): Theoretical approach to high-coverage STM images

et al. 2006

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Theoretical modeling of scanning tunneling microscopy ͑STM͒ measurements is used for the interpretation of images of nitrogen monoxide on Rh͑111͒ surfaces in order to gain insight into the factors which control the contrast of an STM image, especially in the case of high coverage overlayers. Topographic images of NO/Rh͑111͒ for different coverages and adsorption positions were calculated. These results were used to analyze the experimental images obtained for the p͑2 ϫ 2͒-3NO and p͑3 ϫ 3͒-7NO high coverage structures. The theoretical calculations confirm that not all NO molecules present on the surface can be observed experimentally, the image being dominated by the contribution of top NO molecules in the adlayer. In addition, the calculations reveal that destructive interference effects between molecular contributions in the tunnel current play a decisive role for the different contrast of the two high coverage structures. A general discussion of why and how the differences in the adsorbate surface configuration reflect the experimental STM images is given.

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Section: ͒supporting

confidence: 77%

NO structures adsorbed on Rh(111): Theoretical approach to high-coverage STM images

et al. 2006

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“…This approach has been followed in the past 48,49 and has been shown to yield fairly accurate diffusion barrier estimates, when compared to more accurate, but at the same time, much more expensive calculations, for instance, by using the nudged elastic band method. 50 Electron density difference plots were generated for selected adsorbates to analyze the electronic structure of various bonds.…”

Section: Dft Methodsmentioning

confidence: 99%

Effect of Sn on the Reactivity of Cu Surfaces

et al. 2004

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Periodic, density functional theory (DFT-GGA) calculations, using PW91 (self-consistently) and RPBE functionals, have been employed to determine preferred binding sites, adsorbate structures, and binding energies for the adsorption of atomic (H, N, O, S, and C), molecular (NO and CO), and radical (OH) species on Cu(111) and CuSn(0001) alloy surfaces. Our results indicate the following order in the binding energies from the least to the most strongly bound: NO < CO < H < OH < N < O < S < C for Cu-terminated CuSn(0001). On Cu(111), the corresponding relative order of adsorbates from the least strongly bound to the most strongly bound is CO < NO < H < OH < N < O < S < C. On the Sn-terminated CuSn(0001) surface, CO does not adsorb and the relative order of adsorbates from the least strongly bound to the most strongly bound is NO < H < OH < N < S < O < C. For all adsorbates, the binding on Cu-terminated CuSn (0001) is stronger than on Cu(111), resulting from a combination of electronic and strain effects caused by the addition of Sn to Cu. CO dissociation is endothermic on Cu-terminated CuSn(0001) and Cu(111) surfaces, while CO oxidation is exothermic on these surfaces. OH dissociation is endothermic on all three surfaces. On all surfaces studied, thermodynamics of NO decomposition are much more favorable than those of CO and OH dissociation on the corresponding surfaces. Our microcalorimetric studies of the interaction of NO with Cu/SiO 2 and Cu 6 Sn 5 /SiO 2 samples give initial heats of 270 (2.80 eV) and 130 (1.35 eV) kJ/mol, respectively. These values correspond to the decomposition of NO to give adsorbed oxygen plus gaseous N 2 on Cu/SiO 2 and adsorbed oxygen plus gaseous N 2 O on the Sn-terminated phase of Cu 6 Sn 5 /SiO 2 .

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“…The next step is to estimate values of binding energies for adsorption of all species on the surface, for example using experimental results from the literature, results from DFT calculations, or scaling relations (20)(21)(22)(23)(24). In addition, it is necessary to estimate values for the entropies of the adsorbed species, for example using results from experimental studies (25), correlations in the literature (26), results from DFT calculations of vibrational frequencies (27)(28)(29)(30)(31)(32)(33)(34), combined with hindered translator and hindered rotor models for the three modes associated with motion parallel to the surface (35,36), or by assuming models for the extent of mobility on the surface. It is now possible to estimate values for lumped equilibrium constants, K ads,i , to form the adsorbed species from the reactants and/or products, followed by calculation of θ p .…”

Section: Analytical Strategy For Analysis Of Reaction Schemesmentioning

confidence: 99%

Analysis of reaction schemes using maximum rates of constituent steps

Motagamwala

Dumesic

2016

Proc. Natl. Acad. Sci. U.S.A.

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We show that the steady-state kinetics of a chemical reaction can be analyzed analytically in terms of proposed reaction schemes composed of series of steps with stoichiometric numbers equal to unity by calculating the maximum rates of the constituent steps, r max,i , assuming that all of the remaining steps are quasi-equilibrated. Analytical expressions can be derived in terms of r max,i to calculate degrees of rate control for each step to determine the extent to which each step controls the rate of the overall stoichiometric reaction. The values of r max,i can be used to predict the rate of the overall stoichiometric reaction, making it possible to estimate the observed reaction kinetics. This approach can be used for catalytic reactions to identify transition states and adsorbed species that are important in controlling catalyst performance, such that detailed calculations using electronic structure calculations (e.g., density functional theory) can be carried out for these species, whereas more approximate methods (e.g., scaling relations) are used for the remaining species. This approach to assess the feasibility of proposed reaction schemes is exact for reaction schemes where the stoichiometric coefficients of the constituent steps are equal to unity and the most abundant adsorbed species are in quasi-equilibrium with the gas phase and can be used in an approximate manner to probe the performance of more general reaction schemes, followed by more detailed analyses using full microkinetic models to determine the surface coverages by adsorbed species and the degrees of rate control of the elementary steps.chemical kinetics | catalysis | microkinetics C hemical reactions take place through sequences of elementary steps, and the dynamics of the overall stoichiometric reaction are typically controlled by key steps in this sequence of steps. For example, in the case of a catalytic reaction, the reaction kinetics are controlled by the energetics of the transition states for the rate-controlling steps and by the energetics of species that are abundant on the active sites (i.e., the Gibbs free energies of these transition states and adsorbed species relative to the reactants and products of the overall stoichiometric reaction). However, whereas the observed reaction kinetics are controlled by a limited number of transition states and adsorbed species, it is typically required to carry out detailed microkinetic analyses to identify the nature of these key transition states and adsorbed species. Thus, a general strategy to elucidate how the reaction kinetics are controlled by a proposed reaction mechanism is first to carry out density functional theory (DFT) calculations to determine the thermodynamic properties of all adsorbed species and transition states, and then to build a microkinetic model to determine the surface coverages by all adsorbed species and the forward and reverse rates of all elementary steps for a range of reaction conditions (1-5). Sensitivity analyses are then carried out using this microkineti...

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Atomic and molecular adsorption on Rh(111)

Cited by 202 publications

References 41 publications

NO structures adsorbed on Rh(111): Theoretical approach to high-coverage STM images

NO structures adsorbed on Rh(111): Theoretical approach to high-coverage STM images

Effect of Sn on the Reactivity of Cu Surfaces

Analysis of reaction schemes using maximum rates of constituent steps

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