From Static to Reacting Systems on Transition-Metal Surfaces

Kozlov, Sergey M.; Aleksandrov, Hristiyan A.; Moskaleva, Lyudmila V.; Bäumer, Marcus; Neyman, Konstantin M.

doi:10.1016/b978-0-08-097774-4.00733-6

Cited by 3 publications

(1 citation statement)

References 319 publications

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“…Bimetallic Pd–Zn is actively studied 84 – 86 (often in the form of surface alloys 87 – 89 ) because of its catalytic activity in (reverse) water–gas shift 90 – 92 and hydrogenation reactions 93 as well as potential application as selective and highly stable 94 , 95 catalysts for methanol steam reforming. 96 – 98 However, the employment of Pd–Zn catalysts is complicated by the significant dependence of their properties on the Zn–Pd ratio, 91 , 99 NP size 92 and the composition of the subsurface region.…”

Section: Resultsmentioning

confidence: 99%

How to determine accurate chemical ordering in several nanometer large bimetallic crystallites from electronic structure calculations

et al. 2015

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Section: Resultsmentioning

confidence: 99%

How to determine accurate chemical ordering in several nanometer large bimetallic crystallites from electronic structure calculations

et al. 2015

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Understanding Oxygen Activation on Nanoporous Gold

et al. 2019

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Nanoporous gold (np-Au) is a catalytically highly active material, prepared by selectively dealloying silver from a gold–silver alloy. It can promote aerobic CO oxidation and a range of other oxidation reactions. It has been debated whether the remarkable catalytic properties of np-Au are mainly due to its structural features or whether the residual Ag remaining in the material after dealloying is decisive for the activity, especially for the activation of O2. Recent theoretical studies provided evidence that Ag impurities can facilitate the adsorption and dissociation of O2 on np-Au. However, these studies predicted quite a high activation barrier for O2 dissociation on Au–Ag alloy catalysts, whereas experimentally reported activation energies are much lower. In this work we use the stepped Au(321) surface with Ag impurities, which is arguably a realistic model for np-Au material as well as for Au–Ag catalysts in general. We present alternative routes for O2 activation via its direct reaction with adsorbed CO or H2O. In all of the reactions considered, surface atomic O is generated via a sequence of elementary steps with calculated low activation energies of <0.4 eV with respect to coadsorbed reactants. Ag impurities are shown to increase the adsorption energy of O2 and hence the probability of a surface-mediated reaction versus desorption. We considered four possible mechanisms of CO oxidation in dry and humid environments in a microkinetic modeling study. We show that via the proposed mechanisms water indeed promotes O2 dissociation; nevertheless, the “dry” mechanism, in which CO directly reacts with O2, is by far the fastest route of CO2 formation on pure Au and on Au with Ag impurities. Ag impurities lead to significantly higher turnover rates; thus, calculations point to the key role of Ag in promoting the catalytic activity of Au–Ag alloy systems.

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Effect of MgO(100) support on structure and properties of Pd and Pt nanoparticles with 49-155 atoms

Kozlov

Aleksandrov

Goniakowski

et al. 2013

The Journal of Chemical Physics

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Presently, density functional computational studies of nanostructures in heterogeneous catalysts consider either sufficiently big ("scalable with size") unsupported metal nanoparticles (NPs) or small supported metal clusters. Both models may not be sufficiently representative of a few nm in size supported transition metal NPs dealt with in experiment. As a first step in closing the gap between theoretical models and prepared systems, we investigate the effect of a rather chemically inert oxide support, MgO(100), on relative energies and various properties of Pd and Pt NPs that consist of 49-155 atoms (1.2-1.6 nm in size) and exhibit bulk-like fcc structural arrangements. Shapes and interface configurations of metal NPs on MgO were obtained as a result of thorough optimization within the fcc motif using interatomic potentials. Then the stability and properties of the NPs were studied with a density functional method. We comprehensively characterize interaction between the NPs and MgO(100) support, their interface and effect of the support on NP properties. While the effect of MgO on relative stabilities of NPs with different shapes is found to be significant, other properties of the NPs such as electronic structure and interatomic distances within NP do not notably change upon deposition. This work paves the way to large-scale first-principles computational studies of more realistic models of oxide-supported metal catalysts.

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From Static to Reacting Systems on Transition-Metal Surfaces

Cited by 3 publications

References 319 publications

How to determine accurate chemical ordering in several nanometer large bimetallic crystallites from electronic structure calculations

How to determine accurate chemical ordering in several nanometer large bimetallic crystallites from electronic structure calculations

Understanding Oxygen Activation on Nanoporous Gold

Effect of MgO(100) support on structure and properties of Pd and Pt nanoparticles with 49-155 atoms

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