Dissociative adsorption of hydrogen on copper: Stepped versus unstepped surfaces

doi:10.1016/0009-2614(77)80377-1

Chemical Physics Letters

Volume 50, Issue 3, 15 September 1977, Pages 500-502

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Abstract

A simple quantum chemical theory of dissociative adsorption is introduced and applied to the chemisorption of hydrogen on copper. Hydrogen is predicted to chemisorb more readily on the stepped (311) surface than on either of its component low index faces.

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Cited by (5)

Ethanol dimerization to Ethyl acetate and hydrogen on the multifaceted copper catalysts
2021, Surface Science
Citation Excerpt :
The one-pot EA synthesis via ethanol dehydrogenation to ethyl acetate and hydrogen (EDEH) has attracted much attention in recent years because it only consumes ethanol, an inexpensive and promising bio-renewable feedstock, and yields the value-added EA and hydrogen [5–7]. Besides, the EDEH contains several elementary reactions in other important industrial processes, such as the dehydrogenation of ethanol to acetaldehyde (DHEA), steam reforming of ethanol, direct ethanol fuel cell (DEFC), and the hydrogenation of EA to ethanol [8–17]. Hence, studying the process of EDEH contributes to not only the improvement of the EDEH catalysts but also the understanding of other related processes that contain the same elementary reactions.
Ethanol dimerization to form ethyl acetate and hydrogen (EDEH) is the best atomically economic reaction and has also been considered as an environmentally friendly process in ethyl acetate synthesis. Understanding of the catalytic activities for the EDEH while preventing byproduct formation is essential to achieve the total utilization of atoms truly. We performed density functional theory calculations to investigate the EDEH on Cu in the presence of three surfaces, namely Cu(111), Cu(110), and Cu(100). The results show that the rate-limiting step of the EDEH is surface-dependent but temperature-independent at reactions lower than 800 K. The rate-limiting step on Cu(110) is the CH₃CHO dehydrogenation to CH₃CO, whereas that of Cu(111) and Cu(100) is the ethanol dehydrogenation to CH₃CH₂O. In the presence of all three surfaces, the EDEH takes place mostly on both Cu(110) and Cu(100), with the rate-limiting step being the dehydrogenation of ethanol to CH₃CH₂O on Cu(110). We further analyzed the electronic properties of surface Cu atoms and decoupled the electronic and geometric effects. The results indicate that the electronic effect plays a critical role in the three dehydrogenation reactions, whereas the geometric effect mainly affects the CO and HH couplings.
The Cluster Approach in Theoretical Study of Chemisorption
1980, Advances in Quantum Chemistry
This chapter outlines the cluster approach in the theoretical study of chemisorption. It reviews the results obtained in the study of the structures of metal surfaces and adsorbates, as well as in predicting or reproducing bond energies. The flexible cluster-ligand model seems to be the most apt to lend theoretical support in the interpretation of experimental evidence. The chapter also deals with the few studies of surface reactivity that have been presented to date, using trajectories on potential surfaces obtained in various ways. The cluster method seems to be a good intermediate stage on the way to the study of heterogeneous catalysis. Many of the results reported in the chapter is seen to illustrate the localization of the chemisorption phenomenon to the interaction of an adsorbate with a few metal atoms. If clusters of sufficient size are used, the results were seen to converge to the reproduction of metallic bulk properties. Although theoretical methods of the various kinds outlined in this review may prove to be promising, actual catalytic effects still seem to be out of their reach. Though yielding in principle the most detailed information on adsorbate structures, LEED itself requires ordered adsorbate domains of appreciable size, while this is certainly not the case in practical catalysis.
A simple quantum chemical theory of dissociative adsorption
1978, Surface Science
Potential energy curves for the adsorption of a hydrogen atom on the (100), (110), (111) and the stepped (311) crystal faces of copper have been calculated in the pairwise additive model for gas atom-solid interactions. A Morse function is used to represent the lowest singlet pairwise H-Cu interaction potential and its parameters are adjusted so that the calculated maximum bond energies conform with the available experimental data. Bond strength on the low index faces is found to increase with the adatom's local coordination number. Except for the edge sites, the steps on the (311) surface strengthen the bonds to sites on the component low index facets. A systematic study of the convergence of the bond energy as a function of the number of solid atoms is reported. The H-Cu(s) potential is shown to be relatively insensitive to changes in the first layer separation distance of the size inferred from experiment. A new model for diatom-solid potentials is proposed in which the diatom-solid potential is expressed as a sum of the differences between diatom-solid atom London-Eyring-Polanyi-Sato three-body potentials and the diatom singlet potential. This model is used to calculate potential curves for various approaches of a hydrogen molecule towards the same copper faces. H₂ is predicted to be physisorbed on each face. The atom-solid and diatom—solid potentials are used in conjunction with a model formulated by Lennard-Jones to estimate activation energies for dissociative adsorption. The correct order is obtained for the activation energies on the low index faces. Substantially lower activation energies are obtained for approaches toward many of the sites on the two low index facets of the (311) surface as compared to the same approaches towards the individual component faces. Dissociative adsorption is predicted to proceed without activation near the steps on this surface. In general, higher activation energies are obtained when the admolecule is perpendicular to the surface or facet in question. The simple idea that the activation energies are determined by small shifts of the atomic potential relative to the less structure-sensitive molecular potential works well for the low index faces, but is not wholly satisfactory for the stepped (311) surface. All results reported in this paper are negligibly different from those that are fully converged with respect to cluster size in the present model.
Selective hydrogenation of butadiene over TiO<inf>2</inf> supported copper, gold and gold-copper catalysts prepared by deposition-precipitation
2014, Physical Chemistry Chemical Physics
Dynamics of gas-surface interactions: Reaction of atomic oxygen with adsorbed carbon on platinum
1980, The Journal of Chemical Physics

^☆: Acknowledgement is made to the Donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial support of this work.

¹: Supported partially by the NSF.

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Dissociative adsorption of hydrogen on copper: Stepped versus unstepped surfaces☆

Abstract

Trans. Faraday Soc.

Trans. Faraday Soc.

Surface Sci.

J. Chem. Soc. Faraday Trans. I

J. Vacuum Sci. Technol.

Surface Sci.

Surface Sci.

Surface Sci.

Surface Sci.

Phys. Rev. Letters

J. Chem. Phys.

Surface Sci.

Surface Sci.