A comparative study of chemisorption by density functional theory, ab initio, and semiempirical methods: carbon monoxide, formate, and acetate on Cu(110) (original) (raw)

2003, Surface Science

https://doi.org/10.1016/J.SUSC.2003.07.006

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Abstract

We calculate the preferred adsorption sites, molecular structure, infrared spectra, and energies relative to stable gas phase molecules for carbon monoxide, the formate ion, and the acetate ion when adsorbed on the (1 1 0) face of copper. This substrate is modeled using small clusters of (8-46) copper atoms. Our semiempirical calculations compare well with those from ab initio, density functional theory, and with experiments. We offer a method of estimating the adsorption energy.

Key takeaways

sparkles

Semiempirical methods provide significant computational efficiency in studying chemisorption on metal surfaces.
Carbon monoxide, formate, and acetate adsorb preferentially on specific sites of Cu(110), consistent with STM experiments.
Adsorption energies for formate and acetate on Cu(110) are estimated at -23.35 kcal/mol and -22.65 kcal/mol respectively.
Density functional theory (DFT) calculations require larger clusters for accurate adsorption energy predictions, around 20 Cu atoms.
The semiempirical SAM1 method shows promise for modeling transition metals and surface science applications.

Density-functional theory study on the arrangement of adsorbed formate molecules on Cu(110)

Physical Review B, 2007

The interaction of formate molecules with the Cu͑110͒ surface is investigated using density-functional theory calculations. We find that in the most stable structures for low and high coverage, the formate molecules are sitting perpendicular to the Cu͑110͒ surface, and they are adsorbed in a bridge position, i.e., the O u C u O group forms a bridge between two Cu atoms. Other tested configurations are less stable by at least 0.45 eV per formate molecule. In the case of an oxygen-precovered Cu͑110͒ surface with high formate coverage ͓two molecules in a ͑2 ϫ 2͒ unit cell͔ we find a very similar adsorption geometry. We find an attractive interaction between adsorbed formate molecules on the copper surface. Our results are consistent with experimental results by scanning tunneling microscopy and photoelectron diffraction.

Slab versus cluster approach for chemisorption studies. CO on Cu (100)

Chemical Physics, 1993

Local density functional (LDF) slab calculations exhibit good convergence for the chemisorption energy with the number of substrate layers and with the adsorbate-adsorbate distance, in contrast with the poor convergence with cluster size and shape commonly observed in cluster calculations. The major discrepancy of cluster calculations for Cu/CO with experiment, i.e. strong preference for the hollow site, does not recur in the slab calculations, although the hollow site is still slightly preferred. The local density approximation yields an overbinding of GZ 75 kJ/mol, at top sites in line with the LDA overbinding for metal-ligand bonds and for bond energies in general.

Different adsorbate binding mechanisms of hydrocarbons: Theoretical studies for Cu(111)–C2H2 and Cu(111)–C2H4

Applied Catalysis A: General, 1998

Experimental results for acetylene and ethylene adsorption on metal surfaces indicate qualitatively different adsorbate binding mechanisms, depending on the adsorbate and substrate material. Experiments on Cu(111)±C 2 H 2 identify a strongly distorted adsorbate while the adsorption energy is small. In contrast, recent experiments on Cu(111)±C 2 H 4 have identi®ed a weakly physisorbed adsorbate without noticeable structural changes. The qualitatively different binding behavior between C 2 H 2 and C 2 H 4 with Cu(111) has been examined by ab-initio density functional theory (DFT) cluster studies. Restricted geometry optimizations yield potential energy curves E(z) which exhibit two minima for both adsorbates. The outer minimum refers to an undistorted adsorbate (indicating a physisorbed state) while the inner minimum yields a strongly distorted adsorbate (con®rming a competitive binding state). Qualitative differences between the inner and outer potential minima of the two systems can explain their different behavior. The E(z) curves can also rationalize why in experiments for Cu(111)±C 2 H 2 and Cu(111)±C 2 H 4 only one of the two adsorbate states has been veri®ed so far. However, the present calculations suggest to further look for experiments where both adsorbate states can be prepared.

2-Chlorophenol adsorption on Cu(100): First-principles density functional study

Surface Science, 2008

Interactions between a 2-chlorophenol molecule and the Cu(1 0 0) surface have been analyzed using a first-principles density functional theory (DFT) plane-wave method as the first step in gaining a detailed understanding at the molecular level of the copper catalyzed formation of PCDD/F's (dioxin compounds). While the 2-chlorophenol molecule is found to be only very weakly bound to the Cu(1 0 0) surface in a number of vertical and flat-lying configurations, its dissociation into either 2-hydroxyl-phenyl (C 6 H 4 OH) or benzyne (C 6 H 4 ) results in chemisorption on the surface. The dissociative reaction (2-chlorophenol + Cu surface ? 2-chlorophenoxy + H-Cu surface ), which is an initial and key step in the catalytic process, is also found to be exothermic on two considered sites. The 2-chlorophenoxy radical on the Cu(1 0 0) surface transforms into a mono chloro-phenolate and is more stable than the gas-phase species by about 1.74 eV. The most stable configurations occur when the benzyne moiety, hydroxyl group and chlorine atom are all separately chemisorbed on the surface with an overall stability of 0.97 eV.

Dissociative Adsorption of Molecular Oxygen on the Cu(001) Surface: A Density Functional Theory Study

The presence of atomic oxygen on catalytic surfaces is essential for initiating the oxidation of hydrogen chloride to produce chlorine via the so-called Deacon process. This process provides molecular chlorine for the formation of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) in combustion. In this paper, the dissociative adsorption of molecular oxygen on the Cu(OO I) surface has been studied using density functional theory. A periodic p(3 X 2) 4 layer slab was adopted to simulate the adsorption of both molecular and atomic oxygen at a number of adsorption sites. We have found that a bridge-bridge configuration is the most stable structure on Cu(OO I) with the Oc molecule adsorbed horizontally. The activation barrier for the dissociative adsorption of 0 2 resulting from this configuration was calculated to be 5.1 kcal/mol, with an equivalent transition temperature of-66 K. This is in good agreement with the experimental value of 40 K obtained under ultra high vacuum conditions. We have also found that a less energetically favourable, vertically oriented, physisorbed structure leads to an almost negligible reaction barrier for the dissociative adsorption of 0 2 on Cu(OOI) (1.5 kcal/mol), with an equivalent transition temperature of-20 K.

Chemisorption of NCO on Cu(1 0 0): A density functional theory study

Surface Science, 2005

The isocyanate group adsorption on sites of different coordination of Cu(1 0 0) was theoretically studied considering the cluster approach. The site of four-fold symmetry is the most favored. When NCO adsorbs on Cu, it charges negatively. This electron transfer from the substrate is greater for the site of lowest coordination. The projected DOS curves for the most important valence molecular orbitals of isocyanate group indicate a strong mixing between its 2p orbital and 3d xz and 3d yz AOs of Cu. The predicted asymmetric mode at 2187 cm À1 for NCO adsorbed on the hollow site agrees very well with the experimental observed values of 2162-65 cm À1 .

Adsorption Behavior of Organic Molecules: A Study of Benzotriazole on Cu(111) with Spectroscopic and Theoretical Methods

Langmuir, 2019

The adsorption of organic molecules on solid substrates is important to applications in fields such as catalysis, photovoltaics, corrosion inhibition, adhesion, and sensors. The molecular level description of the surface-molecule interaction and of the adsorption structures in these complex systems is crucial to understand their properties and function. Here we present the investigation of one such system, benzotriazole (BTAH) on single crystal Cu(111) in vacuum conditions. BTAH is the most widely used corrosion inhibitor for copper and thus a molecule of great industrial relevance. We show that the co-application of a wide range of spectroscopic techniques with theoretical methods provides unique insight in the description of the atomistic details of the adsorbed structures. Specifically, spectroscopic photoemission, absorption and standing wave experiments combined with ab initio computational modeling allowed us to identify that benzotriazole forms overlayers of intact BTAH when deposited at low temperature and it dissociates into BTA and H at room temperature and above. The dissociated molecule then forms complex structures of mixed chains and dimers of BTA bound to copper adatoms. Our work also reveals that copper adatoms at low concentrations, such as the theoretically predicted superstructures cannot be be resolved by means of current X-ray photoelectron spectroscopy (XPS) as the modelled Cu 2p spectra are practically indistinguishable from those for a Cu surface without adatoms. Overall this study significantly deepens understanding of BTAH on Cu-a system studied for more than 50 years-and it highlights the benefits of combining spectroscopic and computational methods in order to obtain a complete picture of a complex adsorption system.

A first-principles density functional study of chlorophenol adsorption on Cu[sub 2]O(110):CuO

The Journal of Chemical Physics, 2009

First-principles density functional theory and a periodic-slab model have been employed to explore the adsorption of a two-chlorophenol molecule on a Cu 2 O͑110͒ surface containing surface Cu-O bonds, namely, the Cu 2 O͑110͒ : CuO surface. The two-chlorophenol molecule is found to interact very weakly with the Cu 2 O͑110͒ : CuO surface, forming several vertical and flat orientations. These weakly bound states tend to result from interaction between the phenolic hydrogen and an oxygen surface atom. The formation of a two-chlorophenoxy moiety and an isolated hydrogen on the Cu 2 O͑110͒ : CuO surface from a vacuum two-chlorophenol molecule is determined to have an endothermicity of 8.2 kcal/mol ͑0.37 eV͒. The energy required to form a two-chlorophenoxy radical in the gas phase is also found to be much smaller when assisted by the Cu 2 O͑110͒ : CuO surface than direct breaking of the hydroxyl bond of a free two-chlorophenol molecule. The calculated binding energy of a two-chlorophenoxy radical adsorbed directly onto the Cu 2 O͑110͒ : CuO surface is Ϫ12.5 kcal/mol ͑0.54 eV͒. The Cu 2 O͑110͒ : CuO and Cu͑100͒ surfaces are found to have similar energy barriers for forming a surface-bound two-chlorophenoxy moiety from the adsorption of a two-chlorophenol molecule.

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A theoretical study of the CO and NO chemisorption on Cu2O(111)

Surface Science, 1997

The density functional theory coupled to the molecular cluster approach has been used to study the bonding of CO and NO to the Cu20 (111) non-polar surface. Two molecular orientations, X-and O-down (X = C, N), at two distinct sites, mono-and threecoordinated, of the Cu20(111) surface have been considered. Theoretical outcomes indicate that the former coordinative position is more favoured than the latter and that the X-down bonding is definitely stronger than the O-down one. Both XO~Cu(I) G donation and Cu(I)~XO ~ backdonation participate in the adsorbate/substrate interaction. In agreement with literature experimental results, the CO and N O stretching frequencies are significantly red-shifted upon coordination.

A theoretical study of the H2O and H2S chemisorption on Cu2O(111)

Applied Surface Science, 1999

Density functional theory coupled to the molecular cluster approach has been used to study the bonding of two Brønsted Ž. Ž. acids H X, X s O and S to the Cu O 111 non-polar surface. Both molecular and dissociative chemisorption have been 2 2 5 2 have been considered. For both acids, the atop chemisorption corresponds to the absolute minimum, even if the partial 5 deprotonation of H S is found isoenergetic to H S atop .

A new analytical potential energy surface for the adsorption system CO/Cu(100)

The Journal of Chemical Physics, 2010

Electronic structure data and analytical representations of the potential energy surface for the adsorption of carbon monoxide on a crystalline copper Cu͑100͒ substrate are reviewed. It is found that a previously published and widely used analytical hypersurface for this process ͓J. C. Tully, M. Gomez, and M. Head-Gordon, J. Vac. Sci. Technol. A 11, 1914 ͑1993͔͒ represents rather poorly the data obtained from a slab type calculation of the electronic structure. A new, global analytical representation of the potential energy surface for this process is derived via a nonlinear adjustment of parameters. It is more general and fits qualitatively better the electronic structure data. Key characteristic elements of the new surface are the "top" equilibrium adsorption site in the perpendicular arrangement Cu-C-O with Cu-C and C-O distances of 184 and 115 pm, the desorption energy of 0.76 eV and the barrier for lateral diffusion of 33 meV, including approximative corrections for the variation of zero point energy. Anharmonic vibrational fundamentals and overtones are also calculated from six dimensional variational calculations. All these values agree equally well or better with experimental data than previous published theoretical data within estimated uncertainties. The analytical representation is compact and robust, and may be used to describe other adsorption processes of diatomic molecules, including dissociative chemisorption.

Precursor Adsorption on Copper Surfaces as the First Step during the Deposition of Copper: A Density Functional Study with van der Waals Correction

Copper dimethylamino-2-propoxide [Cu(dmap) 2 ] is used as a precursor 8 for low-temperature atomic layer deposition (ALD) of copper thin films. Chemisorption 9 of the precursor is the necessary first step of ALD, but it is not known in this case 10 whether there is selectivity for adsorption sites, defects, or islands on the substrate. 11 Therefore, we study the adsorption of the Cu(dmap) 2 molecule on the different sites on 12 flat and rough Cu surfaces using PBE, PBE-D3, optB88-vdW, and vdW-DF2 methods. 13 We found the relative order of adsorption energies for Cu(dmap) 2 on Cu surfaces is E ads 14 (PBE-D3) > E ads (optB88-vdW) > E ads (vdW-DF2) > E ads (PBE). The PBE and vdW-15 DF2 methods predict one chemisorption structure, while optB88-vdW predicts three chemisorption structures for Cu(dmap) 2 16 adsorption among four possible adsorption configurations, whereas PBE-D3 predicts a chemisorbed structure for all the 17 adsorption sites on Cu(111). All the methods with and without van der Waals corrections yield a chemisorbed molecule on the 18 Cu(332) step and Cu(643) kink because of less steric hindrance on the vicinal surfaces. Strong distortion of the molecule and 19 significant elongation of Cu−N bonds are predicted in the chemisorbed structures, indicating that the ligand−Cu bonds break 20 during the ALD of Cu from Cu(dmap) 2 . The molecule loses its initial square-planar structure and gains linear O−Cu−O 21 bonding as these atoms attach to the surface. As a result, the ligands become unstable and the precursor becomes more reactive 22 65 favored over layer-by-layer growth of the smooth surface. Island 66 growth is one of the obstacles toward the use of ALD in the 67 semiconductor industry. 9 The first step in a typical ALD 68 process is the chemisorption of the precursor molecule on the 69 surface, which is followed by a series of surface reactions, some 70 of which may be irreversible due to desorption of byproducts. 71 The subsequent reactions are not possible in the case of weaker 72

Chemisorption of molecular oxygen on Cu(1 0 0): a Hartree–Fock and density functional study

Journal of Molecular Catalysis A: Chemical, 2001

The interaction of molecular oxygen with the Cu(1 0 0) surface has been studied by using both Hartree-Fock and density functional methods in the framework of the cluster model approach. In this study, we have used the Cu 8 (6,2) cluster in order to simulate the O 2 molecular adsorption on different high symmetry chemisorption sites (top-top, bridge-fourfold, bridge-top, fourfold-fourfold) on the Cu(1 0 0) surface. High level non-local density functional (NLSD) computations indicate that the more stable chemisorption site is the bridge-bridge followed by the top-top, bridge-top and bridge-fourfold ones. The calculated 1s O XPS shifts are in good agreement with the experimental indications.

First-principles calculations for the adsorption of water molecules on the Cu ( 100 ) surface

Physical Review B, 2004

First-principles density-functional theory and supercell models are employed to calculate the adsorption of water molecules on the Cu(100) surface. In agreement with the experimental observations, the calculations show that a H2O molecule prefers to bond at a one-fold on-top (T1) surface site with a tilted geometry. At low temperatures, rotational diffusion of the molecular axis of the water molecules around the surface normal is predicted to occur at much higher rates than lateral diffusion of the molecules. In addition, the calculated binding energy of an adsorbed water molecule on the surfaces is significantly smaller than the water sublimation energy, indicating a tendency for the formation of water clusters on the Cu(100) surface.

Cluster model DFT study of acetylene adsorption on the Cu (100) surface

Journal of Molecular Structure: THEOCHEM, 2003

The density functional theory and the cluster model approach have been used to study the adsorption of the acetylene molecule on the (100) surface of copper. Five possible adsorption sites have been considered: parallel twofold bridge, perpendicular twofold bridge, threefold hollow, diagonal fourfold hollow and aligned fourfold hollow sites. For each case, optimized geometries have been calculated. Vibrational frequencies have been calculated for the two energetically most favored adsorption sites. The results show clearly that on the (100) surface of copper the acetylene molecule adsorbs preferably on a fourfold hollow site. These theoretical results are in good agreement with recent Scanning Tunneling Microscopy results. q

Density Functional Theory Study of the Adsorption of Hydrazine on the Perfect and Defective Copper (100), (110), and (111) Surfaces

Journal of Physical Chemistry C, 2014

We have calculated the adsorption of the reducing agent hydrazine (N 2 H 4 ) on copper surfaces using density functional theory calculations with a correction for the long-range interactions (DFT-D2). We have modeled the perfect and a number of defective Cu(100), (110), and (111) surfaces, which are found in the experimentally produced structures of copper nanoparticles. We have studied adsorption of hydrazine at three types of defects in the surfaces, i.e., monatomic steps, Cu adatoms, and Cu vacancies. Several lowenergy adsorption structures for hydrazine on each perfect and defective surface have been identified and compared. Our calculations reveal that hydrazine bridges surface copper atoms, with the molecule twisted from the gauche toward an eclipsed conformation, except on the adatom (100) and vacancycontaining ( ) and ( ) surfaces, where it adsorbs through one nitrogen atom in gauche and trans conformations, respectively. The strongest adsorption energy is found on the stepped (110) surface, where hydrazine bridges between the copper atoms on the step edge and the terrace, as it stabilizes the low-coordinated copper atoms. Our results show that, although the (110) surface contains a number of low-coordinated atoms that enhance the surface-molecule interactions, the addition of defects on the more stable ( ) and ( ) surfaces provides sites that enable hydrazine binding to almost the same extent. This study also confirms general observations of surface adsorption trends in terms of d-band center and binding energy as a function of coordination number, i.e., the stronger the molecular adsorption, the higher the d-band shifts at low-coordinated sites.

Seriatim ECSTM-ECPMIRS of the adsorption of carbon monoxide on Cu(100) in alkaline solution at CO2-reduction potentials

Electrochemistry Communications, 2018

It was recently demonstrated that the sequential or seriatim application of electrochemical scanning tunneling microscopy (ECSTM) and differential electrochemical mass spectrometry (DEMS) enables the correlation, under actual reaction conditions, of a specific structure on a Cu electrode surface with the generation of a particular CO-reduction product. As an extension of the operando hyphenated-technique approach, we paired ECSTM with electrochemical polarization-modulation IR reflection-absorption spectroscopy (ECPMIRS) to identify a delineating potential that affected the coverage, the molecular orientation, and the adlattice structure of CO adsorbed on Cu(100) in 0.1 M KOH under CO 2-reduction conditions. The results may have significant ramifications on the theory-based reaction mechanism for the formation of C 2 compounds, as well as insights into the mode of coordination between CO and zerovalent Cu.

Oxygen adsorption on Cu(100): First-principles pseudopotential calculations

Physical Review B, 2004

We have studied the adsorption characteristics of atomic and molecular oxygen, incident on the Cu(100) surface. Our pseudopotential first-principles calculations yield trajectories for the O 2 molecule without dissociation barriers at the entrance channel. We discuss the energetics of the O 2 adsorption and dissociation in terms of the elbow plots which are two-dimensional cuts of the full six-dimensional potential-energy surface. The top site is found to be the most reactive one while at the fcc site molecular adsorption takes place. The adsorption energies at horizontal configurations of the O 2 molecule are found to be larger than those at the vertical configurations. The local densities of states reveal differences between the sites with direct dissociative adsorption and the ones with molecular precursor states. We also discuss the interactions between O and Cu atoms adsorbed at the hollow sites on Cu(100), and the corresponding diffusion barriers.

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Density-functional calculation of methane adsorption on graphite (0001

Physical Review B, 2006

Methane adsorbed on graphite was studied using density-functional theory. The structure was fully optimized with strict energy and force convergence criteria. The methane converged to the preferred adsorption sites giving the vibrational frequencies, the energy of adsorption, charge distributions, and the electronic density of states. Under the two coverages studied ͑ ͱ 3 ϫ ͱ 3 and 2 ͱ 3 ϫ 2 ͱ 3͒ and a differing number of graphite layers ͑1-6͒, the methane molecules favored atop sites on the graphite surface with the hydrogen tripod down. We found the methane carbon 3.21 Å above the graphite carbon and the adsorption energy to be 118 meV for the lower coverage. The independent harmonic oscillator vibrational frequency perpendicular to the surface for the CH 4 molecule was computed to be 87 cm -1 . The graphite surface contracted 5.0% and 4.1% for the first and second layers, respectively, from the spacing relative to their bulk values. To benchmark our frequency calculations, we also used second-order Moller-Plesset theory and the local spin density approximation ͑LSDA͒ in GAUSSIAN 03 for the molecule. All of our LDA results are in good agreement with corresponding experiments, while under the generalized gradient approximation approximation we get only qualitatively results.

Self-assembly of acetate adsorbates drives atomic rearrangement on the Au(110) surface

Nature Communications, 2016

Weak inter-adsorbate interactions are shown to play a crucial role in determining surface structure, with major implications for its catalytic reactivity. This is exemplified here in the case of acetate bound to Au(110), where the small extra energy of the van der Waals interactions among the surface-bound groups drives massive restructuring of the underlying Au. Acetate is a key intermediate in electro-oxidation of CO 2 and a poison in partial oxidation reactions. Metal atom migration originates at surface defects and is likely facilitated by weakened Au-Au interactions due to bonding with the acetate. Even though the acetate is a relatively small molecule, weak intermolecular interaction provides the energy required for molecular self-assembly and reorganization of the metal surface.

Density-functional theory study on the arrangement of adsorbed formate molecules on Cu(110)

Physical Review B, 2007

High-Loaded Copper-Containing Sol–Gel Catalysts for Furfural Hydroconversion

International Journal of Molecular Sciences

In this study, the high-loaded copper-containing catalysts modified with Fe and Al were successfully applied for the hydroconversion of furfural to furfuryl alcohol (FA) or 2-methylfuran (2-MF) in a batch reactor. The synthesized catalysts were studied using a set of characterization techniques to find the correlation between their activity and physicochemical properties. Fine Cu-containing particles distributed in an amorphous SiO2 matrix, which has a high surface area, provide the conversion of furfural to FA or 2-MF under exposure to high pressure of hydrogen. The modification of the mono-copper catalyst with Fe and Al increases its activity and selectivity in the target process. The reaction temperature strongly affects the selectivity of the formed products. At a H2 pressure of 5.0 MPa, the highest selectivity toward FA (98%) and 2-MF (76%) was achieved in the case of 35Cu13Fe1Al-SiO2 at the temperature of 100 °C and 250 °C, respectively.

A comparative study of chemisorption by density functional theory, ab initio, and semiempirical methods: carbon monoxide, formate, and acetate on Cu(110) (original) (raw)

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