Unveiling CO adsorption on Cu surfaces: new insights from molecular orbital principles

Gameel, Kareem M.; Sharafeldin, Icell M.; Abourayya, Amr U; Biby, Ahmed H.; Allam, Nageh K.

doi:10.1039/c8cp04253e

Cited by 63 publications

(56 citation statements)

References 36 publications

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“…SAA and pure metal surfaces, whereon surface atoms have a coordination number of 8. We plot DFT calculated Eads(CO) on (100) SAA and pure metal surfaces inFigure 4(a) and we find that our computed values of Eads(CO) on Cu(100) and Ni(100) are in agreement with other DFT using RPBE and experimental studies 60,61. Pt SAAs Pd SAAs Rh SAAs Ir SAAs Ni SAAs-3…”

supporting

confidence: 77%

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

2019

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Highly dilute binary alloys composed of an active platinum group metal (PGM) and a more inert coinage metal are important in the field of catalysis, as they function as active and selective catalysts. Their catalytic properties depend on the surface "ensemble" of PGM atoms, whose size may be altered under reactive conditions. We use density functional theory and investigate the interaction of CO, a molecule common in numerous industrially important chemistries, with alloys that are composed of a PGM (Pt, Pd, Rh, Ir, Ni) doped in coinage metal hosts (Cu, Au, Ag). We study the adsorption of CO on the (211) step and (100) facet and compare our results to those previously obtained on the (111) facet. We determine strong correlations between the adsorption energies of CO across the facets and highlight the corresponding thermochemical scaling relations. Finally, we study the stability of isolated surface dopant atoms with respect to aggregation into clusters and segregation into the bulk, both in the presence and absence of CO. We find that strong COdopant interactions significantly influence the morphology of the catalyst surface, suggesting that it may be possible to establish control over the ensemble size of the dopant by tuning PCO.

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supporting

confidence: 77%

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

2019

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“…This finding is in line with the previous reports [16,21,22]. Although the trend and the preferred adsorption site agrees with the experimental data, previous studies reported Eads changing between ~80 kJ/mol at low coverage (< 0.2 ML) to ~50 kJ/mol around saturation coverage (~0.55 ML) [5,9,17,[23][24][25]35]. The computed value of 135 kJ/mol (for 0.22 ML) and ~90 kJ/mol (for 0.50 ML) appear to be overestimated.…”

Section: Resultssupporting

confidence: 93%

“…However, this kind of a mismatch is expected considering the temperature-pressure gap between the experiments and the DFT simulations (0 K, 0 bar). On the other hand, reported Cu-C and C-O bond lengths of 1.90 ± 0.1 Å and 1.15 ± 0.1 Å [11,35,36], are in perfect agreement with the produced data, especially with on-top adsorption at θCO = 0.50 ML, where most of the previous experimental data is produced.…”

Section: Resultssupporting

confidence: 86%

Theoretical Investigation Of Coverage Effects Of CO Adsorption On Cu(100) Surface

Özbek

2021

Sakarya University Journal of Science

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This work investigates the CO adsorption on the metallic Cu(100) surface using periodic DFT computations. CO adsorption was studied at varying coverages from 1/16 ML to 1/1 ML for a combination of adsorption positions (4-fold, bridge and top). The results showed that adsorption energies are coverage dependent, however, not enough to identify the adsorption site and coverage. However, C-O stretching frequencies are almost unique for studied coverage and adsorption positions. CO adsorption energy changes between -250 kJ/mol to +21 kJ/mol; similarly, the vibrations' range in the 1702 cm -1 to 2110 cm -1 interval, within the studied coverage and adsorption positions. Nevertheless, under the saturation coverage (θCO ≈ 0.55ML) the preferable adsorption site is the on-top position identified with a C-O stretching frequency around ~2100 cm -1 and with ~117 kJ/mol adsorption energy.

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“…These copper states can offer chemically labile empty orbitals for accepting electrons from CO's 5σ molecular orbitals, as shown in the inset, and facilitate the chemisorption of CO molecules on the Cu-rich areas of the surface. 76,77…”

Section: Structural Characterization In Operandomentioning

confidence: 99%

Cu-Modified SrTiO₃Perovskites Toward Enhanced Water–Gas Shift Catalysis: A Combined Experimental and Computational Study

Coletta

Gonçalves

Bernardi

et al. 2020

ACS Appl. Energy Mater.

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The water-gas shift reaction (WGS) is important and widely applied in the production of H2. Cu-modified perovskites are promising catalysts for WGS reactions in hydrogen generation. However, the structure-dependent stability and reaction pathways of such materials remain unclear. Herein, we report catalytically active Cu-modified SrTiO3 (nominally SrTi1−xCuxO3) prepared by a modified polymeric precursor method. Microstructural analysis revealed a partially segregated CuO phase in the as-prepared materials. Operando X-ray diffraction and absorption spectroscopy showed the reduction of CuO into a stable metallic phase under conditions of WGS reactions for all compositions. Among the characterized materials, the x = 0.20 composition showed the highest turnover frequency, lowest activation energy, and the highest WGS rate at 300 °C. According to density functional calculations, the formation of CuO is energetically less favorable compared with, SrTiO3, explaining why the segregated CuO phase on the SrTiO3 surface is reduced to Cu during the catalytic reaction, while SrTiO3 remains. For x = 0.20, the size of the segregated CuO phase is optimum for facilitating the catalytic reaction. In contrast, a higher Cu content (x = 0.3) results in an aggregation of smaller CuO particles, resulting in fewer surface active sites and a net decrease in catalytic performance.

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Unveiling CO adsorption on Cu surfaces: new insights from molecular orbital principles

Abstract: A holistic analysis of adsorption energies, charge transfer, and structural changes has been employed to highlight the variations in adsorption mechanisms upon changing the surface type and the adsorption site.

Cited by 63 publications

References 36 publications

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

Theoretical Investigation Of Coverage Effects Of CO Adsorption On Cu(100) Surface

Cu-Modified SrTiO₃Perovskites Toward Enhanced Water–Gas Shift Catalysis: A Combined Experimental and Computational Study

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Unveiling CO adsorption on Cu surfaces: new insights from molecular orbital principles

Abstract: A holistic analysis of adsorption energies, charge transfer, and structural changes has been employed to highlight the variations in adsorption mechanisms upon changing the surface type and the adsorption site.

Cited by 63 publications

References 36 publications

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

CO-Induced Aggregation and Segregation of Highly Dilute Alloys: A Density Functional Theory Study

Theoretical Investigation Of Coverage Effects Of CO Adsorption On Cu(100) Surface

Cu-Modified SrTiO3Perovskites Toward Enhanced Water–Gas Shift Catalysis: A Combined Experimental and Computational Study

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Cu-Modified SrTiO₃Perovskites Toward Enhanced Water–Gas Shift Catalysis: A Combined Experimental and Computational Study