Chelating Cu-N within Cu+-incorporated MIL-101 (Cr)-NH2 framework for enhanced CO adsorption and CO/CO2 selectivity

Using the high-entropy alloys (HEAs) CoCuGaNiZn and AgAuCuPdPt as starting points we provide a framework for tuning the composition of disordered multi-metallic alloys to control the selectivity and activity of the reduction of carbon dioxide (CO2) to highly reduced compounds. By combining density functional theory (DFT) with supervised machine learning we predicted the CO and hydrogen (H) adsorption energies of all surface sites on the (111) surface of the two HEAs. This allowed an optimization for the HEA compositions with increased likelihood for sites with weak hydrogen adsorption{to suppress the formation of molecular hydrogen (H2) and with strong CO adsorption to favor the reduction of CO. This led to the discovery of several disordered alloy catalyst candidates for which selectivity towards highly reduced carbon compounds is expected, as well as insights into the rational design of disordered alloy catalysts for the CO2 and CO reduction reaction.

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A topological quantum-chemical study of the chemisorption of carbon monoxide on the fcc (112) surfaces of Ni, Pt, Pd, Rh, and Ir

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19901907 ◽

1990 ◽

Vol 55 (8) ◽

pp. 1907-1919

Author(s):

Jiří Pancíř ◽

Ivana Haslingerová

Keyword(s):

Carbon Monoxide ◽

Quantum Chemical ◽

Co Adsorption ◽

Quantum Chemical Study ◽

Chemical Study ◽

Dissociative Chemisorption ◽

Frontier Orbitals ◽

Surface Sites ◽

Charged Surfaces ◽

Topological Quantum

A semiempirical quantum-chemical topological method is applied to the study of the fcc (112) surfaces of Ni, Pt, Pd, Rh, and Ir and the nondissociative as well as dissociative chemisorption of carbon monoxide on them. On Ni, dissociative chemisorption is preferred to linear capture, whereas on Pd and Pt, linear capture is preferred although dissociative chemisorption is also feasible. On Rh and, in particular, on Ir, dissociative chemisorption is energetically prohibited. The high dissociative ability of the Ni surface can be ascribed to a rather unusual charge alteration and to the degeneracy of the frontier orbitals. Negative charges at the surface level are only found on the Ni and Pt surfaces whereas concentration of positive charges is established on the Rh and Ir surfaces; the Pd surface is nearly uncharged. Metals with negatively charged surfaces seem to be able to dissociate molecules of carbon monoxide. It is demonstrated that CO adsorption can take place on all metal surface sites, most effectively in the valley of the step. In all the cases studied, the attachment to the surface is found to be energetically more favourable for the carbon than for the oxygen.

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Adsorption of Carbon Monoxide on Pd/SiO2/Si(111) Studied by Core-Level Photoemission

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19981793 ◽

1998 ◽

Vol 63 (11) ◽

pp. 1793-1802 ◽

Cited By ~ 1

Author(s):

Zdeněk Bastl ◽

Tomáš Šarapatka

Keyword(s):

Carbon Monoxide ◽

Photoelectron Spectroscopy ◽

Co Adsorption ◽

Charge Balance ◽

Adsorption Activity ◽

Chemical States ◽

Adsorbed Co ◽

Pd Clusters ◽

Almost All ◽

P Type

X-Ray photoelectron spectroscopy (XPS) has been used to study the adsorption of carbon monoxide on Pd dispersed on oxidized Si(111) surface. A fraction of the deposited Pd diffusing at room temperature to the SiO2/Si interface increases with decreasing SiO2 thickness. For oxide layers thinner than ≈1 nm, almost all deposited Pd diffuses to SiO2/Si interface forming there Si silicide. Consequently, the amount of adsorbed CO is dependent on the thickness of the thermally grown SiO2 layer. Two different chemical states of adsorbed carbon atoms, the population of which depends on the amount of the Pd deposited, are observed in the C (1s) spectra of adsorbed CO. Adsorption activity of Pd clusters does not depend on whether n- or p-type Si is used. Comparison of the experimental Pd/CO concentration ratios with those calculated assuming several different modes of the Pd growth on SiO2/Si points to the pseudo-Stranski-Krastanow mode (flat clusters with incomplete condensation of the first layer) at 300 K. Changes in charge balance across the Pd/SiO2/Si interface caused by CO adsorption are discussed in terms of the surface photovoltage effect and work function variation.

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The Properties of Cu Ions in Zeolites CuY Studied by IR Spectroscopy

Molecules ◽

10.3390/molecules26154686 ◽

2021 ◽

Vol 26 (15) ◽

pp. 4686

Author(s):

Jerzy Podobiński ◽

Mariusz Gackowski ◽

Grzegorz Mordarski ◽

Katarzyna Samson ◽

Michał Śliwa ◽

...

Keyword(s):

Ir Spectroscopy ◽

Positive Charge ◽

Co Adsorption ◽

The Other ◽

Probe Molecules ◽

Adsorption And Desorption ◽

Other Hand ◽

Close Proximity ◽

No And Co Adsorption ◽

Cu Ions

The properties of both Cu2+ and Cu+ ions in zeolite CuY were followed with NO and CO as probe molecules. Cu2+ was found to be located in SII, SII*, and SIII sites, whereas Cu+ was found in SII and SII* sites. The fine analysis of the spectra of Cu2+-NO and Cu+-CO adducts suggests that both in SII and in SII* sites two kinds of Cu cations exist. They differ in the positive charge, which may be related to the varying numbers of AlO4− in close proximity. The experiments of NO and CO adsorption and desorption evidenced that both Cu2+ and Cu+ sites of highest positive charge bind probe molecules most strongly but activate them to a lesser extent than the Cu sites of lowest positive charge. The experiments of reduction with hydrogen evidenced that the Cu ions of higher positive charge are first reduced by hydrogen. On the other hand, Cu sites of the lowest positive charge are first oxidized by oxygen. The experiments with CuNaY zeolites of various Cu contents suggest that the first introduced Cu (at low Cu contents) created Cu+, which was the most neutralized by framework oxygens. Such Cu cations are the most stabilized by framework oxygens.

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