Density functional theory approach to CO sub(2) adsorption on a spinel mineral: determination of binding coordination

The mechanism of the adsorption of CO sub(2) onto various sites of MgAl sub(2)O sub(4) (100), in particular with regards to binding coordination, was investigated using density functional theory (DFT) calculations. Of the available sites, CO sub(2) binding was calculated to be strongly adsorbed to o...

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Bibliographic Details
Published in:RSC advances 2016-03, Vol.6 (34), p.28607-28611
Main Authors: Moon, Hye Sook, Kwon, Soonchul, Kwon, Sung Hyun, Cho, Min, Seo, Jeong Gil, Lee, Seung Geol
Format: Article
Language:English
Subjects:
Adsorption
Aluminum
Binding energy
Carbon dioxide
Chemical bonds
Density functional theory
Mathematical analysis
Surface chemistry
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Summary:The mechanism of the adsorption of CO sub(2) onto various sites of MgAl sub(2)O sub(4) (100), in particular with regards to binding coordination, was investigated using density functional theory (DFT) calculations. Of the available sites, CO sub(2) binding was calculated to be strongly adsorbed to oxygen atoms on the octahedral Al super(3+) and tetrahedral Mg super(2+) sites, with adsorption energy values of -1.60 eV and -1.86 eV, respectively, which was attributed to the small band gap of the CO sub(2)-MgAl sub(2)O sub(4) system. It is clearly found that strongly adsorbed CO sub(2) molecules bound to MgAl sub(2)O sub(4) using polydentate (e.g., bidentate and tridentate) bonds. We also simulated the adsorption of multiple CO sub(2) molecules on MgAl sub(2)O sub(4), and found three of eight CO sub(2) molecules to be strongly adsorbed using tridentate bonds onto the MgAl sub(2)O sub(4) surface, with an interaction energy of -0.61 eV. The other five CO sub(2) molecules were also adsorbed, but weakly, i.e., using physical interactions with a modest binding energy of
ISSN:2046-2069
DOI:10.1039/c5ra23190f