The FeIV-O• Oxyl Unit as a Key Intermediate in Water Oxidation on the FeIII-Hydroxide: DFT Predictions
Full article
| Общее |
Language:
Английский,
Genre:
Full article,
Status:
In Press,
Source type:
Original
|
| Journal |
International Journal of Quantum Chemistry
ISSN: 0020-7608
, E-ISSN: 1097-461X
|
| Output data |
Year: 2021,
DOI:
10.1002/qua.26610
|
| Tags |
negative spin density, oxyl oxygen, the FeOOH hydroxide, the O O coupling, water oxidation |
| Authors |
Shubin Aleksandr A.
1,2
,
Kovalskii Viktor Yu.
1
,
Ruzankin Sergey Ph.
1
,
Zilberberg Igor L.
1,2
,
Parmon Valentin N.
1,2
,
Tomilin Felix N.
3,4
,
Avramov Pavel V.
5
|
| Affiliations |
| 1 |
Boreskov Institute of Catalysis, Novosibirsk, Russia
|
| 2 |
Novosibirsk State University, Novosibirsk, Russia
|
| 3 |
Kirensky Institute of Physics SB RAS, FRC “Krasnoyarsk Science Center SB RAS”, Krasnoyarsk, Russia
|
| 4 |
National Research Tomsk State University, Tomsk, Russia
|
| 5 |
Department of Chemistry, Kyungpook National University, Daegu, Republic of Korea
|
|
Funding (2)
|
1
|
Russian Foundation for Basic Research
|
15-29-01275
|
|
2
|
Russian Foundation for Basic Research
|
18-33-00932
|
The O-O coupling process in water oxidation on the gamma FeOOH hydroxide catalyst is simulated by means of density functional theory using model iron cubane cluster Fe4O4(OH)4. A key reactive intermediate is proposed to be the HO FeIV O• oxyl unit with terminal oxo radical. The “initial” vertex FeIII(OH) moiety forms this intermediate at the calculated overpotential of 0.93 V by adding one water molecule and withdrawing two proton–electron pairs. The O O coupling goes via water nucleophilic attack on the oxyl oxygen to form the O O bond with a remarkably low barrier of 11 kcal/mol. This process is far more effective than alternative scenario based on direct interaction of two ferryl FeIV O sites (with estimated barrier of 36 kcal/mol) and is comparable with the coupling between terminal oxo center and three-coordinated lattice oxo center (12 kcal/mol barrier). The process of hydroxylation of terminal oxygen inhibits the O O coupling. Nevertheless, being more effective for ferryl oxygen, the hydroxylation in fact enhances selectivity of the O O coupling initiated by the oxyl oxygen.