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| 论文编号: |
122214O120140001 |
| 第一作者所在部门: |
908组 |
| 中文论文题目: |
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| 英文论文题目: |
Density functional theory study into H2O dissociative adsorption on the Fe5C2(0 1 0) surface
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| 论文题目英文: |
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| 作者: |
焦海军
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| 论文出处: |
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| 刊物名称: |
Applied Catalysis A
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| 年: |
2013
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| 卷: |
468 |
| 期: |
2 |
| 页: |
370-383 |
| 联系作者: |
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| 收录类别: |
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| 影响因子: |
3.41
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| 摘要: |
Spin-polarized density functional theory calculations (GGA–PBE) have been carried out to study H2O
adsorption and dissociation on the Fe5C2(0 1 0) surface. It is found that the iron region on the Fe5C2(0 1 0)
surface is active for H2O adsorption and dissociation, while the carbon region is inactive. For H2O adsorption
in the iron region, H2O prefers the top site of the surface iron atoms, and signi？cant hydrogen bonding
interaction has been found at high H2O coverage on the basis of the computed adsorption energies and the
intermolecular O–H distances. In the iron region H2O dissociation (H2O
→ H + OH; OH → H + O) is favored
both kinetically and thermodynamically. On one O pre-covered surface, O-assisted H2O dissociation
becomes favorable kinetically (O + H2O
→ OH + OH) and further OH dissociation (OH → H + O) becomes
dif？cult thermodynamically. Upon the increase of surface O coverage, H2O dissociation becomes dif？cult,
while H2 formation from the surface adsorbed H atoms becomes easy. On the potential energy surface, the
dissociation of four H2O molecules into four surface O and four H2 molecules (4H2O(g)
→ 4O(s) + 4H2(g))
is still thermodynamically favorable by 0.63 eV, and the iron region is fully covered by surface oxygen
atoms. Thermodynamic analysis reveals clearly that the catalyst surface has always adsorbed oxygen
atoms under water environment and their number in the iron region depends on temperature and water
content; and high temperature and low H2O partial pressure can maintain the catalyst stability and excess
H2O partial pressure will result in full oxidation. For the oxidation of one surface carbon atom, it is necessary
to migrate one of the four adsorbed oxygen atoms from the iron region to the carbon region, and
the H2O assisted CO2 formation is more favorable than the direct CO2 formation. The overall surface carbon
oxidation, FexCy+ 4H2O(g)
→ O2FexCy–1+ CO2(g) + 4H2(g), is thermodynamically accessible. Detailed
comparisons show that the Fe(1 0 0) and Fe5C2(0 1 0) surfaces are very similar in H2O adsorption and
dissociation at low coverage. |
| 英文摘要: |
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| 外单位作者单位: |
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| 备注: |
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