【摘 要】
：
The adsorption of H2O molecules and O atoms totaly on 11 surfaces of χ-Fe5C2 has been investigated with spin-polarized density functional theory(GGA-PBE)calculations.All the adsorption structures of H
【机 构】
：
State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiy
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The adsorption of H2O molecules and O atoms totaly on 11 surfaces of χ-Fe5C2 has been investigated with spin-polarized density functional theory(GGA-PBE)calculations.All the adsorption structures of H2O on(111),(-411),(131),(113),(001)and(100)surfaces are top site of surface Fe atom,but their adsorption energies are obvious different; in which the(113)and(100)is the most active and inactive surface for H2O dissociation.With the increasing of H2O coverage,the hydrogen bonding of H2O molecules on the six surfaces are more and more strong,while their average adsorption energies tend to the stable range from 0.60 to 0.70 eV,indicating the hydrogen bonding becomes more and more important for H2O adsorption,but the surface effect is more and more weak.But,it is also found that the networks of hydrogen bonding are obvious different on the six surfaces,which indicates that the surface can determine the network morphology.The calculation results show that H2O dissociation on the C-rich surfaces of(111),(100)and(110)are unfavorable than that on the stoichiometric surfaces of(-411)and(001)both thermodynamically and kinetically.At the temperature range from 500 to 700 K and the H2O/H2 ratio lower than 3,atomic thermodynamic analysis the oxidations of(111),(-411),(131),(113),(001),(100),(110),(11-1),(510)and(511)surfaces at different coverage of O atoms reveals that the C-rich surfaces are more stable than the Fe-rich surfaces.When H2O/H2 ratio is equal to 3,the order of O coverage on 11 surfaces is(510)>(001)>(11-1)>(010)>(511)>(-411)>(111)>(131)=(110)>(113)>(100).
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