CO2在α-U(001)表面的吸附和解离.pdf

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1、物理化学学~E(WuliHuaxueXuebao1OctoberActaP．一Chim．Sin．2011，27(1o)，2319—232523l9【Article]www．whxb．pku．edu．cnCO2在a-u(oo1)表面的吸附和解离李赣罗文华’陈虎翅(表面物理与化学重点实验室，四川绵阳621907；中国工程物理研究院，四川绵阳621900)摘要：采用广义梯度密度泛函理论研究了0．25ML覆盖度下COz在a—u(oo1)表面上的吸附和解离，得到了CO的稳定吸附构型和吸附能，确定了CO的解离过渡态和解离能垒，探讨了CO与表面U原子的相互作

2、用本质．结果表明，cO趋向以C(o)一u多键结合方式在a．u(oo1)面发生强化学吸附，吸附能为1．24—1．67eV；C—O键的活化程度依赖于表面电子向CO发生转移的程度．CO与表面U原子的相互作用主要来自于U原子电子向CO最低空轨道(LUMO)2~o转移，以及C02／1~g／3o,一U6d轨道问杂化而生成新的化学键．以形成3个C—U键和6个O—U键模式在穴位1和穴位2上发生吸附的CO(H1-C0e和H2一C。0e)的解离吸附能分别为3．15和3．13eV。解离能垒分别为0．26和0．36eV，预示着吸附CO分子易于解离形成CO分子和O原子．

3、关键词：密度泛函理论：a-U(O01)表面：CO分子：吸附中图分类号：0641：0647AdsorptionandDissociationofC02onthea-u(o01)SurfaceLIGanLU0WenHua’CHENHu—Chi('KeyLaboratoryforSurfacePhysicsandChemistry,Mianyang62190LSichuanProvince．PR．China；2ChinaAcademyofEngineeringPhysics,Mianyang62190~SichuanProvince,PR．China

4、●Abstract：TheadsorptionanddissociationofCO2onthea—u(001)surfaceat0．25monolayer(ML)coveragewasstudiedusingdensityfunctionaltheory(DFT)withinthegeneralizedgradientapproximation(GGA)．StablestructuresandcorrespondingenergiesofCO2adsorbedonthea—u(oo1)SUrfacewereobtainedwhilethetr

5、ansitionstateandcorrespondingenergybarrierforCO2dissociationwasdetermined．WediscussedtheInteractionmechanismbetweenCO2andthea．U(001)surface。WefoundthatCO2stronglychemisorbedontothea—u(ool1surfaceinamulti-bondingmannerwithadsorptionenergiesof1．24-1．67eVandthedegreeofC—Obondac

6、tivationdependedonthedegreeofelectrontransferfromsurfacetotheadsorbedCO．TheinteractionbetweentheUatomsandtheCO2moleculesmainlycomesfr0mthepopulationoftheCO22丌ulowestunoccupiedmolecularorbitaI(LUMo)byUelectronswithC022rU1~f13o．．U6dorbitaJhybridization．Thedissociativeadsorptio

7、nenergiesfortheCO2adsorbedonthehollow1andhollow2siteswiththreeC—UbondsandsixO—Ubonds(H1．C3O6andH2-C3O6)are3．15and3．13eV．respectively．Thecorrespondingdissociationbarriersare0-26and0．36eV。whichindicatesthatthedissociationofadsorbedCO2intoC0andOoccurseasily．KeyWords：Densityfunc

8、tionaltheory；a-u(OOlsurface；Carbondioxide；AdsorptionReceived：April28，20l1；R