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1、2010年第68卷化学学报Vol.68,2010第20期,2077～2085ACTACHIMICASINICANo.20,2077～2085·研究论文·Ti,V,Nb掺杂MgH2储氢体系的放氢性能及微观机理,abaa张健*黄雅妮毛聪龙春光aab邵毅敏付俊庆彭平a(长沙理工大学汽车与机械工程学院长沙410114)b(湖南大学材料科学与工程学院长沙410082)摘要采用基于密度泛函理论的赝势平面波方法,计算了过渡金属元素Ti,V,Nb掺杂MgH2储氢体系的几何构型、能量与电子结构.结果显示:Ti,V,
2、Nb掺杂原子较Mg表现出更强的“亲氢性”,掺杂原子在吸引周围H原子同时却削弱了体系中的H—Mg键强;掺杂体系相结构稳定性降低,放氢性能提高,且体系放氢能力按MgH2-Ti,MgH2-V,MgH2-Nb顺序依次增强;放氢过程中,掺杂原子与周围H原子所形成的氢化物团簇对改善体系放氢性能表现出主要的催化活性;掺杂元素改善MgH2体系放氢性能的微观机理在于掺杂体系在费米能级附近能隙的变窄、低能级区成键电子数的减少以及H—Mg间相互作用的减弱.关键词MgH2;赝势平面波;放氢性能;电子结构Dehydroge
3、nationPropertiesandMicromechanismsofMgH2HydrogenStorageSystemswithTi,VorNbDoping,abaaZhang,Jian*Huang,YaniMao,CongLong,ChunguangaabShao,YiminFu,JunqingPeng,Pinga(InstituteofAutomobileandMechanicalEngineering,ChangshaUniversityofScienceandTechnology,Ch
4、angsha410114)b(CollegeofMaterialsScienceandEngineering,HunanUniversity,Changsha410082)AbstractUsingthepseudopotentialplane-wavemethodbasedondensityfunctionaltheory,thegeometricalconfiguration,energeticsandelectronicstructuresofMgH2hydrogenstoragesyste
5、mswithtransitionmetalsTi,VorNbdopinghavebeencalculated.ThedopingatomofTi,VorNbexhibitsmorenotableaffinitywithhydrogenascomparedwithMgatom.ThebondingstrengthofMg—Hisweakenedwhenthedopingatompullsnearbyhydrogenatomstowarditself.DuetothedopingofTi,VorNb,
6、thestructuralstabilitiesofMgH2systemsaredecreasedandtheirdehydrogenationpropertiesareimproved,aswellas,thedehydrogenationabilitiesofdopedsystemsareincreasedgraduallyinorderofMgH2-Ti,MgH2-VandMgH2-Nbsystems.Theclustersofhydridesformedfromdopingatomsand
7、hydrogenplaysignificantcatalyticroleinimprovingthedehydrogenationpropertiesofMgH2systems.ThemicromechanismsofimprovedpropertieslieinthenarrowingoftheenergygapnearFermienergylevel,thedecreasingofbondingelectronsnumberaswellastheweakeningofH—Mginteracti
8、onsindopedsystems.KeywordsMgH2;pseudopotentialplane-wave;dehydrogenationproperty;electronicstructure为解决能源短缺、环境污染日益严重和经济可持续发展等问题,开发清洁可再生能源已迫在眉睫.氢能以*E-mail:zj4343@163.comReceivedMay2,2010;revisedJune18,2010;acceptedJuly13,2010.长沙理工大学人才引进基金(No.20
