DFT＋U方法研究Ni掺杂对CeO2结构和储放氧性能影响  

Steric Effects on the Enhanced Oxygen Storage Capacity of Ni Point Defects in Ceria:A First-principles DFT+U Study

作　　者：王欣全[1] 沈美庆[1] 王军[1] 

机构地区：[1]天津大学化工学院,绿色合成与转化教育部重点实验室,天津300072

出　　处：《科技导报》2011年第1期26-29,共4页Science & Technology Review

基　　金：高等学校学科创新引智计划项目(B06006)

摘　　要：铈基材料具有优异的储放氧性能和催化活性,在当今催化领域有着广泛的应用。本研究通过DFT+U方法计算了Ni掺杂引起的CeO2局域结构及全局结构扰动,并分析了原子位置排布与储放氧性能之间的构效关系。当Ni以间隙位形式进入CeO2晶胞时,Ni具有四面体配位特征,部分氧离子远离其初始位置,向类间隙位移动;在产生氧空位之后,全局结构弛豫现象明显。当Ni以取代位形式进入CeO2晶胞时,Ni具有八面体配位特征,与纯NiO结构类似;在产生氧空位之后,由Ni及其最近邻氧离子构成的局域空间发生扩张。结合氧空位生成能计算结果,间隙位Ni离子对储放氧性能的促进较小,取代位Ni离子可促进体系自发产生氧空位。First-principles density functional theory calculations with the inclusion of on-site Coulomb interaction for the Ce4f and Ni3d electrons（DFT＋U） are used to study the effects on the atomistic structures induced by the doping of bulk ceria（CeO2） with Ni atoms at substitutional（S） and interstitial（I） lattice sites.It has been found that for Ce0.97Ni0.03O2-S system,the local structure around dopant possesses octahedral symmetry and expands after the formation of oxygen vacancy;while for Ce0.97Ni0.03O2-I system,the local structure around dopant possesses tetrahedral symmetry and shrinks after the formation of oxygen vacancy.Furthermore,based on the analysis of global displacement,it has been found that the atomic relaxation has been accomplished before the formation of oxygen vacancy for Ce0.97Ni0.03O2-S system,which indicates the possibility of simultaneous formation of the oxygen vacancies around substitutional dopant sites.

关 键 词：氧化铈 过渡金属改性 原子位置扰动 储放氧 密度泛函理论 

分 类 号：O643.36[理学—物理化学]