物理学报
物理學報
물이학보
2013年
11期
431-437
,共7页
路战胜%李沙沙%陈晨%杨宗献?
路戰勝%李沙沙%陳晨%楊宗獻?
로전성%리사사%진신%양종헌?
Cu/CeO2%DFT+U%吸附%电子结构
Cu/CeO2%DFT+U%吸附%電子結構
Cu/CeO2%DFT+U%흡부%전자결구
Cu/CeO2%DFT+U%adsorption%electronic structure
Cu-CeO2体系因其特殊的催化能力而在固体氧化物燃料电池和水煤气转化反应等多个催化领域有重要应用.采用基于密度泛函理论的第一性原理方法,在原子和电子层面上系统地研究了单个Cu原子及Cu小团簇在CeO2(110)面上的吸附构型,价键特性和电子结构,结果表明:1)单个Cu原子的最稳定吸附位是两个表面O的桥位;2) Cu团簇的稳定吸附构型为扭曲的四面体结构;3) Cu原子及Cu团簇的吸附在CeO2(110)面的gap区域引入了间隙态,这些间隙态主要来自于Cu及其近邻的O和表层还原形成的Ce3+,间隙态的出现表明Cu的吸附增强了CeO2(110)表面的活性;4)吸附的单个Cu原子及Cu团簇分别被CeO2(110)面表层的Ce4+离子氧化形成了Cuδ+和Cuδ+4,并伴随着Ce3+离子的形成,这个反应可归结为Cux/Ce4+→Cuδ+x /Ce3+;5) Cu团簇的吸附比Cu单原子的吸附引入了更多的Ce3+离子,进而形成了更多的Cuδ+-Ce3+催化活性中心.结合已报道的Cu/CeO2(111)界面特性,更加全面地探明了Cu与CeO2(111)和(110)两个较稳定低指数表面的协同作用特性,较为系统地揭示了Cu增强CeO2催化特性的原因及Cu与CeO2协同作用的内在机理.
Cu-CeO2體繫因其特殊的催化能力而在固體氧化物燃料電池和水煤氣轉化反應等多箇催化領域有重要應用.採用基于密度汎函理論的第一性原理方法,在原子和電子層麵上繫統地研究瞭單箇Cu原子及Cu小糰簇在CeO2(110)麵上的吸附構型,價鍵特性和電子結構,結果錶明:1)單箇Cu原子的最穩定吸附位是兩箇錶麵O的橋位;2) Cu糰簇的穩定吸附構型為扭麯的四麵體結構;3) Cu原子及Cu糰簇的吸附在CeO2(110)麵的gap區域引入瞭間隙態,這些間隙態主要來自于Cu及其近鄰的O和錶層還原形成的Ce3+,間隙態的齣現錶明Cu的吸附增彊瞭CeO2(110)錶麵的活性;4)吸附的單箇Cu原子及Cu糰簇分彆被CeO2(110)麵錶層的Ce4+離子氧化形成瞭Cuδ+和Cuδ+4,併伴隨著Ce3+離子的形成,這箇反應可歸結為Cux/Ce4+→Cuδ+x /Ce3+;5) Cu糰簇的吸附比Cu單原子的吸附引入瞭更多的Ce3+離子,進而形成瞭更多的Cuδ+-Ce3+催化活性中心.結閤已報道的Cu/CeO2(111)界麵特性,更加全麵地探明瞭Cu與CeO2(111)和(110)兩箇較穩定低指數錶麵的協同作用特性,較為繫統地揭示瞭Cu增彊CeO2催化特性的原因及Cu與CeO2協同作用的內在機理.
Cu-CeO2체계인기특수적최화능력이재고체양화물연료전지화수매기전화반응등다개최화영역유중요응용.채용기우밀도범함이론적제일성원리방법,재원자화전자층면상계통지연구료단개Cu원자급Cu소단족재CeO2(110)면상적흡부구형,개건특성화전자결구,결과표명:1)단개Cu원자적최은정흡부위시량개표면O적교위;2) Cu단족적은정흡부구형위뉴곡적사면체결구;3) Cu원자급Cu단족적흡부재CeO2(110)면적gap구역인입료간극태,저사간극태주요래자우Cu급기근린적O화표층환원형성적Ce3+,간극태적출현표명Cu적흡부증강료CeO2(110)표면적활성;4)흡부적단개Cu원자급Cu단족분별피CeO2(110)면표층적Ce4+리자양화형성료Cuδ+화Cuδ+4,병반수착Ce3+리자적형성,저개반응가귀결위Cux/Ce4+→Cuδ+x /Ce3+;5) Cu단족적흡부비Cu단원자적흡부인입료경다적Ce3+리자,진이형성료경다적Cuδ+-Ce3+최화활성중심.결합이보도적Cu/CeO2(111)계면특성,경가전면지탐명료Cu여CeO2(111)화(110)량개교은정저지수표면적협동작용특성,교위계통지게시료Cu증강CeO2최화특성적원인급Cu여CeO2협동작용적내재궤리.
Cu-CeO2 systems are widely used in solid oxide fuel cells and water gas shift reaction because of its special catalytic ability. The interfacial properties of the Cu/CeO2 (110) with the adsorption of Cu atom and Cu cluster are investigated in terms of first-principles based on density functional theory. It is found that: 1) the single Cu adatom prefers to be adsorbed on the oxygen bridge site;2) the adsorbed tetrahedron structure of Cu4 cluster is the most stable cluster configuration on CeO2(110) surface;3) the metal-introduced gap states in the gap area are mainly from the adsorbed Cu (cluster), its neighboring oxygen and the reduced cerium ion(s), indicating that the activity of CeO2(110) surface is improved by copper adsorption; 4) the adsorbed Cu adatom and Cu4 cluster are oxidized to Cuδ+ and Cuδ+4 by their neighboring Ce ion(s) with the formation of Ce3+ ion(s), the reaction could be summarized as Cux/Ce4+→Cuδ+x /Ce3+; 5) the adsorption of small clusters introduces more Ce3+ ions than a single Cu atom does, indicating that more Cuδ+-Ce3+ catalytic active centers are formed. The current study on Cu/CeO2(110) together with our previous results on Cu/CeO2(111) presents a good understanding of the synergies between Cu and ceria, and reveals the improvement of the activity of ceria by Cu adsorption.
