CAJ | 학술논문

用基于密度泛函理论的第一性原理方法研究了Cu团簇(Cux,x=1-4)在CeO2(111)表面的吸附.研究发现当团簇比较小时(x=2,3),倾向于平铺表面;当x=4时,Cu团簇在CeO2(111)表面以三维的四面体结构吸附较为稳定,从Cu 3d到Ce 4f的电荷转移使Cu团簇带正电荷.由二维的菱形结构到三维的四面体结构的转变势垒为1.05 eV,并且其中一个Cu原子直接迁移到另外三个Cu原子的空位顶部的转变路径比较有利.在Cu团簇与CeO2的相互作用过程中,Cu-O和Cu-Cu相互作用的竞争最终决定了Cu团簇在CeO2上的形貌.这种CeO2(111)负载的带正电的三维Cu团簇将对水分解,进而对水煤气反应具有高的催化活性.
용기우밀도범함이론적제일성원리방법연구료Cu단족(Cux,x=1-4)재CeO2(111)표면적흡부.연구발현당단족비교소시(x=2,3),경향우평포표면;당x=4시,Cu단족재CeO2(111)표면이삼유적사면체결구흡부교위은정,종Cu 3d도Ce 4f적전하전이사Cu단족대정전하.유이유적릉형결구도삼유적사면체결구적전변세루위1.05 eV,병차기중일개Cu원자직접천이도령외삼개Cu원자적공위정부적전변로경비교유리.재Cu단족여CeO2적상호작용과정중,Cu-O화Cu-Cu상호작용적경쟁최종결정료Cu단족재CeO2상적형모.저충CeO2(111)부재적대정전적삼유Cu단족장대수분해,진이대수매기반응구유고적최화활성.
We investigated the adhesion behavior of Cu clusters (Cux, x=1-4) on a CeO2(111) surface using first-principles density functional theory (DFT). We found that small Cux clusters (x=2, 3) tended to adhere as two dimensional (2D) planar structures on the CeO2(111) surface. For the Cu4 cluster, a three dimensional (3D) tetrahedral structure is preferred and the 3D Cu4 particle is positively charged because of charge transfer from Cu 3d to Ce 4f. The transition from a 2D planar structure to 3D particles occurs with a transition barrier of 1.05 eV and the favorable route consists of one Cu atom hopping directly from the interface site to the hollow site above the Cu triangle. Because the Cu-O interactions are comparable with the Cu-Cu intra-cluster interactions, their competition determines the morphologies of the eventual Cu clusters on CeO2. The 3D positively charged Cu4 particle obtained on CeO2 is expected to result in distinct catalytic performance compared to the unsupported Cu4 cluster for water dissociation, and thus the water gas shift reactions.