摘要
过渡金属碳化物良好的催化性能依赖于其组成和形貌结构.研究碳化物的精确结构有利于理解它们的催化性能本质,但是极具挑战性,尤其是对于多组分多元体系.本文利用负离子光电子谱结合密度泛函理论计算研究了二元团簇V_(n)C_(3)0/-(n=1~6)及其对应中性团簇的几何结构与电子结构.负离子光电子谱实验测得了该系列负离子团簇的绝热电子剥离能,即其对应中性团簇V_(n)C_(3)的电子亲和能.理论计算表明,在小尺寸团簇V_(n)C_(3)0/-(n=1~3)中,碳原子与碳原子相互作用成键;随着团簇尺寸增加,主要是钒原子数目增加,碳原子与碳原子倾向于分离开,不再成键.与此同时,团簇中形成了钒-碳和钒-钒键.本文进一步研究了八原子团簇VnCm(n+m=8)的结构,并考察了团簇组成对该类八原子团簇的立方或类立方结构的影响.
Transition metal carbides have been shown to exhibit good catalytic performance that depends on their compositions and morphologies,and understanding such catalytic properties requires knowledge of their precise geometry,determination of which is challenging,particularly for clusters formed by multiple elements.In this study,we investigate the geometries and electronic structures of binary V_(n)C_(3)-(n=1-6)clusters and their neutrals using photoelectron spectroscopy and theoretical calculations based on density functional theory.The adiabatic detachment energies of V_(n)C_(3)-,or equally,the electron affinities of V_(n)C_(3),have been determined from the measured photoelectron spectra.Theoretical calculations reveal that the carbon atoms become separate when the number of V atoms increases in the clusters,i.e.,the C-C interactions present in small clusters are replaced by V-C and/or V-V interactions in larger ones.We further explore the composition dependent formation of cubic or cube-like structures in 8-atom VnCm(n+m=8)clusters.
作者
袁金云
王鹏
徐西玲
张永辉
何领好
许洪光
侯高垒
郑卫军
Jinyun Yuan;Peng Wang;Xiling Xu;Yonghui Zhang;Linghao He;Hong-Guang Xu;Gao-Lei Hou;Wei-Jun Zheng(School of Material and Chemical Engineering,Zhengzhou University of Light Industry,Zhengzhou 450002,China;Beijing National Laboratory for Molecular Sciences,State Key Laboratory of Molecular Reaction Dynamics,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China;Physical Science Laboratory,Huairou National Comprehensive Science Center,Beijing 101400,China;MOE Key Laboratory for Non-Equilibrium Synthesis and Modulation of Condensed Matter,School of Physics,Xi'an Jiaotong University,Xi'an 710049,China)
基金
the Doctoral Start-up Funding of Zhengzhou University of Light Industry(No.2017BSJJ030)
Henan Province Science Fund for Excellent Young Scholars(No.202300410494)
the Beijing Municipal Science and Technology Commission(No.Z191100007219009)for supports
the VSC(Flemish Supercomputer Center),funded by the Research Foundation-Flanders(FWO)
the Flemish Government-department EWI
the support of Xi’an Jiaotong University via the“Young Talent Support Plan”
the“Fundamental Research Funds for Central Universities”。
关键词
钒-碳团簇
光电子谱
密度泛函理论
立方或类立方结构
Vanadium carbide cluster
Photoelectron spectroscopy
Density functional theory
Cubic or cube-like structure