Insight into the effect of surface structure on H2 adsorption and activation over different CuO(111) surfaces: A first-principle study
Insight into the effect of surface structure on H2 adsorption and activation over different CuO(111) surfaces: A first-principle study
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深入了解不同 CuO(111) 表面表面结构对 H-2 吸附和活化的影响：第一性原理研究
DOI：
10.1016/j.commatsci.2016.05.023
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发表时间：
2016-09-01
影响因子：
3.3
通讯作者：
Zhao, Qiang
中科院分区：
文献类型：
--
作者：
Hao, Genyan;Zhang, Riguang;Zhao, Qiang
采用密度泛函理论（DFT）方法，系统研究了H和H2-与CuO（111）表面的相互作用，包括完全表面、氧空位表面和预覆盖氧表面，探讨了表面结构对H2-吸附和活化的影响.结果表明，在完全表面和氧空位表面上，最外层的表面氧位（O-SUF）是H吸附的活性中心，而在预覆盖氧的CuO（111）表面上，H则优先吸附在预覆盖氧位（O-pre）上.在H-2吸附和活化的情况下，H-2是解离吸附在理想表面上，两个解离的H原子吸附在同一个OSUF位上，将OSUF原子从表面上拔出，形成一个吸附在亚表面铜位上的H2O分子（Cu-O），最终导致CuO（111）表面氧空位的形成。对于氧空位表面，H-2以侧吸附方式吸附在单配位（Cu-1）和双配位（Cu-2）的Cu-2位上是两种有利的构型，而且这两种有利构型的解离能垒均高于其相应的吸附能，即H-2在氧空位表面难以解离.对于预覆盖的氧表面，H2以侧吸附或端吸附方式吸附在OSUF位时为解离吸附，其中一个H仍吸附在OSUF位，另一个H吸附在相邻的预覆盖氧位;同时，以侧吸附方式吸附在Opre位时也为解离吸附.因此，H-2主要以解离吸附的形式存在于完整和预覆盖的氧表面上，而H-2主要以分子吸附的形式存在于氧空位表面上，表明H-2在CuO（111）表面的吸附和活化行为对表面结构特别敏感. (C)2016爱思唯尔B. V.保留所有权利。
Using density functional theory (DFT) calculations, the interactions of H and H-2 with different types of CuO(111) surfaces, including the perfect, oxygen-vacancy and pre-covered oxygen surfaces, have been systematically investigated to probe into the effect of surface structures on H-2 adsorption and activation. Our results show that the outermost surface oxygen site (O-SUF) is the active center for H adsorption both on the perfect and oxygen-vacancy surfaces, while H favorably adsorbs at the pre-covered oxygen site (O-pre) on the pre-covered oxygen CuO(111) surface. In the case of H-2 adsorption and activation, H-2 is the dissociative adsorption on the perfect surface, two dissociative H atoms adsorbed at the same OSUF site pull out the OSUF atom from the surface to form a H2O molecule adsorbed at the subsurface copper site (Cu-SUB), which ultimately contributes to the formation of oxygen-vacancy site on CuO(111) surface. For the oxygen-vacancy surface, H-2 adsorbed at the singly (Cu-1) and doubly (Cu-2) coordinated CuSUB sites via the side-on mode are two favorable configurations, moreover, the dissociation barriers for these two favorable configurations is higher than their corresponding adsorption energies, namely, H-2 dissociation is difficult to occur on the oxygen-vacancy surface. For the pre-covered oxygen surface, H-2 initially adsorbed at OSUF site with the side-on or end-on modes is the dissociative adsorption, in which one H is still adsorbed at OSUF site, the other H is adsorbed at the adjacent pre-covered oxygen site; meanwhile, H-2 initially adsorbed at Opre site with the side-on mode is also the dissociative adsorption. Thus, H-2 dominantly exists in the form of the dissociative adsorption with the adsorbed H atoms on the perfect and pre-covered oxygen surfaces, whereas, H-2 mainly exists in the form of molecular adsorption H-2 on the oxygen-vacancy surface, suggesting that the adsorption and activation behaviors of H-2 over CuO(111) surface are particularly sensitive to the surface structure. (C) 2016 Elsevier B.V. All rights reserved.