Huairou, China
Huairou, China

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Yu X.,Anyang University, China | Yu X.,Shanxi Institute of Coal CAS Chemistry | Zhang X.,Anyang University, China | Wang S.,Shanxi Institute of Coal CAS Chemistry | And 4 more authors.
RSC Advances | Year: 2015

To understand the catalytic properties of Au nanoparticles supported on iron oxide, the adsorption structures and energies of Aun (n = 1-4) clusters on the stoichiometric, reduced and hydrated Fe3O4(001) B-terminations were systematically studied by using the GGA density functional theory method including the Hubbard parameter (U) to describe the on-site Coulomb interaction. It was found that the formation of a reduced surface with oxygen vacancies is much easier than that of an oxidized surface with iron vacancies. The most stable hydrated surface has dissociative H2O adsorption with the formation of surface hydroxyls, in agreement with the recent computational and experimental studies. Different adsorption configurations of Aun clusters have been found on the three surfaces. Au clusters prefer to bind with surface iron atoms, compared to surface oxygen atoms. The most stable adsorption configuration of single Au adatoms on the long bridge site to two surface O atoms is supported by a recent experimental study. The adsorbed Au atoms on surface iron atoms are reduced and negatively charged; and the Au atoms interacting either with surface oxygen atoms or the surface hydroxyls have less negative or positive charge. The surface hydroxyls can stabilize the adsorption of Aun clusters. © 2015 The Royal Society of Chemistry.


Yu X.,Anyang University, China | Yu X.,Shanxi Institute of Coal CAS Chemistry | Zhang X.,Anyang University, China | Wang S.,Shanxi Institute of Coal CAS Chemistry | And 4 more authors.
Current Applied Physics | Year: 2015

Spin-polarized density functional theory calculations were performed to investigate the magnetism of bulk and Cu2O surfaces. It is found that bulk Cu2O, Cu/O-terminated Cu2O(111) and (110) surfaces have no magnetic moment, while, the O-terminated Cu2O(100) and polar O-terminated Cu2O(111) surfaces have magnetism. For low index surfaces with cation and anion vacancy, we only found that the Cu vacancy on the Cu2O(110) Cu/O-terminated surface can induce magnetism. For atomic and molecular oxygen adsorption on the low index surfaces, we found that atomic and molecular oxygen adsorption on the Cu-terminated Cu2O(110) surface is much stronger than on the Cu/O-terminated Cu2O(111) and Cu-terminated Cu2O(100) surfaces. More interesting, O and O2 adsorption on the surface of Cu/O terminated Cu2O(111) and O2 adsorption on the Cu-terminated Cu2O(110) surface can induce weak ferromagnetism. In addition, we analysis origin of Cu2O surfaces with magnetism from density of state, the surface ferromagnetism possibly due to the increased 2p-3d hybridization of surface Cu and O atoms. This is radically different from other systems previously known to exhibit point defect ferromagnetism, warranting a closer look at the phenomenon. © 2015 Elsevier B.V.

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