First-Principles Study toward CO Adsorption on Au/Ni Surface Alloys

• Published in: Chemphyschem Vol. 13; no. 17; pp. 3909 - 3915
• Main Authors: Huang, Yu Cheng, Du, Jin Yan, Zhou, Tao, Wang, Su Fan
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 07.12.2012; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Adsorption; alloys; Atoms & subatomic particles; d-band theory; density functional calculations; ligand effects; Materials science; Principles
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201200606

The introduction of a second metal, gold, into a nickel matrix can effectively improve the catalytic performance and thermal stability of the catalysts toward steam reforming of methane. To investigate the effect of Au on the adsorption properties and electronic structure of the Ni(111) surface, we chose CO as a probe molecule and examined CO adsorption on various Au/Ni surfaces. It was revealed that Au addition weakened the absorbate–substrate interactions on the Ni(111) surface. With increasing gold concentration, the binding energy declines further. The variation of the binding energies has been interpreted by exploring the electronic structure of surface nickel atoms. The effect of gold can be quantitatively characterized by the slopes of the fitting equations between the binding energy and the number of gold atoms surrounding the adsorption site. Our results show that the binding energy at top sites can be approximately estimated by counting the number of surrounding gold atoms. On one specific surface, the relative magnitude of the binding energy can be simply judged by the distance between gold and the geometrical center of the adsorption site. This empirical rule holds true for C, H, and O adsorption on the Au/Ni surface. It may be applicable to a system in which a doped atom of larger atomic size is incorporated into the host metal surface by forming a surface alloy. Golden opportunities: The binding energy ordering on a gold‐modified Ni(111) surface can be determined by comparing the distance between gold and the geometrical center of the adsorption site (see picture).