Interfacial reactivity and morphology at the Au/NiO(001) interface

The interest on metal-oxide interfaces is stimulated stimulated by the applications in many fields, such as catalysis, magnetic ecording, hard coatings. In the first stages of growth, gold nanoparticles dispersed on different oxides exhibit unusual electronic properties, depending on cluster size and gold-substrate interaction [1,2]. In particular a partial charge transfer can occur, especially when the substrate is defective since gold tends to nucleate on oxygen vacancies. Thus the properties of goldoxide systems are critically dependent on interface reactions, in turn influenced by substrate preparation. A deeper understanding of the reactivity at the gold-oxide interface is essential to determine and control properties and behaviour of supported gold clusters. In this work we present a study of Au nucleation on top of 10 ML NiO film on Ag(001). By means of XPS, XPD and STM/AFM we studied electronic properties and morphology of the first stages of growth. It was previously reported that deposition of 15 A Au on NiO/Ag(001) causes oxide reduction [3]. We provide detailed and quantitative description of the chemical interactions at this interface. From these results we aim to determine a relation between NiO reduction and morphological modifications (cluster formation and step decoration) in order to understand the driving force of the reduction process. Similar metal-oxide interfaces have been also studied [4,5] to identify a general trend in nucleation and reaction processes. In particular Fe, Pt on NiO and Fe, Pt, Au on MgO have been comparatively investigated. [1] A. Sanchez, S. Abbet, U. Heiz, W.-D. Schneider, H. Hkkinen, R.N. Barnett, U. Landman, J. Phys. Chem. A 103(1999) 9573 [2] Z. Yang, R. Wu, D.W. Goodman, Phys. Rev. B 61 (2000) 14066 [3] R. de Masi, D. Reinicke, F. Mller, P. Steiner, S. Hfner, Surf. Sci. 515 (2002) 523 [4] S. Benedetti, P. Luches, M. Liberati, S. Valeri, Surf. Sci. 572 (2004) L348 [5] P. Luches, S. Benedetti, M. Liberati, F. Boscherini, I.I. Pronin, S. Valeri, Surf. Sci., in pres