The catalytic activity of nanoscale gold has been the subject of intensive research since its discovery some 20 years ago. In 1989, Haruta et al. reported that gold nanoclusters dispersed on several oxide supports could efficiently catalyze the oxidation of CO to CO2 at temperatures as low as 200K [1]. Numerous studies have now been made with the aim of understanding the enhanced reactivity of such gold nanoclusters.
Recently, Lahr and Ceyer reported that a Au/Ni(111) surface alloy, which consists of gold atoms substituted into the topmost nickel layer, catalyzes CO oxidation at even lower temperatures--as low as 70K--implying that the enhanced activity of gold is not limited to supported particles [2]. We have used a combination of scanning tunnelling microscopy (STM), x-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) to study the low temperature adsorption, coadsorption and reaction of CO and O2 on this Au/Ni(111) surface alloy. As a reference we also studied the adsorption and coadsorption of CO and O2 at low temperature on a clean Ni(111) surface.
We will also give a short review of known catalytic properties of Au/Ni(111) surface alloy and discuss the low temperature CO oxidation in this framework.
1. M. Haruta, et al., J. Catal. 115, 301 (1989)
2. D.L. Lahr and S.T. Ceyer, J. Am. Chem. Soc. 128, 1800 (2006)
|