The Size Dependence of the Adsorption Properties of Nickel Clusters on the Surface of Aluminum Oxide

Abstract

Despite the recent activity in the field of research on the properties of systems formed by the adsorption of metal atoms on the surface of oxides, many fundamental issues remain open. Finding out the fundamental features of the behavior of systems of the type under consideration will improve the technological basis for the practical development and application of existing materials. In this regard, in this work, studies of the Ni/Al2O3/Mo(110) system were carried out in ultrahigh vacuum using surface diagnostics methods. Using X‑ray photoelectron and electron Auger spectroscopy, low-energy ion backscattering spectroscopy, and infrared Fourier spectroscopy, it is shown that electronic and adsorption properties of nanoscale nickel clusters on the surface of aluminum oxide significantly depend on the size of the cluster. The properties of clusters no larger than 2 nm are determined by the formation of a bond polarized towards the oxide substrate at the Ni/Al2O3 interface. With the growth of the cluster, depolarization of this connection occurs with the redistribution of electron density to lateral bonds between Ni atoms. Such a dimensional dependence makes it possible to program the properties of metal clusters and the metal oxide system as a whole, in particular, to achieve the required electronic and adsorption-reaction parameters.