Al2O3/Ni3Al(111) supported copper clusters and their interaction with carbon monoxide

JIMENA A. OLMOS ASAR; ERIK VESSELLI; A. BALDERESCHI; MARIA PERESSI

Birmingham

Workshop; Nanoalloy workshop at the TAMC VII Conference, including an MC meeting; 2013

TAMC

Metal nanoclusters present a high density of undercoordinated sites, edges and kinks. For this reason, they can present unique catalytic behaviors that depend, among other factors, on their size, shape and electronic structure, and can be influenced by the support. It is of relevance to understand the properties of the nanocatalyst, as well as its interaction with reactants and products. Furthermore, it is desirable to have a method to synthesize the clusters with a narrow size distribution and reproducible morphologies. In recent years, there has been increased interest in surface structures that can serve as templates for growing regular arrays of nanoclusters. In particular, ultrathin alumina supported on Ni3Al(111) has been shown to act as a good template due to the presence of equidistant preferential nucleation sites (holes) ordered in the corners of a periodic structure.Carbon monoxide is a reactant in many important industrial catalytic processes. CO dissociation, that leads active carbon, is a fundamental step for, e.g., the Fischer-Tropsch processes conversion of CO into hydrocarbons. Another important process is CO oxidation in automobile catalytic converters. This has motivated investigations on the fundamental properties of CO adsorption and/or dissociation onto different substrates using several surface science techniques.In this work we present a structural and electronic study of Cu clusters onto Al2O3/Ni3Al(111). We have observed that the adsorption of Cu in the holes of the oxide is much higher than onto its surface, and the growth of cluster would proceed inside the nucleation sites. We have also studied the interaction of carbon moxonide with these supported clusters, as well as with free standing particles and extended surfaces for comparison. All studies were performed under the DFT approach. We also focused on the molecular dissociation. Preliminary results show that the interaction of CO with clusters changes with the presence of the support and with the coverage degree. The greater malleability of supported clusters could make them more able to stabilize the products, favouring the inclusion of atomic C onto the Cu surface