59th Annual Report on Research 2014

This research funded by ACS PRF takes advantage of a new method to control the amount, oxidation state, and nanostructuring of a transition metal deposited on a solid metal-oxide substrate. Our preliminary results suggest that copper nanostructures can be deposited on solid substrates in a chemical process where the amount of copper deposited is limited by the amount of the reducing surface sites present on a support material, and the size distribution of the nanostructures can be controlled by the deposition conditions. This research has now been completed and published (see submitted list of publications). The most attractive feature of these nanoparticles is that their core is metallic but the surface contains predominantly Cu(I) species. The nanostructures are stable in ambient conditions and withstand elevated temperatures sufficient for a chemical process to occur. The copper-based catalysts are cheap and versatile alternatives to many current systems and have high potential for applications in hydrocarbon conversion (particularly in selective oxidation) that can be used to create commodity chemicals from petroleum products.

The main questions that have been targeted within the first year of research are related to understanding the reactions of dissociation and ligand replacement on the support material itself, which in most test cases is ZnO powder. The major advances have been made in understanding the reactivity of different ZnO surfaces towards dissociating an O-H bond. Following the preliminary investigation, the thrust of the current studies are the competition between O-H and C-Cl dissociation (see submitted list of publications) and the possibility of displacing ligands remaining on a surface following copper nanoparticle deposition (Submitted to J. Phys. Condens. Matter.). Further studies focus on the fate of the thermal decomposition of the remaining ligands with majority of work dedicated to ZnO and some model surfaces to elucidate the chemistry of hexafluoroacetylacetonato and other relevant ligands. In addition, a complex self-reaction of acetone was investigated (J. Catal., accepted) and a number of long-standing controversies about this process have been addressed.

Since thermal desorption is one of the main methods used in these and previous studies, it is worth mentioning that a methodological approach used to decipher complex thermal desorption traces is being transferred to allow general users to follow the directions for data treatment, the methodological proposal supported by the National Science Foundation. However, some of the test systems and reactions are investigated within the framework of this grant; thus the resulting publication will acknowledge both contributions.