Early Career: Tracking the Mechanisms of Catalytic Reactions on Ligand-Protected Gold Nanoclusters

Catalysts enable the production of an enormous array of chemicals on which modern society relies, but reduction of the costs and environmental impacts of this production will necessitate the development of new generations of catalysts that function efficiently in mild conditions.  Furthermore, understanding and quantifying the chemical mechanisms during catalytic reactions will be necessary to optimize catalyst performance.  This project focuses on an emerging class of catalysts, atomically precise metal nanoclusters, which are small nanoparticles that can be produced with precisely known chemical formulas and structures.  These nanoclusters combine many of the advantages of nanoparticle catalysts, particularly exposure of reactive metal surface sites, with those of molecular catalysts, namely tailorable atomic geometries and the ability to produce the exact same catalysts in bulk quantities.  Fully harnessing these advantages could lead to catalysts that require less energy input, form fewer byproducts, or enable new chemical transformations.  Despite these advantages, progress on nanocluster catalysts has been hampered by a lack of understanding, or even direct experimental probes, of the catalytic mechanisms underlying their reactivity.  This project aims to determine the mechanisms underlying key elementary reactions involved in electrocatalytic reduction and oxidation reactions with nanocluster catalysts.  Using the unique capabilities of gas phase cluster chemistry techniques, the team will form and isolate elusive catalytic nanocluster-reactant complexes and probe the extent to which they activate small molecules such as CO2and the structuresof intermediates involved in the reaction.  The extent of activation will be tracked as the composition of the nanocluster is varied, elucidating the specific form of the cluster and the cluster-molecule interactions driving reactivity.  These insights will be used to guide new efforts to precisely engineer more active sites on model catalytic nanoclusters.  These studies will yield improved mechanistic models for efforts to develop more active nanocluster catalysts for a variety of reactions, identify potentially more active nanocluster compositions, and clear examples of successful approaches to engineering active sites, all of which will be necessary to optimize and deploy nanoclusters as effective catalysts.