One of our main goal is to create atomically designed active surfaces by metal nanoclusters and to focus on their catalytic application. Due to their atomically controllable structure and their tunable properties, we are able to developed mono- and bimetallic nanoclusters, inducing new functionalization by ligand exchange reactions and exploring their physical-chemical properties by spectroscopic techniques, leading to well-defined catalytic surfaces
Understanding of the cluster-surface interactions
In our recent work, in situ XAS and infrared spectroscopic measurements revealed the strong influence of the cluster structure and support material in their stability and reactivity in different gas and liquid phase reactions (results published in JPCC2015, CatalToday2018, Catal. Commun2019). However, the fate of the thiolates (ligands) during deposition of the clusters on an oxide support was never considered. This motivated us to study the evolution of the thiolate ligands upon supporting clusters on surfaces like CeO2. S K-edge measurements revealed for the first time ligand migration from the gold clusters to the support, manifested by formation of unexpected oxidized sulfur species (results published in ChemCatChem 2018).
Extension of ligand engineering on supported nanoclusters
New functionalization can be introduced to the nanoclusters by ligand exchange, reaching from introduction of only one ligand up to the exchange of the entire ligand shell with the desired molecules containing selected functional groups. Depending on the ligands, new properties such as solubility, photoluminescence, optical activity or chirality can be selectively introduced. However, are the new properties preserved when the cluster is immobilized on a surface? Selectively inducing new properties on immobilized clusters opens a completely new research perspective and direction in nanomaterials, offering unprecedented possibilities in catalysis and beyond. As a proof of concept, we have performed the first study of ligand exchange reactions with supported clusters which confirmed its feasibility (submitted).
Heterogeneous catalytic research of atomically precise gold nanoclusters : accurate studies of size-dependent properties, atomic structure effects and reaction mechanisms in catalysis. In our recent work, in situ XAS and infrared spectroscopic measurements revealed the strong influence of the cluster structure and support material in their stability and reactivity in different gas and liquid phase reactions (results published in JPCC2015, CatalToday2018).
Asymmetric Heterogeneous Catalysis : Asymmetric catalysis is nowadays well established and a successful route for obtaining several enantiopure products – however, it is mostly limited to homogeneous systems. Studies on the development and characterization of heterogeneous chiral catalysts are still scarce. Au nanoclusters, due to their monodisperse nature and tunability, present perfect model systems for heterogeneous structure-activity studies. In addition, many of them are intrinsically chiral or can be made so by binding of chiral ligands. Therefore, we prepare chiral Au nanoclusters surfaces for testing in heterogeneous asymmetric catalysis, aiming at understanding the interactions between the immobilized chiral catalyst and the reactants, as a first step towards increased development of heterogeneous chiral cluster catalysts.