Postgraduate Seminar Presentation : Engineering Ligand-Protected Gold Nanoclusters for Catalytic Application

Speaker Ricca Rahman Nasaruddin (Supervisors: A/Prof Xie Jianping & Dr Yan Ning)

Host Department of Chemical and Biomolecular Engineering

Date/Time 07 Feb - 07 Feb, 3.00PM

Venue E5-03-22 , Faculty of Engineering, National University of Singapore

Synopsis

Ligand-protected gold nanoclusters (Au NCs) are metallic molecules that have been an attractive material for gold catalysis owing to their atomic precision, unique well-defined structure, ultrasmall size (< 2 nm), high reactivity due to high surface-to-volume ratio, discrete electronic structure and HOMO-LUMO (highest occupies and lowest unoccupied molecular orbital) electronic transition. Although Au NCs have been intensively studied in various chemical transformations (e.g., oxidation, hydrogenation, coupling and electrocatalytic reactions), the structure-catalytic properties relationship of Au NCs, and their catalytic mechanism at molecular level are still ambiguous and not well understood. These aspects are rarely studied probably because many Au NC catalysts were transformed into heterogenous catalysts and their ligands were removed, thus their atomic precision and well-defined structure was disrupted, further blocking a better understanding on their catalytic properties and mechanism at molecular level. Therefore, in this study, the roles of ligands of different length and functional groups to the catalytic properties (i.e., accessibility and catalytic activity) were explored. How ligands affect the selectivity, reaction pathway and catalytic mechanism of Au NCs at molecular level were also studied. Interestingly, ligands nature significantly influenced the catalytic properties of Au NCs. Ligands were also found to be dynamic which caused structural transformation to Au NCs during catalytic reaction. Apart from ligand engineering, metal engineering was also employed to facilitate fundamental understanding on structure-properties relationships of Au NC catalysts. The presence of foreign metal dopants to Au NCs significantly changed the physicochemical properties (i.e., electronic structure) of Au NCs, thus, they also modified the catalytic properties of Au NCs. Fundamental understanding on the roles of ligands and the effects of metal doping to the catalytic properties of Au NCs can facilitate the design of an efficient Au NC catalyst and expand the scope of Au NCs for catalysis.

Biography