Seminar Abstract:
Heterogeneous catalysts form the bedrock of industrial processes, yet little is understood in terms of structure-activity relationships. This is complicated by the fact that heterogeneous catalysts are not structurally identical, and that the catalysts change over the course of the reaction. Comprehensive characterization is necessary in order to determine the catalytic sites and hence mechanisms. In the first part of the talk, I present an amorphous molybdenum sulfide catalyst active for hydrogen evolution, photo-sensitized by semiconductor nanorods to produce solar fuel. The uniformity and large surface area of these molybdenum sulfide coated cadmium chaldogenide nanocrystals facilitate the structural and electronic characterization of the catalytically active species. In the second part of the talk, hydrogen uptake is monitored at the single particle level using darkfield spectroscopy. This non-invasive, in situ technique reveals that the hydrogen storage trajectories of plasmonic particles are shape dependent. Single particle studies of catalytic events allow measurements that would otherwise be obscured by ensemble averaging.