When Noble Metal is Not Noble

"Noble metals are generally considered chemically inert in moist air. However, Rh (Rhodium) nanoparticles frequently have been studied and used as highly active catalysts for purification of automobile and industry exhaust. Being one of the most expensive noble metals (its market price is twice as much as gold), it is important to obtain good catalytic efficiency per Rh unit weight. In order to understand the reaction mechanism at an atomic level and improve the Rh catalytic activity, my research has been focused on model catalysts study of Rh clusters and nanoparticles supported on planar surfaces. In the image presented, we successfully prepared hexagonal islands of Rh nanoparticles with narrow size distribution. We were able to use Rh(CO)2(acac) as a precursor, which is more efficient by means of cost. The organic ligands can help to stabilize the Rh particles from sintering upon heating and maintain the catalytic activity. By gradually heating the sample and removing the ligands, the size and shape of Rh nanoparticles changes can be observed by a Scanning Tunneling Microscope. This allows us to understand the relationship between the reactivates and the Rh nanoparticles size and shape changes."