Scanning Tunneling Microscopy Study on the Precursor-Dependent Formation of Homogeneous Rh Clusters on Al2O3/NiAl(110)

Precursor-dependent structures of Rh/Al2O3 catalysts were examined by adopting a pulse-deposition method to deposit two precursors of rhodium acetate dimer ([Rh(OAc)2]2) and rhodium trichloride anhydrous (RhCl3) from their solution on a clean Al2O3/NiAl(110) surface and analyzing the size and the distribution of the Rh-containing species by using scanning tunneling microscopy (STM). Particularly, homogeneous Rh species containing two Rh atoms each were formed by thermal decomposition of the [Rh(OAc)2]2 precursor in a range of less than 1013 molecules cm–2. In contrast, large metallic Rh particles were formed from the RhCl3 precursor.