CO-induced changes of Ir nanoparticles supported on TiO2 (110)-(1x2) surface

Ir nanoparticles of different sizes are produced on TiO2(110)-(1 x 2) surface and characterized by scanning tunneling microscopy (STM). It was found that at very low coverage Ir is Formed in round shape nanoparticles on titania which are mainly centered on the oxygen deficient rows of the (1 x 2) terraces. The annealing of the iridium covered surface caused an perceivable increase of the particle size only above 700 K. The supported iridium nanoparticles of 1-3 nm exhibit a very high reactivity towards CO. As a result of the CO adsorption at 300 K. crystallites disrupt into smaller particles, and finally into atomically dispersed Ir. This feature was not experienced for larger clusters of 8-10 nm size. (C) 1998 Elsevier Science B.V. All rights reserved.