Reduction of nitric oxide adsorbed on iridium cluster cations at high temperatures

Reactions of NO adsorbed on Irn+ and IrnO+ (n = 3-7) at high temperatures were experimentally investigated using gas-phase thermal desorption spectrometry. IrnNmOm+ and IrnNmOm+x+ were prepared by the reaction with NO at 300 K. After heating, NO molecules were released sequentially. For Ir5+ and Ir6+, heating above 800 K resulted in the release of N2 molecules from Ir5N4O4+, Ir5N5O5+, and Ir6N3O3+after the reduction-decomposition of NO. Similar reactions were also found on Rhn+ clusters. Furthermore, the slightly oxidized Ir7O+ showed high activity for NO reduction, which is considered unique to Ir clusters.