More active Ir subnanometer clusters than single-atoms for catalytic oxidation of CO at low temperature.

This work reported the adsorption and reaction performance of FeO_x supported subnanometer cluster and single-atom Ir catalysts for the oxidation of CO at low temperature. By varying the pretreatment temperature and Ir loading, the single-atom and subnanometer cluster Ir catalysts were obtained. The Ir subnanometer clusters exhibited higher activity for the oxidation of CO with or without the presence of H₂ than the single-atom counterpart. By using adsorption microcalorimetry and in situ infrared spectroscopy measurements, it was found that the Ir subnanometer clusters not only promoted the adsorption and reaction of CO and O₂ but also facilitated the formation of OH species from reaction between H₂ and O₂, thus opening a new reaction pathway between CO and OH species to produce CO₂ compared with that between CO and O species on the single-atom counterpart. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4003-4012, 2017 [ABSTRACT FROM AUTHOR]