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 H 2 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 O 2 but also facilitated the formation of OH species from reaction between H 2 and O 2 , thus opening a new reaction pathway between CO and OH species to produce CO 2 compared with that between CO and O species on the single‐atom counterpart.