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

Abstract

This work reported the adsorption and reaction performance of FeOx 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

Dynamics of Single Pt Atoms on Alumina during CO Oxidation Monitored by Operando X-ray and Infrared Spectroscopies

“…In connection to these findings, the superiority of subnanometric clusters overs single atoms was previously reported for CO oxidation over Ir/FeOx. 46…”

Nitrogen‐Doped Porous Carbon Supported Nonprecious Metal Single‐Atom Electrocatalysts: from Synthesis to Application

“…Zhang et al used infrared to observe the adsorption of CO on single atomic Ir and sub‐nano Ir clusters. It was found that Ir had an absorption peak only at 2043 cm −1 , which proved the existence of Ir single atoms . In addition, the structural characteristics of the atoms in several angstrom scales can be further obtained by Fourier transforming the X‐ray absorption spectrum .…”

“…c) Infrared adsorption of CO on 2.4Ir/Fe‐UC‐ x . Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

A perspective on oxide-supported single-atom catalysts

“…However, it's also well known that aimlessly and endlessly downsizing the metal particles does not necessarily guarantee a better catalytic performance. [8][9][10][11][12][13][14][15] The so-called "size effect" is too simplied to explain various phenomena that have been experimentally observed in different catalytic reactions by all sorts of SACs. In addition, not only does the single atom matter in reactions, but the environment including the oxide support and the metal-support interaction also plays a critical role in the catalytic performance.…”