Hidden impurities generate false positives in single atom catalyst imaging
Author(s)
Allasia, Nicolò
Collins, Sean Michael
Ramasse, Quentin Mathieu
Vilé, Gianvito
Type
Journal Article
Abstract
Single-atom catalysts (SACs) are an emerging class of materials, leveraging maximum atom utilization and distinctive structural and electronic properties to bridge heterogeneous and homogeneous catalysis. Direct imaging methods, such as aberration-corrected high-angle annular dark-field scanning transmission electron microscopy, are commonly applied to confirm the atomic dispersion of active sites. However, interpretations of data from these techniques can be challenging due to simultaneous contributions to intensity from impurities introduced during synthesis processes, as well as any variation in position relative to the focal plane of the electron beam. To address this matter, this paper presents a comprehensive study on two representative SACs containing isolated nickel or copper atoms. Spectroscopic techniques, including X-ray absorption spectroscopy, were employed to prove the high metal dispersion of the catalytic atoms. Employing scanning transmission electron microscopy imaging combined with single-atom-sensitive electron energy loss spectroscopy, we scrutinized thin specimens of the catalysts to provide an unambiguous chemical identification of the observed single-atom species and thereby distinguish impurities from active sites at the single-atom level. Overall, the study underscores the complexity of SACs characterization and establishes the importance of the use of spectroscopy in tandem with imaging at atomic resolution to fully and reliably characterize single-atom catalysts.
Date Issued
2024-10-24
Date Acceptance
2024-05-01
Citation
Angewandte Chemie International Edition, 2024, 63 (44)
ISSN
1433-7851
Publisher
Wiley
Journal / Book Title
Angewandte Chemie International Edition
Volume
63
Issue
44
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/38747260
Subjects
atomically-resolved spectroscopy
catalyst characterization
catalyst impurities
single-atom catalysis
STEM-EELS
Publication Status
Published
Coverage Spatial
Germany
Article Number
e202404883
Date Publish Online
2024-05-15