Direct visualisation of the surface atomic active sites of carbon‐supported Co3O4 nanocrystals via high‐resolution phase restoration

DOI: 10.1002/cphc.202200031

Authors: Ofentse Makgae (Lund University) , Arthur Moya (University of Oxford) , Tumelo Phaahlamohlaka (University of the Witwatersrand) , Chen Huang (University of Oxford) , Neil Coville (University of the Witwatersrand) , Angus Kirkland (University of Oxford) , Emanuela Liberti (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemphyschem

State: Published (Approved)
Published: April 2022

Abstract: The atomic arrangement of the terminating facets on spinel Co3O4 nanocrystals is strongly linked to its catalytic performance. However, the spinel crystal structure offers multiple possible surface terminations depending on the synthesis. Thus, understanding the terminating surface atomic structure is essential in developing high-performance Co3O4 nanocrystals. In this work, we present direct atomic-scale observation of the surface terminations of Co3O4 nanoparticles supported on hollow carbon spheres (HCSs) using exit wavefunction reconstruction from aberration-corrected transmission electron microscopy focal-series. The restored high-resolution phases show distinct resolved oxygen and cobalt atomic columns. The data show that the structure of {100}, {110}, and {111} facets of spinel Co3O4 exhibit characteristic active sites for carbon monoxide (CO) adsorption, in agreement with density functional theory calculations. Of these facets, the {100} and {110} surface terminations are better suited for CO adsorption than the {111}. However, the presence of oxygen on the {111} surface termination indicates this facet also plays an essential role in CO adsorption. Our results demonstrate direct evidence of the surface termination atomic structure beyond the assumed stoichiometry of the surface.

Journal Keywords: Active sites; CO oxidation; Exit wavefunction reconstruction; Facet termination; Spinel cobalt oxide

Subject Areas: Chemistry

Diamond Offline Facilities: Electron Physical Sciences Imaging Centre (ePSIC)
Instruments: E02-JEM ARM 300CF

Added On: 02/05/2022 08:19

Documents:
ChemPhysChem - 2022 - Makgae - Direct visualisation of the surface atomic active sites of carbon%E2%80%90supported Co3O4.pdf

Discipline Tags:

Physical Chemistry Catalysis Chemistry Nanoscience/Nanotechnology

Technical Tags:

Microscopy Electron Microscopy (EM) Transmission Electron Microscopy (TEM)