Nanoparticle catalysts are used in the production of hydrogen for the chemical industry. Accelerating the performance of future catalysts, it is essential to understand how it is affected by the three-dimensional structure.
In a new study, a German-Chinese research team has succesfully visualized the 3D structure of the surface of catalyst nanoparticles at atomic resolution. They used atom probe tomography, spectroscopy, and electron microscopy techniques.
Scientists examined two different types of nanoparticles made of cobalt iron oxide. They studied the particles during the catalysis of the so-called oxygen evolution reaction.
This reaction changes the catalyst surface and makes it inactive. The structural and compositional changes on the surface play a vital role in the electrocatalysts‘ activity and stability.
Imaging small catalyst nanoparticles with the size of around ten nanometres remains a challenging task. Thanks to the atom probe tomography technique, scientists could visualize the distribution of the different types of atoms in the cobalt iron oxide catalysts in three dimensions.
They then combined the technique with other methods to identify how the structure and composition of the surface changed during the catalysis process. It also showed how catalytic performance is affected by this change.
Professor Tong Li from Atomic-scale Characterisation said, “Atom probe tomography has enormous potential to provide atomic insights into the compositional changes on the surface of catalyst nanoparticles during important catalytic reactions such as oxygen evolution reaction for hydrogen production or CO2 reduction.”
The research team includes scientists from the Ruhr-Universität Bochum, the University of Duisburg-Essen and the Max Planck Institute for Chemical Energy Conversion in Mülheim an der Ruhr. Scientists cooperated on the project as part of the Collaborative Research Centre ‘Heterogeneous oxidation catalysis in the liquid phase’.
- Weikai Xiang et al.: 3D atomic-scale imaging of mixed Co-Fe spinel oxide nanoparticles during oxygen evolution reaction, in Nature Communications, 2021, DOI: 10.1038/s41467-021-27788-2