3D atomic-scale imaging of mixed Co-Fe spinel oxide nanoparticles during oxygen evolution reaction.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35013310.
- Also identified by DOI 10.1038/s41467-021-27788-2 and PMC identifier 8748757.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The three-dimensional (3D) distribution of individual atoms on the surface of catalyst nanoparticles plays a vital role in their activity and stability. Optimising the performance of electrocatalysts requires atomic-scale information, but it is difficult to obtain. Here, we use atom probe tomography to elucidate the 3D structure of 10 nm sized Co<sub>2</sub>FeO<sub>4</sub> and CoFe<sub>2</sub>O<sub>4</sub> nanoparticles during oxygen evolution reaction (OER). We reveal nanoscale spinodal decomposition in pristine Co<sub>2</sub>FeO<sub>4</sub>. The interfaces of Co-rich and Fe-rich nanodomains of Co<sub>2</sub>FeO<sub>4</sub> become trapping sites for hydroxyl groups, contributing to a higher OER activity compared to that of CoFe<sub>2</sub>O<sub>4</sub>. However, the activity of Co<sub>2</sub>FeO<sub>4</sub> drops considerably due to concurrent irreversible transformation towards Co<sup>IV</sup>O<sub>2</sub> and pronounced Fe dissolution. In contrast, there is negligible elemental redistribution for CoFe<sub>2</sub>O<sub>4</sub> after OER, except for surface structural transformation towards (Fe<sup>III</sup>, Co<sup>III</sup>)<sub>2</sub>O<sub>3</sub>. Overall, our study provides a unique 3D compositional distribution of mixed Co-Fe spinel oxides, which gives atomic-scale insights into active sites and the deactivation of electrocatalysts during OER.