This work elucidates the structural evolution of a commercial‐type iron oxide‐based high temperature water–gas shift (HT‐WGS) catalyst during activation and deactivation stages. The findings highlight the importance of Cu–FeO
Redox‐induced interconversions of metal oxidation states typically result in multiple phase boundaries that separate chemically and structurally distinct oxides and suboxides. Directly probing such multi‐interfacial reactions is challenging because of the difficulty in simultaneously resolving the multiple reaction fronts at the atomic scale. Using the example of CuO reduction in H2gas, a reaction pathway of CuO → monoclinic m‐Cu4O3→ Cu2O is demonstrated and identifies interfacial reaction fronts at the atomic scale, where the Cu2O/m‐Cu4O3interface shows a diffuse‐type interfacial transformation; while the lateral flow of interfacial ledges appears to control the m‐Cu4O3/CuO transformation. Together with atomistic modeling, it is shown that such a multi‐interface transformation results from the surface‐reaction‐induced formation of oxygen vacancies that diffuse into deeper atomic layers, thereby resulting in the formation of the lower oxides of Cu2O and m‐Cu4O3, and activate the interfacial transformations. These results demonstrate the lively dynamics at the reaction fronts of the multiple interfaces and have substantial implications for controlling the microstructure and interphase boundaries by coupling the interplay between the surface reaction dynamics and the resulting mass transport and phase evolution in the subsurface and bulk.
more » « less- PAR ID:
- 10495712
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Small
- Volume:
- 20
- Issue:
- 11
- ISSN:
- 1613-6810
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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