Tracking the evolution of a single composite particle during redox cycling for application in H2 production

Dragos Neagu, Evangelos I. Papaioannou, Bernhard Tjaden, Xuekun Lu, Cheuk-Man Mak, Michael W. Gaultois, Brian Ray, Paul Shearing, Ian S. Metcalfe

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
16 Downloads (Pure)


Composite materials consisting of metal and metal oxide phases are being researched intensively for various energy conversion applications where they are often expected to operate under redox conditions at elevated temperature. Understanding of the dynamics of composite evolution during redox cycling is still very limited, yet critical to maximising performance and increasing durability. Here we track the microstructural evolution of a single composite particle over 200 redox cycles for hydrogen production by chemical looping, using multi-length scale X-ray computed tomography. We show that redox cycling triggers a centrifugal redispersion of the metal phase and a centripetal clustering of porosity, both seemingly driven by the asymmetric nature of oxygen exchange in composites. Initially, the particle develops a large amount of internal porosity which boosts activity, but on the long term this facilitates structural and compositional reorganisation and eventually degradation. These results provide valuable insight into redox-driven microstructural changes and also for the design of new composite materials with enhanced durability.

Original languageEnglish
Article number5266
Number of pages9
JournalScientific Reports
Publication statusPublished - 24 Mar 2020


  • energy conversion applications
  • composite particle
  • redox cycling


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