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

Lookup NU author(s): Dr Dragos Neagu, Dr Evangelos Papaioannou, Danny Mak, Dr Brian Ray, Professor Ian Metcalfe

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

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.

Publication metadata

Author(s): Neagu D, Papaioannou E, Tjaden B, Lu X, Mak C, Gaultois MW, Ray B, Shearing P, Metcalfe I

Publication type: Article

Publication status: Published

Journal: Scientific Reports

Year: 2020

Volume: 10

Online publication date: 24/03/2020

Acceptance date: 09/03/2020

Date deposited: 02/04/2020

ISSN (electronic): 2045-2322

Publisher: Nature Publishing Group

URL: https://doi.org/10.1038/s41598-020-62237-y

DOI: 10.1038/s41598-020-62237-y

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