Engineering disorder at a nanoscale: A combined TEM and XAS investigation of amorphous versus nanocrystalline sodium birnessite

Rosalie K. Hocking, Hannah J. King, Aimee Hesson, Shannon A. Bonke, Bernt Johannessen, Monika Fekete, Leone Spiccia, Lan-Yun Chang

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

The term amorphous metal oxide is becoming widely used in the catalysis community. The term is generally used when there are no apparent peaks in an X-ray diffraction pattern. However, the absence of such features in X-ray diffraction can mean that the material is either truly amorphous or that it is better described as nanocrystalline. By coprecipitating a sodium birnessite-like phase with and without phosphate (1.5%), we are able to engineer two very similar but distinct materials - one that is nanocrystalline and the other that is amorphous. The two closely related phases were characterized with both Mn K-edge X-ray absorption spectroscopy and high-resolution transmission electron microscopy. These structural results were then correlated with catalytic and electrocatalytic activities for water oxidation catalysis. In this case, the amorphous phosphate-doped material was less catalytically active than the nanocrystalline material.

Original languageEnglish (US)
Pages (from-to)1715-1722
Number of pages8
JournalAustralian Journal of Chemistry
Volume68
Issue number11
DOIs
StatePublished - 2015

ASJC Scopus subject areas

  • Chemistry(all)

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