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 journalArticle

8 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 - Jan 1 2015

ASJC Scopus subject areas

  • Chemistry(all)

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