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

Hocking, Rosalie K., King, Hannah J., Hesson, Aimee, Bonke, Shannon A., Johannessen, Bernt, Fekete, Monika, Spiccia, Leone, and Chang, Shery L.Y. (2015) Engineering disorder at a nanoscale: a combined TEM and XAS investigation of amorphous versus nanocrystalline sodium birnessite. Australian Journal of Chemistry, 68. pp. 1715-1722.

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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.

Item ID: 41582
Item Type: Article (Research - C1)
ISSN: 1445-0038
Funders: Australian Research Council (ARC)
Projects and Grants: ARC Centre of Excellence for Electromaterials Science
Date Deposited: 10 Dec 2015 02:46
FoR Codes: 03 CHEMICAL SCIENCES > 0302 Inorganic Chemistry > 030201 Bioinorganic Chemistry @ 50%
03 CHEMICAL SCIENCES > 0302 Inorganic Chemistry > 030207 Transition Metal Chemistry @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970103 Expanding Knowledge in the Chemical Sciences @ 100%
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