Elsevier

Ultramicroscopy

Volume 219, December 2020, 113116
Ultramicroscopy

Dissecting complex nanoparticle heterostructures via multimodal data fusion with aberration-corrected STEM spectroscopy

https://doi.org/10.1016/j.ultramic.2020.113116Get rights and content
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Highlights

  • Low-level data fusion jointly couples synchronously acquired EDX and EELS datacubes from an aberration-corrected STEM.

  • The descriptive statistics of the EELS dataset are exploited to inpaint sparsely-sampled EDX, even when joint factors are absent.

  • Matrix factorization based on the data geometry of the joint dataset estimates pure spectral components despite strong mixing.

  • The method dissects a complex heterostructure into pure spectral components pertaining to both composition and electronic structure.

  • A physical model providing deeper insight into the photocatalytic behavior of this materials system is presented.

Abstract

With nanostructured materials such as catalytic heterostructures projected to play a critical role in applications ranging from water splitting to energy harvesting, tailoring their properties to specific tasks requires an increasingly comprehensive characterization of their local chemical and electronic landscape. Although aberration-corrected electron spectroscopy currently provides sufficient spatial resolution to study this space, an approach to concurrently dissect both the electronic structure and full composition of buried metal/oxide interfaces remains a considerable challenge. In this manuscript, we outline a statistical methodology to jointly analyze simultaneously-acquired STEM EELS and EDX datasets by fusing them along their shared spatial factors. We show how this procedure can be used to derive a rich descriptive model for estimating both transition metal valency and full chemical composition from encapsulated morphologies such as core-shell nanoparticles. We demonstrate this on a heterogeneous Co-P thin film catalyst, concluding that this system is best described as a multi-shell phosphide structure with a P-doped metallic Co core.

Keywords

Data fusion
electron energy-loss spectroscopy
Energy-dispersive X-ray spectroscopy
Nanostructured catalyst
Scanning transmission electron microscopy

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