Multiscale and multidimensional characterisation of graphene nanomaterials and nanocomposites
File(s)
Author(s)
Li, Yuhan
Type
Thesis
Abstract
Macroscale assemblies and composite structures, built upon graphene and graphene-related nanomaterials, are promising for a range of applications and devices. Consequently, there is growing demand for more comprehensive characterisation of graphene-based structures. The primary challenges revolve around understanding the morphology, dispersion, and spatial arrangement of the individual graphene flakes, as well as their interactions with other materials. This thesis develops multiscale and multidimensional characterisation methodologies for investigating various graphene-based structures, employing a combination of microscopic techniques, image processing and analysis methods.
Confocal laser scanning microscopy (CLSM) is developed as a valuable tool for microstructural investigation of graphene nanomaterials and nanocomposites, exploiting the technique’s distinctive features, including high-contrast and non-invasive imaging, as well as depth discrimination. Using confocal reflection and total interference contrast imaging, the flake thickness distribution in graphene oxide (GO) films is mapped rapidly and quantitatively. In addition to passive characterisation, this thesis shows that CLSM can be used for simultaneous imaging and processing studies: GO films can be selectively reduced in-situ to produce functional patterns at length scales ranging from millimetre to sub-micron.
Full characterisation of graphene dispersion, particularly in nanocomposites, requires methods for volumetric characterisation; a variety of 3D imaging methodologies are therefore developed. General guidelines are established for applying non-destructive CLSM stack imaging in large-scale examination of nanocomposites. 3D characterisation methods based on destructive serial array tomography are developed, enabling correlative optical and electron microscopic imaging. Multiscale correlative characterisation is demonstrated to be highly significant in extracting structural details, unveiling the local organisation, flake orientation, and morphology of various graphene nanocomposites. The rich 3D datasets provide exciting chances to quantify structural features, demonstrated by statistical dispersion/distribution analysis of functionalised graphene nanocomposites. This study provides valuable insights into the real structure of graphene films and nanocomposites; the methodologies developed will be widely applicable in the nanomaterials field.
Confocal laser scanning microscopy (CLSM) is developed as a valuable tool for microstructural investigation of graphene nanomaterials and nanocomposites, exploiting the technique’s distinctive features, including high-contrast and non-invasive imaging, as well as depth discrimination. Using confocal reflection and total interference contrast imaging, the flake thickness distribution in graphene oxide (GO) films is mapped rapidly and quantitatively. In addition to passive characterisation, this thesis shows that CLSM can be used for simultaneous imaging and processing studies: GO films can be selectively reduced in-situ to produce functional patterns at length scales ranging from millimetre to sub-micron.
Full characterisation of graphene dispersion, particularly in nanocomposites, requires methods for volumetric characterisation; a variety of 3D imaging methodologies are therefore developed. General guidelines are established for applying non-destructive CLSM stack imaging in large-scale examination of nanocomposites. 3D characterisation methods based on destructive serial array tomography are developed, enabling correlative optical and electron microscopic imaging. Multiscale correlative characterisation is demonstrated to be highly significant in extracting structural details, unveiling the local organisation, flake orientation, and morphology of various graphene nanocomposites. The rich 3D datasets provide exciting chances to quantify structural features, demonstrated by statistical dispersion/distribution analysis of functionalised graphene nanocomposites. This study provides valuable insights into the real structure of graphene films and nanocomposites; the methodologies developed will be widely applicable in the nanomaterials field.
Version
Open Access
Date Issued
2023-10-06
Date Awarded
2024-03-01
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Shaffer, Milo
Sponsor
Imperial College London ; China Scholarship Council
Publisher Department
Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)