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Fundamentals of the growth mechanism, tailored properties and applications of 3D hollow carbon foams
Citation Link: https://doi.org/10.15480/882.2303
Publikationstyp
Doctoral Thesis
Date Issued
2019
Sprache
English
Author(s)
Herausgeber*innen
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2019-05-14
TORE-DOI
TORE-URI
First published in
Number in series
Band 36
Citation
Technisch-wissenschaftliche Schriftenreihe / TUHH Polymer Composites 36: (2019)
The discovery of 1D carbon nanostructures in the 20th century and subsequently of 2D carbon nanostructures in the past century, a competition for possible applications of this material with outstanding physical properties began. Due to the geometric restriction of 1D and 2D carbon structures, a variety of manufacturing techniques have been developed around of the millennium to synthesise 3D carbon structures, which are also referred to as carbon aerogels or carbon foams. Based on their morphology, these structures offer decisive
advantages over the existing structures and thus potentially new fields of application arise in the field of energy storage systems and catalysts. The growth mechanism of carbon structures has a property-defining influence on their properties. During their growth, carbon atoms arrange in ideal hexagonal lattices, which can also lead to defects that adversely affect the properties. These defects can be reduced by annealing processes such as a high-temperature treatment. Besides to defects, it was also shown that the number of carbon layers significantly affect the properties. This work concerned with the analysis of the growth mechanism of the 3D carbon structure Aerographite. This carbon foam has a tetrapodal morphology and is distinguished by its high mechanical and electrical properties at a density down to
~2 mg/cm3. Here, the influence of the growth mechanism via ex-situ studies and the tailoring of the properties such as electrical conductivity is investigated. The wall thickness of the tetrapods can be specifically varied by means of a targeted process control during the synthesis of Aerographite in the CVD process. A stepwise increase in the electrical conductivity occurs because of a subsequent temperature treatment of Aerographite, as a function of the temperature and its VI holding time. Additionally, the healing of Aerographite by a thermal treatment
and the influence of the graphitisation on the properties of Aerographite is in focus in this work. Furthermore, this study aims a variation of the morphology and the manufacturing process for 3D carbon foams and the identification of possible applications. The focus here is on an application-related morphology and a comparatively simplified manufacturing process of the carbon structure. The developed carbon foam has a hierarchical globular morphology and is produced based on a porous ceramic template. Based on thermodynamic calculations, a wide range of catalytically active materials can be added to the green body, which are remains after the CVD process. Finally, a carbon foam with incorporated catalysts can be used for several applications.
advantages over the existing structures and thus potentially new fields of application arise in the field of energy storage systems and catalysts. The growth mechanism of carbon structures has a property-defining influence on their properties. During their growth, carbon atoms arrange in ideal hexagonal lattices, which can also lead to defects that adversely affect the properties. These defects can be reduced by annealing processes such as a high-temperature treatment. Besides to defects, it was also shown that the number of carbon layers significantly affect the properties. This work concerned with the analysis of the growth mechanism of the 3D carbon structure Aerographite. This carbon foam has a tetrapodal morphology and is distinguished by its high mechanical and electrical properties at a density down to
~2 mg/cm3. Here, the influence of the growth mechanism via ex-situ studies and the tailoring of the properties such as electrical conductivity is investigated. The wall thickness of the tetrapods can be specifically varied by means of a targeted process control during the synthesis of Aerographite in the CVD process. A stepwise increase in the electrical conductivity occurs because of a subsequent temperature treatment of Aerographite, as a function of the temperature and its VI holding time. Additionally, the healing of Aerographite by a thermal treatment
and the influence of the graphitisation on the properties of Aerographite is in focus in this work. Furthermore, this study aims a variation of the morphology and the manufacturing process for 3D carbon foams and the identification of possible applications. The focus here is on an application-related morphology and a comparatively simplified manufacturing process of the carbon structure. The developed carbon foam has a hierarchical globular morphology and is produced based on a porous ceramic template. Based on thermodynamic calculations, a wide range of catalytically active materials can be added to the green body, which are remains after the CVD process. Finally, a carbon foam with incorporated catalysts can be used for several applications.
Subjects
aerographite
CVD process
PNCs
REM
TEM
Raman
DDC Class
600: Technik
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