Hydrogen interaction with nanostructured carbon - electronic and geometric structure changes and applications
Abstract/Contents
- Abstract
- The hydrogenation of carbon nanostructures has been explored in this thesis work. The purpose of studying hydrogen interactions with carbon was twofold -- (a) to understand the electronic and structural changes in graphene induced by hydrogenation and (b) explore hydrogen storage possibilities in carbon materials. Since graphene is a semi metal with zero band gap at the Fermi level, there is a necessity to open a band gap for transistor applications. Several hypotheses have been suggested for opening a band gap, one of which is chemisorbing ad-atoms on graphene layer (like hydrogen). Hydrogenation of graphene grown on Pt(111) was studied using x-ray spectroscopy including x-ray photoelectron spectroscopy (XPS), x-ray absorption (XAS), x-ray emission (XES), resonant inelastic x-ray scattering (RIXS), which provides for an atom specific probe of the electronic structure and the chemical environment of the carbon atoms. Hydrogen adsorption is accompanied by delocalization of the [pi] band contrary to band opening behavior. Finite density of states (DOS) was observed at the Fermi level in the carbon projected DOS. The structural distortion caused by hydrogen adsorption is stabilized through pinning of the graphene to the substrate through the formation of local C-Pt bonds which does not result in band opening due to the delocalization of the [pi] band through substrate hybridization. Surface hydrogen adsorption on few layer graphene/Pt(111) induces changes in the bond symmetry of all the carbon atoms in the various graphene layers resulting in a "diamond like" structure. This propagation of the sp3 hybridization to underneath layers is again stabilized through hybridization between the carbon atoms in the interfacial layer and the substrate. Finally the carbon-Pt system was explored as a potential hydrogen storage candidate. The concept of "spillover" of H atoms from H2 molecules dissociated on the Pt catalyst was exploited towards reducing the kinetic barrier involved in the process of de-hydrogenation of carbon nanotube/Pt composites at near ambient conditions (~8.25 atm. of hydrogen gas at room temperature) yielding a hydrogen storage capacity of 1.6wt%.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2012 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Rajasekaran, Srivats |
|---|---|
| Associated with | Stanford University, Department of Materials Science and Engineering. |
| Primary advisor | Clemens, B. M. (Bruce M.) |
| Primary advisor | Nilsson, Anders, 1956- |
| Thesis advisor | Clemens, B. M. (Bruce M.) |
| Thesis advisor | Nilsson, Anders, 1956- |
| Thesis advisor | Mao, Wendy (Wendy Li-wen) |
| Advisor | Mao, Wendy (Wendy Li-wen) |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Srivats Rajasekaran. |
|---|---|
| Note | Submitted to the Department of Materials Science and Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2012. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2012 by Srivats Rajasekaran
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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