Zhou, Ziyu
(2022)
Performance-driven Micro/nano Functional Materials.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
This is the latest version of this item.
Abstract
Carbon nanotubes (CNTs) is one of the commonly used materials for energy and electronics devices due to the excellency in electrical, thermal, and mechanical properties, stability under harsh environments, and ease of functionalization. To further improve the performance as functional surfaces and catalysts, a better understanding of the wetting and electrochemical properties for CNTs is necessary. On the other hand, the limited conductivity and intrinsic defects of CNTs hinder its integration into the next-generation transparent conductive electrodes (TCEs). Therefore, an alternative with higher figure of merit (FoM) and better flexibility is required.
This dissertation focuses on three main aspects: parahydrophobicity of vertically aligned CNTs (VA-CNTs), the role of different N-doped species in CNTs for oxygen reduction reaction (ORR), and the silver microgrids fabrication approach with particle-free conductive ink. Firstly, we found that the high number density (> 10^11 CNTs/cm^2) of VA-CNTs improves the stability of superhydrophobicity and exhibits a strong water adhesion. Meanwhile, we clarified that the evaporation, rather than water penetration, causes the instability of the wetting state of the VA-CNTs. Secondly, with a combination of the experiments and theoretical calculations, we concluded that the graphitic-N doping sites are more efficient for ORR than pyridinic-N doping sites in N-doped CNTs. Particularly, the result was validated by a consistent N doping concentration about 4.1 at.% and a comparable level of structural defects. Finally, the silver microgrids fabricated by the particle-free conductive ink can achieve a high transmittance of 91.8% and a low sheet resistance of 0.88 Ω/sq with a figure of merit (FoM) of 4900. In addition, the silver microgrids show a better mechanical robustness under tape peeling, bending, and folding tests than commonly used indium tin oxide (ITO). In summary, our work proposes a performance-driven framework for micro/nano functional materials with applications in the microdroplet transportation, fuel cell, and optoelectronic devices.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
6 September 2022 |
| Date Type: |
Publication |
| Defense Date: |
30 June 2022 |
| Approval Date: |
6 September 2022 |
| Submission Date: |
7 July 2022 |
| Access Restriction: |
2 year -- Restrict access to University of Pittsburgh for a period of 2 years. |
| Number of Pages: |
130 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Materials Science and Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
parahydrophobicity, metal-free catalyst, transparent conductor |
| Date Deposited: |
06 Sep 2022 16:27 |
| Last Modified: |
06 Sep 2022 16:27 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/43275 |
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Performance-driven Micro/nano Functional Materials. (deposited 06 Sep 2022 16:27)
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