Physical and chemical tuning of electrocatalysts for renewable energy applications
Abstract/Contents
- Abstract
- With rising concerns over the environment and the need for sustainable energy sources, the development of highly efficient electrocatalysts for renewable energy conversion processes, such as in water splitting electrocatalysis and fuel cells, is becoming increasingly important. Instead of discovering different types of new catalysts as in traditional approaches, my PhD study was focused on developing novel methods to systematically tune the morphologies and electronic structures of existing catalysts, and thus significantly improve their catalytic activities. The first chapter gives a brief introduction of renewable energy technologies including clean H2 generation via water splitting and fuel cell catalysis. Basic principles in H2O-H2-O2 electrocatalysis system, including the reaction mechanisms, design principles of catalysts, as well as the characterization methods, are presented. In the second chapter I demonstrate the morphology tuning of two-dimensional (2D) MoS2 for hydrogen evolution reaction (HER). Instead of synthesizing MoS2 with layers lying flat on the substrate as most previous studies presented, I used rapid sulfurization method to kinetically force the 2D layers to vertically stand on the substrate, which maximally exposes the HER active edge sites on the surface. This unique structure presents no change when synthesized on curved surfaces in high surface area substrates. In addition, the S-edge sites were further activated by doping with transition metals, which successfully doubles the MoS2 HER activity. The tuning of MoS2 layer orientation also provides great inspirations in designing high-performance Li-ion batteries. Chapter three includes the electrochemical tuning of electronic structures and morphologies of catalysts for improved water-splitting catalysis. The unique crystal structure of 2D materials allows guest ions to be intercalated or extracted between the molecular layers, opens up great opportunities to continuously tune the electronic structure of catalysts for optimized activities. Combining with Li-ion battery technologies, I intercalated Li ions into MoS2 catalyst, reducing the oxidation states of Mo and also inducing the 2H to 1T phase transition, which dramatically improves its HER activities. Inspired by this successful demonstration, Li ions were extracted out of LiCoO2 to tune up the oxidation state of Co and thus greatly improves its oxygen evolution reaction (OER) activities. In addition, a highly active bifunctional catalyst for overall water splitting was obtained by treating transition metal oxide (TMO) catalysts with Li-ion battery cycling process which transforms monocrystalline particles into interconnected ultra-small nanoparticles.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Wang, Haotian |
|---|---|
| Associated with | Stanford University, Department of Applied Physics. |
| Primary advisor | Cui, Yi, 1976- |
| Primary advisor | Fisher, Ian |
| Thesis advisor | Cui, Yi, 1976- |
| Thesis advisor | Fisher, Ian |
| Thesis advisor | Jaramillo, Thomas Francisco |
| Thesis advisor | Prinz, F. B |
| Advisor | Jaramillo, Thomas Francisco |
| Advisor | Prinz, F. B |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Haotian Wang. |
|---|---|
| Note | Submitted to the Department of Applied Physics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Haotian Wang
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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