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Nanostructured Tungsten Trioxide Photoanodes for Solar Energy Conversion


Wiggenhorn, David Craig (2014) Nanostructured Tungsten Trioxide Photoanodes for Solar Energy Conversion. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0CKV-SM88.


Nanostructured tungsten trioxide (WO3) photoelectrodes are potential candidates for the anodic portion of an integrated solar water-splitting device that generates hydrogen fuel and oxygen from water. These nanostructured materials can potentially offer improved performance in photooxidation reactions compared to unstructured materials because of enhancements in light scattering, increases in surface area, and their decoupling of the directions of light absorption and carrier collection. To evaluate the presence of these effects and their contributions toward energy conversion efficiency, a variety of nanostructured WO3 photoanodes were synthesized by electrodeposition within nanoporous templates and by anodization of tungsten foils. A robust fabrication process was developed for the creation of oriented WO3 nanorod arrays, which allows for control nanorod diameter and length. Films of nanostructured WO3 platelets were grown via anodization, the morphology of the films was controlled by the anodization conditions, and the current-voltage performance and spectral response properties of these films were studied. The observed photocurrents were consistent with the apparent morphologies of the nanostructured arrays. Measurements of electrochemically active surface area and other physical characteristics were correlated with observed differences in absorbance, external quantum yield, and photocurrent density for the anodized arrays. The capability to quantify these characteristics and relate them to photoanode performance metrics can allow for selection of appropriate structural parameters when designing photoanodes for solar energy conversion.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:tungsten trioxide; tungsten oxide; solar energy; water splitting; photoanodes; nanostructured
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Lewis, Nathan Saul
Thesis Committee:
  • Gray, Harry B. (chair)
  • Okumura, Mitchio
  • Barton, Jacqueline K.
  • Lewis, Nathan Saul
Defense Date:25 November 2013
Non-Caltech Author Email:dcraig (AT)
Record Number:CaltechTHESIS:01102014-204136086
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8050
Deposited By: David Wiggenhorn
Deposited On:17 Jan 2014 00:16
Last Modified:04 Oct 2019 00:03

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