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High-Aspect Ratio Structures in Light-Absorbers and Electrocatalysts for Solar Fuels Devices

Citation

Kempler, Paul Andrew (2020) High-Aspect Ratio Structures in Light-Absorbers and Electrocatalysts for Solar Fuels Devices. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/xpty-9891. https://resolver.caltech.edu/CaltechTHESIS:09232020-234052730

Abstract

Solar fuels devices produce hydrogen fuel from water and sunlight and address a critical societal need for inexpensive, long-duration energy storage. Such devices are prepared from combinations of light-absorbing semiconductors and catalysts to sunlight to drive thermodynamically uphill reactions. This dissertation puts forth strategies for controlling the three-dimensional structure of semiconductors, electrocatalysts, and the film of gas bubbles evolved on the top and bottom of a solar fuels device. High-aspect ratio features led to unexpected effects in semiconductor/electrocatalyst assemblies. Optical losses were decoupled from the mass-loading of cobalt phosphide and copper electrocatalysts integrated onto silicon microwire photocathodes for the photoelectrochemical generation of hydrogen and hydrocarbons, respectively. Anti-reflective silicon microcone arrays were patterned with continuous films of Pt or CoP particles with minimal reflection losses due to the catalyst films. Transparent metal films were prepared from nanostructured metal phosphides, a class of earth-abundant hydrogen evolution catalysts. Silicon microwire array (photo)electrode surfaces were used to force bubbles away from electrocatalyst surfaces, even when oriented against gravity, leading to sustained operation in the absence of external convection.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Solar fuels, Photoelectrochemistry, Electrochemistry, Hydrogen, Energy Storage, Silicon, Bubbles
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Lewis, Nathan Saul
Thesis Committee:
  • Davis, Mark E. (chair)
  • Seinfeld, John H.
  • Giapis, Konstantinos P.
  • Lewis, Nathan Saul
Defense Date:8 September 2020
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0004993
Lockheed Martin Corporation4103810021
Record Number:CaltechTHESIS:09232020-234052730
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:09232020-234052730
DOI:10.7907/xpty-9891
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/acsenergylett.8b00034DOIArticle adapted for Chapter 2.
https://doi.org/10.1021/acsenergylett.0c01334DOIArticle adapted for Chapter 3.
https://doi.org/10.1039/C9SE00294DDOIArticle adapted for Chapter 4.
https://doi.org/10.1021/acs.jpclett.9b02926DOIArticle adapted for Chapter 5.
https://doi.org/10.1039/D0EE00356EDOIArticle adapted for Chapter 6.
https://doi.org/10.1039/D0EE02796KDOIArticle adapted for Chapter 7.
ORCID:
AuthorORCID
Kempler, Paul Andrew0000-0003-3909-1790
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:13964
Collection:CaltechTHESIS
Deposited By: Paul Kempler
Deposited On:29 Sep 2020 23:33
Last Modified:01 Jun 2021 20:54

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