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Title: Silicon Photoelectrode Thermodynamics and Hydrogen Evolution Kinetics Measured by Intensity-Modulated High-Frequency Resistivity Impedance Spectroscopy

Here, we present an impedance technique based on light intensity-modulated high-frequency resistivity (IMHFR) that provides a new way to elucidate both the thermodynamics and kinetics in complex semiconductor photoelectrodes. We apply IMHFR to probe electrode interfacial energetics on oxide-modified semiconductor surfaces frequently used to improve the stability and efficiency of photoelectrochemical water splitting systems. Combined with current density-voltage measurements, the technique quantifies the overpotential for proton reduction relative to its thermodynamic potential in Si photocathodes coated with three oxides (SiO x, TiO 2, and Al 2O 3) and a Pt catalyst. In pH 7 electrolyte, the flatband potentials of TiO 2- and Al 2O 3-coated Si electrodes are negative relative to samples with native SiO x, indicating that SiO x is a better protective layer against oxidative electrochemical corrosion than ALD-deposited crystalline TiO 2 or Al 2O 3. Adding a Pt catalyst to SiO x/Si minimizes proton reduction overpotential losses but at the expense of a reduction in available energy characterized by a more negative flatband potential relative to catalyst-free SiO x/Si.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [1] ; ORCiD logo [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States); The Univ. of Texas at Austin, Austin, TX (United States)
Publication Date:
Report Number(s):
NREL/JA-5900-68410
Journal ID: ISSN 1948-7185
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry Letters
Additional Journal Information:
Journal Volume: 8; Journal Issue: 21; Journal ID: ISSN 1948-7185
Publisher:
American Chemical Society
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; thermodynamics; kinetics; semiconductor photoelectrodes
OSTI Identifier:
1402562

Anderson, Nicholas C., Carroll, Gerard M., Pekarek, Ryan T., Christensen, Steven T., van de Lagemaat, Jao, and Neale, Nathan R.. Silicon Photoelectrode Thermodynamics and Hydrogen Evolution Kinetics Measured by Intensity-Modulated High-Frequency Resistivity Impedance Spectroscopy. United States: N. p., Web. doi:10.1021/acs.jpclett.7b01311.
Anderson, Nicholas C., Carroll, Gerard M., Pekarek, Ryan T., Christensen, Steven T., van de Lagemaat, Jao, & Neale, Nathan R.. Silicon Photoelectrode Thermodynamics and Hydrogen Evolution Kinetics Measured by Intensity-Modulated High-Frequency Resistivity Impedance Spectroscopy. United States. doi:10.1021/acs.jpclett.7b01311.
Anderson, Nicholas C., Carroll, Gerard M., Pekarek, Ryan T., Christensen, Steven T., van de Lagemaat, Jao, and Neale, Nathan R.. 2017. "Silicon Photoelectrode Thermodynamics and Hydrogen Evolution Kinetics Measured by Intensity-Modulated High-Frequency Resistivity Impedance Spectroscopy". United States. doi:10.1021/acs.jpclett.7b01311. https://www.osti.gov/servlets/purl/1402562.
@article{osti_1402562,
title = {Silicon Photoelectrode Thermodynamics and Hydrogen Evolution Kinetics Measured by Intensity-Modulated High-Frequency Resistivity Impedance Spectroscopy},
author = {Anderson, Nicholas C. and Carroll, Gerard M. and Pekarek, Ryan T. and Christensen, Steven T. and van de Lagemaat, Jao and Neale, Nathan R.},
abstractNote = {Here, we present an impedance technique based on light intensity-modulated high-frequency resistivity (IMHFR) that provides a new way to elucidate both the thermodynamics and kinetics in complex semiconductor photoelectrodes. We apply IMHFR to probe electrode interfacial energetics on oxide-modified semiconductor surfaces frequently used to improve the stability and efficiency of photoelectrochemical water splitting systems. Combined with current density-voltage measurements, the technique quantifies the overpotential for proton reduction relative to its thermodynamic potential in Si photocathodes coated with three oxides (SiOx, TiO2, and Al2O3) and a Pt catalyst. In pH 7 electrolyte, the flatband potentials of TiO2- and Al2O3-coated Si electrodes are negative relative to samples with native SiOx, indicating that SiOx is a better protective layer against oxidative electrochemical corrosion than ALD-deposited crystalline TiO2 or Al2O3. Adding a Pt catalyst to SiOx/Si minimizes proton reduction overpotential losses but at the expense of a reduction in available energy characterized by a more negative flatband potential relative to catalyst-free SiOx/Si.},
doi = {10.1021/acs.jpclett.7b01311},
journal = {Journal of Physical Chemistry Letters},
number = 21,
volume = 8,
place = {United States},
year = {2017},
month = {10}
}