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Enhanced Stability and Efficiency for Photoelectrochemical Iodide Oxidation by Methyl Termination and Electrochemical Pt Deposition of n-Si Microwire Arrays

Ardo, Shane and Santori, Elizabeth A. and Emmer, Hal S. and Grimm, Ronald L. and Bierman, Matthew J. and Brunschwig, Bruce S. and Atwater, Harry A. and Lewis, Nathan S. (2019) Enhanced Stability and Efficiency for Photoelectrochemical Iodide Oxidation by Methyl Termination and Electrochemical Pt Deposition of n-Si Microwire Arrays. ACS Energy Letters, 4 (9). pp. 2308-2314. ISSN 2380-8195. https://resolver.caltech.edu/CaltechAUTHORS:20190729-153032767

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Abstract

Arrays of Si microwires doped n-type (n-Si) and surface-functionalized with methyl groups have been used, with or without deposition of Pt electrocatalysts, to photoelectrochemically oxidize I–(aq) to I_3–(aq) in 7.6 M HI(aq). Under conditions of iodide oxidation, methyl-terminated n-Si microwire arrays exhibited stable short-circuit photocurrents over a time scale of days, albeit with low energy-conversion efficiencies. In contrast, electrochemical deposition of Pt onto methyl-terminated n-Si microwire arrays consistently yielded energy-conversion efficiencies of ∼2% for iodide oxidation, with an open-circuit photovoltage of ∼400 mV and a short-circuit photocurrent density of ∼10 mA cm^(–2) under 100 mW cm^(–2) of simulated air mass 1.5G solar illumination. Platinized electrodes were stable for >200 h of continuous operation, with no discernible loss of Si or Pt. Pt deposited using electron-beam evaporation also resulted in stable photoanodic operation of the methyl-terminated n-Si microwire arrays but yielded substantially lower photovoltages than when Pt was deposited electrochemically.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/acsenergylett.9b01529DOIArticle
ORCID:
AuthorORCID
Ardo, Shane0000-0001-7162-6826
Grimm, Ronald L.0000-0003-0407-937X
Brunschwig, Bruce S.0000-0002-6135-6727
Atwater, Harry A.0000-0001-9435-0201
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2019 American Chemical Society. Received: July 17, 2019; Accepted: July 24, 2019; Published: July 25, 2019. This work was supported by the National Science Foundation (NSF) Center for Chemical Innovation (CCI) Powering the Planet grants (Grants CHE-0802907, CHE-0947829, and NSF-ACCF) and made use of the Molecular Materials Resource Center of the Beckman Institute at Caltech and the Kavli Nanoscience Institute at Caltech. S.A. acknowledges support from a U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE) Postdoctoral Research Award under the EERE Fuel Cell Technologies Program. The authors declare no competing financial interest.
Group:Kavli Nanoscience Institute
Funders:
Funding AgencyGrant Number
NSFCHE-0802907
NSFCHE-0947829
Caltech Beckman InstituteUNSPECIFIED
Kavli Nanoscience InstituteUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Issue or Number:9
Record Number:CaltechAUTHORS:20190729-153032767
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20190729-153032767
Official Citation:Enhanced Stability and Efficiency for Photoelectrochemical Iodide Oxidation by Methyl Termination and Electrochemical Pt Deposition on n-Type Si Microwire Arrays. Shane Ardo, Elizabeth A. Santori, Hal S. Emmer, Ronald L. Grimm, Matthew J. Bierman, Bruce S. Brunschwig, Harry A. Atwater, and Nathan S. Lewis. ACS Energy Letters 2019 4 (9), 2308-2314. DOI: 10.1021/acsenergylett.9b01529
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:97497
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:30 Jul 2019 15:48
Last Modified:03 Oct 2019 21:32

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