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Lightly Fluorinated Graphene as a Protective Layer for n-Type Si(111) Photoanodes in Aqueous Electrolytes

Nielander, Adam C. and Thompson, Annelise C. and Roske, Christopher W. and Maslyn, Jacqueline A. and Hao, Yufeng and Plymale, Noah T. and Hone, James and Lewis, Nathan S. (2016) Lightly Fluorinated Graphene as a Protective Layer for n-Type Si(111) Photoanodes in Aqueous Electrolytes. Nano Letters, 16 (7). pp. 4082-4086. ISSN 1530-6984. doi:10.1021/acs.nanolett.6b00773.

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The behavior of n-Si(111) photoanodes covered by monolayer sheets of fluorinated graphene (F–Gr) was investigated under a range of chemical and electrochemical conditions. The electrochemical behavior of n-Si/F–Gr and np^+-Si/F–Gr photoanodes was compared to hydride-terminated n-Si (n-Si−H) and np+-Si−H electrodes in contact with aqueous Fe(CN)_6^(3-/4-) and Br_2/HBr electrolytes as well as in contact with a series of outer-sphere, one-electron redox couples in nonaqueous electrolytes. Illuminated n-Si/F–Gr and np^+-Si/F–Gr electrodes in contact with an aqueous K_3(Fe(CN)_6/K4(Fe(CN)_6 solutions exhibited stable short-circuit photocurrent densities of ∼10 mA cm^(–2) for 100,000 s (>24 h), in comparison to bare Si electrodes, which yielded nearly a complete photocurrent decay over ∼100 s. X-ray photoelectron spectra collected before and after exposure to aqueous anodic conditions showed that oxide formation at the Si surface was significantly inhibited for Si electrodes coated with F–Gr relative to bare Si electrodes exposed to the same conditions. The variation of the open-circuit potential for n-Si/F–Gr in contact with a series of nonaqueous electrolytes of varying reduction potential indicated that the n-Si/F–Gr did not form a buried junction with respect to the solution contact. Further, illuminated n-Si/F−Gr electrodes in contact with Br_2/HBr(aq) were significantly more electrochemically stable than n-Si−H electrodes, and n-Si/F−Gr electrodes coupled to a Pt catalyst exhibited ideal regenerative cell efficiencies of up to 5% for the oxidation of Br^– to Br_2.

Item Type:Article
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URLURL TypeDescription ItemSupporting Information
Nielander, Adam C.0000-0002-3639-2427
Thompson, Annelise C.0000-0003-2414-7050
Plymale, Noah T.0000-0003-2564-8009
Hone, James0000-0002-8084-3301
Lewis, Nathan S.0000-0001-5245-0538
Additional Information:© 2016 American Chemical Society. Received: February 22, 2016; Revised: May 19, 2016; Published: June 20, 2016. N.S.L., A.C.N., and A.C.T. acknowledge NSF Grant CHE- 1214152 for support, and the Beckman Institute Molecular Materials Resource Center and Dr. Bruce S. Brunschwig for facilities and valuable advice. A.C.N. and A.C.T. acknowledge Tom Lee and the UCLA Nanoelectronics Research Facility for valuable advice and access to instrumentation. A.C.N. and N.T.P. acknowledge support from NSF graduate research fellowships. C.W.R. thanks the Link Energy Foundation for a graduate research fellowship. J.A.M. thanks the Amgen Scholars program for a fellowship. This graphene material is based upon work supported by the NSF MRSEC program through Columbia in the Center for Precision Assembly of Superstratic and Superatomic Solids (DMR-1420634) and the Nanoelectronics Research Initiative (NRI) through the Institute for Nanoelectronics Discovery and Exploration (INDEX).
Funding AgencyGrant Number
Caltech Beckman InstituteUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Link Energy FoundationUNSPECIFIED
Amgen Scholars ProgramUNSPECIFIED
Nanoelectronics Research Initiative (NRI)UNSPECIFIED
Institute for Nanoelectronics Discovery and Exploration (INDEX)UNSPECIFIED
Subject Keywords:Photoelectrochemistry, graphene, 2D materials, solar energy conversion, anticorrosion
Issue or Number:7
Record Number:CaltechAUTHORS:20160627-153227823
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Official Citation:Lightly Fluorinated Graphene as a Protective Layer for n-Type Si(111) Photoanodes in Aqueous Electrolytes Adam C. Nielander, Annelise C. Thompson, Christopher W. Roske, Jacqueline A. Maslyn, Yufeng Hao, Noah T. Plymale, James Hone, and Nathan S. Lewis Nano Letters 2016 16 (7), 4082-4086 DOI: 10.1021/acs.nanolett.6b00773
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:68696
Deposited By: Ruth Sustaita
Deposited On:28 Jun 2016 17:58
Last Modified:11 Nov 2021 04:03

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