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, Nathan S Lewis

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

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 Br2/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 K3(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 Br2/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 Br2.

Original languageEnglish
Pages (from-to)4082-4086
Number of pages5
JournalNano Letters
Volume16
Issue number7
DOIs
Publication statusPublished - Jul 13 2016

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Graphene
Electrolytes
graphene
electrolytes
Electrodes
electrodes
nonaqueous electrolytes
Photocurrents
photocurrents
short circuits
Photoelectrons
Hydrides
Short circuit currents
Contacts (fluid mechanics)
Oxides
hydrides
Monolayers
photoelectrons
catalysts

Keywords

  • 2D materials
  • anticorrosion
  • graphene
  • Photoelectrochemistry
  • solar energy conversion

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Mechanical Engineering

Cite this

Lightly Fluorinated Graphene as a Protective Layer for n-Type Si(111) Photoanodes in Aqueous Electrolytes. / Nielander, Adam C.; Thompson, Annelise C.; Roske, Christopher W.; Maslyn, Jacqueline A.; Hao, Yufeng; Plymale, Noah T.; Hone, James; Lewis, Nathan S.

In: Nano Letters, Vol. 16, No. 7, 13.07.2016, p. 4082-4086.

Research output: Contribution to journalArticle

Nielander, AC, Thompson, AC, Roske, CW, Maslyn, JA, Hao, Y, Plymale, NT, Hone, J & Lewis, NS 2016, 'Lightly Fluorinated Graphene as a Protective Layer for n-Type Si(111) Photoanodes in Aqueous Electrolytes', Nano Letters, vol. 16, no. 7, pp. 4082-4086. https://doi.org/10.1021/acs.nanolett.6b00773
Nielander, Adam C. ; Thompson, Annelise C. ; Roske, Christopher W. ; Maslyn, Jacqueline A. ; Hao, Yufeng ; Plymale, Noah T. ; Hone, James ; Lewis, Nathan S. / Lightly Fluorinated Graphene as a Protective Layer for n-Type Si(111) Photoanodes in Aqueous Electrolytes. In: Nano Letters. 2016 ; Vol. 16, No. 7. pp. 4082-4086.
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AB - 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 Br2/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 K3(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 Br2/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 Br2.

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