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)63-/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 language | English |
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Pages (from-to) | 4082-4086 |
Number of pages | 5 |
Journal | Nano letters |
Volume | 16 |
Issue number | 7 |
DOIs | |
Publication status | Published - Jul 13 2016 |
Keywords
- 2D materials
- Photoelectrochemistry
- anticorrosion
- graphene
- solar energy conversion
ASJC Scopus subject areas
- Bioengineering
- Chemistry(all)
- Materials Science(all)
- Condensed Matter Physics
- Mechanical Engineering