Photoelectrochemical Behavior of n-Type GaAs(100) Electrodes Coated by a Single Layer of Graphene

Fan Yang, Adam C. Nielander, Ronald L. Grimm, Nathan S Lewis

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Abstract

The photoelectrochemical behavior of n-type GaAs(100) electrodes coated with a single layer of graphene was compared with the behavior of bare, freshly etched n-type GaAs(100) electrodes, both for electrodes in contact with an aqueous solution containing K3[Fe(CN)6]/K4[Fe(CN)6] and for electrodes in contact with nonaqueous solutions containing a series of one-electron redox couples selected such that the Nernstian solution potentials spanned a range greater than 1 V. Under simulated 1 Sun illumination, the graphene-coated electrodes produced a short-circuit photocurrent density of 20 mA cm-2 for up to 8 h of continuous operation in nonaqueous electrolytes (H2O concentration 0.1%, v/v), while, under the same conditions, the unprotected n-GaAs electrodes showed a rapid decay of the photocurrent density within ∼400 s. Although the graphene monolayers enhanced the stability of n-GaAs photoanodes in nonaqueous electrolytes, the graphene did not fully protect photoanodes operated in contact with Fe(CN)6 3-/4-(aq) from corrosion. The dependence of the open-circuit voltage measured for graphene-coated n-GaAs photoanodes on the Nernstian potential of the solution was effectively identical to that of freshly etched n-GaAs photoanodes, indicating that addition of the graphene layer did not introduce significant pinning of the Fermi level of GaAs beyond the Fermi-level pinning attributable to mid-gap and solution-derived charge-carrier trap states previously observed at GaAs/liquid junctions.

Original languageEnglish
Pages (from-to)6989-6995
Number of pages7
JournalJournal of Physical Chemistry C
Volume120
Issue number13
DOIs
Publication statusPublished - Apr 21 2016

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ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

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