期刊
JOURNAL OF PHYSICAL CHEMISTRY C
卷 120, 期 13, 页码 6989-6995出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpcc.6b00232
关键词
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资金
- U.S. Department of Energy Office of Basic Energy Sciences [DE-FG02-03ER15483]
- Defense Advanced Research Projects Agency (DARPA) [W911NF-09-2-0011]
- Gordon and Betty Moore Foundation [1225]
- NSF
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 K-3[Fe(CN)(6)]/K-4[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 similar to 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.
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