Chemical modification of n-GaAs photoanodes with group VIIIB metal ions: Stability in contact with 1.0 M KOH(aq)-0.10 M K2Se(aq) solutions and I-V properties in contact with 1.0 M KOH(aq)-0.3 M K2Te(aq) electrolytes

Ming X. Tan, Charlotte Newcomb, Amit Kumar, Sharon R. Lunt, Michael J. Sailor, Bruce J. Tufts, Nathan S Lewis

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A quantitative study has been performed on the stability of GaAs surfaces to photoanodic corrosion in contact with the 1.0 M KOH(aq)-0.10 M K2Se(aq)-0.01 M K2Se2(aq) electrolyte. In this electrolyte, chemically etched n-type GaAs electrodes displayed significant photocorrosion in competition with faradaic charge transfer to Se2-(aq). Chemisorption of group VIIIB metal ions, including complexes of Co(III), Os(III), and Ru(III), onto the etched GaAs surface yielded improved current-voltage (I-V) behavior of the GaAs photoanode and also resulted in a significant reduction in photocorrosion. This behavior implies that the chemisorbed metal ions act to increase the rate of hole transfer to the Se2- donor species, as opposed to the passivation of nonradiative surface recombination. Related experiments on n-GaAs photoanodes in contact with the 1.0 M KOH(aq)-0.3 M Te2-(aq)-0.01 M Te22-(aq) electrolyte have also been performed. The I-V properties of n-GaAs, p-GaAs, and Sn-doped In2O3 electrodes have been investigated in this electrolyte, and these measurements have been used to elucidate common mechanistic features of charge-transfer reactions for the Se2-(aq) and Te2-(aq) redox systems.

Original languageEnglish
Pages (from-to)10133-10142
Number of pages10
JournalJournal of Physical Chemistry
Issue number24
Publication statusPublished - 1991


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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