Stabilization of n-type silicon photoanodes in aqueous solution by electrostatic binding of redox ions into charged polymers

Mark D. Rosenblum, Nathan S Lewis

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

Electrostatic binding of redox-active ions into a polymer-coated electrode is demonstrated to be an effective method of improving photoelectrode stability. Pt and n-type Si electrodes have been coated with poly([4,4′-bipyridinium]-1,1′-diylmethylene-1,2-phenylenemethylene dibromide) (poly-oXV2+) and other viologen-based polymer films. The poly-oXV2+/+· system is insoluble in aqueous solutions containing large anions such as ClO4 -, BF4 -, and Fe(CN)6 4-. Cyclic voltmmetry of modified electrodes in aqueous 1.0 M NaClO4 shows behavior consistent with a reversibly electroactive, surface-confined species, E°′ (poly-oXV2+/+·) = -0.45 V vs. SCE. In the presence of electroactive anions, n-type Si electrodes coated with poly-oXV2+ show substantial improvements in photocurrent stability compared to naked n-Si electrodes. Negative ions from solution are sorbed by the positively charged poly-oXV2+ units, providing efficient scavenging of photogenerated holes at the semiconductor surface. No improvement in stability is observed with positively charged solution ions, such as Fe(H2O)6 2+. Variation in coverage of the polymer coating causes changes in the observed stabilization of photocurrent. The method may provide a useful framework for design of improved coatings for the stabilization of aqueous semiconductor/liquid interfaces.

Original languageEnglish
Pages (from-to)3103-3107
Number of pages5
JournalJournal of Physical Chemistry
Volume88
Issue number14
Publication statusPublished - 1984

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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