A Mechanistic Study of the Oxidative Reaction of Hydrogen-Terminated Si(111) Surfaces with Liquid Methanol

Noah T. Plymale, Mita Dasog, Bruce S. Brunschwig, Nathan S Lewis

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

H-Si(111) surfaces have been reacted with liquid methanol (CH3OH) in the absence or presence of a series of oxidants and/or illumination. Oxidant-activated methoxylation of H-Si(111) surfaces was observed in the dark after exposure to CH3OH solutions that contained the one-electron oxidants acetylferrocenium, ferrocenium, or 1,1′-dimethylferrocenium. The oxidant-activated reactivity toward CH3OH of intrinsic and n-type H-Si(111) surfaces increased upon exposure to ambient light. The results suggest that oxidant-activated methoxylation requires that two conditions be met: (1) the position of the quasi-Fermi levels must energetically favor oxidation of the H-Si(111) surface and (2) the position of the quasi-Fermi levels must energetically favor reduction of an oxidant in solution. Consistently, illuminated n-type H-Si(111) surfaces underwent methoxylation under applied external bias more rapidly and at more negative potentials than p-type H-Si(111) surfaces. The results under potentiostatic control indicate that only conditions that favor oxidation of the H-Si(111) surface need be met, with charge balance at the surface maintained by current flow at the back of the electrode. The results are described by a mechanistic framework that analyzes the positions of the quasi-Fermi levels relative to the energy levels relevant for each system.

Original languageEnglish
Pages (from-to)4270-4282
Number of pages13
JournalJournal of Physical Chemistry C
Volume121
Issue number8
DOIs
Publication statusPublished - Mar 2 2017

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Methanol
Hydrogen
methyl alcohol
Oxidants
Liquids
hydrogen
liquids
Fermi level
Oxidation
oxidation
Electron energy levels
reactivity
Lighting
energy levels
illumination
Electrodes
electrodes
Electrons
electrons

ASJC Scopus subject areas

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

Cite this

A Mechanistic Study of the Oxidative Reaction of Hydrogen-Terminated Si(111) Surfaces with Liquid Methanol. / Plymale, Noah T.; Dasog, Mita; Brunschwig, Bruce S.; Lewis, Nathan S.

In: Journal of Physical Chemistry C, Vol. 121, No. 8, 02.03.2017, p. 4270-4282.

Research output: Contribution to journalArticle

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