Electrochemical quartz crystal microbalance studies of electron addition at nanocrystalline tin oxide/water and zinc oxide/water interfaces: Evidence for band-edge-determining proton uptake

Buford I. Lemon, Joseph T. Hupp

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Electrochemical quartz crystal microbalance (EQCM) measurements provide compelling evidence for charge-compensating cation uptake by nanocrystalline SnO2 and ZnO electrodes during electron addition. Comparative light water/heavy water measurements establish that the adsorbed or intercalated ions are protons or deuterons. Additional studies as a function of pH implicate water, rather than hydronium ions, as the proton source. The new results, when combined with previous results for titanium dioxide in nonaqueous electrolytes, suggest that charge-compensating cation intercalation is a general mode of reactivity for metal oxide semiconductors. Finally, the new observations raise significant fundamental questions concerning (1) chemical control of band energetics, (2) possible band-edge-unpinning phenomena, and (3) relationships between band edge energies and driving forces for isolated electron transfer reactions.

Original languageEnglish
Pages (from-to)2426-2429
Number of pages4
JournalJournal of Physical Chemistry B
Issue number14
Publication statusPublished - Apr 3 1997


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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