Systematic modulation of quantum (electron) tunneling behavior by atomic layer deposition on nanoparticulate SnO2 and TiO2 photoanodes

Chaiya Prasittichai, Jason R. Avila, Omar K. Farha*, Joseph T. Hupp

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

65 Scopus citations


Ultrathin films of TiO2, ZrO2, and Al 2O3 were conformally created on SnO2 and TiO2 photoelectrodes via atomic layer deposition (ALD) to examine their influence upon electron transfer (ET) from the electrodes to a representative molecular receptor, I3-. Films thicker than 2 Å engender an exponential decrease in ET time with increasing film thickness, consistent with tunneling theory. Increasing the height of the barrier, as measured by the energy difference between the transferring electron and the bottom of the conduction band of the barrier material, results in steeper exponential drops in tunneling rate or probability. The variations are quantitatively consistent with a simple model of quantum tunneling of electrons through square barriers (i.e., barriers of individually uniform energy height) that are characterized by individually uniform physical thickness. The findings demonstrate that ALD is a remarkably uniform and precise method for modifying electrode surfaces and imply that standard tunneling theory can be used as a quantitative guide to intentionally and predictively modulating rates of ET between molecules and electrodes.

Original languageEnglish (US)
Pages (from-to)16328-16331
Number of pages4
JournalJournal of the American Chemical Society
Issue number44
StatePublished - Nov 6 2013

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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