Palladium Catalysis of O2 Reduction by Electrons Accumulated on TiO2 Particles during Photoassisted Oxidation of Organic Compounds

Chong Mou Wang, Adam Heller, Heinz Gerischer

Research output: Contribution to journalArticle

311 Citations (Scopus)

Abstract

Our earlier theoretical analysis suggested that the quantum efficiency of photoassisted oxidation of organic compounds in water by O2 on n-TiO2 surfaces can be limited by the kinetics of the reduction of O2. When the rate of O2 reduction is not sufficiently fast to match the rate of reaction of holes, an excess of electrons will accumulate on the TiO2 particles, and the rate of electron-hole recombination will increase. We now show experimentally that electrons do indeed accumulate on slurried TiO2 particles during photoassisted oxidation of 1.6 M aqueous methanol and that electrons on the slurried particles persist for at least ∼ 1 min even in O2-saturated solutions. The rate of particle depolarization, i.e. of electron transfer to dissolved O2, is increased and the negative charge on the TiO2 particles is completely eliminated upon incorporation of Pd0 in the surface of the TiO2 particles. We also show that incorporation of Pd0 in the surface increases the quantum efficiency of the photoassisted oxidation of 10−2 M aqueous 2,2-dichloropropionate 3-fold at 0.01 wt % Pd and 7-fold at 2 wt % Pd.

Original languageEnglish
Pages (from-to)5230-5234
Number of pages5
JournalJournal of the American Chemical Society
Volume114
Issue number13
DOIs
Publication statusPublished - 1992 Jun 1

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ASJC Scopus subject areas

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

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