Intrinsic Relation between Hot Electron Flux and Catalytic Selectivity during Methanol Oxidation

Si Woo Lee, Woonghyeon Park, Hyosun Lee, Hee Chan Song, Yousung Jung, Jeong Young Park

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Catalytic selectivity, or the production of only one desired molecule that may be used as a fuel or chemical out of several thermodynamically possible molecules, is the foundation of surface chemistry. During catalytic reactions, electronic excitation taking place on the surface creates energetic electrons called "hot electrons" that have a significant impact on catalytic reactions. Despite its importance in fundamentally understanding electronic excitation on the surface, no reports show the relation between hot electron flow and catalytic selectivity. Here, using a Pt/n-type TiO2 Schottky nanodiode, we show the intrinsic relation between hot electron flow and catalytic selectivity. On the Pt thin film, hot electron flow was generated by methanol oxidation exhibiting a two-path reaction of either full oxidation to CO2 or partial oxidation to methyl formate; a steady-state chemicurrent was detected. We show that the activation energy of the chemicurrent is quite close to that of the turnover frequency, indicating that the chemicurrent originated from the catalytic reaction on the Pt thin film. The dependence of the chemicurrent on methanol partial pressure was investigated by varying the partial pressure of methanol (1-4 Torr). We show that hot electron generation is more effective in the reaction pathway that produces methyl formate. On the basis of these results, we conclude that the selectivity for methyl formate production correlates well with hot electron generation because of the higher exothermicity of generating the intermediate, as was confirmed using theoretical calculations based on the density functional theory.

Original languageEnglish
Pages (from-to)8424-8432
Number of pages9
JournalACS Catalysis
Volume9
Issue number9
DOIs
StatePublished - 6 Sep 2019

Keywords

  • catalytic nanodiode
  • chemical energy conversion
  • chemicurrent
  • exothermic energy
  • hot electron
  • methanol oxidation
  • selectivity

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