Electrochemistry of aqueous pyridinium: Exploration of a key aspect of electrocatalytic reduction of CO2 to methanol

Yong Yan, Elizabeth L. Zeitler, Jing Gu, Yuan Hu, Andrew Bruce Bocarsly

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106 Scopus citations

Abstract

The mechanism by which pyridinium (pyrH+) is reduced at a Pt electrode is a matter of recent controversy. The quasireversible cyclic voltammetric wave observed at -0.58 V vs SCE at a Pt electrode was originally proposed to correspond to reduction of pyrH+ to pyridinyl radical (pyrH). This mechanistic explanation for the observed electrochemistry seems unlikely in light of recent quantum mechanical calculations that predict a very negative reduction potential (-1.37 V vs SCE) for the formation of pyrH. Several other mechanisms have been proposed to account for the discrepancy in calculated and observed reduction potentials, including surface adsorption of pyrH, reduction of pyrH+ by two electrons rather than one, and reduction of the pyrH+ proton to a surface hydride rather than a π-based radical product. This final mechanism, which can be described as inner-sphere reduction of pyrH+ to form a surface hydride, is consistent with experimental observations.

Original languageEnglish (US)
Pages (from-to)14020-14023
Number of pages4
JournalJournal of the American Chemical Society
Volume135
Issue number38
DOIs
StatePublished - Sep 25 2013

All Science Journal Classification (ASJC) codes

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

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