A method for kinetic study of methanol oxidation at Pt electrodes by electrochemical in situ infrared spectroscopy

Ling Wen Liao, Shao Xiong Liu, Qian Tao, Bin Geng, Pu Zhang, Cheng Ming Wang, Yan Xia Chen, Shen Ye

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

In this contribution, we describe a method to estimate the kinetics of the indirect pathway in methanol oxidation reaction (MOR) at Pt electrode by using electrochemical in situ infrared spectroscopy combined with a thin-layer flow cell. Based on a quantitative relationship between the coverage of adsorbed carbon monoxide (COad) and its infrared band intensities determined experimentally, COad coverages during MOR are estimated from the simultaneously recorded time-resolved IR measurements. By assuming that CO ad oxidation goes through Langmuir-Hinshelwood mechanism, its rate constant is estimated in pure supporting electrolyte under otherwise identical condition. Based on the result, the rates of COad formation and COad oxidation during MOR are deduced from the COad coverage-time curve. The methodology is exemplified with MOR on Pt electrode at +0.6 V (versus RHE) in 0.1 M HClO4 with 2 M methanol. It is found that under forced-flow condition: (i) the maximum reaction rate for CO ad oxidation is ca. 0.004 molecule site-1 s-1 which is 100 times smaller than the maximum rate for COad formation from methanol dehydrogenation; (ii) with increase in COad coverage from zero to 0.5 ML, the current efficiency of the indirect pathway for MOR increases and reaches ca. 17% under steady state. The general applicability of such a method is shortly discussed.

Original languageEnglish
Pages (from-to)233-240
Number of pages8
JournalJournal of Electroanalytical Chemistry
Volume650
Issue number2
DOIs
Publication statusPublished - 2011 Jan 1
Externally publishedYes

Keywords

  • Attenuated total reflection configuration
  • Flow-cell
  • Infrared spectroscopy
  • Kinetic study
  • Methanol oxidation
  • Platinum electrode

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemical Engineering(all)
  • Electrochemistry

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