Oxidation of 1-propanol on a Pt film electrode studied by combined electrochemical, in situ IR spectroscopy and online mass spectrometry measurements

The electrochemical adsorption and oxidation of 1-propanol and its incomplete oxidation products propionaldehyde and propionic acid on Pt film electrodes in acidic solution were studied using a combination of in situ Fourier transform infrared spectroscopy in an attenuated total reflection configuration (ATR-FTIRS) and online differential electrochemical mass spectrometry (DEMS). The potential dependent adlayer formation and volatile (side) products were monitored simultaneously in potentiodynamic, potentiostatic and adsorbate stripping experiments under continuous, controlled electrolyte flow. Mechanistic consequences derived from these measurements are discussed. Most important, we can identify an adsorbed propionyl species, which is formed from 1-propanol and propionaldehyde and which is likely to act as precursor for COad formation, and adsorbed propionate. The latter is in adsorption-desorption equilibrium with propionic acid, which is formed as a little active side. product rather than representing an active intermediate in the 1-propanol oxidation. Main product of 1-propanol oxidation is propionaldehyde; CO2 is a minority product which is (almost) exclusively formed via COad oxidation. Contributions from a direct reaction pathway to CO2 formation are negligible. (C) 2013 Elsevier Ltd. All rights reserved.