In situ ATR-SEIRAS study of electro oxidation of dimethyl ether on a Pt electrode in acid solutions

The electrooxidation of dimethyl ether (DME) was studied on a Pt film electrode in HClO4 solution using surface enhanced infrared absorption spectroscopy (SEIRAS) and cyclic voltammetry. (CH2OCH3)(ad) and eta(2)(O,C)-H2CO are inferred as the adsorbed intermediates resulting from the dissociative adsorption of DME in the hydrogen adsorption region. Adsorbed CO was also found, with coverages increasing rapidly upon DME adsorption, probably due to the further dissociation of (CH2OCH3)(ad) and eta(2)(O,C)- H2CO. In the main oxidation region no adsorbed species, excluding CO, were found. However, for low DME concentration (0.025 M), vibration bands associated with adsorbed CH3COO or CH3OCOO were observed between 0.3 and 0.95 V. These results lead to the conclusion that the reaction products could depend on the concentration of the fuel. Additional discussion of the reaction mechanism is also presented. (c) 2005 Elsevier B.V. All rights reserved.