Electrochemical behaviors of dimethyl ether on platinum single crystal electrodes. Part I: Pt(1 1 1)

The electrochemical behaviors of dimethyl ether (CH3–O–CH3, DME), which is regarded as a promising fuel for the fuel cell, on platinum single crystal electrode in acidic solutions have been investigated in detail by electrochemical measurements. In 0.5 M H2SO4 solution, DME is dissociatively adsorbed on Pt(1 1 1) electrode surface in the low potential region between 0.2 and 0.5 V (vs. RHE) and further oxidized to CO2 around 0.8 V. One of the stable adsorbed intermediates for DME decomposition on Pt(1 1 1) is carbon monoxide (CO) and its coverage is approximately constant (ca. 0.37) between 0.3 and 0.5 V. The adsorption of hydrogen and anion significantly affects the DME dissociation process. The kinetic analysis on DME decomposition process shows that the apparent reaction rate of DME decomposition on Pt(1 1 1) in the initial stage reaches a maximum around 0.35 V. No direct oxidation of DME has been observed on Pt(1 1 1) electrode surface. As a model reaction system, cyanide-modified Pt(1 1 1) electrode surface shows no activity on both decomposition and oxidation of DME.