Electrochemical oxidation/reduction reactions of ethanol in 1 M HClO4 were studied on porous Pt, Pt0.92Ru0.08, Pt0.85Ru0.15, and Ru under potentiodynamic conditions. The electrodes with defined bulk and surface compositions were made by electrodeposition on porous Au substrates. Cyclic voltammetry in combination with on-line mass spectrometry (DEMS) was employed to correlate faradaic currents with ion currents associated to reaction products. The formation of both CO2 and ethanal was unequivocally identified during ethanol oxidation on PtRu and Pt by using d 3-ethanol. On pure Ru neither faradaic currents were observed nor oxidation/reduction products could be detected by mass spectrometry. The reduction of ethanol on Pt and PtRu to methane and ethane was found in the potential range of hydrogen adsorption. The yields of oxidation and reduction products and the corresponding onset potentials for their formation are greatly influenced by the Ru content. Alloys with high Ru content exhibit a lower reaction rate for ethanol electrooxidation. On the other hand, the selectivity for ethanal production is significantly enhanced for PtRu as compared to pure Pt.

The reactivity of isopropanol on polycrystalline Pt in acid solutions was investigated using in-situ Fourier transform IR spectroscopy (FFIRS) and on-line differential electrochemical mass spectrometry (DEMS). The electro-oxidation products are acetone and CO2; the former is observed when isopropanol is present in the bulk of the solution, and the latter is produced from strongly adsorbed species. Both bulk and adsorbed isopropanol electro-reduction yield propane. H-D exchange is observed during propane formation when the reaction takes place in a D20 + DC10 4 solution. This observation suggests the formation of adsorbates bonded to the surface through the Ca atom of the isopropanol molecule. FTIR spectra of adsorbed species show the presence of-CH 3 and-COH groups. The most probable adsorbate structures are (CH3-C-CH3)Pt, (CH3-CH-CHa)Pt and (CH3-COH-CH3)Pt, presumably accompanied by (CH3-CO-CH 3)Pt.

The electrochemical behavior of n-propanol (n-PrOH) on polycrystalline Pt in acid solutions was investigated using in situ Fourier transform infrared spectroscopy (FTIRS) and on line differential electrochemical mass spectrometry (DEMS). The main products of n-PrOH oxidation are CO,, propanal and propionic acid. Different types of adsorbates with one, two or three C atoms were detected. Ethane and propane are produced from n-PrOH adsorbates during potential cycling in the H-adatom potential region. An increase in the quantity of adsorbed CO was observed after hydrogenation of n-PrOH adsorbates.

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