Oxidation of Methanol on Oxygen Covered Ptn/Ru(0001) Layers

Thin pseudomorphic as well as thick “Pt(111)-like” Pt/Ru(0001) bimetallic substrates have been used to study the oxidation of methanol (CD3OH) to CO2. Specifically, molecular (cold deposited) and ordered atomic (annealed) oxygen precovered Ptn/Ru(0001) layers with n = 1–15 ML have been studied. Thereby, the thickness of the Pt films primarily influences the adsorption probability of O2 and much less the energy barriers for methanol reactions. In particular, no indication of a strain effect could be detected, and the reactions of methanol on Ptn/Ru(0001) multilayer films closely follow the known reaction scheme on Pt(111) substrates: On O2/Ptn/Ru(0001), methanol is directly oxidized to formate (DCOO) and eventually desorbs as CO2 (300 K). The formate producing reaction is thereby promoted by dissociating O2 molecules (130 K) and, at higher temperatures (130–200 K), by disordered atomic oxygen. This is in contrast to methanol postadsorbed onto ordered atomic oxygen covered Ptn/Ru(0001) layers, which exhibit...