CONTROLLING REACTION SELECTIVITY IN THE OXIDATION OF METHANOL AT CU(110) SURFACES

When deuterated methanol (CD3OH) and dioxygen mixtures are coadsorbed at Cu(110) surfaces at room temperature and above, the main reaction p roduct can be switched between formaldehyde and formate by changing th e mixture composition. For oxygen-rich mixtures formaldehyde is the ma jor product but when methanol is in 5:1 excess only formate is produce d. It is proposed that the reaction mechanism is controlled by the mic roscopic structure of the surface: when the reactants are adsorbed seq uentially, separate islands of oxygen and methoxy develop which inhibi t further oxidation but when reactants are coadsorbed a homogeneous mi xture of adsorbates is produced creating a facile pathway to formate.