OXIDATION OF METHANOL AT CU(110) SURFACES - NEW TPD STUDIES

Previous temperature-programmed desorption (TPD) and molecular beam st udies have concluded that formaldehyde desorption is the only signific ant pathway in methanol oxidation at Cu(110) surfaces. We present here new TPD data for the adsorption of deuterated methanol (CD3OH) at a p reoxidized Cu(110) surface and show that formate can be the major prod uct of the reaction but that the experimental conditions adopted in ea rlier studies (specifically, preadsorption of oxygen and the adsorptio n of methanol at low temperatures) preclude formate formation. We prop ose that the reaction pathway is sensitive to the local structure of t he methoxy/oxygen adlayer and suggest a model based upon this idea tha t reconciles the available experimental evidence. We also confirm the presence of two states of methoxy at the Cu(110)/O(a) surface and assi gn them to methoxy species with and without stabilization by surface o xygen.