The aluminium–alcohol interface: Methanol on clean Al(1 1 1) surface

The adsorption and decomposition pathways of methanol on Al(1 1 1) at 90 K and 300 K have been studied using UPS, work function and thermal desorption spectroscopy measurements over a wide temperature range. Dissociative adsorption of methanol occurs at 90 K for low coverage (Θ<1/4 monolayer) to CH3Oads. and H and the chemisorbed intact methanol were found as the dominant adsorbate species at Θ≅1 monolayer (1.4 L exposure) coverage. The relative energy shift of the O–H orbital (7a′) to higher binding energy indicates a strong hydrogen bonding in the multilayer. As a stable reaction intermediate, the surface methoxy species was formed on heating the multilayer to ∼170 K. This methoxy overlayer decomposed at high temperature, desorbed as CH4 and H2, and left only O on the surface. A methoxy species was observed for 300 K adsorption which has different band energy and shape compare to simple methoxy overlayer observed at 170 K. The work function of aluminium decreased largely due to the adsorption of methanol.