Methanol Decomposition on Co(0001): Influence of the Cobalt Oxidation State on Reactivity

Reaction of methanol (CH3OH) on metal surfaces has received lots of concerns because of its potential application in hydrogen (H-2) production and fuel cells. In this work, we have studied the decomposition of CH3OH on Co(0001) and its oxide surfaces using temperature-programmed desorption to understand the effect of surface oxidation on the production of H-2 via CH3OH decomposition. On a clean Co(0001) surface, CH3OH molecules decompose into CO and H atoms easily in the temperature range of 280-350 K, resulting in a maximum yield of 0.27 ML for H-2 production. With O atoms on the Co(0001) surface, methoxy groups can be easily formed. As the surface temperature rises to about 370 K, methoxy groups begin to decompose followed by an immediate desorption of H-2 and CO at the same temperature, resulting in a maximum yield of H-2 which increases to 0.42 ML on the similar to 0.25 ML O atom-covered Co(0001) surface. However, on the CoO- and Co3O4-like surfaces, CH3OH is selectively decomposed to CH2O and CO2, respectively, and the H-2 production is decreased significantly, while the activities of CoO- and Co3O4-like surfaces are much lower than that of the O atom-covered Co(0001) surface. Therefore, avoiding the formation of oxide surfaces is helpful for H-2 production from CH3OH decomposition.