The role of surface defects in the adsorption of methanol on Fe3O4(001)

The adsorption of methanol (CH3OH) at the Fe3O4(001)-c(2x2) surface was studied using X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and temperature-programmed desorption (TPD). CH3OH adsorbs exclusively at surface defects sites at room temperature to form hydroxyl groups and methoxy (CH3O) species. Active sites are identified as step edges, iron adatoms, antiphase domain boundaries in the c(2x2) reconstruction, and above Fe atoms incorporated in the subsurface. In TPD, recombinative desorption is observed around 300 K, and a disproportionation reaction to form methanol and formaldehyde occurs at 470 K.