The oxygenndash;water reaction on Pd(100): Observation of a precursor complex

摘要

The oxygenndash;water reaction on Pd(100) has been studied by electron energy loss spectroscopy (EELS) and low energy electron diffraction. A precursor complex for hydroxyl formation was identified in the ngr;(Ondash;H) loss region of the vibrational spectrum when water was adsorbed on the Pd(100)thinsp;p(2times;2)O surface. The observations indicate that the precursor complex contains several water molecules. The formation of the waterndash;oxygen precursor complex and thus the reaction is inhibited by the presence of hydrogen on the surface. The reaction is demonstrated to start at the defects of thep(2times;2)O structure. Water does not adsorb on the perfectp(2times;2)O structure above 140 K, at low pressures.