Substrate mediated stabilization of methylphosphonic acid on ZnO non-polar surfaces'

The adsorption of methylphosphonic acid (MPA, formula CH₃–PO₃H₂) on ZnO(10-10) surfaces has been investigated by first-principles density-functional total energy calculations. We show that substrate mediated interactions between co-adsorbates can significantly affect the binding energy of MPA on the ZnO surface, which leads to a preferential molecular dimer assembly along the polar 0001] direction (i.e. along the Zn–O dimer direction). We propose that this is caused by a local charge compensation mechanism due to the relaxation of the ZnO surface and suggest that this concept can be applied to other adsorbates on metal oxide surfaces with metal–oxygen dimers.