Adsorption of N2 and N2O on Ni(7 5 5) surface: ab initio periodic density functional study

Adsorption of N2 and N2O at various sites on Ni(7 5 5) has been investigated by density functional theory (DFT) method (periodic DMol3). Several possible adsorption structures (attaching the nitrogen atom to the surface, or lying parallel) are found for both molecules. There is a clear binding energy preference of N2 and N2O for step sites in contrast to the case of CO. It is revealed that the decomposition of N2O occurs exclusively near the step, but not on the terrace. Two decomposition channels can be considered; dissociative adsorption and spontaneous decomposition during TPD ramp. Three possible candidates for the precursor of the spontaneous decomposition of N2O during TPD ramp are discussed.