Density Functional Theory Study of NHx (x=0-3) and N2 Adsorption on IrO2(110) Surfaces

The oxidation of ammonia (NH3) and the reduction of nitrogen (N-2) are two important processes in chemistry. In this study, we used density functional theory calculations to investigate the adsorptions of NHx (x = 0-3) and N-2 on IrO2(110) surfaces, with density of states (DOS) analysis providing information relating to bond character and state interactions. These adsorbates have higher binding energies on the IrO2(110) surface than on the RuO2(110)) surface because the former forms stronger a bonds with the adsorbed molecules. The surface adsorptions of NH2 and NH on the IrO2(110) surface proceed with similar binding energies and similar hybridizations of the nitrogen atoms. In addition, the orientations of NH2 and NH adsorbed on the IrO2(110) surface are governed by lateral interactions with surface oxygen atoms (O(cus)or O-br), rather than by hydrogen bonding. We calculated the binding energy for the adsorption of N-2 on the IrO2(110) surface to be 1.10 eV. The weakening of the N N triple bond was evident from our DOS results; strong bonding forces, including sigma- and pi-type interactions, exist between the N-2 molecule and the surface, suggesting that N2 molecules are moderately activated by IrO2(110) surfaces.