A Comparative Density-Functional Theory Investigation of Oxygen Adsorption on Stepped Ni Surfaces 3(hkl) x (111) [hkl = (111), (100), (110)]: Role of Terrace Orientation

Based on density functional theory calculation, we have investigated oxygen adsorption at a series of stepped nickel surfaces, which have a common single height (111) step and fixed-size terrace but various terrace orientation. Three stepped surfaces Ni(331), Ni(115), and Ni(551), which have different terrace orientation (111), (100), and (110) respectively, are considered in the calculations. Detailed results about energetics, geometries, electronic structure and magnetic properties are present, and compared with available theoretical and experimental results. Our results indicate that oxygen atoms always trend to bind at sites near (111) step and the binding between oxygen and step nickel atoms is stronger in the surfaces with more open terrace plane. The calculated energetics, geometry and magnetic properties of clean surface can be understood by the nearest-neighbor (NN) coordination model. Moreover, the calculations also suggest that the adsorption energy and site preference ordering at the stepped surfaces can be understood by a simple perturbation picture based on nearest-neighbor coordination number and the adsorption energy of the corresponding step and terrace plane decomposed using the microfacet notation.