Adsorption and oxidation of NO on Au(1Â 1Â 1) surface: Density functional studies

Experiments reveal that NO molecules react with atomic O on the Au(1 1 1) surface at low temperature to form NO2. We studied this process using a density functional method and periodic slab models. Structures and energies of all low-coverage adsorption complexes have been determined. Very small calculated adsorption energy of NO on regular Au(1 1 1) surface, ∼20 kJ mol−1, implies that the NO adsorption detected on Au(1 1 1) at ∼175 K takes place on defects. (NO + O)/Au(1 1 1) species form NO2/Au(1 1 1) without an activation barrier, releasing 170 kJ mol−1. No qualitative difference between the reactivity of two- and four-layer Au(1 1 1) films is found.