Density-functional study for the NO_x (x = 1, 2) dissociation mechanism on the Cu(1 1 1) surface

Spin-polarized density functional theory calculation is employed to study the adsorption and dissociation of NO₂ molecule on Cu(1 1 1) surface. It is shown that the most favorable adsorption structure is the NO₂ (T,T-O-,O′-nitrito) configuration which has an adsorption energy of -1.49 eV. The barriers for step-wise NO₂ dissociation reaction, NO _2(g) → N_(a) + 2O_(a), are 1.05 (for O-N-O bond activation), and 2.08 eV (for N-O bond activation), respectively, and the entire process is 0.6 eV exothermic. The energetics of single N-O dissociation with and without the presence of N atom or O atom on the surface are also calculated. The results indicate that in the presence of O atom on Cu(1 1 1) surface would raise the N-O dissociation barrier, whereas in the presence of N atom decrease it. The interaction nature between adsorbates and substrate is analyzed by the local density of states (LDOS) calculation.