Ab initio study of the adsorption and dissociation of NO2 on pristine and Cu decorated ZnO(0001)-3 × 3

Abstract

Due to the importance of reducing environmental pollution, especially NO2, we have studied the adsorption of this contaminant to eliminate it from the atmosphere. We perform ab initio calculations of the NO2 adsorption on pristine and copper decorated zinc oxide (0001)-3 × 3 surface. Several high symmetry sites have been tested of the NO2 molecule adsorption. The structural and electronic properties of the most stable configurations are reported. The adsorption energies values show that the molecule is chemisorbed. The minimum energy pathways (MEP), to study the NO2 dissociation process, were calculated by the climbing image nudged elastic band (CI-NEB) method. The activation energy of the first stage NO2 dissociation on pristine ZnO surface is 0.14 eV, 1.83 eV lower than the 1.97 eV on the Cu decorated system. On the other hand, for the second dissociation process, the activation energy when Cu is present has a value of 1.16 eV which is 0.8 eV lower than the 1.96 eV needed on the pristine surface. Our results suggest that NO2 adsorption and first dissociation is possible on pristine ZnO(0001), but copper decoration allows a second dissociation stage providing a possible mechanism of the NO2 transformation into harmless substances.