Dissociation of N2O on anatase TiO2 (001) surface – The effect of oxygen vacancy and presence of Ag cluster

Abstract

The increase in concentration of nitrous oxide (N2O) in the atmosphere is one of the major contributors to the greenhouse effect, ozone depletion and climate change. Therefore, it is important to decompose harmful N2O molecule into harmless N2. In the present work, we have studied the decomposition of N2O on anatase TiO2 (001) surface using first principle calculations. The results indicates that the N2O molecule is physisorbed on perfect TiO2 surface without any dissociation, and is dissociated into N2 and oxygen on the reduced TiO2 surface. In addition, it has been found that the interaction between N2O and TiO2 is augmented by the presence of Ag cluster on anatase (001) surface. On the basis of Bader charge analysis and electron density difference plot, it has been found that the excess charge in the reduced anatase TiO2 (001) surface is transferred to the adsorbed N2O molecule, which results the weakening of N–O bond of N2O followed by the decomposition of N2O into N2 and O. Vibrational frequency analysis also performed to confirm the decomposition of N2O molecule. From the pathway for N2O dissociation on reduced TiO2 and Ag/TiO2 surfaces, it has been observed that the dissociation reaction of N2O on TiO2 surface is highly exothermic with activation energy barrier of 0.25eV. The results presented in this work show that the reduced anatase TiO2 with (001) facet is a good catalyst for the decomposition of N2O molecule.