Density functional theory of NO2 and N2O adsorption on the transition metal modified TiO2 surface

The geometric structure and electronic properties of transition metal M (M = Cu, Fe, Mn)-TiO2 (101) surface adsorbed by NO2 and N2O were calculated by density functional theory (DFT) and DFT + U theory. Eight models were established to explore the effect of NO2 and N2O adsorption, and the results show that transition metal adsorption has different effects on the redox reaction of NO2 and N2O. From the stability of adsorption structure, the adsorption of NO2/N2O on Mn atom is more stable, and the adsorption of N2O on Fe atom is more stable than that of NO2. The analysis of charge transfer and electronic structure show that a large number of free active electrons are formed around the Mn and Fe atoms, which are connected with the N atoms of NO2/N2O, and one N atom in N2O changes from losing electrons to gaining a small number of electrons. This means that the Mn and Fe atoms can stimulate more active electrons to exchange with NO2 and N2O, that is, they can exchange more electrons with NO2/N2O before selective catalytic reduction (SCR) reaction, which is beneficial to the succeeding catalytic reaction.