Density functional theory study of NO adsorption on the transition metal M (M=Cu, Fe and Mn) modified TiO2 surface

Abstract

To study the effect of different kinds of transition metals and their proportions on NO adsorption on TiO2 surface, the density functional theory (DFT) method was used to calculate the energetic, geometric structure and electronic structure of the adsorption of NO on transition metal M (M = Cu, Fe and Mn)-anatase TiO2 (101) surface. The above transition metals were adsorbed on anatase TiO2 (101) surface in three different adsorption ratios, which are single transition metal adsorption model, mixed 2:2 and 1:3 ratio models. On the basis of the study, 13 models were established to study the effects of transition metals and adsorption ratio on NO oxidation to determine the optimal adsorption model. It has been found from the energetic calculations that mixed adsorption model is more stable for the adsorption of NO. The results of electronic structure and charge distribution analysis showed that a large quantity of active electron clusters are distributed around Mn and Fe atoms, which are attached to a large area of N atoms in NO, indicating that Mn and Fe can provide more electrons for catalytic reaction and facilitate electron exchange between catalyst and NO. Among all the adsorption models, the 3Fe+1Mn–TiO2 and 3Mn+1Fe–TiO2 models are superior, i.e., they can exchange more electrons with NO before the catalytic reaction, which is conducive to the subsequent catalytic reaction.