DFT modelling of the NO reduction process at the Cu-doped SrTiO3(1 0 0) stepped surface

Abstract

Three-way catalytic converters are used to convert the toxic CO and NO automotive emissions into more environmentally sustainable products as CO2 and N2/N2O. In the recent years, the strict control of NOX emission has stimulated research on the catalytic NO reduction processes. Our aim is to use the DFT to investigate the capabilities of doped, rare earth element free perovskites (SrTiO3) step to catalyze the NO reduction process. Here we are focusing the attention on the role of the Cu doping and on the structural defects on the reactivity. In this paper, we investigate the ability of steps to catalyze the complete (to N2) and partial (to N2O) NO reduction considering three mechanisms of the Langmuir-Hinshelwood and of the Eley-Rideal type also in the presence of Cu dopants. Both the number of the oxygen vacancies and the dopant play a role on the process. Energy profiles show that the reduction of NO to N2 is possible at both pure and doped steps, even if with different mechanisms. The partial reduction to N2O is not favored. The Cu doping can modify the mechanism, but its ability to improve the catalytic properties of the step seems to be limited to the capability of stabilizing oxygen vacancies.