Insight into the Superior Catalytic Activity of MnO2 for Low-Content NO Oxidation at Room Temperature

To achieve efficient low-content NO oxidation at room temperature is a hot but challenging topic in heterogeneous catalysis, and MnO2-based oxide catalysts have recently drawn so much attention owing to the potential activity. However, the activity origin of MnO2 and the critical rate-limiting factor are vague, impeding further catalyst optimization. Herein, by combining the first-principles calculations and microkinetic analyses, we systematically investigate the low-content NO oxidation process catalyzed by MnO2. On MnO2(110) exposed by two kinds of active sites (Mn5c and the lattice Obri), the favorite pathway contributing to NO oxidation is figured out by examining the complicated reaction network. This reveals that the Mars–van Krevelen mechanism with the lattice Obri involved is preferred rather than the Langmuir–Hinshelwood one occurring at the Mn5c sites alone. First, NO adsorbs at Mn5c (as NO*) and is oxidized by the lattice Obri, forming NO2# (# denotes the Obri vacancy, Ovac) that can desorb wi...