Insight into room-temperature catalytic oxidation of NO by CrO2(110): A DFT study

The NO oxidation processes on CrO2(110) was investigated by virtue of DFT +U calculation together with microkinetic analysis, aiming to uncover the reaction mechanism and activity-limiting factors for CrO2 catalyst. It was found that NO oxidation on CrO2(110) has to be triggered with the lattice O-bri involved (Mars-van Krevelen mechanism) rather than the Langmuir-Hinshelwood path occurring at the Cr-5c sites alone. Specifically, the optimal reaction path was identified. Quantitatively, the microkinetic analysis showed that CrO2(110) can exhibit a high turnover rate of 0.978 s(-1) for NO oxidation at room temperature. Such an activity could originate from the bifunctional synergetic catalytic mechanism, in which the Cr-5c, sites can exclusively adsorb NO and the O-bri is very reactive and provides oxidative species. However, it is worth noting that, as the reactive O-bri, tightly binds NO2, the nitrate species was found to be difficult removed and constituted the key poisoning species, eventually limiting the overall activity of CrO2. This work demonstrated the considerable catalytic ability of CrO2 for NO oxidation at room temperature, and the understanding may facilitate the further design of more active Cr-based catalyst. (C) 2019 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.