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

Abstract The NO oxidation processes on CrO 2 (110) was investigated by virtue of DFT + U calculation together with microkinetic analysis, aiming to uncover the reaction mechanism and activity-limiting factors for CrO 2 catalyst. It was found that NO oxidation on CrO 2 (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 CrO 2 (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 NO 2 , the nitrate species was found to be difficult removed and constituted the key poisoning species, eventually limiting the overall activity of CrO 2 . This work demonstrated the considerable catalytic ability of CrO 2 for NO oxidation at room temperature, and the understanding may facilitate the further design of more active Cr-based catalyst.