Targeted NO Oxidation and Synchronous NO<sub>2</sub> Inhibition via Oriented <sup>1</sup>O<sub>2</sub> Formation Based on Lewis Acid Site Adjustment
Songxia Wang, Wen Cui, Ben Lei, Xing’an Dong, Yin Tang, Fan Dong
Abstract
An appealing strategy for ensuring environmental benefits of the photocatalytic NO oxidation reaction is to convert NO into NO 3 – instead of NO 2, yet the selectivity of products remains challenging. Here, such a scenario could be realized by tailoring the exposure of Lewis acid sites on the surface of ZrO 2, aiming to precisely regulate the ROS evolution process for the selective oxidation of NO into NO 3 – . As evidenced by highly combined experimental characterizations and density functional theory (DFT) simulations, Lewis acid sites serving as electron acceptors could induce itinerant electron redistribution, charge-carrier transfer, and further oxidation of •O 2 –, which promotes the oriented formation of 1 O 2 . As a result, monoclinic ZrO 2 with more Lewis acid sites exhibited an outstanding NO conversion efficiency (56.33%) and extremely low NO 2 selectivity (5.04%). The ROS-based reaction process and promotion mechanism of photocatalytic performance have been revealed on the basis of ESR analysis, ROS-quenching experiments, and in situ ROS-quenching DRIFTS. This work could provide a critical view toward oriented ROS formation and advance a unique mechanism of selective NO oxidation into NO 3 – .