Targeted NO Oxidation and Synchronous NO2 Inhibition via Oriented 1O2 Formation Based on Lewis Acid Site Adjustment.

Abstract

An appealing strategy for ensuring environmental benefits of the photocatalytic NO oxidation reaction is to convert NO into NO3- instead of NO2, 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 ZrO2, aiming to precisely regulate the ROS evolution process for the selective oxidation of NO into NO3-. 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 •O2-, which promotes the oriented formation of 1O2. As a result, monoclinic ZrO2 with more Lewis acid sites exhibited an outstanding NO conversion efficiency (56.33%) and extremely low NO2 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 NO3-.