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 <i>in situ</i> 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^-.