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 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, chargecarrier 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 − .

Triangle Cl−Ag1−Cl Sites for Superior Photocatalytic Molecular Oxygen Activation and NO Oxidation of BiOCl

“…Subsequently, surface reaction pathways of photocatalytic NO oxidation over Ag 1 /BiOCl and other samples were investigated using in situ FT‐IR (Figure 4f–g). As the reaction proceeded, nitrate species were observed to gradually accumulate on the surface of Ag 1 /BiOCl, as revealed by peak intensities of major bidentate bonding (b‐NO 3 − , 1572, 1475, and 1439 cm −1 ), [22] minor monodentate (1350 cm −1 ), [23] and corresponding vibrations of N=O double bond (1680–1800 cm −1 ) [24] . The generation of nitrate on Ag 1 /BiOCl is likely induced by a reaction between the super oxide radical and the nitrogen monoxide via ⋅O 2 − ads +NO→NO 3 − ads , with ⋅O 2 − peaks observed at 1023 and 1085 cm −1 .…”

“…Impressively, 97 % NO 3 À selectivity of ClÀ Ag 1 À Cl sites in Ag 1 /BiOCl was significantly higher than that (87 %) of OÀ Ag 1 À O sites in Ag 1 /P25 (Figure 4e Subsequently, surface reaction pathways of photocatalytic NO oxidation over Ag 1 /BiOCl and other samples were investigated using in situ FT-IR (Figure 4f-g). As the reaction proceeded, nitrate species were observed to gradually accumulate on the surface of Ag 1 /BiOCl, as revealed by peak intensities of major bidentate bonding (b-NO 3 À , 1572, 1475, and 1439 cm À 1 ), [22] minor monodentate (1350 cm À 1 ), [23] and corresponding vibrations of N=O double bond (1680-1800 cm À 1 ). [24] The generation of nitrate on Ag À peaks observed at 1023 and 1085 cm À 1 .…”

Dual active sites of single-atom copper and oxygen vacancies formed in situ on ultrathin TiO2(B) nanosheets boost the photocatalytic dehalogenative C–C coupling synthesis of bibenzyl

“…On the perfect (010) surface of the TiO 2 (B) nanosheet, benzyl bromide and bibenzyl molecules prefer to be adsorbed at Lewis acid sites such as Ti 4+ and V O sites [57][58][59][60][61][62] due to the high electrostatic interaction of reactant molecules and photocatalyst surface. The stronger adsorption capacity of benzyl bromide than bibenzyl can be attributed to the higher polarity of benzyl bromide.…”

Photocatalytic NOx removal and recovery: progress, challenges and future perspectives

“…15–17 At present, conventional photocatalytic technologies, including NO x oxidation, NO x decomposition, and selective NO x reduction, have been vigorously developed, spanning from material design to elucidation of the underlying mechanisms. 6,18–20 Meanwhile, the tendency of photocatalytic removal of NO x has been gradually transformed from oxidation, purification, and then to resource utilization. Particularly, the photocatalytic NO x reduction for ammonia synthesis has achieved milestone progress in recent years.…”