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Abstract
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Photocatalytic NO removal is usually accompanied by the generation of NO2, which hasan intermediate with amuch higher toxicity than NO. Therefore, it is critically important to develop new photocatalysts with the ability of NO selectively conversionting NO to avoid the production of toxic intermediate NO2. Herein, we report the novel CN/OH/g-C3N4 structures with large and unique pores to explore the synergistic roles of functional cyano and hydroxylcyano and hydroxyl functional groups in the photocatalytic NO removal of NO over g-C3N4 have been systematically studied. The photocatalytic NO removal experiments showed thatAccording to the results, the NO2 production rate of toxic intermediate NO2 onver cyano and hydroxylCN/OH groups-modified g-C3N4 (DCN-O-R) was limited to be 4.8%, which wais much lower than that of CN–g-C3N4 modified only by cyano functional groups (DCN, 38.6%) and pure g-C3N4 (50.0%). Meanwhile, the photocatalytic NO conversion efficiency over DCN-O-R is higher than that of DCN and g-C3N4. The effects of the functional groups on the energy band positions, optical properties, types of reactive oxygen species (ROSs), NO adsorption- activation sites and photocatalytic NO conversionreaction pathways of DCN-O-R were furtherwas also explored. It was found that the introduction insertion of cyano CN group favorably changes the energy band of g-C3N4 favors towards the production generation of •O2-. NO can only be only oxidized by h+ to NO2 by the photogenerated holesinstead of NO3-. When NO2 is adsorbed on the hydroxyl groups of the surface, it can be deeply further oxidized to the final product NO3- by •O2- to the final product NO3-. The synergistic effect of bifunctional groups regulates the conversion pathway from NO→NO2 to NO→NO2→NO3-. This work provides a strategy to abate toxic intermediates during the NO removal process, underlining the importance of surface/interface molecular engineering in regulatingion the catalytic reaction pathways.
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