Facile synthesis of surface N-doped Bi₂O₂CO₃: Origin of visible light photocatalytic activity and in situ DRIFTS studies

Graphical abstract: Surfactant (CTAB) can induce nitrogen interstitially doping in the Bi₂O₂CO₃ surface, leading to the formation of localized states from N−O bond, which probably account for the origin of the visible light activity. Moreover, the photocatalytic NO oxidation processes over Bi₂O₂CO₃ were successfully monitored for the first time by in situ DRIFTS. - Highlights: • Interstitially doping N in the Bi₂O₂CO₃ surface was achieved at room temperature. • N-doped Bi₂O₂CO₃ exhibited significantly enhanced visible light photocatalytic activity compared to the pristine Bi₂O₂CO₃. • The formation of localized states from N−O bond could account for the visible light activity of Bi₂O₂CO₃. • The photocatalytic NO oxidation process was monitored by in situ DRIFTS. - Abstract: Bi₂O₂CO₃ nanosheets with exposed {001} facets were prepared by a facile room temperature chemical method. Due to the high oxygen atom density in {001} facets of Bi₂O₂CO₃, the addition of cetyltrimethylammonium bromide (CTAB) does not only influence the growth of crystalline Bi₂O₂CO₃, but also modifies the surface properties of Bi₂O₂CO₃ through the interaction between CTAB and Bi₂O₂CO₃. Nitrogen from CTAB as dopant interstitially incorporates in the Bi₂O₂CO₃ surface evidenced by both experimental and theoretical investigations. Hence, the formation of localized states from N−O bond improves the visible light absorption and charge separation efficiency, which leads to an enhancement of visible light photocatalytic activity toward to the degradation of Rhodamine B (RhB) and oxidation of NO. In addition, the photocatalytic NO oxidation over Bi₂O₂CO₃ nanosheets was successfully monitored for the first time using in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS). Both bidentate and monodentate nitrates were identified on the surface of catalysts during the photocatalytic reaction process. The application of this strategy to another relevant bismuth based photocatalyst, BiOCl, demonstrated that surface interstitial N doping could also be achieved in this case. Therefore, our current route seems to be a general option to modify the surface properties of bismuth based photocatalysts.