The photocatalytic removal of gaseous NOₓ is commonly accompanied by secondary pollution, which necessitates the development of highly efficient nanostructured catalysts with a decreased propensity to toxic intermediate production. Herein, we describe the synthesis of plasmonic Bi/Bi₂O₂₋ₓCO₃ and demonstrate the presence of surface oxygen vacancies therein, revealing that the maximal NOₓ removal efficiency of Bi/Bi₂O₂₋ₓCO₃ under visible light irradiation reached 50.5% and exceeded that of a commercial photocatalyst, while the production of toxic NO₂ as a by-product was completely suppressed (the selectivity reached up to 98%). In-situ introduction of plasmonic Bi on the surface of Bi₂O₂₋ₓCO₃ promoted the generation of H₂O₂ by capturing electrons from the defect states of Bi₂O₂₋ₓCO₃ via the two-electron reduction of O₂ and thus inhibited NO₂ production (as confirmed by scavenger experiments), additionally broadening the light absorption range of the above photocatalyst. Moreover, surface oxygen vacancies in Bi–O layers provided a channel for electron transfer between Bi and Bi₂O₂₋ₓCO₃, which resulted in increased charge separation efficiency (maximum photocurrent = 1.1 μA cm⁻², 14.5 times higher than that of pristine Bi₂O₂CO₃). Furthermore, the toxicity assessment authenticated good biocompatibility of Bi/Bi₂O₂₋ₓCO₃. Thus, this study sheds light on the possible roles of H₂O₂ in NOₓ degradation and provides an efficient surface engineering strategy to prepare highly reactive and selective photocatalysts. Copyright © 2019 Elsevier B.V. All rights reserved.
CitationLu, Y., Huang, Y., Zhang, Y., Huang, T., Li, H., Cao, J.-J., & Ho, W. (2019). Effects of H₂O₂ generation over visible light-responsive Bi/Bi₂O₂₋ₓCO₃ nanosheets on their photocatalytic NOₓ removal performance. Chemical Engineering Journal, 363, 374-382. doi: 10.1016/j.cej.2019.01.172
- NO oxidation
- Oxygen vacancy