Recently, an increasing attention is paid to crystal defects due to the significant influence on the catalytic properties of material. Herein, the WO3 and fluorinated WO3 (F-WO3) samples have been prepared by an in situ hydrothermal method. On one hand, we have found that under visible light irradiation (420nm), the photocatalytic activities of F-WO3 samples are obviously reduced, which has been mainly attributed to the generation of W vacancies by fluorination. This finding is obviously distinct from the previous reports, in which the photocatalytic activities of semiconductors can be effectively improved by fluorination. On the other hand, after being further processed by H2O2 again, the generated W vacancies by fluorination can 2 be remedied easily; moreover, the WO3/WO30.333H2O heterojunctions have formed with a novel flower shape (H2O2-F-WO3). It is amazing that under visible light irradiation (420nm), the activity of H2O2-F-WO3 sample is 4.3 and 3.0 times higher than that of F-WO3 and WO3, respectively. The significantly improved activity is mainly attributed to the remedy of W vacancy and the formation of the WO3/WO30.333H2O heterojunction. Compared with conventional defect remedy method (e.g., calcination), this vacancy remedy method with H2O2 is facile, energy-saving, which could be extended to develop the other efficient photocatalysts.
Herein, we, for the first time, have developed a facile anion intercalation method to prepare uniform Bi2O2[BO2(OH)]/Bi2O3 and Bi2O2[BO2(OH)] nanosheets, in which H2O2 is employed as the exfoliating reagent to break the weak Bi−O bonds (2.572 Å) between [Bi2O2]n2n+ layers, then allowing borate ion to precisely intercalate into [Bi2O2]n2n+ layers. Further, density functional theory (DFT) calculations reveal that both O 2p and B 2p of [BO3]3− layer obviously contribute to an downshift of valence band (VB) and upshift of conduction band (CB), leading to a wider band gap of Bi2O2[BO2(OH)]. Thus, Bi2O2[BO2(OH)]/Bi2O3 exhibit a higher photocatalytic activity than Bi2O3 for the degradations of rhodamine B (RhB) under ultraviolet light irradiation (λ < 420 nm), which may be resultant from a synergetic effect of double internal electronic field that has improved charge separation efficiency. For featured layered materials, anion intercalation is an artful facile strategy to develop new, efficient photocatalysts.
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