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首页> 外文期刊>RSC Advances >The relationship between microstructure and photocatalytic behavior in lanthanum-modified 2D TiO2 nanosheets upon annealing of a freeze-cast precursor
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The relationship between microstructure and photocatalytic behavior in lanthanum-modified 2D TiO2 nanosheets upon annealing of a freeze-cast precursor

机译：镧改性2D TiO2纳米片中微观结构与光催化行为的关系在退火时退火

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摘要

Titanium dioxide modified with 3 wt% La was prepared via a green freeze-casting method, and its photocatalytic activity was tested in terms of its ability to degrade 4-chlorophenol (4-CP) and remove total organic carbon (TOC). Under annealing conditions, the freeze-cast precursor was transformed into an La-modified anatase with a well-defined 2D TiO2 nanosheet morphology. Rietveld refinement of the X-ray diffraction patterns confirmed the substitutional nature of the La cation that induced local structural variations and involved subtle ion displacement in the TiO2 lattice due to the ionic size effect. Despite nearly identical tetragonal structures, replacement of Ti with La alters the photocatalytic activity through a reduction in band gap energies and an increase in charge carrier mobility. Material annealed at 650 degrees C exhibited the highest photocatalytic performance and achieved efficient TOC removal. Upon annealing at 800 degrees C, nanoscale lanthanum-enriched regions were generated due to the diffusive migration of La cations and phase transition from anatase to rutile. The La3+ cation, acting as a structural promoter, supported 2D TiO2 growth with well controlled crystallite size, surface area and porosity. La3+ could be regarded as a potential electronic promoter that can reduce the band gap of 2D TiO2 nanosheets and can provide a signature of the electron transfer and carrier charge separation. Both methods, kinetics of degradation of 4-CP and TOC, provided similar results, revealing that the photocatalytic activity under UV light irradiation increased in the order 950C < 500 degrees C < 800 degrees C < 650 degrees C < TiO2-P25.
机译：通过绿色冷冻铸造方法制备用3wt％La改性二氧化钛，并在其降解4-氯酚（4-CP）的能力方面测试其光催化活性并去除总有机碳（TOC）。在退火条件下，将冷冻浇注的前体转化到具有明确定义的2D TiO2纳米片形态的La-改性的锐钛矿中。 X射线衍射图案的RIETVELD细化证实了LA阳离子的替代性质，其诱导局部结构变化，并且由于离子尺寸效应而涉及TiO2晶格中的微妙离子位移。尽管几乎相同的四方结构，但通过减少带隙能量和电荷载流子迁移率的增加，替换TI的Ti改变光催化活性。在650摄氏度下退火的材料表现出最高的光催化性能并取得有效的TOC去除。在800℃下退火时，由于La阳离子的扩散迁移和从锐钛矿对金红石的相转变产生纳米级富含富含植物的富含植物的区域。 La3 +阳离子，作为结构启动子，负载2D TiO2生长，具有良好控制的微晶尺寸，表面积和孔隙率。 LA3 +可以被视为潜在的电子推动者，其可以减少2D TiO2纳米片的带隙，并且可以提供电子转移和载流子电荷分离的签名。两种方法，4-CP和TOC降解的动力学，提供了类似的结果，揭示了UV光照射下的光催化活性在950℃<500摄氏度<800℃C

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  • 来源
    《RSC Advances》 |2019年第40期|共16页
  • 作者

    Bakardjieva Snejana; Mares Jakub; Fajgar Radek; Zenou Victor Y.; Maleckova Michaela; Chatzisymeon Efthalia; Bibova Hana; Jirkovsky Jaromir;

  • 作者单位

    Czech Acad Sci Inst Inorgan Chem Husinec Rez 25068 Czech Republic;

    Czech Acad Sci Inst Inorgan Chem Husinec Rez 25068 Czech Republic;

    Czech Acad Sci Inst Chem Proc &

    Fundamentals Rozvojova 2-135 Prague 16502 Czech Republic;

    Nucl Res Ctr Negev Dept Mat Engn IL-84190 Beer Sheva Israel;

    Charles Univ Prague Fac Sci Hlavova 2030-8 Prague 12842 Czech Republic;

    Univ Edinburgh Inst Infrastruct &

    Environm Sch Engn Edinburgh EH9 3JL Midlothian Scotland;

    Czech Acad Sci J Heyrovsky Inst Phys Chem Dolejskova 2155-3 Prague 18223 Czech Republic;

    Czech Acad Sci J Heyrovsky Inst Phys Chem Dolejskova 2155-3 Prague 18223 Czech Republic;

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