物理化学学报 >> 2021, Vol. 37 >> Issue (8): 2009045.doi: 10.3866/PKU.WHXB202009045

所属专题: 二维光催化材料

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核壳结构NH2-UiO-66@TiO2的制备及其可见光下的甲苯降解性能研究

周易1, 欧阳威龙1, 王岳军2, 王海强1,*(), 吴忠标1   

  1. 1 浙江大学环境技术研究所,杭州 310058
    2 浙江天蓝环保技术股份有限公司,杭州 311202
  • 收稿日期:2020-09-14 录用日期:2020-11-16 发布日期:2020-11-23
  • 通讯作者: 王海强 E-mail:haiqiangwang@zju.edu.cn
  • 基金资助:
    国家自然基金面上项目(51878598);国家自然基金面上项目(51978603)

Core-Shell Structured NH2-UiO-66@TiO2 Photocatalyst for the Degradation of Toluene under Visible Light Irradiation

Yi Zhou1, Weilong Ouyang1, Yuejun Wang2, Haiqiang Wang1,*(), Zhongbiao Wu1   

  1. 1 Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China
    2 Zhejiang Tianlan Environmental Protection Technology Co., Ltd., Hangzhou 311202, China
  • Received:2020-09-14 Accepted:2020-11-16 Published:2020-11-23
  • Contact: Haiqiang Wang E-mail:haiqiangwang@zju.edu.cn
  • About author:Haiqiang Wang, Email: haiqiangwang@zju.edu.cn; Tel.: +86-571-87953088
  • Supported by:
    the National Natural Science Foundation of China(51878598);the National Natural Science Foundation of China(51978603)

摘要:

金属有机骨架(MOFs)在可见光光催化方面具有重要的应用价值,但其通常受制于稳定性不佳和光生电荷复合率高的缺点。与无机半导体复合是提高MOFs活性的有效途径之一。本文以水热法制备NH2-UiO-66,在其表面包裹非晶态的TiO2层,制备出一种核壳结构的MOF@TiO2催化剂(NH2-UiO-66@TiO2),并考察了其在可见光下对甲苯的降解性能。实验结果表明其性能优于NH2-UiO-66及直接固混法制备的样品。在可见光照射下,其3 h内的甲苯降解效率可达76.7%,是NH2-UiO-66的1.48倍。四次重复使用实验证明其光催化性能稳定,仅有轻微失活,且经乙醇洗涤后可恢复活性。采用X射线衍射(XRD)等表征手段考察了其物理化学特性,并根据表征结果和光催化活性数据探究了NH2-UiO-66@TiO2光催化性能的提升机理。结果表明,NH2-UiO-66@TiO2一方面得益于NH2-UiO-66的可见光激发特性和超大的比表面积(914.9 m2·g-1),可以拓宽光吸收范围,有效吸附和活化污染物; 另一方面在于包覆的TiO2与NH2-UiO-66形成了异质结,可以有效拓宽光吸收范围,提高光生电子空穴对的利用率。电子和空穴对一经形成即可通过界面转移。空穴会在NH2-UiO-66的HOMO与H2O结合形成羟基自由基(·OH)。同时,电子在TiO2的导电与氧分子结合生成超氧自由基(·O2-)。两种自由基数量的增加致使甲苯有效氧化。本研究可为核壳结构的MOF@光催化剂设计和室内空气的光催化净化提供参考。

关键词: 核壳结构, 可见光, 光催化剂, NH2-UiO-66, TiO2

Abstract:

Metal-organic frameworks (MOFs) are of significant interest for photocatalysis using visible light, but they are typically limited by the instability and high recombination ratio of photoexcited pairs. Integrating MOFs into an inorganic semiconductor is one of the most widespread methods to promote their activity. In this study, a core-shell structured MOF@TiO2 (NH2-UiO-66@TiO2) was synthesized as an efficient photocatalyst for the degradation of toluene. Pristine NH2-UiO-66 was synthesized by a hydrothermal method as the core, which was then coated with an amorphous TiO2 shell. Compared with pristine NH2-UiO-66 and other samples prepared by the direct mixing of NH2-UiO-66 and TiO2, NH2-UiO-66@TiO2 exhibited a higher degradation rate of toluene. Using NH2-UiO-66@TiO2 as a catalyst, the degradation efficiency of toluene reached 76.7% within 3 h, which is 1.48 times higher than that of NH2-UiO-66. The degradation performance was also stable in four repeated reuse experiments, and the slight deactivation was reactivated after washing with ethanol. A series of characterization methods were used to determine the physicochemical properties of NH2-UiO-66@TiO2, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Using the measured physicochemical properties, the photocatalytic mechanism of NH2-UiO-66@TiO2 was explored. NH2-UiO-66 is an ideal photocatalyst, with visible-light response and a huge specific surface area (914.9 m2·g-1), which is favorable for the utilization of sunlight as well as the absorption of pollutants in indoor air. In addition, a new interface formed between the two components (NH2-UiO-66 and TiO2), which efficiently broaden the light absorption area and enhanced the utilization of photogenerated species. The photogenerated holes and electrons could transfer through the interlayer as soon as they were formed. It is speculated that holes would transfer to the HOMO of NH2-UiO-66, and then combine with H2O molecules to form hydroxyl radicals (·OH). At the same time, more electrons tended to combine with oxygen molecules in the conduction band of TiO2 rather than recombine with holes. Consequently, the recombination rate of electrons and holes decreased, while the quantity of oxygen radicals and hydroxyl radicals increased. Toluene was efficiently oxidized by these two types of radicals. Owing to the outstanding properties mentioned above, the strategy of constructing NH2-UiO-66@TiO2 is considered to be an effective approach. This work may provide new insights into the design of core-shell structured MOF@photocatalysts for the photocatalytic degradation of indoor air pollutants.

Key words: Core-shell structure, Visible light responsed, Photocatalyst, NH2-UiO-66, TiO2

MSC2000: 

  • O643