核壳结构NH_(2)-UiO-66@TiO_(2)的制备及其可见光下的甲苯降解性能研究  

Core-Shell Structured NH_(2)-UiO-66@TiO_(2) Photocatalyst for the Degradation of Toluene under Visible Light Irradiation

作　　者：周易[1] 欧阳威龙 王岳军 王海强[1] 吴忠标[1] Yi Zhou;Weilong Ouyang;Yuejun Wang;Haiqiang Wang;Zhongbiao Wu(Department of Environmental Engineering,Zhejiang University,Hangzhou 310058,China;Zhejiang Tianlan Environmental Protection Technology Co.,Ltd.,Hangzhou 311202,China)

机构地区：[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

出　　处：《物理化学学报》2021年第8期101-108,共8页Acta Physico-Chimica Sinica

基　　金：国家自然基金面上项目(51878598,51978603)资助。

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NH_(2)-UiO-66,在其表面包裹非晶态的TiO_(2)层,制备出一种核壳结构的MOF@TiO_(2)催化剂(NH_(2)-UiO-66@TiO_(2)),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NH_(2)-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NH_(2)-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NH_(2)-UiO-66@TiO_(2)光催化性能的提升机理。结果表明,NH_(2)-UiO-66@TiO_(2)一方面得益于NH_(2)-UiO-66的可见光激发特性和超大的比表面积(914.9 m^(2)·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TiO_(2)与NH_(2)-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NH_(2)-UiO-66的HOMO与H_(2)O结合形成羟基自由基(·OH)。同时,电子在TiO_(2)的导电与氧分子结合生成超氧自由基(·O_(2)^(−))。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。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@TiO_(2)(NH_(2)-UiO-66@TiO_(2))was synthesized as an efficient photocatalyst for the degradation of toluene.Pristine NH_(2)-UiO-66 was synthesized by a hydrothermal method as the core,which was then coated with an amorphous TiO_(2) shell.Compared with pristine NH_(2)-UiO-66 and other samples prepared by the direct mixing of NH_(2)-UiO-66 and TiO_(2),NH_(2)-UiO-66@TiO_(2) exhibited a higher degradation rate of toluene.Using NH_(2)-UiO-66@TiO_(2) as a catalyst,the degradation efficiency of toluene reached 76.7%within 3 h,which is 1.48 times higher than that of NH_(2)-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 NH_(2)-UiO-66@TiO_(2),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 NH_(2)-UiO-66@TiO_(2) was explored.NH_(2)-UiO-66 is an ideal photocatalyst,with visible-light response and a huge specific surface area(914.9 m^(2)·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(NH_(2)-UiO-66 and TiO_(2)),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 NH_

关 键 词：核壳结构 可见光 光催化剂 NH_(2)-UiO-66 TiO_(2) 

分 类 号：O643[理学—物理化学]