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 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 (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.

摘要高 ε Nd (t)-ε Hf (t)花岗岩是研究陆壳生长的有力证据.CNK=1.01~1.05)的高钾钙碱性 I 型花岗岩, 具有正的 ε Nd (t)值(3.28~3.55). 其中两个样 品的锆石 206 Pb/ 238 U 加权平均年龄分别为(229.9±2.0)和(229.3±2.3) Ma, 对应的 ε Hf (t)分别为 9.8~12.6 和 8.4~13.1. 229 Ma 代表了花岗岩结晶年龄, 结合对近年来国内外关于哀牢山深 变质杂岩的年代学资料的统计分析, 可以认为哀牢山深变质岩并非前人所认为的是扬子 地台前寒武纪结晶基底的一部分, 而是由中元古代、新元古代、海西早期、印支期和喜马 拉雅期等不同时代岩石组成的变质杂岩. 滑石板高 ε Hf (t)花岗岩的形成经历了两个阶段: 二叠纪受到流体、 熔体交代的地幔楔部分熔融底侵到下地壳形成岛弧下地壳; 晚三叠世碰 撞后阶段上涌的软流圈地幔热导致新生下地壳重熔. 滑石板高 ε Nd (t)-ε Hf (t)花岗岩记录了 哀牢山构造带经历过的一次地壳增生事件.

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