新型金属有机骨架(MOFs)材料是一类比较新颖的可用作光催化剂的潜在材料.它是由金属离子或金属簇单元与有机配体通过配位作用自组装形成的一类具有周期性多维网络结构的多孔晶态材料.MOFs结构具有高度的有序性、一定程度上的可设计性和可剪裁性,其高度发达的孔结构使得它具有超高的比表面积.MOFs结构中的金属簇被认为可以扮演半导体量子点的角色,同时其有机配体基于"天线效应",在光激发条件下用来活化这些金属簇,从而使得MOFs成为可能的光催化剂.ZIF-9由角共享四面体CoN4单元组成,其中Co2+阳离子和苯并咪唑阴离子之间的配位键是N供体配体,因而具有良好的热稳定性和较高的碳氮含量.本文在一定浓度的甲醇溶液中通过光沉积法将CuO附着于ZIF-9表面上,用于光催化活性测试,并与g-C3N4/CuO催化剂进行了比较.结果表明,ZIF-9/CuO催化剂活性是g-C3N4/CuO催化剂的19.4倍.这是由于比表面积的不同,导致所吸附的染料与暴露的活性位点的不同.通过SEM,TEM,EDS,XRD,XPS,UV-Vis和稳态瞬态荧光等手段系统研究了催化剂反应动力学行为及内在机理.稳态荧光结果表明,染料的荧光发射峰和ZIF-9的吸收峰之间没有明显的重叠,染料的激发电子可以在该反应系统中从染料分子转移到ZIF-9上.除了一部分电子直接传输到达ZIF-9表面,更多的电子将最终通过CuO到达催化剂表面,最后与反应溶液中的H+结合生成H2,EY-ZIF-9/CuO(40%)的荧光衰减可以用双指数荧光衰减动力学即动态淬火机理.表明CuO的引入可以增强染料EY分子的聚集,从而增加该催化剂活性.%An efficient CuO-modified zeolitic imidazolate framework-9 (ZIF-9) photocatalyst is successfully prepared at room temperature under mild conditions. It is observed that the ZIF-9/CuO photocata-lyst is effective for H2 generation under visible light with sacrificial agent conditions. When the CuO is introduced, the photocatalytic properties of ZIF-9 are greatly improved and when the content of CuO is 40%, the photocatalytic activity reaches a maximum of 78.74 μmol after 5 h. This results from the 200–300 nm cube structure of ZIF-9 being able to adsorb more dye molecules and the CuO, which connects with ZIF-9, greatly improving the electronic transmission efficiency. Moreover, the interaction between the dye molecule Eosin Y (EY) and the catalyst is also studied by transient flu-orescence spectroscopy. A series of characterizations, such as SEM, TEM, XPS, XRD, UV-vis, FTIR, transient fluorescence and photocurrent, are conducted, and the results are in good agreement with the experimental result. In addition, the possible reaction mechanism over EY-sensitized ZIF-9/CuO under visible light irradiation is proposed.
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