Su Senda, Li Xiaoman, Zhang Xu, Zhu Jingting, Liu Guodong, Tan Mengyao, Wang Yingying, Luo Min
State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, School of Chemistry and Chemical Engineering, Ningxia University, Yinchuan, Ningxia 750021, PR China.
State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering, School of Chemistry and Chemical Engineering, Ningxia University, Yinchuan, Ningxia 750021, PR China.
J Colloid Interface Sci. 2022 Sep;621:406-415. doi: 10.1016/j.jcis.2022.04.006. Epub 2022 Apr 8.
The incorporation of polyoxometalates (POMs) in metal-organic frameworks (MOFs) with host-guest structure have proven to be effective strategy to rational design of heterogeneous catalysis. In this study, the Keggin-type POM@MIL-101(Cr) composite catalysts (PMo, PW and SiW) are synthesized for nitrogen fixation reaction without sacrificial agents at room temperature in the first time. The SiW molecules are encapsulated in smaller cavities of MIL-101(Cr) by solvothermal method and in larger cavities by impregnation method, respectively. Solvothermal synthesized catalyst has a performance of 75.56 μmol·h·g and TOF value of 1.95 h, which are about 10 and 88 times than that of NaSiWO. The excellent performance is ascribed to the synergistic effect of SiW and MIL-101(Cr). The MIL-101(Cr) adsorbs a large amount of N and generates sufficiently photogenerated electrons under sunlight irradiation, and electrons quickly transfer to the SiW through hydrogen bonds. Moreover, the agglomeration effect of the homogeneous catalyst SiW is weakened due to encapsulation with more exposed active sites. This work provides a feasible route to design and synthesize nanocomposite materials with exceptional performance for photocatalytic nitrogen fixation.
将具有主客体结构的多金属氧酸盐（POMs）引入金属有机框架（MOFs）已被证明是合理设计多相催化的有效策略。在本研究中，首次合成了Keggin型POM@MIL-101(Cr)复合催化剂（PMo、PW和SiW），用于在室温下无牺牲剂的固氮反应。通过溶剂热法将SiW分子分别封装在MIL-101(Cr)的较小孔穴中，通过浸渍法封装在较大孔穴中。溶剂热合成的催化剂性能为75.56 μmol·h·g，TOF值为1.95 h，分别约为NaSiWO的10倍和88倍。优异的性能归因于SiW和MIL-101(Cr)的协同效应。MIL-101(Cr)在阳光照射下吸附大量N并产生足够的光生电子，电子通过氢键迅速转移到SiW上。此外，由于封装使得更多活性位点暴露，均相催化剂SiW的团聚效应减弱。这项工作为设计和合成具有优异光催化固氮性能的纳米复合材料提供了一条可行的途径。
