Xu Caiyun, Pan Yating, Wan Gang, Liu Hang, Wang Liang, Zhou Hua, Yu Shu-Hong, Jiang Hai-Long
Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Soft Matter Chemistry, Collaborative Innovation Center of Suzhou Nano Science and Technology, Department of Chemistry , University of Science and Technology of China , Hefei , Anhui 230026 , P.R. China.
SLAC National Accelerator Laboratory , 2575 Sand Hill Rd , Menlo Park , California 94025 , United States.
J Am Chem Soc. 2019 Dec 4;141(48):19110-19117. doi: 10.1021/jacs.9b09954. Epub 2019 Nov 22.
The tailorable structure and electronic structure of metal-organic frameworks (MOFs) greatly facilitate their modulated light harvesting, redox power, and consequently photocatalysis. Herein, a representative MOF, UiO-66, was furnished by installing Fe onto the Zr-oxo clusters, to give Fe-UiO-66, which features extended visible light harvesting, based on metal-to-cluster charge transfer (MCCT). The Fe-UiO-66 with unique electronic structure and strong oxidizing power exhibits visible light-driven water oxidation, which is impossible for pristine UiO-66. More strikingly, under visible irradiation, the generated holes over Fe-UiO-66 are able to exclusively convert HO to hydroxide radicals, initiating and driving the activation of stubborn C-H bond, such as toluene oxidation. The electrons reduce O to O radicals that further promote the oxidation reaction. The related catalytic mechanism and the structure-activity relationship have been investigated in detail. As far as we know, this is not only an unprecedented report on activating "inert" MOFs for photocatalytic C-H activation but also the first work on extended light harvesting and enhanced photocatalysis for MOFs by introducing an MCCT process.
金属有机框架材料（MOFs）可剪裁的结构和电子结构极大地促进了其对光捕获、氧化还原能力的调控，进而推动了光催化作用。在此，通过在锆氧簇上引入铁原子，制备了一种具有代表性的MOF——UiO-66，得到了Fe-UiO-66，其基于金属到簇的电荷转移（MCCT）实现了扩展的可见光捕获。具有独特电子结构和强氧化能力的Fe-UiO-66表现出可见光驱动的水氧化反应，而原始的UiO-66则无法实现这一反应。更引人注目的是，在可见光照射下，Fe-UiO-66上产生的空穴能够将HO专门转化为羟基自由基，引发并驱动顽固C-H键的活化，如甲苯氧化反应。电子将O还原为O自由基，进一步促进氧化反应。详细研究了相关的催化机理和结构-活性关系。据我们所知，这不仅是关于活化“惰性”MOFs用于光催化C-H活化的前所未有的报道，也是通过引入MCCT过程实现MOFs扩展光捕获和增强光催化的首例工作。
