Environmentally friendly synthesis of flexible MOFs M(NA)2 (M = Zn, Co, Cu, Cd) with large and regenerable ammonia capacity
Environmentally friendly synthesis of flexible MOFs M(NA)2 (M = Zn, Co, Cu, Cd) with large and regenerable ammonia capacity
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环保合成具有大容量可再生氨容量的柔性 MOF M(NA)(2)（M = Zn、Co、Cu、Cd）
DOI：
10.1039/c8ta02845a
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发表时间：
2018-06-07
影响因子：
11.9
通讯作者：
Mu, Bin
中科院分区：
文献类型：
--
作者：
Chen, Yang;Shan, Bohan;Mu, Bin
采用nh3辅助合成和溶剂蒸发转化两种环保高效的方法合成了M(NA)(2) （M = Zn, Co, Cu, Cd; NA = nicotinate）柔性MOFs。二维M(NA)(2) （M = Zn, Co）和三维M(NA)(2) （M = Cu, Cd）材料表现出特殊的结构转变。这些框架可由M(NA)(2)(H2O)(4) （M = Zn, Co, Cu, Cd）脱水得到，为零维超分子结构。有趣的是，M(NA)(2) （M = Zn, Co, Cd）在液态水吸附后的结构转变是可逆的。由于这些mof的柔性结构，它们表现出异常的NH3吸附性能。二维Zn(NA)(2)对NH3的吸附表现出开门行为。在第一个循环中，它的层在0.22巴的压力下打开，在1巴的压力下产生10.2毫摩尔克（-1）的两步NH3吸收。闸门开启压力随周期向较低值移动。Co(NA)(2)具有17.5 mmol g（-1）的巨大NH3吸收量，在报道的数值中排名第一。NH3在Cu(NA)(2)和Cd(NA)(2)上的吸附，经过3个循环后，吸附速率增加，吸附平衡更快。它们在1bar时的最大容量分别为13.4和6mmol g（-1）。更重要的是，所有mof在150℃的真空加热条件下70 min都可以再生，并且都保持了容量。M(NA)(2) （M = Zn, Co, Cu）具有合成环境友好、吸附容量大、可再生等优点，是很有前途的NH3吸附材料。
Two environmentally friendly and efficient synthesis methods, NH3-assisted synthesis and solvent-evaporated conversion, have been developed for the synthesis of a series of M(NA)(2) (M = Zn, Co, Cu, Cd; NA = nicotinate) flexible MOFs. The two-dimensional M(NA)(2) (M = Zn, Co) and three-dimensional M(NA)(2) (M = Cu, Cd) materials exhibit peculiar structural transformation. These frameworks can be obtained from dehydration of M(NA)(2)(H2O)(4) (M = Zn, Co, Cu, Cd) which are zero-dimensional supramolecular structures. Interestingly, the structural transformation of M(NA)(2) (M = Zn, Co, Cd) is reversible after liquid water adsorption. Due to the flexible structure of these MOFs, they exhibit abnormal NH3 adsorption properties. The two-dimensional Zn(NA)(2) shows a gate-opening behavior for NH3 adsorption. Its layers opened at a pressure of 0.22 bar in the first cycle, resulting in a two-step NH3 uptake with a capacity of 10.2 mmol g(-1) at 1 bar. The gate-opening pressure shifted to a lower value with cycles. Co(NA)(2) has a huge NH3 uptake of 17.5 mmol g(-1), which is top-ranking among the reported values. For the NH3 adsorption over Cu(NA)(2) and Cd(NA)(2), the adsorption rates increase and adsorption equilibrium is achieved faster after three cycles. Their maximum capacity at 1 bar is 13.4 and 6 mmol g(-1), respectively. More importantly, all MOFs can be regenerated under vacuum and heating conditions of 150 degrees C for 70 min, and they all retained the capacity. The advantages of environmentally friendly synthesis, large adsorption capacity, and regenerable properties indicate that M(NA)(2) (M = Zn, Co, Cu) are promising candidates for NH3 adsorption.