As a new type of porous crystalline composite material, MOF-COF has shown great advantages in metal separation. Herein, a CoMOF-COF was designed for highly selective separation of trace Pb 2+ ions. The designed CoMOF-COF has a high density of nitrogen-oxygen functional groups and can selectively separate metal ions . There is a strong affinity between the designed CoMOF-COF material and metal Pb 2+ ions, which can be attributed to the ordered heterogeneous porous structure and large amounts of nitrogen-and oxygen-containing functional groups. The composite showed high adsorption selectivity for Pb 2+ ions and had adsorption capacity of 33 mg g −1 , with high chemical stability. Based on this solid phase extraction material, a high sensitivity detection method for Pb 2+ ions was established, which has the detection limit of 37.3 ng L −1 , precision of 1.9 %. Linear detection range is 0.2–10 ng mL −1 , and the detection of Pb 2+ ions in actual water samples was realized. Through this study, it is proved that the strong affinity between the designed CoMOF-COF materials and metal Pb 2+ ions can be attributed to the soft and hard acid-base theory, which reveals the structure-activity relationship between the porous heterostructure of such materials and metal separation, providing a highly selective separation material for the separation of other environmental pollutants .
Wenqian Li,Dongsheng Zhao,Wencui Li,Rongmei Wen,Xin Liu,Liying Liu,Ting Li,Liming Fan
By taking advantages of confinement effect can effectively prevent dye aggregation caused luminescent quenching, Eosin Y (EY) was encapsulated into a chemorobust porous CoMOF as secondary fluorescent signal to construct the dual-emitting sensor of EY@CoMOF. And the photo-induced electron transfer from CoMOF to EY molecules induced EY@CoMOF presenting a weak blue emission at 421 nm and a strong yellow emission at 565 nm. Those dual-emission features also endow EY@CoMOF itself great potentials as a self-calibrating ratiometric sensor in visually and efficiently monitoring hippuric acid (HA) in urine, with fast response, high sensitivity and selectivity, excellent recyclable, and low LOD (0.24 μg/mL). Furthermore, based on a tandem combinational logic gate, an intelligent detection system was designed to improve the practicability and convenience of HA detection in urine. To the best of our knowledge, this is the first example of dye@MOF based sensor for HA detection. And this work provides a promising approach for developing dye@MOF based sensors to intelligent detect bioactive molecules.
Silicon (Si) is considered as the most promising candidate for anode materials in the next-generation lithium-ion batteries (LIBs). Regulating the morphology and structure of Si plays a vital role in alleviating the volume expansion and improving electronic conductivity. Herein, an ingenious core-shell structure (denoted as CoMOF-D@Si@C) is synthesized by depositing Si uniformly on the pyrolytic metal-organic frameworks (MOFs) via chemical vapor deposition (CVD) method and then encapsulated with a carbon shell. The CoMOF-D@Si@C exhibits excellent rate capability and cycle performance, which delivers a high-rate capability of ~957 mAh g −1 at 10 A g −1 and a reversible capacity of 1493 mAh g −1 after 400 cycles. In particular, the capacity is maintained at 648 mAh g −1 after 1200 cycles at a high current density of 4 A g −1 with a rapid increase of the Coulombic efficiency (CE) to 99.8% after only 5 cycles and the average CE (99.7%) in the whole cycling at 4 A g −1 . Profiting from the outer carbon shell, uniform Si deposition and inner porous pyrolytic MOF structure, this architecture can maintain structural stability and provide constructive conductivity during cycling processes. The superior electrochemical performance of the CoMOF-D@Si@C composite makes it a promising anode material for LIBs.
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