Search

MnCo2O4 is derived from a Co/Mn bimetallic metal‐organic framework (MOF). Then Ni‐MOF is directly grown on the surface of the obtained MnCo2O4 to form a nano‐flower structure with small balls. A large surface area, abundant active sites of MnCo2O4 and porosity of Ni‐MOF allow the prepared MnCo2O4/Ni‐MOF composite material to deliver an excellent electrochemical performance. At the same time, an appropriate thermal treatment temperature of the MnCo2O4 precursor is also very important for controlling the morphology of the obtained MnCo2O4 and electrochemical performances of the resulted composite material including electric conductivity, specific capacitance and rate performance. The prepared MnCo2O4‐600/Ni‐MOF shows an ultrahigh rate performance (when the current density increases from 1 to 10 A g−1, the capacitance retention rate is as high as 93.41 %) and good cycle stability (the assembled asymmetric supercapacitor advice delivers a capacitance retention rate of 94.74 % after 20 000 charge and discharge cycles) as well as a relatively high specific capacitance. These excellent electrochemical properties indicate that MnCo2O4/Ni‐MOF has a good application prospect in the market. [ABSTRACT FROM AUTHOR]

MnCo 2 O 4 is derived from a Co/Mn bimetallic metal-organic framework (MOF). Then Ni-MOF is directly grown on the surface of the obtained MnCo 2 O 4 to form a nano-flower structure with small balls. A large surface area, abundant active sites of MnCo 2 O 4 and porosity of Ni-MOF allow the prepared MnCo 2 O 4 /Ni-MOF composite material to deliver an excellent electrochemical performance. At the same time, an appropriate thermal treatment temperature of the MnCo 2 O 4 precursor is also very important for controlling the morphology of the obtained MnCo 2 O 4 and electrochemical performances of the resulted composite material including electric conductivity, specific capacitance and rate performance. The prepared MnCo 2 O 4 -600/Ni-MOF shows an ultrahigh rate performance (when the current density increases from 1 to 10 A g -1 , the capacitance retention rate is as high as 93.41 %) and good cycle stability (the assembled asymmetric supercapacitor advice delivers a capacitance retention rate of 94.74 % after 20 000 charge and discharge cycles) as well as a relatively high specific capacitance. These excellent electrochemical properties indicate that MnCo 2 O 4 /Ni-MOF has a good application prospect in the market., (© 2021 Wiley-VCH GmbH.)

A novel dual-emission ratiometric fluorescent sensor (CDs@Eu-MOFs) has been synthesized successfully by encapsulating water-soluble fluorescent CDs into the chambers of Eu-MOFs via a simple one-pot hydrothermal method, which can be used for the detection of Hg 2+ in environmental water samples. The synthesized CDs@Eu-MOFs inherited simultaneously the excellent luminescence performance of Eu 3+ and CDs and exhibited good structural and fluorescence stability in aqueous solution. The presence of Hg 2+ changed the fluorescence intensity of CDs, while the fluorescence intensity of Eu-MOFs hardly changed, which could be used as the recognition part and the reference part respectively to construct the ratiometric fluorescence sensor. The obtained Hg 2+ fluorescent probe showed a wide linear range (0-300 μM) and a low detection limit (0.12 nM). The developed method can be used as a multi-functional fluorescent sensor with high sensitivity and good selectivity for the determination of Hg 2+ in actual water samples., Competing Interests: Declaration of competing interest About this paper, no any interest conflict exists., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A novel composite (CDs@ZIF-8) based on carbon dots (CDs) and zeolitic imidazolate framework (ZIF-8) was successfully synthesized by encapsulating CDs into the pores of ZIF-8 through a simple one-pot solvothermal method. The as-synthesized CDs@ZIF-8 inherited simultaneously the strong adsorption capacity of ZIF-8 and the excellent optical properties of CDs. The composite exhibited excellent dispersibility and high structural and fluorescence stability in aqueous solution, which could be employed as an excellent turn-off mode fluorescent probe to detect Cu 2+ . The large specific surface area and strong adsorption properties of ZIF-8 enabled the resultant composite to effectively enrich Cu 2+ for further improving the analytical sensitivity. The possible fluorescence quenching mechanism has also been discussed in detail and it was found that the effective fluorescence quenching of Cu 2+ to CDs@ZIF-8 could be attributed to the strong ability of Cu 2+ to combine with the carboxyl group or amino group on the CD surface and the strong adsorption capacity of ZIF-8; their synergistic effect resulted in effective fluorescence quenching.