The stability of MOFs in aqueous solutions——research progress and prospects

Metal-organic frameworks(MOFs)are favored in the fields of adsorption,separation,catalysis,electrochemistry,and magnetism due to their advantages of large specific surface area,high porosity,controllable pore size adjustment,and dispersion of metal active sites.The application of MOFs involves multiple fields,which requires that MOFs have good water stability,as gaseous and liquid water inevitably exist in industrial processes.In this paper,the research status of the stability of MOFs in aqueous solutions was reviewed in recent years,including the design and synthesis,the influencing factors,and the applications of MOFs in water stability.

The introduction of cobalt element into nickel-organic framework for enhanced supercapacitive performance

Metal-organic frameworks(MOFs) as promising electrodes for supercapacitors are attracting increasing research interest. Herein, we report an effective strategy to improve the electrochemical performance of Ni-MOF for supercapacitor by introducing a secondary Co ion. The Co substitution of Ni in Ni-MOF can improve the intrinsic reactivity and stability. As a result, the bimetallic Co/Ni-MOF-1:15 with an optimal Co/Ni ratio delivers high specific capacitance(359 F/g at 0.5 A/g), good rate performance(81.5% retention at 5 A/g) and cycling stability(81% retention after 5000 cycles). These results demonstrate that the bimetallic synergistic strategy is an effective way to improve the pseudocapacitive performance of MOFs.

Rational design of Prussian blue analogue-derived manganese-iron oxides-based hybrids as high-performance Li-ion-battery anodes

The unique components and architecture of Prussian blue analogous(PBAs) offer great potential for the construction of various functional nanostructures. Herein, we reported the preparation of a series of Mn–Fe oxides-based hybrids using Mn–Fe PBA as a template and an organic carbon source by calcination.The study focuses on revealing the interaction between the microstructure and electrochemical performance of the products obtained at different calcination temperatures. Notably, the as-derived porous Fe–Fe0.33Mn0.67O/C nanocubes(i.e., M600) exhibited the best rate capability and cycle life compared with other samples(~890 m Ah/g at 0.1 A/g, 626.8 m Ah/g after 1000 cycles at 1.0 A/g with a 99% capacity retention). These can be attributed to the fact that the porous structure provides shorter Li+diffusion path and promotes the penetration of electrolyte. Besides, the N-doped C formed by the carbonization of organic ligands can buffer the volume change and prevent the aggregation of Fe_(0.33)Mn_(0.67)O nanoparticles during the discharge/charge cycles. Moreover, the presence of metallic Fe enhances the conductivity and the electrochemical activity, which accelerates the electrochemical reactions. Therefore, reasonable design of microstructure and compositions of functional nanocomposites is the key to obtain ideal electrochemical properties.