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Abstract Rechargeable zinc‐air batteries (ZABs) are cost‐effective energy storage devices and display high‐energy density. To realize high round‐trip energy efficiency, it is critical to develop durable bi‐functional air electrodes, presenting high catalytic activity towards oxygen evolution/reduction reactions together. Herein, we report a nanocomposite based on ternary CoNiFe‐layered double hydroxides (LDH) and cobalt coordinated and N‐doped porous carbon (Co‐N‐C) network, obtained by the in‐situ growth of LDH over the surface of ZIF‐67‐derived 3D porous network. Co‐N‐C network contributes to the oxygen reduction reaction activity, while CoNiFe‐LDH imparts to the oxygen evolution reaction activity. The rich active sites and enhanced electronic and mass transport properties stemmed from their unique architecture, culminated into outstanding bi‐functional catalytic activity towards oxygen evolution/reduction in alkaline media. In ZABs, it displays a high peak power density of 228 mW cm−2 and a low voltage gap of 0.77 V over an ultra‐long lifespan of 950 h.

The bi-metallic zeolitic imidazole framework (ZIF) exhibits greater attention because of its attractive physicochemical properties. Herein, we report the non-enzymatic selective electrochemical detection of catechol (CC) using cobalt–nickel zeolitic imidazolate framework nanofibres (Ni-ZIF-67 NFs) fabricated by the electrospinning route. Owing to donor–acceptor and hydrogen bonding interactions between the metal ions and imidazole, forming tetrahedral coordination with an increased crystalline state further provides excellent mechanical stability. The porous nature of the Ni-ZIF-67 NFs sample gives good catalytic property; as a result, the response of nanofibre composite is linearly proportional to the concentration of CC in the range of 10 nM–1 mM with the detection limit of 4 nM. The prepared electrode shows good anti-interference ability and reproducibility. Finally, the fabricated electrode has been successfully utilized for the detection of targeted analytes for real-time sample analysis i.e. tea and coffee samples with significant results. Ni-ZIF-67 NFs have been successfully fabricated by electrospinning method and utilized for the detection of catechol. The bi-metallic ZIF material shows high stability, improved electrocatalytic behaviour having a detection range of 10 nM–1 mM with the detection limit of 4 nM should be useful further for diverse bio-sensing applications. [ABSTRACT FROM AUTHOR]

Size-controlled zeolite imidazole frameworks (ZIF-8) with similar pore structures and surface areas were synthesized by altering the types of precursors and used in generating CO 2 separation membranes. The use of zinc nitrate, zinc acetate and zinc chloride resulted in the formation of ZIF-8 materials that were 88, 240 and 533 nm in size (ZIF-8(S), ZIF-8(M) and ZIF-8(L)), respectively. ZIF-8 particles were homogeneously distributed within a polystyrene- block -poly(ethylene- ran -butylene)- block -polystyrene (SEBS) block copolymer matrix without significantly destroying the microphase-separated structure of SEBS to form mixed matrix membranes (MMMs), which was confirmed via small-angle X-ray scattering (SAXS), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The mutual interaction, mechanical strength and interfacial properties of the ZIF-8 filler particles and the SEBS matrix were characterized via Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and a universal tensile machine (UTM). The introduction of ZIF-8 led to considerable enhancement in gas permeability regardless of framework dimensions. In particular, MMMs loaded to 30 wt% with ZIF-8(M) exhibited approximately 2.5-fold enhancement with regard to CO 2 permeability, increasing from 170.6 to 454.6 Barrer (1 Barrer=1×10 −10 cm 3 (STP) cm cm −2 s −1 cmHg −1 ) at 35 °C without significant CO 2 /N 2 loss (from 12.4 to 12.0) and yielded CO 2 /CH 4 selectivity enhancement (from 4.3 to 5.4) compared to unmodified neat SEBS membranes. The high performance of MMMs based on ZIF-8(M) could be attributed to (1) the larger mass transfer resistance of SEBS/ZIF-8(S) and/or (2) the larger interfacial free volume between the polymer matrix and the inorganic filler particles of SEBS/ZIF-8(L). The efforts of this study provide insight with regard to the optimized size of ZIFs contained within microphase-separated block copolymers for the creation of highly efficient CO 2 separation membranes. [ABSTRACT FROM AUTHOR]

Solvothermal surface coating was employed to form hetero-nanostructures consisting of a polystyrene (PS) core and ZIF-8 shell. Upon selective removal of the PS core, hollow zeolite imidazole frameworks (H_ZIF-8) with a particle size of 700 nm and surface area of 1528.5 m 2 /g were generated. Synthesis was confirmed by Field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) analysis. Free-standing mixed matrix membranes (MMMs) were prepared by dispersing H_ZIF-8 filler in poly(vinyl chloride)- g -poly(oxyethylene methacrylate) (PVC- g -POEM) graft copolymer matrix. PVC- g -POEM worked well as a robust matrix to homogeneously disperse H_ZIF-8 with good interfacial contact due to the microphase-separated, amphiphilic properties of the hydrophobic glassy PVC main chains and the hydrophilic rubbery POEM side chains. Secondary bonding interactions were responsible for the good interfacial properties of the MMMs, as confirmed by Fourier-transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), FE-SEM, and XRD analysis. MMMs exhibited significantly enhanced CO 2 permeability relative to pure PVC- g -POEM membranes: an 8.9-fold increase in permeability from 70.0 to 623 Barrer (1 Barrer=1×10 −10 cm 3 (STP)·cm/cm 2 s cmHg) with only a small decrease in CO 2 /CH 4 selectivity from 13.7 to 11.2 at 35 °C, as measured via the time-lag method. [ABSTRACT FROM AUTHOR]