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Metal–organic framework–derived carbon nanostructures have generated significant interest in electrochemical capacitors and oxygen/hydrogen catalysis reactions. However, they appear to show considerably varied structural properties, and thus exhibit complex electrochemical–activity relationships. Herein, a series of carbon polyhedrons of different sizes, between 50 nm and µm, are synthesized from zeolitic imidazolate frameworks, ZIF‐8 (ZIF‐derived carbon polyhedrons, ZDCPs) and their activity is studied for capacitance and the oxygen reduction reaction (ORR). Interestingly, a well‐correlated performance relationship with respect to the particle size of ZDCPs is evidenced. Here, the identical structural features, such as specific surface area (SSA), microporosity, and its distribution, nitrogen doping, and graphitization are all strictly maintained in the ZDCPs, thus allowing identification of the effect of particle size on electrochemical performance. Supercapacitors show a capacity enhancement of 50 F g−1 when the ZDCPs size is reduced from micrometers to ≤200 nm. The carbonization further shows a considerable effect on rate capacitance—ZDCPs of increased particle size lead to drastically reduced charge transportability and thus inhibit their performance for both the charge storage and the ORR. Guidelines for the capacitance variation with respect to the particle size and SSA in such carbon nanostructures from literature are presented. Carbon‐based nanostructures are indispensable for supercapacitors, fuel cells, and batteries. Advancement in this area requires critical understanding of the form and function. Here, a well‐correlated relationship is demonstrated for the performance of supercapacitors and the oxygen reduction reaction with respect to particle size of metal–rganic frameworks–derived carbon. Surface area, pore‐size distribution, nitrogen doping, and graphitization are all maintained identical.

The catalytic activity of both ZIF-8 and Zr/ZIF-8 has been investigated for the synthesis of chloromethyl ethylene carbonate (CMEC) using carbon dioxide (CO2) and epichlorohydrin (ECH) under solvent-free conditions. Published results from literature have highlighted the weak thermal, chemical, and mechanical stability of ZIF-8 catalyst, which has limited its large-scale industrial applications. The synthesis of novel Zr/ZIF-8 catalyst for cycloaddition reaction of ECH and CO2 to produce CMEC has provided a remarkable reinforcement to this weak functionality, which is a significant contribution to knowledge in the field of green and sustainable engineering. The enhancement in the catalytic activity of Zr in Zr/ZIF-8 can be attributed to the acidity/basicity characteristics of the catalyst. The comparison of the catalytic performance of the two catalysts has been drawn based on the effect of different reaction conditions such as temperature, CO2 pressure, catalyst loading, reaction time, stirring speed, and catalyst reusability studies. Zr/ZIF-8 has been assessed as a suitable heterogeneous catalyst outperforming the catalytic activities of ZIF-8 catalyst with respect to conversion of ECH, selectivity and yield of CMEC. At optimum conditions, the experimental results for direct synthesis of CMEC agree well with similar literature on Zr/MOF catalytic performance, where the conversion of ECH, selectivity and the yield of CMEC are 93%, 86%, and 76%, respectively.

Metal‐organic framework (MOF)‐derived architectures are regarded as an effective electromagnetic wave (EMW)‐absorbing materials owing to their adjustable compositions and microstructures. The combination of MOFs with carbon nanofibers (CNFs) is a practical method to increase the EMW absorption ability. In this work, cobalt‐based zeolitic imidazolate framework‐67 (ZIF‐67) serves as a self‐sacrificing precursor to fabricate Co‐carbon nanofiber (Co‐CNF) composites via an in situ electrospinning strategy. Comparative studies on ex situ and in situ, electrospinning strategies for EMW absorption are conducted. A unique structural evolution mechanism from ZIF‐67 to Co nanoparticles is explored. Numerous small Co nanoparticles are evenly distributed on the surface of in situ synthesized Co‐CNF (in‐Co‐CNF) resulting from the collapse of the ZIF‐67 framework, whereas the ZIF‐67 framework remains on the surface of ex situ synthesized Co‐CNF (ex‐Co‐CNF), encapsulating large Co nanoparticles. A lower reflection loss (RL) of −48.6 dB at 6.8 GHz with 3.5 mm is achieved for the in‐Co‐CNF because of the improved conduction, polarization, and magnetic losses, whereas the ex‐Co‐CNF only exhibits an RL of −18.3 dB at 9.3 GHz with the same thickness. A radar cross‐section (RCS) simulation and a Tesla wireless transmission experiment are conducted to validate the EMW absorption of Co‐CNF composites in real applications. With 5G and AI robotics rising, electromagnetic radiation risks signal security and health. This work investigates the electromagnetic wave absorption of Co/CNF composites via in situ and ex situ electrospinning strategies. The in situ synthesized sample exhibits superior absorption properties due to enhanced structural uniformity, improved Co distribution, and optimized impedance matching, achieving a minimum RL of −48.6 dB at 6.9 GHz.

In this paper, a statistical analysis with response surface methodology (RSM) has been used to investigate and optimize process variables for the greener synthesis of chloromethyl ethylene carbonate (CMEC) by carbon dioxide (CO2) and epichlorohydrin (ECH). Using the design expert software, a quadratic model was developed to study the interactions effect between four independent variables and the reaction responses. The adequacy of the model was validated by correlation between the experimental and predicted values of the responses using an analysis of variance (ANOVA) method. The proposed Box-Behnken design (BBD) method suggested 29 runs for data acquisition and modelling the response surface. The optimum reaction conditions of 353 K, 11 bar CO2 pressure, and 12 h using fresh 12% (w/w) Zr/ZIF-8 catalyst loading produced 93% conversion of ECH and 68% yield of CMEC. It was concluded that the predicted and experimental values are in excellent agreement with ±1.55% and ±1.54% relative errors from experimental results for both the conversion of ECH and CMEC yield, respectively. Therefore, statistical modelling using RSM can be used as a reliable prediction technique for system optimization for greener synthesis of chloromethyl ethylene carbonate via CO2 utilization.

In article number 1901517, Srinivas Gadipelli and co‐workers present direct evidence of carbon nanoparticle size–dependent electrochemical activity for the supercapacitors and oxygen reduction reaction. For this, the carbon polyhedrons with size between few tens of nanometers to microns are designed from a zeolitic imidazolate framework (ZIF‐8), and all other parameters, such as surface area, microporosity, pore‐size distribution, nitrogen‐doping and graphitization are maintained identically.

Single metal-organic frameworks (MOFs), constructed from the coordination between one-fold metal ions and organic linkers, show limited functionalities when used as precursors for nanoporous carbon materials. Herein, we propose to merge the advantages of zinc and cobalt metals ions into one single MOF crystal ( i.e. , bimetallic MOFs). The organic linkers that coordinate with cobalt ions tend to yield graphitic carbons after carbonization, unlike those bridging with zinc ions, due to the controlled catalytic graphitization by the cobalt nanoparticles. In this work, we demonstrate a feasible method to achieve nanoporous carbon materials with tailored properties, including specific surface area, pore size distribution, degree of graphitization and content of heteroatoms. The bimetallic-MOF-derived nanoporous carbon are systematically characterized, highlighting the importance of precisely controlling the properties of the carbon materials. This can be done by finely tuning the components in the bimetallic MOF precursors and thus designing optimal carbon materials for specific applications.

In order to reduce the fire risk of rigid polyurethane foams (RPUF), three kinds of zeolitic imidazolate frameworks (ZIFs) were prepared. The results of Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM and X-ray diffraction (XRD) showed that ZIFs were successfully prepared. The combustion test results showed that the heat and smoke production of the composite containing ZIFs was obviously reduced. In particular, the peak heat release rate (PHRR) of ZIF-8/RPUF decreased from 740.85 kW/m2 (Ref. RPUF) to 489.56 kW/m2, while the PHRR of ZIF-7/RPUF and ZIF-11/RPUF is 598.39 and 583.36 kW/m2, respectively. The addition of ZIFs improved the thermostability of the composite. The T50% of ZIF-8/RPUF, ZIF-7/RPUF and ZIF-11/RPUF increased to 364, 382 and 380 °C, respectively. The maximum light absorption of ZIF-7/RPUF and ZIF-11/RPUF was about 88%, which is higher than that of ZIF-8/RPUF (75%). The results of Raman spectroscopy showed that the ID/IG value of Ref. RPUF is 2.96, while the ID/IG value of ZIFs/RPUF reduces to less than 2.80. The main mechanism of ZIFs for reducing the fire risk of RPUF was the catalysis and incarbonization of ZIFs during combustion based on the results of thermogravimetric analysis and Raman spectroscopy of char residue.

This review (with 145 refs.) summarizes the progress that has been made in the use of zeolitic imidazolate frameworks in chemical sensing and biosensing. Zeolitic imidazolate frameworks (ZIFs) are a type of porous material with zeolite topological structure that combine the advantages of zeolite and traditional metal–organic frameworks. Owing to the structural flexibility of ZIFs, their pore sizes and surface functionalization can be reasonably designed. Following an introduction into the field of metal–organic frameworks and the zeolitic imidazolate framework (ZIF) subclass, a first large section covers the various kinds and properties of ZIFs. The next large section covers electrochemical sensors and assays (with subsections on methods for gases, electrochemiluminescence, electrochemical biomolecules). This is followed by main sections on ZIF-based colorimetric and luminescent sensors, with subsections on sensors for metal ions and anions, for gases, and for organic biomolecules. The last section covers SERS-based assays. Several tables are presented that give an overview on the wealth of methods and materials. A concluding section summarizes the current status, addresses current challenges, and gives an outlook on potential future trends. Graphical abstract In recent years, ZIFs and their composites have been widely used as probes in chemical sensing, and these probes have shown great advantages over other materials. This review describes the current progress on ZIFs toward electrochemical, luminescence, colorimetric, and SERS-based sensing applications, highlighting the different strategies for designing ZIFs and their composites and potential challenges in this field.

The mechanical properties of seven zeolitic imidazolate frameworks (ZIFs) based on five unique network topologies have been systematically characterized by single-crystal nanoindentation studies. We demonstrate that the elastic properties of ZIF crystal structures are strongly correlated to the framework density and the underlying porosity. For the systems considered here, the elastic modulus was found to range from 3 to 10 GPa, whereas the hardness property lies between 300 MPa and 1.1 GPa. Notably, these properties are superior to those of other metal-organic frameworks (MOFs), such as MOF-5. In substituted imidazolate frameworks, our results show that their mechanical properties are mainly governed by the rigidity and bulkiness of the substituted organic linkages. The framework topology and the intricate pore morphology can also influence the degree of mechanical anisotropy. Our findings present the previously undescribed structure-mechanical property relationships pertaining to hybrid open frameworks that are important for the design and application of new MOF materials.

Petrochemical wastewater contains p-nitrophenol, a highly toxic, bioaccumulative and persistent pollutant that can harm ecosystems and environmental sustainability. In this study, ZIF-8-PhIm was prepared for p-nitrophenol removal from petrochemical wastewater using solvent-assisted ligand exchange (SALE) with 2-phenylimidazole(2-PhIm). The ZIF-8-PhIm’s composition and structure were characterised using the XRD, SEM, FT-IR, 1H NMR, XPS and BET methods. The adsorption effect of ZIF-8-PhIm on p-nitrophenol was investigated with the static adsorption method. Compared to the ZIF-8 materials, ZIF-8-PhIm exhibited stronger π-π interactions, produced a multistage pore structure with larger pore capacity and size, and had increased hydrophilicity and exposure of adsorption sites. Under optimised conditions (dose = 0.4 g/L, T = 298 K, C0 = 400 mg/L), ZIF-8-PhIm achieved an adsorption amount of 828.29 mg/g, which had a greater p-nitrophenol adsorption capacity compared to the ZIF-8 material. The Langmuir isotherm and pseudo-second-order kinetic models appropriately described the p-nitrophenol adsorption of ZIF-8-PhIm. Hydrogen bonding and π-π interactions dominated the p-nitrophenol adsorption of ZIF-8-PhIm. It also had relatively good regeneration properties.