•Zeolitic Imidazolate Frameworks-derived carbon with hollow structure was synthesized.•The hollow carbon exhibits high activity in catalytic ozonation of 4-nitrophenol.•The carbon can be easily ...separated from the solution and has good reusability.•Factors that affect 4-nitrophenol degradation are examined.•SO4− is the main reactive species participating in 4-nitrophenol degradation.
Zeolitic imidazolate framework (ZIF)-derived carbons have been considered promising catalysts for the degradation of organics in water through peroxymonosulfate (PMS)-based oxidation processes. The construction of hierarchical hollow, porous structures while retaining the properties of ZIF-derived carbons is highly desirable for a catalyst but remains an arduous challenge. Herein, ZIF-67 (Co(mim)2, mim = 2-methylimidazolate) derived carbon with hollow, porous structures is achieved by pyrolysis of architectures consisting of polystyrene cores and ZIFs shells. The properties of the resulting sample are characterized, and its superior performance for 4-nitrophenol (4-NP) degradation via PMS activation is investigated. Factors that affect 4-NP degradation are examined, including the catalyst and PMS dose, solution pH, temperature and 4-NP concentration. Moreover, the catalyst can be easily separated from the solution with a magnet and has good stability and reusability. Electron paramagnetic resonance spectroscopy (EPR) and radical scavenger tests indicate that SO4− is the main reactive species participating in 4-NP degradation. This work provides a new prospect for the design of high-performance ZIF-derived carbon catalysts for PMS-based oxidation processes.
Here first a 2D dual‐metal (Co/Zn) and leaf‐like zeolitic imidazolate framework (ZIF‐L)‐pyrolysis approach is reported for the low‐cost and facile preparation of Co nanoparticles encapsulated into ...nitrogen‐doped carbon nanotubes (Co‐N‐CNTs). Importantly, the reasonable Co/Zn molar ratio in the ZIF‐L is the key to the emergence of the encapsulated microstructure. Specifically, high‐dispersed cobalt nanoparticles are fully encapsulated in the tips of N‐CNTs, leading to the full formation of highly active Co–N–C moieties for oxygen reduction and evolution reactions (ORR and OER). As a result, the obtained Co‐N‐CNTs present superior electrocatalytic activity and stability toward ORR and OER over the commercial Pt/C and IrO2 as well as most reported metal‐organic‐framework‐derived catalysts, respectively. Remarkably, as bifunctional air electrodes of the Zn–air battery, it also shows extraordinary charge–discharge performance. The present concept will provide a guideline for screening novel 2D metal‐organic frameworks as precursors to synthesize advanced multifunctional nanomaterials for cross‐cutting applications.
2D dual‐metal zeolitic imidazolate framework with leaf‐like microstructure is rationally chosen as material platform for the facile fabrication of high‐dispersed cobalt nanoparticles encapsulated into nitrogen‐doped carbon nanotubes as bifunctional air electrodes for a high‐performance rechargeable zinc–air battery.
A defect‐free zeolitic imidazolate framework‐8 (ZIF‐8)/graphene oxide (GO) membrane with a thickness of 100 nm was prepared using two‐dimensional (2D) ZIF‐8/GO hybrid nanosheets as seeds. Hybrid ...nanosheets with a suitable amount of ZIF‐8 nanocrystals were essential for producing a uniform seeding layer that facilitates fast crystal intergrowth during membrane formation. Moreover, the seeding layer acts as a barrier between two different synthesis solutions, and self‐limits crystal growth and effectively eliminates defects during the contra‐diffusion process. The resulting ultrathin membranes show excellent molecular sieving gas separation properties, such as with a high CO2/N2 selectivity of 7.0. This 2D nano‐hybrid seeding strategy can be readily extended to the fabrication of other defect‐free and ultrathin MOF or zeolite molecular sieving membranes for a wide range of separation applications.
Thin sieves: Zeolitic imidazolate framework‐8 (ZIF‐8)/graphene oxide (GO) membrane with a thickness of 100 nm was prepared using 2D ZIF‐8/GO hybrid nanosheets as seeds. The nanohybrid seeding facilitates uniform crystallization of ZIF‐8 on the porous substrate, and the GO promotes crystal intergrowth, leading to high‐quality molecular sieving membranes.
•Hybrid zeolitic imidazolate frameworks (HZIFs) inherit the merits of zeolite and ZIFs.•Wide applications of HZIFs in catalysis, ion storage, microwave adsorption, and so on.•Systematically summary ...of reported HZIFs.•The challenges and perspectives of the rational design and syntheses of new HZIFs.
Zeolites are widely used in industrial catalysis and many aspects of our daily life. Zeolitic imidazolate frameworks (ZIFs) have been developed by mimicking the structural characteristics of zeolite through coordination chemistry method. ZIFs have attracted extensive attention because of their high surface area and adjustable pore size and pore environment. The emerging hybrid zeolitic imidazolate frameworks (HZIFs) contain TO4 unit of zeolite and metal-imidazole tetrahedral unit (MIm4) of ZIFs which fill the gap between zeolite and ZIFs. HZIFs inherit the merits of zeolite and ZIFs such as high stability, high porosity and so on. HZIFs has wide applications in electrocatalysis, photocatalysis, ion storage, capacitors, electrochemical identification, microwave adsorption and so on. The emergence of this material has greatly promoted the progress and development of material chemistry, coordination chemistry and structural chemistry. In this review, we systematically summarize the development of HZIFs including material design, structural diversity, synthesis methods, morphology control/derivatization and their multi-field applications. The challenges and perspectives of the rational design and syntheses of new HZIFs are also discussed.
Controlling the shape of metal–organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping ...of inorganic nanoparticles, post‐synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein, we report using a simple wet‐chemistry process at room temperature to control the anisotropic etching of colloidal ZIF‐8 and ZIF‐67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, by an acid–base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal–ligand bonds; that, along these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution.
Post‐synthetic wet‐chemical anisotropic etching of colloidal ZIF‐8 and ZIF‐67 crystals enables uniform reshaping of them into unprecedented shapes, including cubic and tetrahedral crystals, and even hollow boxes, by an acid–base reaction and subsequent sequestration of leached metal ions.
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•The application of ZIF/ZIF derivative based composite photocatalysts was reviewed.•Special attention has been paid to the catalytic mechanism.•The synergistic effects between the ...components are discussed.•The challenges and opportunities in this interesting field are presented.
To solve the problem of the global energy shortage and the widespread pollution of the environment, semiconductor photocatalytic technology has been widely studied. Zeolitic imidazolate frameworks, a sub-family of metal-organic frameworks, have emerged as potential candidates for photocatalysis due to their intrinsic porous characteristics, abundant functionalities, rapid electron transfer ability, and exceptional thermal and chemical stabilities. Besides, a thermal treatment of zeolitic imidazolate frameworks can result to functional materials that have the similar structure characteristic, but superior light sensitivity and charge transfer properties. Moreover, the photocatalytic activity of zaeolitic imidazolate frameworks and their derivatives can be largely improved by combining photoactive semiconductors/ molecules which serve as light harvesting centers/electronic mediators. This paper presents a first review of the application of zaeolitic imidazolate frameworks and their derivatives -based materials for visible-light-induced photocatalytic hydrogen evolution and pollutants treatment. The representative studies are carefully summarized and discussed. Special emphasis is given to the synergistic effects between the components in the composite catalyst for enhanced photocatalysis. At the end of this review, the current achievements together with major challenges in the field are discussed and the next possible development directions are proposed.
A zeolitic‐imidazolate‐framework (ZIF) nanocrystal layer‐protected carbonization route is developed to prepare N‐doped nanoporous carbon/graphene nano‐sandwiches. The ZIF/graphene oxide/ZIF ...sandwich‐like structure with ultrasmall ZIF nanocrystals (i.e., ≈20 nm) fully covering the graphene oxide (GO) is prepared via a homogenous nucleation followed by a uniform deposition and confined growth process. The uniform coating of ZIF nanocrystals on the GO layer can effectively inhibit the agglomeration of GO during high‐temperature treatment (800 °C). After carbonization and acid etching, N‐doped nanoporous carbon/graphene nanosheets are formed, with a high specific surface area (1170 m2 g−1). These N‐doped nanoporous carbon/graphene nanosheets are used as the nonprecious metal electrocatalysts for oxygen reduction and exhibit a high onset potential (0.92 V vs reversible hydrogen electrode; RHE) and a large limiting current density (5.2 mA cm−2 at 0.60 V). To further increase the oxygen reduction performance, nanoporous Co‐Nx/carbon nanosheets are also prepared by using cobalt nitrate and zinc nitrate as cometal sources, which reveal higher onset potential (0.96 V) than both commercial Pt/C (0.94 V) and N‐doped nanoporous carbon/graphene nanosheets. Such nanoporous Co‐Nx/carbon nanosheets also exhibit good performance such as high activity, stability, and methanol tolerance in acidic media.
A zeolitic‐imidazolate‐framework nanocrystal layer‐protected carbonization route is developed to prepare N‐doped carbon/graphene nano‐sandwiches. These act as a highly active and stable nonprecious metal catalyst for oxygen reduction.
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•ZIF-8/NF-TiO2 photoanode was fabricated via electro-anodization and in-situ growth.•The photo-electrocatalytic activity was attributed to heterojunction and synergy.•Light and bias ...potential improved the charge generation, separation and transfer.•The synergistic factor in photo-electrocatalytic process was calculated to be 3.5.•Sulfamethazine (SMZ) degradation mechanisms and pathway were investigated.
Traditional photoanodes decreased in mass transfer rate via coating powdered catalysts on conductive glass. In this work, we obtained a visible light-driven semiconductor- metal organic frameworks (MOFs) hybrid photoelectrode, which was constructed by electro-anodization and deposition growth process. The ZIF-8/NF-TiO2 photoelectrode was based on hollow TiO2 nanotubes, and ZIF-8 nanoparticles were deposited on the surface of the pyramid-shaped rutile TiO2 substrate after N and F co-doping. Compared with unmodified anatase TiO2, the reaction rate of ZIF-8/NF-TiO2 increased by 21.7 times, and the synergistic factor in the photo-electrocatalytic process could reach to 3.5. The porous structure of ZIF-8, the intrinsic band difference between anatase and rutile TiO2 greatly improved light utilization, and promoted electron–hole separation. The electrode could be easily recycled and exhibit excellent repeatability, and the degradation efficiency almost unchanged after 8 cycles. Moreover, possible degradation pathways and photo-electrocatalytic degradation mechanisms of sulfamethazine were proposed. This progress could bring novel insights for the design of semiconductor-MOFs hybrid photo-electrocatalysts.
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•The diverse structural and functional properties of ZIFs have been discussed.•Diverse synthesis approaches for ZIFs have been described for their sensing applications.•The ...performance of ZIF-based sensing systems is assessed in terms of quality assurance.•The challenges and future outlook of ZIF-based sensing techniques are also discussed.
Zeolitic imidazolate frameworks (ZIFs) can be classified as metal–organic frameworks (MOFs) or metal-azolate frameworks (MAFs) with unique topologies. The presence of five membered heterocyclic ring structure in imidazole ring-based linkers facilitates their robust coordination with bridging metal nodes. This stable coordination imparts numerous advantageous properties (e.g., facile and reproducible crystallization, nanoscale processability, high loading capacities, and good biocompatibility) to ZIFs. Further, the technical advancements in the synthesis of porous coordination polymers have contributed to the diversification in the fabrication approaches needed for the ZIFs and to the characterization of their structural and functional attributes (e.g., ZIF-8 and ZIF-67). In light of this advancement in ZIF technologies, we describe the synthesis methods for the fabrication of ZIFs in relation to their resulting properties. This review also highlights the application of ZIF-based probes for sensing of a diverse array of targets (e.g., gas molecules, metabolites, pesticides, and metals). Further, a performance comparison between various ZIF-based sensing systems has been made for the listed target analytes in terms of various quality assurance (QA) criteria (e.g., sensor response and recovery time, limit of detection (LOD), specificity, and reproducibility). At last, the current challenges and future outlook for this research field are also discussed to help expand their real-world applications.
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•The magnetic Co@NC-800 exhibited excellent cycle stability in PMS activation.•Co nanoparticles under confinement promoted the catalytic ability and stability.•A two-pathway mechanism ...was presented in Co@NC-800/PMS system.•The Co@NC-800/PMS showed high efficiency in various antibiotics and water bodies.
The integration of metal nanoparticles into carbon materials has catch considerable attention. In this study, we have successfully fabricated the N-doped porous carbon encapsulated magnetic Co nanoparticles (Co@NC-800) through a two-step pyrosis of zeolitic imidazolate frameworks (ZIF-67). The obtained Co@NC-800 exhibited excellent stability in activating peroxymonosulfate (PMS) towards tetracycline (TC) degradation without obvious Co leaching and magnetically separable. The removal efficiency reached up to 90.1% within 3 min and 74.7% of total organic carbon (TOC) removal efficiency could be obtained in 30 min towards TC by Co@NC-800/PMS system. Mechanism explorations revealed the encapsulated Co nanoparticles in the porous N-doped carbon promoted the catalytic activity and stability. The two-pathway mechanism study indicated that radical and non-radical oxidations acted together in TC degradation. Moreover, some potential factors, including PMS dosage, TC concentration, solution pH value, anion/organic matters and temperature were investigated. The Co@NC-800/PMS system exhibited high efficiency in removal of various antibiotics (oxytetracycline, chlortetracycline and deoxytetracycline). Even in actual water bodies (tap water, river water and pharmaceutical wastewater), the Co@NC-800/PMS system displayed excellent performance. This study proposed a design of metal nanoparticles under confinement for fabricating highly active catalysts towards PMS activation.
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