Pores Of ZIF-8 Research Articles

Encapsulating Fe3O4 Nanoparticles and Carbon Dots in a Metal-Organic Framework for Magnetic Fluorescent Taggants.

Magnetic fluorescent composite nanomaterials have broad application prospects in the fields of biological imaging, anticounterfeiting identification, suspicious object tracking, and identification of latent fingerprints in forensic medicine. For an effective taggant, a clearly visible identifying mark is necessary to enable observers to capture labeling information quickly and accurately, even from a distance. The preparation method of magnetic fluorescent composite materials is complicated and usually needs different surface modification and assembly processes. The limited loading capacity of fluorescent materials also limits the fluorescence properties of the composite, so it is difficult to produce obvious fluorescence as a taggant to meet the requirements of visible labeling. In this study, a core-shell structure of a magnetic fluorescent composite was prepared by using the metal-organic framework ZIF-8 as the host of fluorescent materials and an encapsulation shell coated on the Fe3O4 nanoparticles. The porous ZIF-8 is beneficial for increasing the loading capacity of fluorescent materials to ensure the fluorescence performance of the composite materials. Further modification of the composite surface prevented the desorption of fluorescent materials from the pores of ZIF-8, enabling the samples to maintain good fluorescence properties even after multiple washing cycles. The preparation method is simple, rapid, and cost-effective, and the prepared magnetic fluorescent composite nanomaterial has high magnetic separation performance and fluorescence performance, making it a promising material for identification, marking, and tracking.

ZIF-8 Vibrational Spectra: Peak Assignments and Defect Signals.

Zeolitic imidazolate framework (ZIF-8) is a promising material for gas separation applications. It also serves as a prototype for numerous ZIFs, including amorphous ones, with a broader range of possible applications, including sensors, catalysis, and lithography. It consists of zinc coordinated with 2-methylimidazolate (2mIm) and has been synthesized with methods ranging from liquid-phase to solvent-free synthesis, which aim to control its crystal size and shape, film thickness and microstructure, and incorporation into nanocomposites. Depending on the synthesis method and postsynthesis treatments, ZIF-8 materials may deviate from the nominal defect-free ZIF-8 crystal structure due to defects like missing 2mIm, missing zinc, and physically adsorbed 2mIm trapped in the ZIF-8 pores, which may alter its performance and stability. Infrared (IR) spectroscopy has been used to assess the presence of defects in ZIF-8 and related materials. However, conflicting interpretations by various authors persist in the literature. Here, we systematically investigate ZIF-8 vibrational spectra by combining experimental IR spectroscopy and first-principles molecular dynamics simulations, focusing on assigning peaks and elucidating the spectroscopic signals of putative defects present in the ZIF-8 material. We attempt to resolve conflicting assignments from the literature and to provide a comprehensive understanding of the vibrational spectra of ZIF-8 and its defect-induced variations, aiming toward more precise quality control and design of ZIF-8-based materials for emerging applications.

Adsorption enhances CH4 transport-driven hydrate formation in size-varied ZIF-8: Micro-mechanism for CH4 storage by adsorption-hydration hybrid technology

The adsorption-hydration hybrid technology holds significant potential for future CH4 storage applications. However, the transport of CH4/H2O and the mechanisms governing hydrate formation within metal-organic framework (MOF) systems remain unclear. In this study, the mechanism of CH4 adsorption, transport, and hydrate formation within ZIF-8 pores of different sizes was delineated utilizing the magnetic resonance imaging (MRI) technique. Primarily, CH4 undergoes physisorption within the inner cavity of ZIF-8, facilitating diffusion through the pores, which preferentially accumulate in larger pore spaces. Due to favorable interactions between CH4 and pre-absorbed water on the ZIF-8 surface, ZIF-8–01 and ZIF-8–02 preferentially facilitate substantial hydrate formation within larger pore spaces. The continuous hydrate growth depletes CH4 in the pore space, enabling two-way migration of adsorbed CH4 to support ongoing hydrate formation. This limited availability of adsorption sites within ZIF-8 induces the diffusion of surrounding CH4 into smaller pore spaces, facilitating the conversion of bound water. The size of the particles considerably influences the transport of physically adsorbed CH4 and impacts hydrate formation. Similar patterns are observed in the adsorption mass transfer coefficients of ZIF-8–01 and ZIF-8–02, which range from 0.0038 to 0.0044 and 0.0031 to 0.0124, respectively. The presence of more adsorption vacancies in the early stage leads to rapid diffusion adsorption of CH4 owing to strong adsorption effects. As adsorption within ZIF-8 pore cavities approaches saturation, increased water transport elevates internal gas-liquid two-phase resistance, slowing the kinetics of late-stage CH4 adsorption. At 6 MPa, CH4 with a larger particle size preferentially overcomes the gas-liquid energy barrier, expediting transport and promoting hydrate formation. Furthermore, the optimal particle sizes of ZIF-8 substantially influence physisorption and significantly improve the kinetics of hydrate formation.

Exploring the compositional space of a metal–organic framework with ionic liquids to develop porous ionic conductors for enhanced signal and selectivity in VOC capacitive sensors

Incorporation of ionic liquids into ZIF-8 pores to obtain solid-ionic conductors that work as active layers in printed gas capacitive sensors to detect water and non-methane volatile organic vapours.

CO2 adsorption mechanisms at the ZIF-8 interface in a Type 3 porous liquid

Porous liquids (PLs) are an attractive material for gas separation and carbon sequestration due to their permanent internal porosity and high adsorption capacity. PLs that contain zeolitic imidazole frameworks (ZIFs), such as ZIF-8, form PLs through exclusion of aqueous solvents from the framework pore due to its hydrophobicity. The gas adsorption sites in ZIF-8 based PLs are historically unknown; gas molecules could be captured in the ZIF-8 pore or adsorb at the ZIF-8 interface. To address this question, ab initio molecular dynamics was used to predict CO2 binding sites in a PL composed of a ZIF-8 particle solvated in a water, ethylene glycol, and 2-methylimidazole solvent system. The results show that CO2 energetically prefers to reside inside the ZIF-8 pore aperture due to strong van der Waals interactions with the terminal imidazoles. However, the CO2 binding site can be blocked by larger solvent molecules that have greater adsorption interactions. CO2 molecules were unable to diffuse into the ZIF-8 pore, with CO2 adsorption occurring due to binding with the ZIF-8 surface. Therefore, future design of ZIF-based PLs for enhanced CO2 adsorption should be based on the strength of gas binding at the solvated particle surface.

ZIF-8/Graphene Oxide Hybrid Membranes as Breathable and Protective Barriers against Chemical Warfare Agents.

Personal protective equipment against chemical warfare agents and other toxic chemicals must be protective, be breathable, and have a low thermal burden. Selectively permeable membranes are promising candidates for such equipment. In this study, a hybrid membrane consisting of a continuous and thin zeolitic imidazolate framework (ZIF)-8 layer on an oxygen-rich small-flake graphene oxide layer was produced using a simple and scalable synthesis method. The small intrinsic pores of ZIF-8 allow it to selectively separate chemicals via size exclusion while permitting water vapor to permeate out. The ZIF-8/graphene oxide membrane had high selectivity for the penetration of water vapor over nerve agent simulants (ratio of dimethyl methylphosphonate to water vapor transmittance rates of ∼312) with a high water vapor transmittance rate of 3000 g m-2 day-1. This protective barrier layer is a promising material for next-generation protective clothing with enhanced comfort and operability.

Different molecular structure of zeolite imidazole acid framework with curcumin loading and its antibacterial property

To address the food safety problems caused by pathogenic bacteria, four different curcumin-loading zeolite imidazolate framework-8 complexes (CCM-ZIF-8) with antibacterial and antioxidant properties were synthesized at different temperatures, which showed different molecular structures. From the results of Fourier infrared spectroscopy, X-ray diffraction, BET analysis, and thermogravimetric analysis, the complexes formed at high temperature in the one-pot method (HT-1S) had the highest curcumin (CCM) loading rate, in which CCM was almost occupied in the internal pores of ZIF-8. However, this complex had yet to show the best performance in antioxidant and antibacterial. Compared to this, the complexes (RT-1S) formed at room temperature in the one-pot method presented a higher scavenging rate for 2,2-difenil-1-pikrilhidrazil radicals and 2,2-Azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radicals than other complexes. Moreover, RT-1S had the best antibacterial property against S. aureus, which could damage bacterial cell membranes and lead to cell death. Furthermore, the relationship between CCM-ZIF-8's chemical structures and properties was deeply discussed. It may provide a better approach to the application of ZIF-8 material.

Resolving Molecular Size and Homologues with a Self-Assembled Metal–Organic Framework Photonic Crystal Detector

Traditional environmental photonic sensing based on the balanced reflection of a photonic structure can hardly be applied to distinguish molecular size and homologues, since the refractive index change introduced by these analytes can be too similar to be unambiguously distinguished. Here, a sensing method based on the pore size selectivity and organics adsorption–desorption capacity of self-assembled ZIF-8 photonics crystal is demonstrated, which can tell apart different molecular sizes, homologues, and organics with similar structures and physical properties. Specificity is improved by the inherent relationships between the pore size of ZIF-8 metal–organic frameworks and the associated molecular diffusion rates in the pores, so that the combination of the observed peak shift and recovery time are unique to each analyte. Using this method, selective detection of molecular size is also demonstrated in the case of linear vs cyclic molecules, since only the former can penetrate inside the ZIF-8 pores to induce a large wavelength shift. The reflection peak shift caused by the linear molecules was found to be about 30–40 nm, an order of magnitude larger compared to those for the cyclic molecules. A relationship between the diffusion rate of linear molecules in ZIF-8 pore and the recovery time of photonic crystal reflective peak is further established, linking the recovery time and the linear molecular diffusion coefficient. Finally, different linear molecules are identified by their associated recovery time to detect homologues or organics with similar refractive index.

Confinement-enhanced Li+ ion dynamics in an ionic liquid-based electrolyte in porous material.

While Ionic Liquids (IL) are promising liquid electrolyte components for Li-ion batteries due to their high electrochemical stability and low volatility and flammability, unfavorable Lithium-anion clusters lead to poor Li+ transport properties such as low transference numbers. A confinement of ILs in nanoporous materials could overcome these problems, based on altered structural and dynamic properties of the confined ILs. We investigate the coordination and the Li+ dynamics in an IL/Li-salt mixture of 1-butyl-1-methylpyrrolidinium bis(trifluormethyl-sulfonyl)imide (Pyr14TFSA) and LiTFSA and reveal in how far the confinement has positive or negative effects on ion clustering in the electrolyte. To this end, the electrolyte is confined in mesoporous silica SBA-15 (pore diameter 8 nm or 4 nm) or the metal-organic framework (MOF) ZIF-8 (pore diameter 1.16 nm). Raman spectra elucidate the Li-anion coordination and the interaction of the ions with the walls. Temperature-dependent 7Li spin relaxation rates, analyzed within the model of Bloembergen, Purcell and Pound (BPP), allow statements on the local Li+ environment, the local Li+ dynamics and its activation. In the SBA-15 materials the Li+ coordination is unchanged with persisting Li-TFSA clusters. Furthermore, the local dynamics of Li+ is reduced upon confinement, as expected due to geometrical restrictions. At the same time, however, both structural and dynamic parameters do not show a pronounced dependence on the pore size. Surprisingly, upon confinement in ZIF-8 Li+ displays faster local dynamics and a more asymmetric environment in comparison to the bulk electrolyte. The enhanced dynamics is accompanied by a reduced coordination to TFSA-, suggesting the breakup of Li-TFSA clusters. Differences between the porous materials are attributed to the nature of the wall surface, as Raman spectra suggest that in SBA-15 the TFSA- ion is preferentially interacting with the pore walls, whereas in ZIF-8 the Pyr14+ ion is immobilized by the pore walls. These results demonstrate a strong influence of internal interfaces on IL structure and dynamics and bear potential for further tailoring ion dynamics.

Grain boundaries passivation of high efficiency and stable perovskite photodetector by polyoxometalate-based composite SiW 11@ZIF-8

Polyoxometalates (POMs) can enable energy level tuning to match perovskite layers. They are considered electronic bridges to modify perovskite and improve the performance of photovoltaic devices. Therefore, in the present work, we dispersed the vacancy POMs K₈[α-SiW₁₁O₃₉]·H₂O ({SiW₁₁}) in the metal-organic frameworks (MOFs) to modify the perovskite layer. {SiW₁₁} could adjust the energy level between the layers of the perovskite photodetector. Moreover, the hydrogen bonds formed between SiW₁₁@ZIF-8 and perovskite effectively passivated the grain boundaries (GBs) of the perovskite layer. X-ray diffraction spectroscopy (XRD) showed that the crystallinity of perovskite was significantly improved. In addition, scanning electron microscopy (SEM) images demonstrated that the average size of perovskite grains increased from 254.50 to 719.27 nm, proving the effective passivation of the GBs. Furthermore, a series of tests such as infrared spectroscopy (IR), N₂ adsorption/desorption isotherms, transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) also proved that {SiW₁₁} could be successfully loaded into the pores of ZIF-8 through electrostatic interactions. The photocurrent of the SiW₁₁@ZIF-8 doped device reached 41.95 μA, about three times as high as that of the blank device (14.41 μA). Also, under unencapsulated conditions, it could still maintain more than 90% stability for nearly 700 h. This work demonstrates the potential application of POM@MOF-type composites in the field of perovskite photodetectors.

Engineering the ZIF-8 Pore for Electrochemical Sensor Applications-A Mini Review.

Zinc imidazole framework-8, abbreviated as ZIF-8, is a member of the metal organic framework (MOF) family. The chemical architecture of ZIF-8 consists of zinc metal duly coordinated with an organic ligand/fragment, resulting in a cagelike three-dimensional network with unique porosity. Because of such a unique architecture and physicochemical property, ZIF-8 has recently been explored in various applications such as gas storage, catalysis, electrochemical sensing, drug delivery, etc. Electrochemical sensors are currently a hot topic in scientific advances, where small, portable, Internet of Things (IoT)-enabled devices powered by electrochemical output show a newer path toward chemo and biosensor applications. The unique electrochemical property of ZIF-8 is hence explored widely for possible electrochemical sensor applications. The application and synthesis of the bare ZIF-8 have been widely reported for more than a decade. However, new scientific advancements depict tailoring the bare ZIF-8 structure to achieve smart hybrid ZIF-8 materials that show more advanced properties compared to bare ZIF-8. The framework is formed by joining inorganic (metal-containing) units with organic linkers by reticular synthesis, which results in the formation of a cross-linked crystalline network with permanent porosity. This unique porosity of ZIF-8 has recently been utilized for the encapsulation of suitable guest species to enhance the native physicochemical activity of ZIF-8. These engineered ZIF-8 materials show excellent results, especially for electrochemical sensing application. This review is intended to describe the research, including the one done by our group, where the ZIF-8 pore size is used for encapsulating nanoparticles, enzymes, and organic compounds to avail suitable sensor applications.

Designing heterogeneous MOF-on-MOF membrane with hierarchical pores for effective water treatment

Rationally regulating the separation pores is an effective way to achieve efficient separation membrane. However, the developed metal-organic framework (MOF) membranes for water treatment are all formed by one kind of MOF, which can only provide rigid pores, makes it difficult to achieve high flux and excellent rejection ratio simultaneity. Here, we proposed a facile strategy for the synthesis of heterogeneous MOF-on-MOF membrane with hierarchical pores, by site-specific grown ZIF-8 layer on UiO-66-NH2 layer. Thus unique architecture of the obtained double-layered MOF membrane (UiO-66-NH2@ZIF-8) endows multidimensional separation pores: (i) the large pores of UiO-66-NH2 can facilitate water transportation, (ii) the molecular-sieving pores of ZIF-8 can intercept dyes, (iii) UiO-66-NH2 acting as active sites can promote the growth of ZIF-8. As a result, the optimized UiO-66-NH2@ZIF-8 membrane exhibits high flux (36.7 L m−2 h−1 bar−1) and excellent dye rejections (>97.0%). Through analysis and comparison, the regulated multi-type pores play an important role in membrane performance. Coupled with the facile membrane preparing method, this work can used as a potential approach of designing other advanced MOF membrane for water treatment.

Two-dimensional assembly made up of ZIF-8 particles for the high-efficient capture of the iodine and dyes

The removal of the pollutants from the environment is the need of the environmental protection. ZIF-8 is promising adsorbents, and the construction of ZIF-8 assembly is essential to boost its performance. Here, we showed the easy synthesis of two-dimensional (2D) assembly built by ZIF-8 particles (2D A-ZIF-8) for the high-efficient capture of the iodine (I2) and dyes. The assembly was synthesized by the controllable reaction of 2-methylimidazole (2-MIM) with 2D Zn-glycerol (Zn-GL) precursor. Time-dependent experiments showed the predominant replacement of GL at outer boundary and then basic plane of the precursor by 2-MIM. The assembly can be synthesized with high output and combined the advantage of large accessible surface of 2D sheets, the plentiful pores of ZIF-8 and enhanced stability of assembly, endowing the large potential as adsorbent. The high adsorption capacity of I2 (200 wt%) was achieved on A-ZIF-8, while it is about 128 wt% on traditional dodecahedronal ZIF-8. The assembly also showed the excellent adsorption capacity for methyl orange (MO) (46.3 mg g-1) and methylene blue (MB) (46.5 mg g-1) at a concentration of 50 mg L-1. It can be easily separated for reuse benefited from the large size and enhanced stability of assembly.

ZIF-8 encapsulated upconversion nanoprobes to evaluate pH variations in food spoilage.

Anovel nanoassembly was constructed through encapsulating upconversion nanoparticles (UCNPs) into a metal-organic framework structure (ZIF-8), in which doxorubicin (DOX) was absorbed into pores of ZIF-8. The blue emission of UCNPs was quenched by DOX through the fluorescence resonance energy transfer (FRET) strategy. When the nanoprobe was exposed to food samples with different pH values, ZIF-8 collapsed to release DOX molecules, resulting in upconversion recovery. The porous structure of ZIF-8 provides abundant space for DOX absorption, which significantly improves the detection capacities and accuracy. It is shown that the probe has a good linear relationship when pH values vary from 2.5 to 7.4, and can distinguish pH variations as low as 0.5 in real samples. This strategy has been successfully used to determine food spoilage by determination of pH variations.

White light-emission based on dye@ZIF-8 crystals encapsulating yellow and blue dyes

This work applies an in-situ growth method to synthesize the ZIF-8 composites encapsulating yellow and blue dyes, namely RhB and C120, respectively. These two dyes are successfully introduced into ZIF-8 crystals, proved via the nitrogen adsorption, FTIR and powder XRD measurements. Then, these two types of dye@ZIF-8s are mixed, to achieve a white light-emission with CIE coordinates of (0.345, 0.294) under the excitation light at 365 nm. The encapsulation of dyes in isolated pores of ZIF-8 effectively mitigates the aggregation-induced quenching and the energy re-absorption between dyes. Also, the photo stability of this white-light material is investigated for practical application.

The experimental and theory research on the sorption kinetic of CH4 and C2H4 in ZIF-8/water-glycol slurry

The zeolitic imidazolate framework (ZIF)-8/water-glycol slurry shows great potential in separating low carbon hydrocarbons. In the present study, the physical properties of the ZIF-8/water-glycol slurry were determined, and the hydrophobicity and glycophilicity of the ZIF-8 material were demonstrated by measuring the contact angle between liquid droplets with a ZIF-8 material, for the first time. It was observed that the increase in pressure could weaken the hydrophobicity of ZIF-8. In addition, the sorption kinetics of CH4 and C2H4 in the slurry were investigated. It was noted that the relatively high temperature and pressure could increase the dissolution rates of CH4 and C2H4 in the slurry. A kinetic model for describing the dissolution of CH4 and C2H4 in the slurry was proposed, wherein the diffusion of gas molecules in the glycol membrane around ZIF-8 particles and those in the inner pores of ZIF-8 were concurrently considered for the first time. The simulation results correlated with the experimental data. Finally, multistage simulation separation experiments for CH4/C2H4 gas mixtures using the slurry were performed. It was observed that after a four-stage simulation separation operation, the concentration of C2H4 decreased from 49.72 mol% in the feed gas to 4.68 mol%. The experimental and modeling results will be helpful for the practical separation application of the ZIF-8 slurry system.

High ionic conductivity and ion conduction mechanism in ZIF-8 based quasi-solid-state electrolytes: a positron annihilation and broadband dielectric spectroscopy study.

The low ionic conductivity and electrode-electrolyte interface instability issues with solid polymer electrolytes jeopardize their electrochemical performances in lithium-ion batteries (LIBs). The use of quasi-solid-state electrolytes (QSSEs) with concentrated Li salt embedded inside the pore networks of metal organic frameworks (MOFs) can successfully address the aforementioned issues. Owing to the sieve effect of zeolitic imidazolate framework-8 (ZIF-8) towards selective cation permeability over anions through the interconnected pore network, a unique QSSE with LiTFSI salt concentrated in the ZIF-8 skeleton used as a filler in poly(ethylene oxide) has been synthesized. LiTFSI gets embedded inside the interconnected pore network of ZIF-8 that furnishes unhindered pathways for Li+ ion migration leading to a very high ionic conductivity of ∼6 × 10-4 S cm-1. The higher ionic conductivity is directly related to the Li+ ion conduction through the pore network of ZIF-8 which has been experimentally evident from complementary methods viz. Positron annihilation and broadband dielectric spectroscopy. The design route towards these types of QSSEs encompassing porous MOFs paves the way for realizing Li superionic conductors suitable for practical application in commercial LIBs with high safety and stability.

A Highly Permeable Mixed Matrix Membrane Containing a Vertically Aligned Metal–Organic Framework for CO2 Separation

Delicately regulating the distribution morphology of a filler is an effective strategy to promote the separation performance of mixed matrix membranes (MMMs). Herein, we describe a highly permeable metal-organic framework (MOF)-based MMM comprising vertically aligned ZIF-8 (V-ZIF-8) and polysulfone (PSF). The V-ZIF-8 is distributed uniformly within the PSF matrix. With this unique distribution morphology of ZIF-8, the shortest gas transport pathways are formed in the membrane. Meanwhile, the molecular-sieving pores of ZIF-8 can allow CO2 to pass through and crowding out N2. The obtained V-ZIF-8/PSF membrane shows a high CO2 permeability of 89.7 Barrer and a CO2/N2 selectivity of 30.0 that is stable over a period of 50 h. The CO2 permeability is enhanced about 11.8 times than that of the pure PSF membrane. The results prove that the vertically aligned distribution morphology of an MOF in a polymer matrix is an effective method to improve the separation performance of a membrane, providing a new concept for designing more advanced membranes.

Application in Anticounterfeiting for Multistimuli Smart Luminescent Materials Based on MOF-on-MOF.

The generation of smart responsive materials that can perform multiple drastic optical outputs upon different triggers provides a good platform to encode and hide the information and create multilevel security. In this paper, a smart multiresponsive MOF-on-MOF material was reported using one MOF (HPU-14) as a platform to grow ZIF-8 on the outer layer, combining different emitter centers such as anthracene (ANT) and lanthanide ions (Ln3+) confined into two MOFs. Due to the existence of ANT in the pores of ZIF-8, this composite material can exhibit reversible photoswitching behavior under a 365 nm ultraviolet (UV) lamp and enable "resetting and reusing" dynamic anticounterfeiting application. Meanwhile, when treated by an acid/alkali gas, this material can also display reversible switching behavior under 254 nm UV irradiation, which is attributed to the loading of Ln3+ on HPU-14. We demonstrated that this excellent practical anticounterfeiting material can decipher the right information only by following a strict stimuli sequence. Therefore, this MOF-on-MOF material synthesis technology for sophisticated counterfeiters, which makes the protected information highly secure, could open a new way to design multilevel anticounterfeiting materials.

Carbon dots and gold nanoparticles doped metal-organic frameworks as high-efficiency ECL emitters for monitoring of cell apoptosis

Synthesis of highly efficient, cost-effective, Easy labeling electrochemiluminescence (ECL) luminescent materials is attractive in developing highly sensitive ECL sensors for many applications such as clinical diagnostics, biosecurity, and environmental monitoring. Herein, by doping carbon dots (CDots) and gold nanoparticles (AuNPs) into zeolitic imidazolate framework (ZIF-8), novel high-efficiency ECL emitters CDots@ZIF-8/AuNPs nanocomposites were prepared. Our experiment indicated that ZIF-8 in the nanocomposites not only act as carrier for ECL labels, but as an ECL accelerator to convert the CDots to CDots•–, causing the enhanced ECL intensity of CDots in K2S2O8 solution. AuNPs, which have excellent conductivity, were formed in the pores of ZIF-8 to further enhance the ECL signals. As a result, the nanocomposites showed a final about 7-fold ECL intensity as compared to the pure CDots. AuNPs in the nanocomposites could also provide a platform for effective attaching the biomolecular, making the nanocomposites ideally suited for building biosensor. As a proof of concept, the prepared CDots@ZIF-8/AuNPs was successfully applied in the rapid and simple ECL monitoring of caspase-3 activity during cell apoptosis, which gives impetus to the design of new ECL luminescent materials with ultimate applications in highly sensitive bioanalysis.