Zeolitic Imidazolate Framework Research Articles

Facile synthesis of multifunctional zeolitic imidazolate framework-8 coatings on diverse bare substrates using a one-step strategy

Rational growth of metal–organic frameworks (MOFs) with controllable morphology and surface properties has been challenging. In this study, facile synthesis of zeolitic imidazolate framework-8 (ZIF-8) in solutions as well as direct in-situ growth of ZIF-8 on various untreated substrates was studied systematically. ZIF crystals with controllable morphology and size were prepared by simply adjusting the ethanol content in the co-solvent system, achieving a rational synthesis of ZIFs in controlled environments. More importantly, co-solvent content was proved to be crucial in the inter-dimensional topotactic phase transformation from a 2-dimensional ZIF-L to a three-dimensional ZIF-8. Then, the facile in-situ crystallization of ZIF-8 on a variety of untreated substrates was studied. With the use of co-solvents, ZIF-8 crystals were formed uniformly and continuously on all substrates regardless of the nature of the support material, including organic supports such as nylon membranes, 3D printed meshes, melamine sponges, mask filter layers, fabric, metallic support stainless-steel meshes, and ceramic pellet. This facile coating strategy provided controllable crystal coating morphology, size, and coating density, without surface modification/pre-treatment steps which are commonly used in the synthesis of high-quality ZIF coatings/membranes. The ZIF-8 coated substrates prepared in a co-solvent system displayed superior performance in some environmental remediation and biomedical applications. For example, the ZIF-8-coated nylon membrane achieved an impressive 96 ∼ 98 % small oil droplet removal from emulsions while maintaining a high water flux of ∼ 1200 L m−2h−1 bar−1. The superhydrophobic ZIF-8-coated melamine sponges were effective for fast oil adsorption. Last but not least, the ZIF-8-coated masks demonstrated greatly improved antibacterial activities. Overall, the co-solvent synthesis method reported in this work has enabled a one-step universal strategy for the direct growth of zeolitic imidazolate framework coating on diverse bare substrates with controlled surface properties and thus showed significant commercial potential in environmental and biological applications.

Insights into the thermal stabilization mechanism of zeolitic imidazolate framework-8 for poly(vinyl chloride)

The thermal stability of zeolitic imidazolate framework-8 (ZIF-8) for poly(vinyl chloride) (PVC) has received attention, but its thermal stabilization mechanism needs further clarification. Herein, the stearic acid-modified ZIF-8 with high specific surface area and large pore volume was effectively synthesized by using zinc stearate as the zinc source for the first time. Modification of stearic acid results in larger adsorption capacity of ZIF-8 for HCl and better thermal stability effect for PVC, especially long-term thermal stability. Moreover, the thermal stability mechanism of ZIF-8 for PVC was demonstrated by experiments and theoretical calculations. In addition to absorbing HCl to eliminate autocatalytic degradation of PVC, ZIF-8 disintegrates and may form 2-methylimidazole-Zn-Cl salt complex instead of free ZnCl2, avoiding the negative zinc burning effect. Furthermore, the Diels-Alder reaction between imidazole ring and degraded PVC prevents the extension of the conjugated double bonds of PVC and delays the deepening of the color of PVC.

A novel ZIF-8 mediated nanocomposite colorimetric sensor array for rapid identification of matcha grades, validated by density functional theory

The rapid and intelligent assessment of matcha grades remains crucial in quality control. This study proposed a colorimetric sensor array (CSA) mediated with zeolitic imidazolate framework-8 (ZIF-8) to identify matcha grades. The ZIF-8 mediated CSA was innovatively developed by encapsulating the pH indicator and metal porphyrin within the ZIF-8 structure, improving their stability and functionality. ZIF-8 mediated CSA exhibited significantly increased sensitivity towards matcha samples driven by the preconcentration of volatile organic compounds (VOCs) facilitated by ZIF-8. As a result, the response signal values of the CSA increased by 1.13–4.75 times after ZIF-8 mediation. Subsequently, qualitative models for identifying matcha grades were established using K-Nearest Neighbor and Artificial Neural Network (ANN). The ANN model showed the higher discrimination accuracy. Compared with common CSA, the ANN model based on ZIF-8 mediated CSA achieved a better identification rate of 95 %, and recognition accuracy was improved by 7.5 % in the model. These results indicated that the ZIF-8 mediated CSA with a porous structure demonstrated enhanced specificity in capturing VOCs. Ultimately, the density functional theory has confirmed that the ZIF-8-mediated CSA exhibits high selectivity towards matcha's characteristic VOCs. These results highlight the potential of this novel CSA for the rapid identification and grading of matcha.

Fast tailoring the ZIF-8 surface microenvironment at ambient temperature to boost glucose oxidase-like activity of AuNPs for biosensing

Rational design and tailoring of the surface microenvironment surrounding the catalytic sites, such as noble metal nanoparticles, is an effective way to enhance the catalytic activity of mimicking enzymes. However, it remains on-going challenges to regulate the microenvironment of the catalytic sites due to the lack of tunable variability in structural precision of conventional solid catalysts. Herein, three types of zeolitic imidazolate framework-8 (ZIF-8) with different major crystal facet orientations, i.e., cubic with (100) facets (denoted ZIF-8c), truncated dodecahedral with (100), (110) facets (denoted ZIF-8tr), and dodecahedral with (110) facets (denoted ZIF-8r), were developed facilely using an electrochemical method by switching the potential at ambient temperature. Because the Zn2+ nodes were predominantly exposed on the (100) facets of ZIF-8, while the ligands were mainly exposed on the (110) facets. Hence, gold nanoparticles (AuNPs) showed differential glucose oxidase (GOx)-like activities when anchored in situ on different crystal facets of ZIF-8 and obeyed the following order ZIF-8c/Au>ZIF-8tr/Au>ZIF-8r/Au. Notably, both the metal nodes and aromatic linkers of ZIF-8 interacted with AuNPs through coordination and π-π interactions. The Zn2+ nodes facilitated the formation of the electron-deficient Au species. The electron transfer from AuNPs to Zn2+ sites effectively boosted the catalytic activity. It was known that directly tailoring the microenvironment at the supporting sites of noble metal catalysts to boost catalysis through a facile electrochemical method was not reported. Based on the favorable GOx-like activity and long-term stability of ZIF-8tr/Au, a highly sensitive electrochemical biosensing platform for assaying squamous cell carcinoma antigen (SCCA) was developed. It enabled fg-level detection of cancer marker.

Recent advances in immunotherapy-involved combination cancer therapy based on ZIF-8

This paper introduces and briefly describes the tumor immune cycle to clarify the action mechanisms and principles of classical immunotherapy. We then focus on the classification of immunotherapies. Immunotherapy strategies can be classified into three categories according to the target of action: immunotherapy based on the regulation of dendritic cells, immunotherapy based on polarized tumor-associated macrophages, and immunotherapy based on the suppression of regulatory T cells. Subsequently, the latest research progress in the use of Zeolitic Imidazolate Framework-8 (ZIF-8) as a vehicle to combine immunotherapy with other therapeutic approaches is examined. Finally, prospects for the application of nanocomposites in combination therapy for tumor immunotherapy are outlined.

Accelerating the Hydrogen Evolution Kinetics with a Pulsed Laser-Synthesized Platinum Nanocluster-Decorated Nitrogen-Doped Carbon Electrocatalyst for Alkaline Seawater Electrolysis.

Efficient and durable electrocatalysts for the hydrogen evolution reaction (HER) in alkaline seawater environments are essential for sustainable hydrogen production. Zeolitic imidazolate framework-8 (ZIF-8) is synthesized through pulsed laser ablation in liquid, followed by pyrolysis, producing N-doped porous carbon (NC). NC matrix serves as a self-template, enabling Pt nanocluster decoration (NC-Pt) via pulsed laser irradiation in liquid. NC-Pt exhibits a large surface area, porous structure, high conductivity, N-rich carbon, abundant active sites, low Pt content, and a strong NC-Pt interaction. These properties enhance efficient mass transport during the HER. Remarkably, the optimized NC-Pt-4 catalyst achieves low HER overpotentials of 52, 57, and 53mV to attain 10mA cm-2 in alkaline, alkaline seawater, and simulated seawater, surpassing commercial Pt/C catalysts. In a two-electrode system with NC-Pt-4(-)ǀǀIrO2(+) as cathode and anode, it demonstrates excellent direct seawater electrolysis performance, with a low cell voltage of 1.63mV to attain 10mA cm-2 and remarkable stability. This study presents a rapid and efficient method for fabricating cost-effective and highly effective electrocatalysts for hydrogen production in alkaline and alkaline seawater environments.

Zeolitic imidazolate framework-67/barium zirconate titanate nanocomposite, Part I: Synthesis, characterization, and boosted photocatalytic activity

Using BaTi0.85Zr0.15O3/ZIF-67 (BTZ/ZIF-67) nanocomposite, tetracycline (TC) was photodegraded. Characterization of the samples was carried out using a variety of techniques, including XRD, FESEM-EDS (Field Emission Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy), FT-IR (Fourier Transform Infra-Red), TEM (Transmission Electron Microscopy), BET (Brunauer-Emmett-Teller), BJH (Barrett-Joyner-Halenda), PL (Photoluminescence), TG-DTG (Thermogravimetry and Derivative Thermogravimetry), and UV–Vis DRS (Diffuse Reflectance Spectroscopy). BTZ/ZIF-67 nano-composites were synthesized using a one-step co-precipitation method. BTZ (30 %wt)/ZIF-67 showed the most impressive photocatalytic ability among the binary photocatalysts. Averaging the crystallite sizes of the nanocomposite samples identified by Scherrer and Williamson-Hall methods was 43.3 nm and 65.0 nm, respectively. The pHpzc values of samples of BTZ and BTZ (30 %wt)/ZIF-67 were approximately 6.7 and 10.0, respectively. Using the proposed method, we measured 357, 414, and 377 nm absorption edges for ZIF-67, BTZ, and BTZ (30 %wt)/ZIF-67 samples, which correspond to 3.47, 2.99, and 3.28 eV bandgap energies, respectively. The specific surface areas of BTZ, ZIF-67, and BTZ (30 %wt)/ZIF-67 nanocomposite are 122.15, 1218, and 1509 m2g−1, respectively. Under optimum conditions (0.8 g/L of the catalyst, CTC: 30 mg/L, and a pH 5), 89.5 % of total organic carbon (TOC) was removed within 180 min. Compared to BTZ photocatalyst, the BTZ (30 %wt)/ZIF-67 nanocomposite has a significantly larger surface area, thus enhancing photocatalytic activity. A synergistic effect was observed in the photodegradation of TC under Hg-lamp irradiation with the proposed BTZ/ZIF-67 composite. It is possible to alter the photocatalytic activity of the catalyst by changing the BTZ (30 %wt)/ZIF-67 ratio.

Rationally tailored configuration of multifunctional scavengers by encapsulating nanoscale Fe0 and FeS into zeolite imidazole framework–8 with reinforced perrhenate/pertechnetate confinement

In order to probe into the potential application prospects of multifunctional scavengers in remediating nuclear wastewater, we combined versatile functionality of nanoscale Fe0 and FeS with tailorable porosity of zeolitic imidazole frameworks–8 (ZIF–8) to manufacture two multifunctional scavengers for ReO4– confinement i.e., NZVI@ZIF–8 by reduction approach and FeS@ZIF–8 by coprecipitation approach. Batch approaches unveiled that as–manufactured scavengers illustrated an reinforced performance towards ReO4– confinement. The pseudo-second-order model was well simulated with the kinetic of ReO4– confinement. Thermodynamic analysis unraveled that ReO4– confinement was endothermic and spontaneous. The mechanism was explored via characterization alters of structure and composition of NZVI@ZIF–8 and FeS@ZIF–8 before and after ReO4– confinement. Specifically, fourier transform infrared spectrometer (FTIR) and X-ray diffraction (XRD) indicated that NZVI and FeS were successfully encapsulated into ZIF–8, and NZVI@ZIF–8 and FeS@ZIF–8 remained stable after ReO4– confinement. X–ray absorption fine structure (XAFS) unveiled that various Fe mineral phases were formed on the scavenger surfaces under various reaction conditions. X-ray photoelectron spectroscopy (XPS) unraveled existence of Re(VI)/Re(IV) on scavengers surfaces, unveiling ReO4– was initially enriched NZVI@ZIF–8 and FeS@ZIF–8 surfaces with subsequent reduction into Re(VI)/Re(IV). This work proposed an innovative perspective to tailored multifunctional scavengers in nuclear waste management.

Robust ZIF-8 based superhydrophobic coating with anti-icing, anti-corrosion, and substrate universality

The design of superhydrophobic materials based on zeolite imidazolate frameworks (ZIF) has attracted considerable attention due to their exceptional chemical stability, high specific surface area, and environmental friendliness. However, research in the fields of anti-corrosion and anti-icing remains in its infancy, and the mechanical stability of reported ZIF-based superhydrophobic surfaces is generally poor. In this study, we synthesized ZIF-8@PDA materials in an aqueous system and followed with stearic acid (STA) modification to achieve low surface energy, resulting in ZIF-8@PDA@STA. Subsequently, we applied a spray-coating method to sequentially construct WPU and ZIF-8@PDA@STA layer on aluminum alloy substrates, achieving a ZIF-8@PDA@STA/WPU superhydrophobic coating with exceptional mechanical stability. This coating retained its superhydrophobicity even after 5600 cm of abrasion distance. Furthermore, results from surface wettability, electrochemical and anti-icing tests demonstrated that the coated aluminum alloy exhibited excellent interfacial non-wetting, self-cleaning, anti-fouling, and significantly enhanced corrosion resistance and delayed icing properties. Additionally, the facile preparation of this coating on various substrates facilitates the large-scale application of such materials. The construction of this multifunctional ZIF-8 based superhydrophobic coating is expected to greatly expand the application of ZIF materials across diverse fields.

Ammonium perchlorate catalyzed with novel n-Al modified on ZIF-67 with silane coupling agent: Superior catalytic activity, advanced decomposition kinetics and mechanisms

Ammonium perchlorate (AP) is commonly utilized as an oxidizer in composite solid propellants (CSPs), and the thermal decomposition of AP has a significant impact on the combustion behaviour of CSPs. Aluminum nanoparticles (n-Al) as a prospective metal fuel have received a lot of interest, however properly extracting energy from n-Al remains a great challenge. Native oxide layer limits the energetic performance of n-Al by impeding sufficient combustion and slowing down mass/heat transport. Development of the high energy storage based on metastable intermolecular composite (MIC) is always a desirable way. This group of hybrid materials uses zeolitic imidazole framework (ZIF) as the precursors of the metal oxides as the oxidizers in conventional nanothermite. Coating n-Al on the surface of ZIF-67 with a silane coupling agent to erase or disturb the oxide layer on the n-Al surface improves n-Al combustion. n-Al@ZIF-67 was synthesized and integrated into AP matrix. The catalytic activity of n-Al@ZIF-67 on AP decomposition was assessed via DSC and TGA/DTG. Whereas n-Al@ZIF-67/AP nanocomposite demonstrated decomposition enthalpy of 2350 J/g; pure AP demonstrated 836 J/g, ZIF-67/AP demonstrated 1680 J/g, and n-Al/AP demonstrated 1170 J/g. While Al@ZIF-67/AP nanocomposite demonstrated one decomposition temperature at 327 oC; pure AP decompose at two decomposition stages at 298 oC, and 453 oC. n-Al@ZIF-67/AP showed a violent reaction with high intensity of flame, and micro-explosion occurred due to rapidly disrupted oxide layer that covered Al core. Decomposition kinetics was investigated. n-Al@ZIF-67/AP demonstrated apparent activation energy of 125.3 ± 1.23 kJ/mol compared with 173.16 ± 1.95 kJ/mol for pure AP. Co3O4 NPs as the combustion product from ZIF-67 can expose active surface sites; the ability of adsorption of released NH3 gas, which inhibition AP from decomposition, offering efficient combustion. This work provides a new strategy for advanced CSPs by introducing ZIF-67 to construct bifunctional properties for AP decomposition, and n-Al combustion.

In situ growth of ZIF-8 on cellulose microspheres with high doxorubicin loading capacity and pH-sensitive for oral drug delivery

Metal-organic framework (MOF) nanoparticles are a class of porous nanomaterials with wide application prospects. Zeolitic imidazolate framework (ZIF) materials have high loading performance and pH-sensitive characteristics, which means they have great development prospects in the development of drug carrier systems. Herein, cellulose microspheres (CM) were used as a carrier for the nucleation and growth of ZIF-8 nanocrystals. CM@ZIF-8 was prepared in situ, which was more convenient, flexible, cost-effective, and highly safe. CM@ZIF-8, as a novel carrier, was used to monitor the release of the anticancer drug Doxorubicin (DOX) and prevent it from dissipating before reaching its goal. The designed DOX-loaded CM@ZIF-8 (CM@ZIF-8-DOX) system was characterized by FTIR, SEM, N2 sorption isotherm, XRD, and Cytotoxicity assay (cells survival rate 95.08 %). CM@ZIF-8-DOX exhibited controlled drug release behavior in simulated in-vitro tumor microenvironments (81.2 % drug release throughout 72h). CM@ZIF-8 simultaneously had a high loading capacity of DOX (Qe = 159.71 mg∙g−1), and the amount released under acidic conditions (pH 5.0) was greater (63.4 % after 15 h) than under neutral conditions (pH 7.4) due to the detachment of the coordination between metal ions and ligands (37.6 % after 15 h).

Visible light-induced photocatalytic degradation of anticancer drugs via zeolitic imidazole framework (ZIF-8@ZIF-67): mechanistic insights

Visible light-induced photocatalytic degradation of anticancer drugs via zeolitic imidazole framework (ZIF-8@ZIF-67): mechanistic insights

Bimetal-organic framework derived single-atom-like Co/Fe catalysts for peroxydisulfate activation: The dual amplification of radical and nonradical pathways

A novel single-atom-like Co/Fe catalyst (i.e., Co/Fe-N-C) was synthesized by pyrolysis of a Zn/Co/Fe zeolitic imidazolate framework, and applied in peroxydisulfate (PDS) activation for removal of organic contaminants from wastewater. The isolated diatomic metal-nitrogen sites were detected by X-ray adsorption fine-structure. The degradation of four contaminants (i.e., phenol, bisphenol A, 2,4-dichlorophenol, and N-methyl-2-pyrrolidone) with a concentration of 100 mg/L could be degraded separately within 20 min by the Co/Fe-N-C system with 10 mmol/L of PDS, 0.5 g/L of catalyst dosage, and initial pH of 3. Besides, 79.2 % of phenol could be mineralized in 120 min, and the turn-over frequency value of the catalyst was calculated to be 27.17 min−1, which was higher than the commonly reported homogeneous PS-AOPs. Moreover, the Co/Fe-N-C exhibited high stability (mineralization rate over 70 % after 5 cycles), a wide initial pH range (3−9), and high catalytic performance at 5–20 mmol/L of PDS concentrations. Based on the analysis of radical scavenging experiments and electron spin resonance spectra, the radical and non-radical pathways for PDS activation were proved in the system, and the contribution of phenol degradation by each pathway was clarified.

Polymetallic MnW/Co3O4 porous composites derived from polyoxometalate-induced “cage-within-cage” zeolitic imidazolate frameworks with high efficiency towards NOx reduction

Exploitation of highly active, economical and environmentally friendly catalysts is the primary imperative for addressing the pivotal concerns confronting NOx pollution. Transition metal oxides have shown good application prospects in NOx purification due to their plentiful availability and affordable pricing. Herein, a confinement-pyrolysis strategy for preparation of MnW/Co3O4 composites with porous structures and high dispersion of active components transformed from polyoxometalate (POM)-encapsulated zeolitic imidazolate frameworks (ZIFs) was showcased. The strong interaction of Mn and Co contributes to the production of rich Mn3+ and Co3+ content (Mn4+ + Co2+ → Mn3+ + Co3+; Mn2+ + Co3+ → Mn3+ + Co2+). Compared with W/Co3O4, the Mn addition can increase the accessibility of active sites, induce more oxygen vacancies, acid sites and defects formation at the interfacial regions, promote the adsorption and activation of NH3 and NO, resulting in a 10–50 % higher NOx conversion at the 100−300 °C under 40,000 h−1. More encouragingly, experimental results suggested that the Mn-containing catalyst also exhibits much better tolerance against SO2, H2O, and HC than the Mn-free catalyst. This work demonstrates that guest@host POM@ZIF-functionalized derivative materials possess promising application perspective for low-temperature NOx reduction.

Selective micropollutants removal in wastewaters by non-radical activation of peroxymonosulfate: Multiparameter analysis of electron-donating capacity

Understanding the electron-donating capacity (EDC) of pollutants in selective advanced oxidation systems is crucial for efficient wastewater decontamination. A novel catalyst, composed of a zeolitic imidazolate framework (ZIF)-derived Co3O4 and carbon nanotubes (CNTs), was synthesized for peroxymonosulfate (PMS) activation. This multiphase PMS activation system efficiently degraded organic pollutants (OPs) with high EDC, indicated by their Hammett constant (σρ) and energy of the highest occupied molecular orbital (EHOMO), achieving a mineralization rate of 83.63 % within 15 min. Singlet oxygen and Co(IV) were identified as the primary reactive species in wastewater decontamination. The electron transfer pathway played a pivotal role in converting Co(II) to Co(IV) and oxidizing OPs. Moreover, the multiphase PMS activation system maintained high activity and selectivity in practical hospital wastewater decontamination. This study offers insights into selective decontamination for complex wastewaters, leveraging the EDC of OPs and the advantages of non-radical-dominated advanced oxidation processes.

Development of a highly sensitive and selective electrochemical aptasensor for the detection of Staphylococcus aureus in various samples

Food poisoning caused by toxins produced by Staphylococcus aureus (S. aureus) is a significant global public health concern, impacting both developing and developed countries. One effective method for detecting S. aureus is the use of electrochemical aptasensors. This study introduces a highly sensitive and selective electrochemical aptasensor designed for detecting of S. aureus bacteria. The aptasensor incorporates ferrocene (Fc) as an electrochemical signal tag, which is covalently bonded to a zeolitic imidazolate framework-8 (ZIF-8). To enhance the performance of the working electrode, a nanocomposite of three-dimensional reduced graphene oxide and chitosan is used to create a nanomaterial film with a large surface area and excellent conductivity. The S. aureus-specific aptamer sequence is immobilized as the bio-recognition element, and cDNA-ZIF-8-Fc is hybridized with the immobilized aptamer. Differential pulse voltammograms of the modified electrode are recorded before and after the interaction between the immobilized aptamer and S. aureus. The changes in peak current serve as the analytical signal for the quantitative measurement of S. aureus. The designed aptasensor can detect S. aureus within a linear concentration range of 15.0 to 1.5 × 107 CFU mL−1, with a limit of detection (LOD) of 5.3 CFU mL−1. The results demonstrate that the aptasensor effectively quantifies S. aureus selectively in the presence of other bacterial species. Additionally, satisfactory results are obtained when measuring S. aureus in tap water and milk samples.

Enhanced ammonia yield rate from nitrogen on collapsed dodecahedral-shaped Co/NC electrocatalyst

Nowadays, multi-component non-precious metal catalysts have been considered as a significant strategy for enhancing the yield of synthesizing NH3 by electrocatalytic nitrogen reduction reaction (E-NRR). In the present work, carbon composites doped with well-dispersed Co and N (Co/NC) were prepared by pyrolyzing zeolitic imidazolate framework-67 (ZIF-67) at various temperatures protected under a N2 flow. Co/NC exhibits a collapsed dodecahedral morphology with a mesoporous structure (3.5-4 nm). The chemical states of Co/N and the structural defects of C are closely related to the carbonization temperature. In a N2-saturated 0.1 M KOH electrolyte, the as-prepared catalysts exhibit an NH3 yield rate (Y(NH3)) of 60.57 μg h-1 mgcat.-1 and a Faradaic efficiency (FE) of 23.3% at -0.1 V (vs the reversible hydrogen electrode, RHE) at ambient conditions. The enhanced E-NRR activity of Co/NC may primarily originate from an associative distal pathway on the Co-N3-C sites and the carbon defects in an alkaline electrolyte. Specifically, this work presents a three-component E-NRR catalyst with excellent stability and great activity based on Co/NC.

Z-scheme heterostructure of ZnO@NPC/Au/ZnIn2S4 for chemical replacement reaction-mediated signal-on photoelectrochemical assay of mercury ion

Herein, an advanced Zn-based metal organic framework (Zn-MOF) derived ZnO embedded in a nitrogen-doped porous carbon (ZnO@NPC) polyhedron/Au/ three-dimensional (3D) chrysanthemum-like ZnIn2S Z-scheme heterojunction was employed for the chemical replacement reaction-mediated signal-on photoelectrochemical (PEC) sensing detection of mercury ions (Hg2+). The p-type ZnO@NPC polyhedron was initially prepared by carbonising the zeolitic imidazolate framework (ZIF)-8 polyhedron, followed by modification with Au nanoparticles (NPs) via an in situ photocatalytic reduction method. Subsequently, the ZnO@NPC/Au polyhedron was combined with n-type 3D chrysanthemum-like ZnIn2S4 through physical adsorption, forming the ZnO@NPC polyhedron/Au/3D chrysanthemum-like ZnIn2S4 Z-scheme heterostructure. The newly constructed heterostructure exhibited strong visible light–harvesting capacity, and considerably improved photoelectric conversion efficiency. The 3D chrysanthemum-like ZnIn2S4 functioned not only as a photosensitiser but also as an Hg2+ recognition probe. Importantly, the PEC sensor exhibited a considerably increased photocurrent response to Hg2+. This is presumably because the introduction of Hg2+ triggered a selective Zn-to-Hg chemical replacement reaction, leading to the in-situ formation of a ZnO@NPC/Au/ZnIn2S4/HgS heterojunction, which further improved charge separation. Consequently, Hg2+ was sensitively detected with a wide linear range from 0.5 pM to 2 μM and a low detection limit of 0.07 pM. Furthermore, the proposed sensor was validated by detecting Hg2+ in food and aqueous environments, indicating its potential application in food safety and environmental monitoring.

A rewritable and shape memory hydrogel doped with fluorescein-functionalized ZIF-8 for information storage and fluorescent anti-counterfeiting

The emergence of stimuli-responsive fluorescence anti-counterfeiting technology has garnered increasing attention in the era of intelligent internet. Smart fluorescent hydrogels combine the characteristics of luminous materials with the unique structure of hydrogels, offering the potential for dynamic reversible erasing and multi-tiered data encryption. In this work, a fluorescent hydrogel was constructed by zeolitic imidazolate framework-8 loaded with fluorescein and then mixed with polyvinyl alcohol hydrogel, sodium carboxymethyl cellulose and borax, which could be used for image hiding in visible light. The reversible bonds cross-linked fluorescent hydrogel was stretchable and self-healing with a three-dimensional network structure. The hydrogel presented bright green fluorescence under 365 nm UV light, which was quenched by adding copper ions. Meanwhile, the imprint of the hydrogel could be cleared by L-Cysteine and repeatedly recorded information many times. The alkali-induced shape memory capability was further utilized to achieve multi-tiered data encryption by deforming it to a 3D-specific shape through splicing or folding. The rewritable and multi-dimensional encrypted hydrogel is expected to improve data security and reduce resource consumption.

N-coordinated iron sites dispersed in porous carbon frameworks to activate peroxymonosulfate for efficient sulfisoxazole degradation and real hospital wastewater decontamination

Herein, an N-coordinated Fe site dispersed in porous carbon frameworks (Fe-NC) fabricated from zeolitic imidazolate frameworks encapsulated with iron acetylacetonate (Fe(acac)3 @ZIFs) was employed to activate peroxymonosulfate (PMS) for the attenuation of sulfisoxazole (SIZ) and treating real hospital wastewater. The constructed Fe-NC/PMS system exhibited good catalytic stability for SIZ degradation, maintaining excellent degradation performance over multiple cycles with virtually no leaching. The quenching experiments, electron paramagnetic resonance (EPR) capture analyses, and semi-quantitative measurements showed that singlet oxygen (1O2) and high-valent metal-oxo species were mainly responsible for SIZ degradation by Fe-NC/PMS. Significantly, ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) was used to trace 134 pharmaceutical contaminants in real hospital wastewater. Effective degradation was achieved for 87 % of the pharmaceutical contaminants by the Fe-NC/PMS process. Seventy-four pharmaceutical contaminants were eliminated. Taken together, this work successfully established the Fe-NC/PMS technology using the developed iron-based materials and explored its application to real hospital wastewater treatment, providing an eco-friendly and effective strategy for treating wastewater.