Fe-based Metal-organic Frameworks Research Articles

Synthesize of in-situ polymerized PVDF/Fe-MILs membranes for highly efficient organic pollutants degradation and photocatalytic self-cleaning

Catalytic membrane combined with advanced oxidation processes (AOPs) could overcome the problem of secondary pollution that is caused by the difficulty of powder catalyst recovery. In this work, Fe-based metal-organic frameworks (MIL-101(Fe) or NH2-MIL-101(Fe)) were immobilized on polyvinylidene fluoride (PVDF) membrane to construct the photocatalytic membrane for organic pollutants degradation. Herein, the in-situ polymerization of PVDF/MIL-101(Fe) and PVDF/NH2-MIL-101(Fe) membranes were synthesized via non-solvent induced phase conversion method. The experimental results showed that all the catalytic membranes exhibit enhanced photocatalytic activity compared to pristine PVDF membrane. Among them, PVDF/NH2-MIL-101(Fe) (M3) showed the best photocatalytic activity. 90% of methylene blue (MB) was degraded by M3 under 90 min simulated solar irradiation. Moreover, the M3 has excellent stability, the degradation efficiency remained almost unchanged after repeated use 4 times. Free radical trapping experiments showed that superoxide radical (·O2−) is the main reactive species in the photocatalytic degradation of MB. Furthermore, the flux recovery ratio (FRR) of M3 was 83% after 10 min of simulated solar irradiation. MIL-101(Fe) and NH2-MIL-101(Fe) with excellent hydrophilicity and photocatalytic performance can not only endow the photocatalytic membranes with an excellent anti-fouling ability for pollutants but also endow the photocatalytic membranes with good self-cleaning ability for the degradation of the foulants deposited on the membrane. In this study, the PVDF/Fe-MILs membranes show excellent photocatalytic performance, stability and self-cleaning ability, which have broad application prospects in the field of water treatment.

Trinuclear Fe Clusters for Highly Efficient CO2 Photoreduction.

Photocatalytic reduction of CO2 into valuable chemicals or fuels is considered a promising solution to mitigate the energy crisis. In this work, efficient CO2 to CO conversion was achieved, accompanied by a class of trinuclear Fe clusters as photocatalysts. Under optimal conditions, the highest catalytic rate could be up to 140.9 μmol/h in 6 h with the assistance of photosensitizers (PS). The trinuclear Fe Clusters can be used as secondary building units to construct Fe-based metal-organic frameworks (MOFs). However, the catalytic activity of Fe-based MOFs is weaker than that of clusters in both the cases of extra PS-assisted MOFs and integrated PS into MOFs. The simpler synthesis, lower cost, and higher catalytic activity make the Fe clusters a better catalyst. Additionally, steady-state fluorescence tests confirmed the transfer of photogenerated electrons from PS to the clusters during the photocatalytic reaction.

Room temperature synthesized metal organic frameworks of Lawsonia inermis: Potential candidates for sensing and cellular imaging

A novel environmentally benign synthesis of Zn and Fe based metal organic frameworks (MOFs) of Lawsonia inermis leaf extract prepared in-house by a simple room temperature extraction technique is presented. BET isotherm and HRTEM analyses revealed mesoporous nature of the newly synthesized MOFs [6.4 nm (Zn-NLw), 3.6 nm (Fe-NLw)]. Their potential for host-guest interaction facilitating sensing applications was demonstrated by selective binding of histidine (His) and tryptophan (Trp) recognized from fluorescence. Addition of His and Trp, induced significant changes in the emission maxima of MOFs (at 470 nm) demonstrating their sensing capacity for these molecules. Host-guest interaction was further investigated by electrochemical studies evidenced as a function of variation in oxidation-reduction peaks. Cytocompatibility of the MOFs were assessed by MTT assay, impact on cellular architecture, degree of cellular uptake while their application in cell imaging was investigated by confocal microscopy analysis. The results suggest excellent biocompatibility of Zn-NLw and Fe-NLw in vitro with significant level of uptake by cells. Fe-NLw exhibited time dependent subcellular localization with distinct luminescence characteristics at a short time period of 30 min as well as at 2 h. These results therefore validate the potential application of Zn-NLw and Fe-NLw in biosensing and fluorescence based bioimaging.

Fabrication of 3D bi-functional binder-free electrode by hydrothermal growth of MIL-101(Fe) framework on nickel foam: A supersensitive electrochemical sensor and highly stable supercapacitor

In present investigation, we report unique and successful fabrication of 3D bi-functional binder free electrode by hydrothermal growth of Fe based metal organic frameworks on nickel foam (MIL-101(Fe)/NF) for supersensitive electrochemical sensor and high capacitance supercapacitor. The materials characteristics were investigated by XRD, FTIR, RAMAN, FE-SEM, and BET techniques. The FE-SEM results revealed the formation of octahedral spindles nanosheets of MIL-101(Fe) fully covered on the nickel foam. In applications involving an electrochemical sensor or a supercapacitor, the binder-free MIL-101(Fe)/NF electrode provided excellent results by modestly avoiding dead mass of binders. The determination capability of MIL-101(Fe)/NF electrode as an electrochemical sensor of lead (Pb2+) ions has been investigated by differential pulse voltammetry (DPV) technique. According to the findings, the MIL-101(Fe)/NF exhibits excellent sensing performance towards Pb2+ ions with low detection limit of 0.169 nM and high sensitivity of 22.6 µA/M. Moreover, the electrode exhibits ideal sensor characteristics such as good selectivity, reproducibility, repeatability and stability. In addition, the structure of MIL-101(Fe)/NF electrode provides elevated electro-active sites, which altogether provides shorter path for electron passage and electrolyte diffusion process, which resulted in a high specific capacitance. At a scan rate of 10 mVs−1, the MIL-101(Fe)/NF electrode exhibits a specific capacitance of 210 Fg−1. Capacitance retention of greater than 98% is demonstrated by the fabricated electrode, even after 1000 cycles. The present investigated results and novel strategies to develop multifunctional materials will open innovative avenues for material scientist.

In-Situ Formation of NiFe-MOF on Nickel Foam as a Self-Supporting Electrode for Flexible Electrochemical Sensing and Energy Conversion

Ni- and Fe-based metal-organic frameworks (NiFe-MOFs) have abundant valence states and have the potential to be used as bifunctional electrode materials. However, unannealed NiFe-MOFs are still not widely used in electrode materials, including electrochemical sensing, supercapacitors, and overall water splitting. In addition, the direct growth of active material on a conductive carrier has been developed as a binder-free strategy for electrode preparation. This strategy avoids the use of insulating binders and additional electrode treatments, simplifies the preparation process of the NiFe-MOFs, and improves the conductivity and mechanical stability of the electrode. Therefore, in this study, we employed a simple solvothermal method combined with an in situ growth technique to directly grow NiFe-MOF-X (X = 4, 8, 12) nanomaterials of different sizes and morphologies on nickel foam at low reaction temperatures and different reaction times. The NiFe-MOF-8 electrode exhibited high capacitive properties, with an area-specific capacitance of 5964 mF cm−2 at 2 mA cm−2 and excellent durability. On the other hand, NiFe-MOF-12 exhibited strong catalytic activity in electrocatalytic tests performed in a 1 M KOH aqueous solution, demonstrating hydrogen evolution reaction (η10 = 150 mV) and oxygen evolution reaction (η50 = 362 mV) activities. The electrochemical sensing tests demonstrated a good response to BPA. Overall, our results suggest that the direct growth of NiFe-MOFs on nickel foam using a simple solvothermal method combined with an in situ growth technique is a promising strategy.

Cascade amplification of tumor chemodynamic therapy and starvation with re-educated TAMs via Fe-MOF based functional nanosystem

Tumor microenvironment is characterized by the high concentration of reactive oxygen species (ROS), which is an effective key used to open the Pandora’s Box against cancer. Herein, a tumor-targeted nanosystem HFNP@GOX@PFC composed of ROS-cleaved Fe-based metal–organic framework, hyaluronic acid (HA), glucose oxidase (GOX) and perfluorohexane (PFC) has been developed for tumor cascade amplified starvation and chemodynamic therapy (CDT). In response to the high concentration of hydrogen peroxide (H2O2) intratumorally, HFNP@GOX@PFC endocytosed by tumor cells can specially be disassembled and release GOX, PFC and Fe2+, which can collectively starve tumor and self-produce additional H2O2 via competitively glucose catalyzing, supply oxygen to continuous support GOX-mediated starvation therapy, initiate CDT and cascade amplify oxidative stress via Fe2+-mediated Fenton reaction, leading to the serious tumor damage with activated p53 signal pathway. Moreover, HFNP@GOX@PFC also significantly initiates antitumor immune response via re-educating tumor-associated macrophages (TAMs) by activating NF-κB and MAPK signal pathways. In vitro and in vivo results collectively demonstrate that nanosystem not only continuously initiates starvation therapy, but also pronouncedly cascade-amplify CDT and polarize TAMs, consequently efficiently inhibiting tumor growth with good biosafety. The functional nanosystem combined the cascade amplification of starvation and CDT provides a new nanoplatform for tumor therapy.

Fe-based metal-organic framework as a chemiresistive sensor for low-temperature monitoring of acetone gas

This work demonstrates the potential of a novel iron-based metal-organic framework (Fe-MOF or VNU-15) to effectively detect low-concentration volatile organic compounds (VOCs), particularly acetone (CH3COCH3). A facile solvothermal strategy was used to synthesize Fe-MOFs, comprising Fe(II)/Fe(III) and two distinct linkers—BDC (benzene-1,4-dicarboxylate) and NDC (naphthalene-2,6-dicarboxylic acid). As a first step, Fe-MOFs were characterized to determine their pure phase formation and identify their structural and morphological characteristics. Fe-MOFs processed via the solvothermal method demonstrated high crystallinity, high thermal stability, polyhedral crystal-shaped surface morphology, and a surface area of 735 m2g−1, making them suitable for gas-sensing applications. Laboratory-scale gas-sensing devices were fabricated by printing Fe-MOF powder onto patterned interdigitated electrodes, with performance measurements conducted on these devices in response to exposure to various target gases at temperatures between 25 and 200 °C and gas concentrations between 1 and 10 ppm. Gas-sensing tests confirmed that the VNU-15 sensor selectivity detects CH3COCH3 with a gas response of 1.68–10 ppm and a response time of 64 s, followed by a recovery time of 166 s at 50 °C. This study demonstrates the feasibility of using novel MOF-based sensing channels as low-temperature gas sensors, providing new insights into gas-sensing technology.

Metal-Organic Framework with a Redox-Active Bridge Enables Electrochemically Highly Selective Removal of Arsenic from Water.

Selective removal of trace, highly toxic arsenic from water is vital to ensure an adequate and safe drinking water supply for over 230 million people around the globe affected by arsenic contamination. Here, we developed an Fe-based metal-organic framework (MOF) with a ferrocene (Fc) redox-active bridge (termed Fe-MIL-88B-Fc) for the highly selective removal of As(III) from water. At a cell voltage of 1.2 V, Fe-MIL-88B-Fc can selectively separate and oxidize As(III) into the less harmful As(V) state in the presence of a 100- to 1250-fold excess of competing electrolyte, with an uptake capacity of >110 mg-As g-1 adsorbent. The high affinity between the uncharged As(III) and the μ3-O trimer (-36.55 kcal mol-1) in Fe-MIL-88B-Fc and the electron transfer between As(III) and redox-active Fc+ synergistically govern the selective capture and conversion of arsenic. The Fe-based MOF demonstrates high selectivity and capacity to remediate arsenic-contaminated natural water at a low energy cost (0.025 kWh m-3). This study provides valuable guidance for the tailoring of effective and robust electrodes, which can lead to a wider application of electrochemical separation technologies.

Development of an intelligent heterojunction fenton catalyst for chemodynamic/starvation synergistic cancer therapy

Chemodynamic therapy (CDT) as an emerging modality in cancer treatment, its implementation remains a daunting challenge by the lack of smart Fenton catalyst under acidic tumor microenvironments. Herein, we have successfully constructed a Fe3O4@MIL-100 heterojunction by growing Fe-based metal-organic framework (MIL-100) onto the surface of Fe3O4 nanoparticles. The as-made heterojunction after encapsulating glucose oxidase (termed FMG) is demonstrated as a pH-responsive intelligent Fenton nanosystem with the synergistic effect of starvation therapy (ST). Density functional theory (DFT) calculations reveal that such heterojunction could greatly reduce the energy barrier of the Fenton reaction, which better explains the mechanism of Fenton performance improvement. Moreover, the encapsulated glucose oxidase has successfully activated the ST process, in which its generated H2O2 and gluconic acid further improve the CDT efficiency. More O2 from the enhanced CDT in turn promotes the enzymatic reaction of glucose oxidase. The Fenton/cascade enzymatic reaction operates in a self-feedback manner as proposed. In vitro and in vivo experiments demonstrate that such intelligent Fenton nanoreactors provide a powerful anticancer mechanism for effective tumor ablation with enough safety. This work provides insights into the developments of MOF-based heterojunctions as powerful anticancer treatment nanoreactors.

Catalytic thermal degradation of tetracycline based on iron-based MOFs and annealed derivative in dark condition

Excessive use of tetracycline (TC) in livestock farming has led to serious pollution. The catalytic thermal degradation of TC by iron-based metal-organic frameworks (MOFs) was proposed for the first time, and the mechanism was studied. Three Fe-based MOFs with the same composition (MIL-53, MIL-88B, and MIL-101) and their annealing derivatives (collectively designated as Fe-MILs) have the ability to thermo-catalytic TC degradation. Meanwhile, the annealing derivatives showed more excellent degradation performance than raw materials. The improvement of properties after annealing at 350 °C was attributed to the exposure of Fe–O clusters and the formation of oxygen vacancies, which caused by the removal of dicarboxylate ligands. The optimum sample in Fe-MILs exhibited a degradation efficiency of 94.22% for TC within 60min at 70 °C. In addition, the TC removal rate at room temperature (25 °C) could also reach 90.6% by extending the reaction time to 10h. The Mars-van Krevelen mechanism and the surface electron transfer between the catalyst and contaminant were the thermal catalysis mechanisms of the Fe-MILs. The hydroxyl radical was the main active species in the degradation of TC. TC was also found to promote the generation of singlet oxygen and superoxide radical to participate in the subsequent decolorization and degradation of dyes on the catalyst system. In this study, iron-based MOFs and annealed derivative with thermal catalytic performance were discovered, and it was proposed that the influence of thermal catalysis should be considered in the photocatalytic degradation of TC by iron-based MOFs.

Application of Photo-Fenton-Membrane Technology in Wastewater Treatment: A Review.

Photo-Fenton coupled with membrane (photo-Fenton-membrane) technology offers great potential benefits in future wastewater treatment because it can not only degrade refractory organics, but also separate different pollutants from water; additionally, it often has a membrane-self-cleaning ability. In this review, three key factors of photo-Fenton-membrane technology, photo-Fenton catalysts, membrane materials and reactor configuration, are presented. Fe-based photo-Fenton catalysts include zero-valent iron, iron oxides, Fe-metal oxides composites and Fe-based metal-organic frameworks. Non-Fe-based photo-Fenton catalysts are related to other metallic compounds and carbon-based materials. Polymeric and ceramic membranes used in photo-Fenton-membrane technology are discussed. Additionally, two kinds of reactor configurations, immobilized reactor and suspension reactor, are introduced. Moreover, we summarize the applications of photo-Fenton-membrane technology in wastewater, such as separation and degradation of pollutants, removal of Cr(VI) and disinfection. In the last section, the future prospects of photo-Fenton-membrane technology are discussed.

Colorimetric and fluorescence detection of circulating tumor cells based on a bimetallic-organic framework

An ultrasensitive colorimetric and fluorescence dual-readout method was developed for detecting circulating tumor cells (CTCs) using a CuFe-based bimetallic-organic framework (CuFe-NH2-MIL-101, bi-MOF). Incorporation of Cu into an Fe-based metal–organic framework (MOF) led to improved fluorescence compared with that of monometallic analogues. The synthesized bi-MOF exhibited improved fluorescence. The synthesized bi-MOF also exhibited enzyme-mimetic activity. The CTCs were bound by biotinylated antibodies and then selected and enriched by streptavidin-coated magnetic beads. With peroxidase-mimicking activity and enhanced fluorescence, the CuFe bi-MOF functioned as a signal-amplifying nanoprobe for colorimetric and fluorescence detection. The absorbance increased with increasing concentration of tumor cells, whereas the fluorescence intensity gradually decreased. Under optimized conditions, the sensor exhibited a detection range of 102–107 cells mL−1. The detection limit of this cytosensor could reach 7 cells mL−1. Moreover, this sensor showed reliable applicability in real serum samples. Overall, this dual-readout strategy holds potential for the detection of CTCs in clinical diagnostics.

Enhanced efficiency and stability of carbon-based CsPbI2Br perovskite solar cells by introducing metal organic framework-derived Fe3O4@NC interfacial layer

Carbon-based CsPbI2Br perovskite solar cells (C–PSCs) have the advantages of low cost and stable performance, but the poor contact and energy mismatch between the perovskite layer and the carbon electrode lead to low power conversion efficiency (PCE). In this work, uniform spindle-shaped Fe3O4@NC composites have prepared by calcining Fe-based metal organic framework (Fe-MOF) NH2-MIL-88B(Fe), which has synthesized by solvothermal reaction using 2-aminoterephthalic acid as nitrogen and carbon sources. Using Fe3O4@NC composite and UV-Ozone treated Fe3O4@NC composite (Fe3O4@NC UVO) as the interfacial layer between the perovskite layer and the carbon electrode, the devices with a structure of FTO/SnO2/CsPbI2Br/interfacial layer/Carbon exhibit a maximum PCE of 12.25%, which is about 19.28% higher than that of the pristine device. The improved optoelectronic performance is mainly attributed to more matched energy level, denser interface contact, better carrier separation performance and better conductivity. After 19 days of storage at room temperature and ambient humidity, Fe3O4@NC UVO device has retained 87% of the initial PCE. This work provides a simple and effective strategy to improve the PCE and stability of carbon-based CsPbI2Br PSCs with Fe-MOFs-derived carbon materials.

Efficient CO2 Capture under Humid Conditions on a Novel Amide-Functionalized Fe-soc Metal-Organic Framework.

CO2 is the main source of the greenhouse gases, and its capture from flue gas under humid conditions is challenging but important for promoting carbon neutrality. Herein, we report a novel soc topology Fe-based metal-organic framework (Fe-dbai) with highly efficient postcombusion CO2 capture performance by integrating multiple specific functionalities, such as unsaturated metal sites and amide functional groups. The CO2 adsorption capacity and CO2/N2 selectivity of Fe-dbai are high up to 6.4 mmol/g and 64 (298 K, 1 bar), respectively, superior to many other reported MOFs. More importantly, the CO2 working capacity of Fe-dbai under 60% RH conditions preserves 94% of that under dry conditions in the breakthrough experiments of CO2/N2 (15:85, v/v) mixtures. The molecular simulation highlights that the electronegative amide CO- group has a good affinity for CO2 and can improve the interaction between Fe UMS and CO2. Although H2O molecules will occupy a small fraction of the adsorption sites, the confinement effect it produces can enhance the adsorption affinity of the framework for CO2, which results in Fe-dbai retaining most of the CO2 adsorption capacity under humid conditions. The excellent CO2 capture performance makes Fe-dbai a potential candidate for the practical application of CO2 capture.

Hierarchical wormlike engineering: Self-assembled SnS2 nanoflake arrays decorated on hexagonal FeS2@C nano-spindles enables stable and fast sodium storage

The exploitation of advanced electrode materials with an unique hierarchical architecture and physicochemical feature undertakes an extremely prominent role in achieving rapid ion-transport and remarkable performance to further promote the development of highly efficient sodium-ion batteries (SIBs). Herein, a multi-step synthesis tactic involving in-situ polymerization of dopamine, high-temperature sulfuration and subsequent solvothermal was put forward for the construction of exquisitely hierarchical wormlike architecture by growing SnS2 nanoflake arrays on hexagonal FeS2@C nano-spindles (FeS2@C@SnS2) utilizing tailor-made Fe-based metal–organic framework nanorod as an initial template. The experimental results combined with theoretical analysis thoroughly disclose that the successful construction of the hierarchical wormlike FeS2@C@SnS2 architecture can markedly afford sufficient active reaction sites and favorable Na+ adsorption, as well as accelerate ion-diffusion kinetics and enhance surface-capacitive contribution, thereby synergistically making its higher initial coulombic efficiency, more outstanding cycling capability and rate performance than FeS2@C and SnS2 samples. Specifically, the FeS2@C@SnS2 composite delivers an attractive reversible capacity up to 585.7 mAh g−1 over 1000 cycles at 1.0 A g−1, outstanding high-rate, and durable sodium storage features (only 0.07 % capacity fading each cycle over 2800 cycles at 20.0 A g−1). Moreover, ex-situ experimental characterizations systematically unravel the FeS2@C@SnS2 experiences phase transformations of preliminarily proceeding with the Na+ insertion, followed by the conversion and further alloying-dealloying reaction mechanism. Prompted by the above advantages, the FeS2@C@SnS2||Na3V2(PO4)3@C full cell presents its potential application feasibility toward SIBs, achieving good cycling performance and seductive specific capacity.

Visible light enhanced persulfate activation for degradation of tetracycline via boosting adsorption of persulfate by ligand-deficient MIL-101(Fe) icosahedron

In this work, Fe-based metal-organic frameworks (Fe-MOFs) are prepared by a simple solvothermal method, in which acetic acid/N, N-dimethylformamide (HAc/DMF) mixture solvents are employed to regulate the particle morphology, exposed facets and ligand defects. At HAc/DMF = 0/50, 5/45 and 8/42 (volume ratio), the irregular particles (MIL-53(Fe)), elongated icosahedrons (5H-MIL-101(Fe)) and icosahedrons (8H-MIL-101(Fe)) are obtained, respectively. Under visible light irradiation (λ > 420 nm) and the addition of sodium persulfate (PS), 5H-MIL-101(Fe) shows the highest degradation activity for tetracycline (TC). Specifically, 80% of TC has been removed by 5H-MIL-101(Fe) within 25 min, and the degradation kinetics rate is 3.03 times higher than that over MIL-53(Fe). The improvement of catalytic activity is mainly attributed to the active facets exposed and ligand defects of 5H-MIL-101(Fe). Density functional theory (DFT) calculation further confirms that the active facets exposed and ligand defects of 5H-MIL-101(Fe) favor the adsorption and activation of PS, benefiting the generation of •SO4−. Besides, a probable degradation pathway of TC is proposed based on trapping experiments and liquid chromatography-mass spectrometry (LC-MS) test. Furthermore, the toxicities of intermediates are predicted by the quantitative structure-activity relationship (QSAR) mathematical model. This work demonstrates that visible light enhanced PS activation (Vis-PSA) can more effectively degrade organic pollutants, and this work also provides a simple strategy to precisely regulate ligand defects and actively exposed facets of Fe-MOFs to enhance the adsorption and activation of PS.

Photoexcitation of Fe3 O Nodes in MOF Drives Water Oxidation at pH=1 When Ru Catalyst Is Present.

Artificial photosynthesis strives to convert the energy of sunlight into sustainable, eco-friendly solar fuels. However, systems with light-driven water oxidation reaction (WOR) at pH=1 are rare. Broadly used [Ru(bpy)3 ]2+ (bpy=2,2'-bipyridine) photosensitizer has a fixed +1.23 V potential which is insufficient to drive most water oxidation catalysts (WOCs) in acid, while Fe2 O3 , featuring the highly oxidizing holes, is not stable at low pH. Here, the key examples of Fe-based metal-organic framework (MOF) water oxidation photoelectrocatalysts active at pH=1 are presented. Fe-MIL-126 and Fe MOF-dcbpy structures were formed with 4,4'-biphenyl dicarboxylate (bpdc), 2,2'-bipyridine-5,5'-dicarboxylate (dcbpy) linkers and their mixtures. Presence of dcbpy linkers allows integration of metal-based catalysts via coordination to 2,2'-bipyridine fragments. Fe-based MOFs were doped with Ru-based precursors to achieve highly active MOFs bearing [Ru(bpy)(dcbpy)(H2 O)2 ]2+ WOC. Materials were analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infra-red (FTIR) spectroscopy, resonance Raman, X-ray absorption spectroscopy, fs optical pump-probe, electron paramagnetic resonance (EPR), diffuse reflectance and electric conductivity measurements and were modeled by band structure calculations. It is shown that under reaction conditions, FeIII and RuIII oxidation states are present, indicating rate-limiting electron transfer in MOF. Fe3 O nodes emerge as photosensitizers able to drive prolonged O2 evolution in acid. Further developments are possible via MOF's linker modification for enhanced light absorption, electrical conductivity, reduced MOF solubility in acid, Ru-WOC modification for faster WOC catalysis, or Ru-WOC substitution to 3d metal-based systems. The findings give further insight for development of light-driven water splitting systems based on Earth-abundant metals.

Graphene supported FeS2 nanoparticles with sandwich structure as a promising anode for High-Rate Potassium-Ion batteries

Pyrite FeS2 now emerges as a promising anode for potassium-ion batteries (PIBs) due to its low cost and high theoretical capacity. However, the significant volume expansion, low electrical conductivity, and the ambiguous mechanism related to potassium storage severely hinder its development for PIBs anodes. Herein, FeS2 nanostructures are skillfully dispersed on the graphene surface layer by layer (FeS2@C-rGO) to form a sandwich structure by using Fe-based metal organic framework (Fe-MOF) as precursors. The unique structural design can improve the transfer kinetics of K+ and effectively buffer the volume expansion during cycling, thereby enhancing the potassium storage performance. As a result, the FeS2@C-rGO delivers a high capacity of 550 mAh/g at a current density of 0.1 A/g. At a high rate of 2 A/g, the capacity can maintain 171 mAh/g even after 500 cycles. Moreover, the electrochemical reaction mechanism and potassium storage behavior are revealed by in-situ X-ray diffractionand density functional theory calculations. This work not only provides a novel insight into the structural design of electrode materials for high-performance PIBs, but also proposes a valuable understanding of the potassium storage mechanism of the FeS2-based anode.

Research progress on degradation of organic pollutants based on metal–organic frameworks materials

As an advanced oxidation process, Fenton oxidation has attracted much attention because its reactants and products are green and pollution - free. The traditional Fenton oxidation method has some problems, such as high PH requirement and low utilization rate of hydrogen peroxide. Over the past few years, the advancements in application research of Metal-Organic Frameworks (MOFs) have presented innovative and effective ideas for addressing the aforementioned issues. This paper presents the recent advancements in Fenton oxidation technique utilizing Fenton-based materials. Based on literature analysis, it can be seen that Fe-based MOFs were initially used for catalytic reaction and the research shows that the catalytic activity of Fe-based MOFs can be increased by increasing the number of unsaturated Fe metal sites. And the doping of other metals into Fe-based MOF or dual ligand Fe-based MOFs can play a role in changing the structure and increasing the unsaturated metal sites which can further expand the direct application of MOFs in the Fenton oxidation method. However, due to the limited types of iron-based MOFs, non-iron-based MOFs materials and indirect use of MOFs have been reported in the indirect use of MOFs, catalytic active substances can be compounded into MOFs materials through in-situ growth, forming a synergistic effect to improve the efficiency of degradation by means of carbonization or pyrolysis of MOFs, MOFs derived materials can be obtained.

A magnetic porous carbon material derived from an MIL-101(Fe) complex for efficient magnetic solid phase extraction of fluoroquinolone antibiotics.

Extraction and determination of trace hazardous components from complex matrices continue to attract public attention. In this work, magnetic porous carbon (MPC) was prepared for efficient magnetic solid phase extraction (MSPE) of fluoroquinolone (FQ) antibiotics in food and water samples. To prepare the MPC, an Fe-based metal-organic framework (MIL-101(Fe)) was grown on a network of graphene oxide and multi-walled carbon nanotubes through a hydrothermal method, and then a carbonization process under a nitrogen atmosphere was carried out to obtain the MPC with high specific surface area and good magnetism. Four target FQs including ciprofloxacin (CIP), enrofloxacin (ENO), lomefloxacin (LOM) and ofloxacin (OFX) were enriched using the as-prepared MPC and determined by coupled high-performance liquid chromatography. Under the optimal conditions, the established MSPE-HPLC-UV detection method exhibited a linear range of 0.5-800 μg L-1 and detection limits of 0.11-0.18 μg L-1 with relative standard deviations (RSDs) of 0.5-4.8%. When applied in the determination of the above four FQs in real samples such as lake water, milk and pork, good recoveries between 85.2 and 103.7% were obtained, and the RSDs were less than 4.8%. This work indicates that the MPC material can be a good adsorption material and has good application prospects in antibiotics enrichment and/or removal from complex samples.