Electron transfer mediated photo-Fenton-like synergistic catalysis of Fe,Cu-doped MIL-101 coupled with Ag3PO4: Quantitative evaluation and DFT calculations

Widespread use of tetracycline (TC) results in its persistent residue and bioaccumulation in aquatic environments, posing a high toxicity to non-target organisms. In this study, a bimetal-doped composite material Ag3PO4/MIL-101(Fe,Cu) has been designed for the treatment of TC in aqueous solutions. As the molar ratio of Fe/Cu in composite is 1:1, the obtained material AP/MFe1Cu1 is placed in an aqueous environment under visible light irradiation in the presence of 3 mM peroxydisulfate (PDS), which forms a photo-Fenton-like catalytic system that can completely degrade TC (10 mg/L) within 60 min. Further, the degradation rate constant (0.0668 min-1) is 5.66 and 7.34 times higher than that of AP/MFe and AP/MCu, respectively, demonstrating a significant advantage over single metal-doped catalysts. DFT calculations confirm the strong adsorption capacity and activation advantage of PDS on the composite surface. Therefore, the continuous photogenerated electrons (e-) accelerate the activation of PDS and the production of SO4•-, resulting in the stripping of abundant photogenerated h + for TC oxidation. Meanwhile, the internal circulation of FeⅢ/FeⅡ and CuⅡ/CuⅢ in composite also greatly enhances the photo-Fenton-like catalytic stability. According to the competitive dynamic experiments, SO4•- have the greatest contribution to TC degradation (58.93%), followed by 1O2 (23.80%). The degradation intermediates (products) identified by high-performance liquid chromatography-mass spectrometry (HPLC/MS) technique indicate the involvement of various processes in TC degradation, such as dehydroxylation, deamination, N-demethylation, and ring opening. Furthermore, as the reaction proceeds, the toxicity of the intermediates produced during TC degradation gradually decreases, which can ensure the safety of the aquatic ecosystem. Overall, this work reveals the synergy mechanism of PDS catalysis and photocatalysis, as well as provides technical support for removal of TC-contaminated wastewater.

Recent progress of metal-organic framework-based nanozymes with oxidoreductase-like activity

Nanozymes, a class of synthetic nanomaterials possessing enzymatic catalytic properties, exhibit distinct advantages such as exceptional stability and cost-effectiveness. Among them, metal-organic framework (MOF)-based nanozymes have garnered significant attention due to their large specific surface area, tunable pore size and uniform structure. MOFs are porous crystalline materials bridged by inorganic metal ions/clusters and organic ligands, which hold immense potential in the fields of catalysis, sensors and drug carriers. The combination of MOFs with diverse nanomaterials gives rise to various types of MOF-based nanozyme, encompassing original MOFs, MOF-based nanozymes with chemical modifications, MOF-based composites and MOF derivatives. It is worth mentioning that the metal ions and organic ligands in MOFs are perfectly suited for designing oxidoreductase-like nanozymes. In this review, we intend to provide an overview of recent trends and progress in MOF-based nanozymes with oxidoreductase-like activity. Furthermore, the current obstacles and prospective outlook of MOF-based nanozymes are proposed and briefly discussed. This comprehensive analysis aims to facilitate progress in the development of novel MOF-based nanozymes with oxidoreductase-like activity while serving as a valuable reference for scientists engaged in related disciplines.

Preparation of gold nanoparticles loaded MOF-199 for SERS detection of 5-hydroxyindole-3-acetic acid in serum

5-Hydroxyindole-3-acetic acid (5-HIAA) is regarded as a biomarker for diagnosis of carcinoid tumors, and it is of great significance to developing a precision assay for monitoring 5-HIAA levels. In this work, gold nanoparticles loading on the surface of MOF-199 (Au NPs/MOF-199) is prepared to propose a surface enhanced Raman scattering (SERS) assay for 5-HIAA. When 4-mercaptopyridine (4-MPy) is used as a SERS probe, on Au NPs/MOF-199, limit of detection (LOD) at 10-9 mol/L can be achieved. In addition, Au NPs/MOF-199 substrate with good preparation reproducibility shows long-term storage stability at 4 °C. Under optimal condition, the Au NPs/MOF-199-based SERS method is applied to determine 5-HIAA in serum. The concentration linear range is from 10-9 to 10-5 mol/L and LOD is of 6.40 × 10-11 mol/L. Much importantly, Au NPs/MOF-199 substrate exhibits specific response toward 5-HIAA against other metabolites in the serum due to the capturing selectivity from porous MOF-199. The recoveries obtained on spiked human serum samples locate in the span from 94.30% to 106.00% with RSD of 4.01-7.43%. Au NPs/MOF-199-based SERS sensing strategy is a promising avenue for on-field monitoring biomedical species for clinic diagnosis purpose.

Enhanced degradation of tetracycline under natural sunlight through the synergistic effect of Ag3PO4/MIL-101(Fe) photocatalysis and Fenton catalysis: Mechanism, pathway, and toxicity assessment

Here, we show that the adverse environmental and health effects of tetracycline (TC) can be efficiently reduced by encapsulating Ag₃PO₄ into MIL-101(Fe) to construct a Ag₃PO₄/MIL-101(Fe) heterojunction composite through advanced oxidation processes, such as Fenton catalysis, photocatalysis, and photo-Fenton catalysis. Notably, the reaction can be driven by natural sunlight and does not require any artificial energy source. Remarkably, the optimal degradation of TC can be achieved under different compositions of the composite system through photocatalysis and photo-Fenton catalysis. For photo-Fenton catalysis, the maximum degradation rate of TC (2.5730 min^-1) is achieved when the mass ratio of MIL-101(Fe) to Ag₃PO₄ in the composite is 5:1, which is 31.65- and 3.12-fold of that in the Ag₃PO₄ + PDS + Sunlight and MIL-101(Fe) + PDS+ Sunlight catalyst systems, respectively. Moreover, the internal conversion of matrix during photocatalysis and Fenton catalysis processes inhibits the photocorrosion of Ag₃PO₄ and improves the reusability of the composite. Furthermore, it is found that both radical and non-radical species participate in the TC degradation. Besides, the degradation products and catalytic mechanism of Ag₃PO₄ and Ag₃PO₄/MIL-101(Fe) systems are explored. The toxicity evaluation results suggest that the intermediates produced during Ag₃PO₄/MIL-101(Fe) catalysis have a lower biotoxicity than those produced during Ag₃PO₄ catalysis. Overall, this work provides an effective strategy to inhibit the inherent photocorrosion of Ag₃PO₄ and establishes an efficient catalytic system for the treatment of organic-contaminated wastewater under natural sunlight conditions.

Efficient adsorption and degradation of dyes from water using magnetic covalent organic frameworks with a pyridinic structure

Covalent organic frameworks (COFs) have promising applications in environmental remediation owing to their precise directional synthesis and superior adsorption ability. However, magnetic COFs with pyridinic N have not been studied as bifunctional materials for the adsorption and catalytic degradation of dyes. Therefore, in this study, a magnetic COF with a pyridinic structure (BiPy-MCOF) was successfully synthesized using a solvothermal method, which exhibited higher methyl orange (MO) removal than other common adsorbents. The best degradation efficiency via the Fenton-like reaction was obtained by pre-adsorbing MO for 3 h at pH 3.1. Both adsorption and catalytic degradation resulted in better removal of MO under acidic conditions. The introduction of pyridinic N improved MO adsorption and degradation on BiPy-MCOF. The electrostatic potential (ESP) showed that pyridinic N had a strong affinity for MO adsorption. Density functional theory calculations confirmed the potential sites on MO molecules that may be attacked by free radicals. Possible degradation pathways were proposed based on the experimental results. Moreover, BiPy-MCOF could effectively degrade MO at least four times, and a high degradation efficiency was obtained in other dyes applications. The coupling of adsorption and degradation demonstrated that the as-prepared BiPy-MCOF was an effective material for organic dyes removal from water.

Active site regulated Z-scheme MIL-101(Fe)/Bi2WO6/Fe(III) with the synergy of hydrogen peroxide and visible-light-driven photo-Fenton degradation of organic contaminants

Water pollution control is one of the major challenges currently faced. With the development of photocatalytic technology, an increasing number of new and efficient catalysts have been developed, but most of the catalysts have limited light capture ability and catalytic degradation efficiency. Therefore, in this work, hydrogen peroxide was further introduced to establish a photo-Fenton system to improve the photocatalytic effect by constructing a Z-scheme, and the degradation ability of the catalyst was maximized. Moreover, we successfully adhered bismuth tungstate nanosheets onto the surface of a MIL-101(Fe) framework and changed the number of active sites with iron ions of different doping amounts. We found that the number of active sites in the photo-Fenton system does not increase linearly, but increases and decreases regularly, which is similar to the change in band structure after doping. In addition, the results of the radical scavenger experiment and electron paramagnetic resonance (EPR) revealed that both hydroxide radical (˙OH) and superoxide radical (˙O₂^-) participated in methylene blue (MB) degradation, of which ˙OH was the main active species for pollutant degradation. Based on high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, the possible degradation pathways were proposed. We believed that this work will provide insights into the heterojunction photo-Fenton system.

Hierarchical porous metal–organic gels and derived materials: from fundamentals to potential applications

This review summarizes recent progress in the development and applications of metal–organic gels (MOGs) and their hybrids and derivatives dividing them into subclasses and discussing their synthesis, design and structure–property relationship.

Adsorptive removal of dyes from wastewater using a metal-organic framework: A review

Water pollution from synthetic dyes is a growing environmental concern because many dyes have carcinogenic effects on humans and aquatic life. Adsorption is a widely used technology for the separation and removal of dyes from wastewater. However, the dye removal process using conventional adsorbents is not sufficiently efficient for industrial wastewater. Metal-organic frameworks (MOFs) addresses these drawbacks. MOF showed excellent dye removal and degradation capacity owing to its multifunctionality, water-stability, large surface area, tunable pore size and recyclability. Magnetic MOFs retained excellent performance up to several consecutive cycles. Modified MOFs performed as Fenton-like catalysis process which generated abundant reactive radicals that degraded complex organic dyes into simple and less toxic forms which were further adsorbed onto the MOF. This review systematically compiles in-depth studies on the adsorptive removal of dyes from wastewater, MOF adsorption mechanisms, major influencing factors, to adsorption efficiency of MOFs. While all MOFs adsorb dyes through electrostatic attraction, the type of MOF, presence of functional groups, ligands, and pH significantly control the adsorption mechanism. Before developing an MOF, optimization and upgradation of factors and interaction between available adsorption site and adsorbate is needed. Finally, the prospects and new frontiers of MOFs in sustainable water treatment is discussed.

Preparation of novel and highly active magnetic ternary structures (metal-organic framework/cobalt ferrite/graphene oxide) for effective visible-light-driven photocatalytic and photo-Fenton-like degradation of organic contaminants

Herein, MIL-101(Fe), CoFe₂O₄, novel binary (MIL-101(Fe)/CoFe₂O₄, MIL-101(Fe)/GO and CoFe₂O₄/GO), and ternary (MIL-101(Fe)/CoFe₂O₄/(3%)GO and MIL-101(Fe)/CoFe₂O₄/(7%)GO) magnetic composites based upon the MIL-101(Fe) were synthesized. The XRD, FESEM, TEM, EDX, BET-BJH, FTIR, VSM, DRS, PL, EIS and other electrochemical analyses were applied to characterize samples. The MIL/CoFe₂O₄/(3%)GO demonstrated the best performance compared to other samples for visible light photocatalytic and photo-Fenton-like degradation of Direct Red 23 (DtR-23), Reactive Red 198 (ReR-198) dyes as well as Tetracycline Hydrochloride (TC-H) antibiotic. Degradation of dyes using the ternary composite after 70 min of visible light irradiation was greater than that of 99%. The presence of the optimum GO as a strong electron acceptor in MIL/CoFe₂O₄/(3%)GO not only led to the effective separation of charge carriers and thus reduction of their recombination but also increased the absorption of visible light. The composite possessed good durability in terms of stability and reusability. The PL, EIS and electrochemical analyses indicated that the MIL/CoFe₂O₄/(3%)GO improved the optical properties and photocatalytic performance.

Cu2O/Fe3O4/MIL-101(Fe) nanocomposite as a highly efficient and recyclable visible-light-driven catalyst for degradation of ciprofloxacin

Nowadays, the widespread production and use of antibiotics have increased their presence in wastewater systems, posing a potential threat to the environment and human health. The development of advanced materials for treating antibiotics in wastewater has always received special attention. This study aimed to synthesize a novel Cu₂O/Fe₃O₄/MIL-101(Fe) nanocomposite and use it to degrade ciprofloxacin (CIP) antibiotics in an aqueous solution under visible light irradiation. The optical, structural, and morphological attributes of the developed nanocomposite were analyzed by XRD, FTIR, FE-SEM, TGA, DRS, BET, VSM, and UV-Vis techniques. Optimum circumstances for CIP photocatalytic degradation were acquired in 0.5 g L^-1 of catalyst dosage, pH of 7, and CIP concentration of 20 mg L^-1. The degradation efficiency was achieved 99.2% after 105 min of irradiation in optimum circumstances. The chemical trapping experiments confirmed that hydroxyl and superoxide radicals significantly contributed to the CIP degradation process. The results of this study indicated that Cu₂O/Fe₃O₄/MIL-101(Fe) nanocomposite was a highly stable photocatalyst that could effectively remove antibiotics from aqueous solutions. The CIP degradation efficiency only decreased by 6% after five cycles, indicating the excellent recyclability of Cu₂O/Fe₃O₄/MIL-101(Fe) nanocomposites.

A green synthesized recyclable ZnO/MIL-101(Fe) for Rhodamine B dye removal via adsorption and photo-degradation under UV and visible light irradiation

Metal-organic frameworks (MOFs) have recently debuted as participants and solid supports in catalysts for environmental application in water treatment. Visible light active nanocomposites; ZnO/MIL-101(Fe); were synthesized via a hydrothermal method by loading ZnO; prepared by a green method; on a porous MIL-101(Fe) to be used as a heterogeneous catalyst for Rhodamine B dye (RhB) degradation as a model pollutant. The effect of adding acetic acid during the preparation of MIL-101(Fe) was studied; [A] used for the samples prepared by acetic acid. The prepared catalysts were characterized by XPS, XRD, zeta potential, TGA, FTIR, N₂ adsorption-desorption measurements, SEM, EDX, elemental mapping, TEM, and UV-VIS diffuse reflectance spectroscopy. The loading of ZnO on MIL-101(Fe) decreased the band gap from 3.2 eV for ZnO to be 2.85 eV for ZnO/MIL-101(Fe)[A], this low band gap explaining the obtained high activity under visible light irradiation. The mechanism of the photocatalytic degradation of RhB was investigated by introducing different scavengers to compete for the possible reactive species involved in the degradation process. The trapping experiments indicated that h⁺ and ^•OH have a vital role in the RhB degradation. The reusability of MIL-101(Fe) was also investigated after three runs. Thus, the synthesized ZnO/MIL-101(Fe)[A] could be used as an alternative catalyst for the photocatalytic degradation of coloured wastewater as it can successfully degrade 97.1% of Rhodamine B (10 mg/L) with high reaction rate (k = 0.0339 min^-1) under visible light irradiation for 300 min using 0.5 g/L of the catalyst. The as-prepared ZnO/MIL-101(Fe) and ZnO/MIL-101(Fe)[A] have competitive photocatalytic dye degradation activity.

Iron-nickel bimetallic metal-organic frameworks as bifunctional Fenton-like catalysts for enhanced adsorption and degradation of organic contaminants under visible light: Kinetics and mechanistic studies

Iron-nickel bimetallic organic frameworks (FeNi_X-BDC, H₂BDC: terephthalic acid) were developed as bifunctional materials for adsorption and photo-Fenton degradation of organic dyes with different charge properties. Significantly enhanced adsorption capacity of FeNi_1/15-BDC towards methylene blue (MB) and methyl orange (MO) was achieved, 5.3 and 2.6 times higher than that of pristine Fe-BDC, which was attributed to enlarged specific surface area and pore volume and the decreased surface charges induced by Ni doping. The adsorption kinetics demonstrated that chemisorption was dominant and intra-particle diffusion was the rate-controlling step. Two-stage degradation including slow induction stage and rapid oxidation stage fitted with pseudo-zero-order kinetics well. The increased rate constants (2.472 vs. 1.188 min^-1 for MB; 0.616 vs. 0.421 min^-1 for MO) in the induction stage as well as the superior removal capability by asynchronism relative to synchronism jointly corroborating the improved adsorption performance was favor for subsequent degradation. Notably, this heterogeneous system not only exhibited obvious advantages like wider pH working range (3-9), better stability and reusability of catalysts, but also achieved the dual objectives of in-situ decontamination and adsorbent regeneration. The coupling of adsorption and degradation along with synergism between photocatalysis and Fenton-like process are responsible for the reinforced removal of organic contaminants.

Catalytic enrichment of plasma with hydroxyl radicals in the aqueous phase at room temperature

Iron oxide on mesoporous silica gave a synergy with plasma jet for HO˙ radical production at neutral pH.

Integration of homogeneous and heterogeneous advanced oxidation processes: Confined iron dancing with cyclodextrin polymer

A novel catalyst which integrates heterogeneous and homogenous Fenton reactions is designed and fabricated by encapsulating 2,5-dihydroxy-1,4-benzoquinone (2,5-DBQ) in ECDP-Fe₃O₄, a composite of Fe₃O₄ nanoparticles immobilized on a β-cyclodextrin polymer (ECDP) with ethylene diamine tetraacetic acid (EDTA) as cross-linking agent. The 2,5-DBQ@ECDP-Fe₃O₄ has superior catalytic performance for 4-nitrophenol and 2,4-dichlorophenol degradation compared with control systems. Mechanism study revealed that although the initial active site is Fe₃O₄ loaded on ECDP, the actually catalyst is the iron ions released from Fe₃O₄ but confined within the composite. EDTA in β-cyclodextrin polymer can improve both the solubility and adsorption capacity to H₂O₂ of Fe₃O₄. The quinone molecules 2,5-DBQ in the β-cyclodextrin cavity can accelerate Fe³⁺/Fe²⁺ cycle adjacent to the cavity, thus in favor of the decomposition of H₂O₂ into OH as main reactive oxidizing species. The current catalyst integrates the advantages of homogeneous and heterogeneous advanced oxidation processes and is promising in practical applications.

Magnetic Fe3O4-deposited flower-like MoS2 nanocomposites for the Fenton-like Escherichia coli disinfection and diclofenac degradation

Fenton reaction can disinfect bacteria and degrade organic pollutants via the generation of OH through the reaction of Fe(II) and H₂O_2. However, its high efficiency only at very acidic conditions and the formation of Fe(III) sludge limit its practical application. Herein, magnetic Fe₃O₄-deposited flower-like MoS₂ (MF) composites were fabricated to disinfect Escherichia coli and degrade diclofenac (DCF) with addition of small amount of H₂O₂ at a wide pH range (from 3.5 to 9.5). MF can efficiently inactivate bacteria and remove DCF at broad pH from 3.5 to 9.5. For example, 1.2 × 10⁶ CFU mL^-1 cells are completely disinfected by MF in 30 min at pH 6 with 5 mM H₂O₂, while 10 mg L^-1 DCF is fully degraded in 7 min at pH 6 with 1 mM H₂O₂. MoS₂ facilitates the conversion cycle of Fe(III)/Fe(II) and improves the generation of OH. MF can be easily collected by magnet after use. Confocal image, SEM images, the leakage of K⁺ and DNA were employed to determine the damage of cell membrane. Meanwhile, the theoretical density functional theory and the degradation intermediates determination were employed to provide the degradation pathway of DCF. MF exhibit excellent reusability and good catalytic performance towards sanitary sewage.

MIL-101(Cr)–cobalt ferrite magnetic nanocomposite: synthesis, characterization and applications for the sonocatalytic degradation of organic dye pollutants

In this study, for the first time, a novel magnetically recyclable MIL-101(Cr)/CoFe₂O₄ nanocomposite was prepared via a facile solvothermal method. The morphology, structural, magnetic and optical properties of the nanocomposite were characterized via field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), UV-visible spectroscopy (UV-visible) and BET surface area analysis. Furthermore, the sonocatalytic activity of the MIL-101(Cr)-based magnetic nanocomposite was explored for the degradation of organic dye pollutants such as Rhodamine B (RhB) and methyl orange (MO) under ultrasound irradiation in the presence of H₂O₂. Under optimized conditions, the degradation efficiency reached 96% for RhB and 88% for MO. The sonocatalytic activity of MIL-101(Cr)/CoFe₂O₄ was almost 12 and 4 times higher than that of the raw MIL-101(Cr) and pure CoFe₂O₄, respectively. The improved sonocatalytic performance of the as-prepared binary nanocomposite can be attributed to the relatively high specific surface area of MIL-101(Cr) and magnetic property of CoFe₂O₄, as well as the fast generation and separation of charge carriers (electrons and holes) in MIL-101(Cr) and CoFe₂O₄. In addition, the trapping tests demonstrated that ·OH radicals are the main active species in the dye degradation process. Moreover, the most influencing factors on the sonocatalytic activity such as the H₂O₂ amount, initial dye concentration and catalyst dosage were investigated. Finally, the nanocomposite was magnetically separated and reused without any observable change in its structure and performance even after four consecutive runs.

A magnetically separable MIL-101(Cr)/CoFe₂O₄ binary nanocomposite was prepared via a hydrothermal route and applied as a sonocatalyst for the efficient degradation of organic dyes.

Synthesis and characterization of a novel manganese ferrite–metal organic framework MIL-101(Cr) nanocomposite as an efficient and magnetically recyclable sonocatalyst

A magnetic MnFe₂O₄/MIL-101(Cr) nanocomposite was synthesized and applied as a novel sonocatalyst for enhanced degradation of organic dye pollutants.

Enhanced photocatalysis using metal-organic framework MIL-101(Fe) for organophosphate degradation in water

Metal-organic frameworks (MOFs) are attractive novel classes of porous materials with diverse potentiality and easily tailored structures. It is desirable to evaluate the performance of MOFs as photocatalysts for organic contaminant removal in aqueous matrixes. In this study, iron-based MIL-101(Fe) was synthesized and a photo-Fenton reaction system (multiple wavelength light + MIL-101(Fe) + H₂O₂) was developed for elimination of tris(2-chloroethyl) phosphate (TCEP). Degradation pattern of TCEP followed an S-shape curve, which included a slow induction period and a rapid radical oxidation process. Transport of reactants into MIL-101(Fe) and the activation of electron transport within Fe-O clusters of MIL-101(Fe) may be the dominant mechanisms in the induction period, while a pseudo-first-order kinetics was observed in the hydroxyl radical oxidation process. Removal efficiencies in these two stages highly depended on the reaction conditions. Irradiation at 420 nm and acid condition were conductive, while high temperature and high [H₂O₂]:[MIL-101(Fe)] mass ratio accelerated the reaction. Before complete mineralization, eleven degradation products were generated, and the dominant degradation pathways included cleavage, hydroxylation, carbonylation, and carboxylation. Under acid condition (pH = 3), only 1% mass loss was observed after 60-min reaction, but the iron leakage was aggravated when pH increased. Furthermore, this MOF-photo-Fenton system demonstrated a robust performance on TCEP degradation in actual wastewater matrixes under acid condition. Generally, the MOF-photo-Fenton system is a potential technology for elimination of organic pollutants in aqueous solution.

Rapid in situ microwave synthesis of Fe3O4@MIL-100(Fe) for aqueous diclofenac sodium removal through integrated adsorption and photodegradation

Metal-Organic Frameworks (MOFs) are efficient adsorbent and catalyst, however, the prepare of MOFs can be extremely time consuming. The rapid in situ microwave synthesis process offers the possibility of MOFs to a large-scale application. In this study, Fe₃O₄@MIL-100(Fe) was rapidly prepared via microwave in 30 min using Fe₃O₄ as metal precursor and applied as the adsorbent and photocatalyst to remove diclofenac sodium (DCF) from water. Fe₃O₄@MIL-100(Fe) exhibited an excellent adsorption effect to DCF with the maximum adsorption capacities of 400 mg/L. The presence of H₂O₂ could promote the removal of DCF during photocatalytic process. Approximately 99.4% of the DCF was removed in Fe₃O₄@MIL-100(Fe)/vis/H₂O₂ system via adsorption removal and consequent photocatalytic degradation. The high efficiency was attributed to the large BET surface area (1244.62 m²/g) and abundant iron metal sites (Fe(III) and Fe(II)) of Fe₃O₄@MIL-100(Fe). The adsorptive, photocatalytic property of Fe₃O₄@MIL-100(Fe) and the Fenton-like reaction were the main mechanisms for DCF removal. TOC analyzer was served to assess the mineralization of solutions treated by Fe₃O₄@MIL-100(Fe)/vis/H₂O₂ in 12 h. High elimination of TOC (87.8%) was observed during the DCF mineralization process. In addition, the major products were illuminated using HPLC-Q-TOF-MS and DCF degradation pathways were also proposed.

Simultaneous efficient adsorption and accelerated photocatalytic degradation of chlortetracycline hydrochloride over novel Fe-based MOGs under visible light irradiation assisted by hydrogen peroxide

Two novel porous MOGs were prepared for degrading CTC, and JLUE-MOG-1 exhibited an enhanced performance because of the photo-Fenton synergistic effect.

High-Density Ultra-small Clusters and Single-Atom Fe Sites Embedded in Graphitic Carbon Nitride (g-C3N4) for Highly Efficient Catalytic Advanced Oxidation Processes

Ultra-small metal clusters have attracted great attention owing to their superior catalytic performance and extensive application in heterogeneous catalysis. However, the synthesis of high-density metal clusters is very challenging due to their facile aggregation. Herein, one-step pyrolysis was used to synthesize ultra-small clusters and single-atom Fe sites embedded in graphitic carbon nitride with high density (iron loading up to 18.2 wt %), evidenced by high-angle annular dark field-scanning transmission electron microscopy, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and ⁵⁷Fe Mössbauer spectroscopy. The catalysts exhibit enhanced activity and stability in degrading various organic samples in advanced oxidation processes. The drastically increased metal site density and stability provide useful insights into the design and synthesis of cluster catalysts for practical application in catalytic oxidation reactions.