Research on the Construction of a Series of Transition Metal-Substituted Keggin-Type TMSPOMs@PCN-224 Composites through the Encapsulation Method and Their Electron Transfer Mechanism in CO2RR

In order to take advantage of the distinct reversible multielectron transfer properties of polyoxometalates (POMs) and increase the electron density at the active sites during the electrochemical reduction of CO2 (CO2RR), a range of transition metal-doped polyoxometalates (TMSPOMs) was entrapped within the porphyrin-based framework of PCN-224 via an encapsulation method, known as TMSPOMs@PCN-224 (TMSPOMs = [XW11O39MII(H2O)]n-, [XW11O40VIV]n-, M = CoII, MnII; X = Si, n = 6; X = P, n = 5). The central elements (Si, P) and the incorporated transition metals (VIV, CoII, and MnII) both play a role in adjusting the electronic structure and electron transfer during the CO2RR process. Remarkably, the composite material with cobalt substitution displayed significantly improved performance. Through fine-tuning the POM loading, the electrocatalytic activity was optimized, leading to an impressive Faradaic efficiency for CO production (FECO) of 89.9% for SiW11Co@PCN-224, a significant improvement compared to the 12.1% FECO of PCN-224. Furthermore, the electrochemical stability of this catalyst was demonstrated over 20 h. Comparative analyses involving six composite materials indicated a relationship between the negative charge of the polyanions and their ability to facilitate effective electron transfer, ultimately enhancing the catalyst's performance. Meanwhile, these findings were supported by density functional theory (DFT) calculations.

{Ru(C6 H6 )}-Decorating Heteropolymolybdate for Highly Activity Photocatalytic Oxidation of Benzyl Alcohol to Benzaldehyde

An unclassical structure of {Ru(C6 H6 )}-based polyoxometalate, Cs6 H4 [Te2 Mo12 O46 {Ru(C6 H6 )}] ⋅ 16.5H2 O (1), has been successfully constructed from {Te2 Mo12 O46 }-type heteropolymolybdate and {Ru(C6 H6 )} group, which structure type was discovered for the first time. Compound 1 not only possesses strong light-harvesting ability, but also exhibits high carrier separation efficiency and lower charge transfer resistance. Under visible light irradiation, compound 1 displayed excellent catalytic activity and circularity in the conversion of benzyl alcohol to benzaldehyde (yield=94 %; turnover number=500; turnover frequency=20.8 h-1 ). Finally, the electron paramagnetic resonance measurement and energy level matching analysis provide theoretical basis for the derivation of the reaction mechanism.

Inhibition of USP1 ameliorates hypertensive nephropathy through regulating oxidative stress and ferroptosis: A precise treatment via SJB3-019A nanodelivery

Hypertensive nephropathy is second only to diabetes for the causation of chronic kidney disease worldwide. As the mortality and morbidity of hypertensive nephropathy keep increasing, it is important to elucidate its pathogenesis and develop new treatment strategies. In this study, an angiotensin II (Ang II)-induced renal cell system was established, and the expression of ubiquitin specific peptidase 1 (USP1) in human kidney (HK-2) cells was found to be regulated by Ang II treatment through quantitative RT-PCR and Western blot assay. The detection of glutathione peroxidase (GSH-Px), malondialdehyde (MDA) and lipid reactive oxygen species (ROS) levels revealed that interference with USP1 reversed Ang II-induced oxidative stress and ferroptosis, which was enhanced by overexpression of USP1. Subsequently, USP1 inhibitor SJB3-019A loaded in MIL-100 and PEGTK was modified to fabricate SJB3-019A@MIL-PEGTK nanoparticles, which was confirmed to exhibit excellent alleviation of hypertension-induced oxidative stress and ferroptosis in renal cells both in vitro and in vivo. Our study identified an important pathogenesis of hypertensive nephropathy and SJB3-019A@MIL-PEGTK nanoparticle was used to develop an effective clinical treatment for hypertensive nephropathy.

Metal-organic frameworks as photocatalysts in energetic and environmental applications

Metal-organic frameworks (MOFs) are an exciting new class of porous materials with great potential for photocatalytic applications in the environmental and energy sectors. MOFs provide significant advantages over more traditional materials when used as photocatalysts due to their high surface area, adaptable topologies, and functional ability. In this article, we summarize current developments in the use of MOFs as photocatalysts for a variety of applications, such as CO2 reduction, water splitting, pollutant degradation, and hydrogen production. We discuss the fundamental properties of MOFs that make them ideal for photocatalytic applications, as well as strategies for improving their performance. The opportunities and challenges presented by this rapidly expanding field are also highlighted.

Exploring the role of sandwich-type polyoxometalates in {K10(PW9O34)2M4(H2O)2}@PCN-222 (M = Mn, Ni, Zn) for electroreduction of CO2 to CO

To overcome the drawbacks of high solubility and instability of polyoxometalates (POMs) in aqueous solution and to expand their application in the electrocatalytic reduction of CO₂ (ECR), we assemble sandwich-type POMs, K₁₀[(PW₉O₃₄)₂M₄(H₂O)₂] (M = Mn, Ni, Zn, shortened as P₂W₁₈M₄), into the hexagonal channel of a porphyrin-based metal-organic framework (MOF) PCN-222 to form P₂W₁₈M₄@PCN-222 composites. Their ECR behavior displays polyoxoanion-dependent activity. P₂W₁₈Mn₄@PCN-222 demonstrates a faradaic efficiency of 72.6% for the CO product (FE_CO), more than four times that of PCN-222 (FE_CO = 18.1%), and exhibits exceptional electrochemical stability over 36 h. P₂W₁₈Ni₄@PCN-222 and P₂W₁₈Zn₄@PCN-222 slightly increase (26.9%) and decrease (3.2%) in FE_CO, respectively. We combine the results with density functional theory (DFT) calculations to help understand the intrinsic reasons which reveals that the rate-determining step (RDS) reaction energy of P₂W₁₈Mn₄@PCN-222 and P₂W₁₈Ni₄@PCN-222 is significantly reduced compared to that of PCN-222. It is different in P₂W₁₈Zn₄@PCN-222. Frontier molecular orbitals electron distribution results hint at directional electron transfer from P₂W₁₈Mn₄/P₂W₁₈Ni₄ to the porphyrin ring active center in PCN-222, promoting the electro-reduction of CO₂ activity. By contrast, P₂W₁₈Zn₄ may accumulate electrons from PCN-222, thus facilitating the hydrogen evolution reaction (HER). This work reveals the critical role of sandwich-type POMs in manipulating the electron transfer pathway during the electrocatalytic process. Our findings would broaden the scope of POM applications in electrochemical carbon dioxide reduction.

Photoelectrochemical biosensor based on SiW12@CdS quantum dots for the highly sensitive detection of HPV 16 DNA

A highly sensitive biosensor for detecting HPV 16 DNA was prepared based on Keggin-type polyoxometalate (SiW₁₂)-grafted CdS quantum dots (SiW₁₂@CdS QDs) and colloidal gold nanoparticles (Au NPs), which exhibited remarkable selectivity and sensitivity upon target DNA detection because of its excellent photoelectrochemical (PEC) response. Here, an enhanced photoelectronic response ability was achieved with the strong association of SiW₁₂@CdS QDs by polyoxometalate modification, which was developed through a convenient hydrothermal process. Furthermore, on Au NP-modified indium tin oxide slides, a multiple-site tripodal DNA walker sensing platform coupled with T7 exonuclease was successfully fabricated with SiW₁₂@CdS QDs/NP DNA as a probe for detecting HPV 16 DNA. Due to the remarkable conductivity of Au NPs, the photosensitivity of the as-prepared biosensor was improved in an I3-/I- solution and avoided the use of other regents toxic to living organisms. Finally, under optimized conditions, the as-prepared biosensor protocol demonstrated wide linear ranges (15-130 nM), with a limit of detection of 0.8 nM and high selectivity, stability, and reproducibility. Moreover, the proposed PEC biosensor platform offers a reliable pathway for detecting other biological molecules with nano-functional materials.

A facile synthesis of K3PMo12O40/WO3 crystals for effective sonocatalytic performance

Proper treatment of hazardous contaminants in the air, land, and water is crucial to environmental remediation. Sonocatalysis, by using ultrasound and suitable catalysts, has shown its potential in organic pollutant removal. In this work, K₃PMo₁₂O₄₀/WO₃ sonocatalysts were fabricated via a facile solution method at room temperature. Techniques such as powder X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the structure and morphology of the products. By using the K₃PMo₁₂O₄₀/WO₃ sonocatalyst, an ultrasound-assisted advanced oxidation process has been developed for the catalytic degradation of methyl orange and acid red 88. Almost all dyes were degraded within 120 min of ultrasound baths, proving that the K₃PMo₁₂O₄₀/WO₃ sonocatalyst has the advantage of speeding up the decomposition of contaminants. The impacts of key parameters, including catalyst dosage, dye concentration, dye pH, and ultrasonic power were evaluated to understand and reach optimized conditions in sonocatalysis. The remarkable performance of K₃PMo₁₂O₄₀/WO₃ in the sonocatalytic degradation of pollutants provides a new strategy for the application of K₃PMo₁₂O₄₀ in sonocatalysis.

Recent advances of metal-organic framework-based and derivative materials in the heterogeneous catalytic removal of volatile organic compounds

Since the environmental hazards of volatile organic compounds (VOCs) are well known, heterogeneous catalysis has become one of the most popular methods to treat VOCs due to its environmental friendliness and simplicity of operation. Although a large number of reports have reviewed the application of catalytic oxidation for the degradation of VOCs, relatively few reports are based on this direction of metal organic frameworks (MOFs) and MOF derivatives. Herein, this paper reviews the recent applications of heterogeneous catalytic technologies in the degradation of VOCs, including photocatalysis, thermal catalysis and other catalytic approaches. The applications of MOFs and their derivatives in VOCs degradation, such as the progress of MOF-derived metal oxides in the treatment of toluene, were highlighted. The mechanisms of VOCs degradation by different catalytic approaches were systematically presented. Finally, we presented the views and directions of VOCs treatment technology development. We hope that this reaction type-oriented review will provide important insights into MOFs and MOF-derived materials for VOCs pollution control.

Fabrication of Fe-BTC on aramid fabrics for repeated degradation of isoproturon

Catalytic degradation is a promising and ideal technology in environmental remediation. Among them, catalytic oxidation and photocatalysis respectively based on catalysts and photocatalysts both trigger broad interests because of their high removal activity. However, the reusability of the powder catalysts still faces substantial challenges. Here, a simple strategy is proposed to load Fe-BTC catalyst on aramid fabrics (AF) to construct Fe-BTC MOF @ aramid fabric (Fe-BTC@AF) composite materials with layer-by-layer in situ self-assembly methods. The experimental results illustrated that 98% isoproturon could be removed by Fe-BTC@AF₂₀ with oxidant H₂O₂, while the single Fe-BTC@AF₂₀ could photo-degrade 99% isoproturon within 7 h. Meanwhile, it could sustain a high degradation rate of more than 80%, even if it had gone through 5 degradation cycles. Thus, the Fe-BTC@AF composite has a significant advantage in the recycling ability for degradation of isoproturon, which will have potential applications in the efficient removal of organic contaminants in water.

Saiz P, Reizabal A, Wuttke S, Celaya-Azcoaga L, Valverde A, Fernández de Luis R. A State-of-the-Art of Metal-Organic Frameworks for Chromium Photoreduction vs. Photocatalytic Water Remediation

Hexavalent chromium (Cr(VI)) is a highly mobile cancerogenic and teratogenic heavy metal ion. Among the varied technologies applied today to address chromium water pollution, photocatalysis offers a rapid reduction of Cr(VI) to the less toxic Cr(III). In contrast to classic photocatalysts, Metal-Organic frameworks (MOFs) are porous semiconductors that can couple the Cr(VI) to Cr(III) photoreduction to the chromium species immobilization. In this minireview, we wish to discuss and analyze the state-of-the-art of MOFs for Cr(VI) detoxification and contextualizing it to the most recent advances and strategies of MOFs for photocatalysis purposes. The minireview has been structured in three sections: (i) a detailed discussion of the specific experimental techniques employed to characterize MOF photocatalysts, (ii) a description and identification of the key characteristics of MOFs for Cr(VI) photoreduction, and (iii) an outlook and perspective section in order to identify future trends.

Metal-organic framework-based materials for the abatement of air pollution and decontamination of wastewater

Developing new and efficient technologies for environmental remediation is becoming significant due to the increase in global concerns such as climate change, severe epidemics, and energy crises. Air pollution, primarily due to increased levels of H₂S, SO_x, NH₃, NO_x, CO, volatile organic compounds (VOC), and particulate matter (PM) in the atmosphere, has a significant impact on public health, and exhaust gases harm the natural sulfur, nitrogen, and carbon cycles. Similarly, wastewater discharged to the environment with metal ions, herbicides, pharmaceuticals, personal care products, dyes, and aromatics/organic compounds is a risk for health since it may lead to an outbreak of waterborne pathogens and increase the exposure to endocrine-disrupting agents. Therefore, developing new and efficient air and water quality management systems is critical. Metal-organic frameworks (MOFs) are novel materials for which the main application areas include gas storage and separation, water harvesting from the atmosphere, chemical sensing, power storage, drug delivery, and food preservation. Due to their versatile structural motifs that can be modified during synthesis, MOFs also have a great promise for green applications including air and water pollution remediation. The motivation to use MOFs for environmental applications prompted the modification of their structures via the addition of metal and functional groups, as well as the creation of heterostructures by mixing MOFs with other nanomaterials, to effectively remove hazardous contaminants from wastewater and the atmosphere. In this review, we focus on the state-of-the-art environmental applications of MOFs, particularly for water treatment and air pollution, by highlighting the groundbreaking studies in which MOFs have been used as adsorbents, membranes, and photocatalysts for the abatement of air and water pollution. We finally address the opportunities and challenges for the environmental applications of MOFs.

MOF/POM hybrids as catalysts for organic transformations

Insertion of molecular metal oxides, e.g. polyoxometalates (POMs), into metal-organic frameworks (MOFs) opens up new research opportunities in various fields, particularly in catalysis. POM/MOF composites have strong acidity, oxygen-rich surface, and redox capacity due to typical characteristics of POMs and the large surface area, highly organized structures, tunable pore size, and shape are due to MOFs. Such hybrid materials have gained a lot of attention due to astonishing structural features, and hence have potential applications in organic catalysis, sorption and separation, proton conduction, magnetism, lithium-ion batteries, supercapacitors, electrochemistry, medicine, bio-fuel, and so on. The exceptional chemical and physical characteristics of POMOFs make them useful as catalysts in simple organic transformations with high capacity and selectivity. Here, the thorough catalytic study starts with a brief introduction related to POMs and MOFs, and is followed by the synthetic strategies and applications of these materials in several catalytic organic transformations. Furthermore, catalytic conversions like oxidation, condensation, esterification, and some other types of catalytic reactions including photocatalytic reactions are discussed in length with their plausible catalytic mechanisms. The disadvantages of the POMOFs and difficulties faced in the field have also been explored briefly from our perspectives.

Water dispersible cobalt single-atom catalysts with efficient Chemiluminescence enhancement for sensitive bioassay

Single-atom catalysts (SACs) have been applied in various fields as they display extremely high utilization efficiency of catalytic sites. A majority of SACs prepared by high-temperature calcination suffer from poor water dispersion and lose of labelling groups. Herein cobalt SACs (CSACs) were synthesized with a solvothermal method by adopting hybridized MOFs Fe₂O₃/MIL-100(Fe) as the carriers to load cobalt atoms. Compared with original MOFs MIL-100(Fe), the carriers possess superior loading capacity, and the loading amount of cobalt element is up to 4.69 wt%. The implantation of cobalt atoms in hybridized MOFs Fe₂O₃/MIL-100(Fe) vastly improved the specific surface of the carriers for 68 times. CSACs at 1.0 μg mL^-1 can catalyze H₂O₂ to generate numerous reactive oxygen species and enormously boost the chemiluminescent emission of luminol-H₂O₂ system up to 2297 times. The CSACs also exhibit satisfactory dispersion in aqueous medium. Benefiting from these attracting features, the CSACs were applied as sensitive signal probes for detecting carbendazim in Chinese medicinal herbs with a chemiluminescent immunoassay method. The dynamic range is 10 pg mL^-1 - 50 ng mL^-1 and the limit of detection is 1.8 pg mL^-1. The proof-of-principle work paves a pathway to the exploitation of SACs as sensitive probes for tracing biological recognition events.

Recent Progress in the Development of MOF-Based Photocatalysts for the Photoreduction of Cr(VI)

There has been a direct correlation between the rate of industrial development and the spread of pollution on Earth, particularly in the last century. The organic and inorganic pollutants generated from industrial activities have created serious risks to human life and the environment. The concept of sustainability has emerged to tackle the environmental issues in developing chemical-based industries. However, pollutants have continued to be discharged to water resources, and finding appropriate techniques for the removal and remedy of wastewater is in high demand. Chromium is one of the high-risk heavy metals in industrial wastewaters that should be removed via physical adsorption and/or transformed into less hazardous chemicals. Photocatalysis as a sustainable process has received considerable attention as it utilizes sunlight irradiation to remedy Cr^(VI) via a cost-effective process. Numerous photocatalytic systems have been developed up to now, but metal-organic frameworks (MOFs) have gained growing attention because of their unique versatilities and facile structural modulations. A variety of MOF-based photocatalysts have been widely employed for the photoreduction of Cr^(VI). Here, we review the recent progress in the design of MOF photocatalysts and summarize their performance in photoreduction reactions.

Simplified creation of polyester fabric supported Fe-based MOFs by an industrialized dyeing process: Conditions optimization, photocatalytics activity and polyvinyl alcohol removal

MIL-53(Fe) was successfully prepared and deposited on the surface carboxylated polyester (PET) fiber by an optimized conventional solvothermal or industrialized high temperature pressure exhaustion (HTPE) process to develop a PET fiber supported MIL-53(Fe) photocatalyst (MIL-Fe@PET) for the degradation of polyvinyl alcohol (PVA) in water under light emitting diode (LED) visible irradiation. On the basis of several characterizations, MIL-Fe@PET was tested for the photocalytic ability and degradation mechanism. It was found that temperature elevation significantly enhanced the formation and deposition of MIL-53(Fe) with better photocatalytic activity. However, higher temperature than 130°C was not in favor of its photocatalytic activity. Increasing the number of surface carboxyl groups of the modified PET fiber could cause a liner improvement in MIL-53(Fe) loading content and photocatalytic ability. High visible irradiation intensity also dramatically increased photocatalytic ability and PVA degradation efficiency of MIL-Fe@PET. Na₂S₂O₈ was used to replace H₂O₂ as electron acceptor for further promoting PVA degradation in this system. MIL-Fe@PET prepared by HTPE process showed higher MIL-53(Fe) loading content and slightly lower PVA degradation efficiency than that prepared by solvothermal process at the same conditions. These findings provided a practical strategy for the large-scale production of the supported MIL-53(Fe) as a photocatalyst in the future.

Filling Polyoxoanions into MIL-101(Fe) for Adsorption of Organic Pollutants with Facile and Complete Visible Light Photocatalytic Decomposition

Transition metal-substituted polyoxometalates (POMs) were filled into a metal–organic framework (MOF) to construct a series of POM@MOF composites (PMo₁₂O₄₀@MIL-101, PMo₁₁VO₄₀@MIL-101, PMo₁₀V₂O₄₀@MIL-101). The composite materials possess ultra-high adsorption ability, especially for PMo₁₀V₂O₄₀@MIL-101, with an adsorption capacity of 912.5 mg·g⁻¹ for cationic antibiotic tetracycline in wastewater, much higher than that of isolated MIL-101(Fe) and the commonly used adsorption materials, such as activated carbon and graphene oxide. In particular, they can be used as efficient photocatalysts for the photodegradation of antibiotics under visible light irradiation. The complete photodegradation of the adsorbed species can induce the facile reusability of these composites for multiple cycles. This work opens an avenue to introduce POMs into an MOF matrix for the simultaneous adsorption and photodegradation of antibiotics.

Green synthesis of MIL-100(Fe) derivatives and revealing their structure-activity relationship for 2,4-dichlorophenol photodegradation

MIL-100(Fe), a kind of iron-based metal-organic framework materials (MOFs), can be synthesized at room temperature or hydrothermal conditions, which are promising precursor materials for preparing photocatalysts to degrade some recalcitrant chlorophenols in industrial wastewater. However, the relationship between the structural characterization of MIL-100(Fe) derivatives and their photodegradation behavior of chlorophenol pollutants is still unclear. Thus, in this work, a porous Z-scheme α-Fe₂O₃/MIL-100(Fe) composite was successfully fabricated via partial-pyrolysis of MIL-100(Fe) precursor synthesized through green synthesis route, which was further used for degrading high-concentration of 2,4-dichlorophenol under visible-light illumination (λ > 420 nm). The effects of synthesis route and pyrolysis temperature of MIL-100(Fe) on the degradation efficiencies of as-derived materials for 2,4-dichlorophenol were investigated. The structure-activity relationship was illuminated in detail. Otherwise, the influence of several process factors, i.e., initial concentration and pH of the 2,4-dichlorophenol solution, catalyst dosage on the degradation efficiency of 2,4-dichlorophenol has also been performed. The removal efficiency of 2,4-dichlorophenol with the initial concentration of 100 mg L^-1 reached up to 87.65% under optimized conditions. Lastly, the possible mechanism was explored based on trapping experiments and some other characterization results. The study in this paper not only exhibited new insight into the modified α-Fe₂O₃ material with high photocatalytic activity but also provided a promising method for treating wastewater containing 2,4-dichlorophenol or other similar organic pollutants.

Light-Induced Efficient Hydroxylation of Benzene to Phenol by Quinolinium and Polyoxovanadate-Based Supramolecular Catalysts

Direct Hydroxylation of benzene to phenol with high yield and selectivity has been the goal of phenol industrial production. Photocatalysis can serve as a competitive method to realize the hydroxylation of benzene to phenol owing to its cost-effective and environmental friendliness, however it is still a forbidding challenge to obtain good yield, high selectivity and high atom availability meanwhile. Here we show a series of supramolecular catalysts based on alkoxohexavanadate anions and quinolinium ions for the photocatalytic hydroxylation of benzene to phenol under UV irradiation. We demonstrate that polyoxoalkoxovanadates can serve as efficient catalysts which can not only stabilize quinolinium radicals but also reuse H₂ O₂ produced by quinolinium ions under light irradiation to obtain excellent synergistic effect, including competitive good yield (50.1 %), high selectivity (>99 %) and high atom availability.

Heterogenisation of polyoxometalates and other metal-based complexes in metal–organic frameworks: from synthesis to characterisation and applications in catalysis

This review provides a thorough overview of composites with molecular catalysts (polyoxometalates, or organometallic or coordination complexes) immobilised into MOFs via non-covalent interactions.

Boosting free radical type photocatalysis over Pd/Fe-MOFs by coordination structure engineering

The development of novel heterogeneous photocatalytic systems, along with a deep understanding of the relationship between the catalytic center chemical environment and the catalytic performance, is of great significance.

POM@MOF Hybrids: Synthesis and Applications

The hybrid materials that are created by supporting or incorporating polyoxometalates (POMs) into/onto metal–organic frameworks (MOFs) have a unique set of properties. They combine the strong acidity, oxygen-rich surface, and redox capability of POMs, while overcoming their drawbacks, such as difficult handling, a low surface area, and a high solubility. MOFs are ideal hosts because of their high surface area, long-range ordered structure, and high tunability in terms of the pore size and channels. In some cases, MOFs add an extra dimension to the functionality of hybrids. This review summarizes the recent developments in the field of POM@MOF hybrids. The most common applied synthesis strategies are discussed, together with major applications, such as their use in catalysis (organocatalysis, electrocatalysis, and photocatalysis). The more than 100 papers on this topic have been systematically summarized in a handy table, which covers almost all of the work conducted in this field up to now.

Selective Photocatalytic Oxidation of Thioanisole on DUT-67(Zr) Mediated by Surface Coordination

DUT-67(Zr) was obtained by a solvothermal route and applied to photocatalytic selective synthesis of thioanisole under light illuminating. The conversion of thioanisole is up to 95%, and the selectivity of methyl phenyl sulfoxide is 98%. The activity of DUT-67(Zr) is over 10 times higher than that of UiO-66. This great increased activity is attributed to the high percentages of oxygen vacancies on DUT-67(Zr). The ESR result shows there are more oxygen vacancies that can expose high density unsaturated Zr sites on DUT-67(Zr). The in situ FTIR reveals that unsaturated Zr sites on DUT-67(Zr) possess Lewis acidity which facilitate the adsorption of the substrates to form the coordination species, promoting the activation of thioanisole. The absorption edge of DUT-67(Zr) with coordination species red-shifts to 360 nm, which can be presented by DRS. Furthermore, the oxygen molecules can be activated by excited electrons to form ^•O₂^-. Finally, a possible photocatalytic process of oxidating thioanisole to methyl phenyl sulfoxide based on the coordination effect between DUT-67(Zr) and thioanisole is proposed at a molecular level.

Strategies for Incorporating Catalytically Active Polyoxometalates in Metal-Organic Frameworks for Organic Transformations

Polyoxometalates (POMs) can benefit from immobilization on solid supports to overcome their difficulty in processability and stability. Among the reported solid supports, metal-organic frameworks (MOFs) offer a crystalline, versatile platform for depositing highly active POMs. The combination of these structures can at times benefit from the combined reactivity of both the POM and MOF, sometimes synergistically, to improve catalysis while balancing desirable properties like porosity, substrate diffusion, or stability. In this Review, we survey the strategies for immobilizing POMs within MOF structures, with an emphasis on how physical and catalytic properties of the parent materials are affected in the composite when employed in organic transformations.

MIL-100(Fe) and its derivatives: from synthesis to application for wastewater decontamination

MIL-100(Fe), an environmental-friendly and water-stable metal-organic framework (MOF), has caught increasing research and application attention in the recent decade. Thanks to its mesoporous structure and eximious surface area, MIL-100(Fe) has been utilized as precursors for synthesizing various porous materials under high thermolysis temperature, which makes the derivatives of MIL-100(Fe) pretty promising candidates for the decontamination of wastewater. Herein, this review systematically summarizes the versatile synthetic methods and conditions for optimizing the properties of MIL-100(Fe) and its derivatives. Then, diverse environmental applications (i.e., adsorption, photocatalysis, and Fenton-like reaction) of MIL-100(Fe) and its derivatives and the corresponding removal mechanisms are detailed in the discussion. Finally, existing knowledge gaps related to fabrications and applications are discussed to close and promote the future development of MIL-100(Fe) and its derivatives toward environmental applications. Graphical abstract.

MIL-100(Fe)/Ti3C2 MXene as a Schottky Catalyst with Enhanced Photocatalytic Oxidation for Nitrogen Fixation Activities

A new microporous MIL-100(Fe)/Ti₃C₂ MXene composite was constructed as a non-noble metal-based Schottky junction photocatalyst with improved nitrogen fixation ability. Ti₃C₂ MXene nanosheets exhibited excellent metal conductivity and were employed as two-dimensional support to optimize the composite's energy band structure. MIL-100(Fe) with a large specific surface area was used as an adsorbent and a photocatalytic oxidation center. The MIL-100(Fe)/Ti₃C₂ MXene composite not only exhibited higher thermal stability but also showed significantly increased nitrogen fixation activity under visible light. The NO conversion rate of the composite catalyst was about four and three times higher than that of the pure Ti₃C₂ MXene and the pure MIL-100(Fe) samples, respectively. Although adsorption plays an important role in the nitrogen fixation process, the synergistic effects of the Schottky junctions are the main cause of the enhanced photocatalytic activity. The built-in electric field can be generated to form charge-transfer channels, which help to achieve a desirable photocatalytic activity.

Hydrothermal Synthesize of HF-Free MIL-100(Fe) for Isoniazid-Drug Delivery

Sustainable development of drug delivery materials with good biocompatibility and controlled-release is a popular topic among researchers. In this research study, we demonstrated the potential of the metal-organic framework, that is MIL-100(Fe), as a drug delivery platform for isoniazid (INH). The MIL-100(Fe) was prepared by using the hydrofluoric acid-free hydrothermal method. Several physical measurements were conducted to characterize the MIL-100(Fe), including x-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen sorption, and thermal-gravimetric (TG). The synthesized MIL-100(Fe) has octahedron-shaped particles with superior properties, that is large surface area (1456.10 m2/g) and pore volume (1.25 cm3/g). The drug loading rate and capacity were determined by means of adsorption kinetic and isotherm. The studied INH@MIL-100(Fe) adsorption system kinetics follow the pseudo-first-order model, while the isotherm system follows the Langmuir model with the maximum adsorption capacity of 128.5 mg/g at 30 °C. MIL-100(Fe) shows adequate biocompatibility, also exhibits a reasonable and controlled drug release kinetics. The results obtained show that MIL-100 (Fe) can be a good choice of drug delivery platform among other available platforms.

TiO2 nanocrystals with the {001} and {101} facets co-exposed with MIL-100(Fe): an egg-like composite nanomaterial for efficient visible light-driven photocatalysis

The exposure of a specific crystal face to a specific composition or a suitable carrier composition with synergistic effects can effectively improve the photocatalytic activity of the material and enhance its practical value. For choosing an ideal carrier, the primary factor is a large specific surface area. Herein, by using MIL-100(Fe) as the carrier, an egg-like TiO₂/MIL-100(Fe) composite was successfully prepared, for the first time, via a facile two-pot hydrothermal method. XRD, SEM, TEM and other characterization methods showed that when the molar ratio of Ti : Fe was 0.3 : 1, the morphology of the TiO₂/MIL-100(Fe) composite was completely egg-like. The TEM results showed that the {001} and {101} facets of TiO₂ in the TiO₂/MIL-100(Fe) composite were co-exposed. The BET results showed that the TiO₂/MIL-100(Fe) composite had a large specific surface area and pore size. The larger pore size provided an effective channel for the photocatalytic degradation of MB and the interfacial effect of TiO₂ and MIL-100(Fe). The separation efficiency of the photogenerated electron–hole pairs was effectively improved. The efficiency of 30% TiO₂/MIL-100(Fe) in the photocatalytic degradation of MB reached 99.02% in 30 min under visible light. All these findings showed that the composite of the effectively charge-separated photocatalytic semiconductor and the porous MOF with a high specific surface area had a high potential application value for the photocatalytic degradation of organic pollutants.

The exposure of a specific crystal face to a specific composition and the search for a suitable carrier composition with synergistic effects can effectively improve the photocatalytic activity of the material and enhance its practical value.

Removing Cr (VI) in water via visible-light photocatalytic reduction over Cr-doped SrTiO3 nanoplates

It is crucial to develop a high-efficiency visible-light responsive photocatalyst for settling the increasing contamination stemmed from toxic heavy metal ions in wastewater. In this study, Cr-doped SrTiO₃ (CrSTO) nanoplates were synthesized by a facile one-pot solvothermal method with ethylene glycol as both the solvent and morphology controller. The resultant CrSTO nanoplates are about 100 nm in size and 20 nm in thickness, which are composed of SrTiO₃ nanocrystals about 19 nm in diameter. Furthermore, they possess the mesopore 3.0 nm in size, endowing their much higher specific surface area than the commercial SrTiO₃ particles. The Cr element is doped into the crystal lattice of SrTiO₃ by the substitution of Cr³⁺ for Sr²⁺, which enables the absorption edge redshift to the visible light region, thus elevating the visible-light absorption capability. In addition, the CrSTO-0.9 nanoplate with 0.9% Cr element content exhibits the highest photocatalytic performance for the Cr(VI) reduction under visible light irradiation, which can reduce nearly all Cr(VI) within 3.5 h and preserve the excellent stability after six recycles. This kind of CrSTO nanoplates may serve as a potential and promising photocatalyst for efficient Cr(VI) removal in wastewater.