Locking Effect in Metal@MOF with Superior Stability for Highly Chemoselective Catalysis

Copper doped carbon dots for selective determination of regulated aniline additives and safe hair dyeing

BACKGROUND

Hair dyes, as common daily chemical products, have been integrated into human daily life. However, the aniline additives contained in traditional hair dyes pose potential threats to health. Therefore, it is of great importance to develop an eco-friendly and convenient detection method and to explore safe alternatives. In this context, enzymatic catalysis technology has received widespread attention due to its safety and eco-friendliness.

RESULTS

Herein, copper-doped carbon dots (CuCDs) with laccase-like activity were prepared by a one-step calcination of copper sulfate, amaranth and ammonium chloride. The resultant CuCDs are monodispersed ellipsoidal crystals with an average diameter of 3.4 nm and active copper centers similar to that of natural laccase. Enzyme kinetics experiments demonstrated that the maximum rate constant (Vmax) obtained from CuCDs is 59 times greater than that of natural laccase, and the Michaelis-Menten constant (Km) is only about half that of natural laccase, indicating a high affinity for laccase substrate. The CuCDs also exhibited a superior stability in comparison with the natural laccase, as over 90 % of their catalytic activity can be maintained in wide pH, temperatures and more than 30 days storage. In the presence of oxygen, CuCDs can not only catalyze the chromogenic reaction of o-phenylenediamine (OPD) and p-phenylenediamine (PPD), allowing for the selective and rapid quantification of these aniline additives in hair dye products, but also catalyze the polymerization of dopamine (DA) under ambient conditions for hair dyeing.

SIGNIFICANCE

This work not only provides an effective method for the determination of aniline additives in hair dyes, but also offers new approaches for safe hair dyeing, and expands the application of carbon nanomaterials in the cosmetics field.

One-step in-situ growth of histidine-modified ZIF-90 on natural eggshell membrane for efficient extraction of p-nitrophenol and 3-methyl-4-nitrophenol in human urine and environmental water

Monitoring of p-nitrophenol (PNP) and 3-methyl-4-nitrophenol (PNMC) in human urine and environmental water is of great importance for human health assessment and environmental protection, as they are both urinary metabolites of some poisonous pesticides and priority environmental pollutants. However, efficient extraction of trace levels of PNP and PNMC from complex matrices remains challenging. This study presented the synthesis of histidine-modified ZIF-90 on natural eggshell membrane (ESM@His-ZIF-90) via a facile one-step in-situ growth strategy, and its application as an adsorbent for dispersive membrane extraction (DME) of PNP and PNMC in human urine and environmental water. The ESM@His-ZIF-90 exhibited extraordinary extraction efficiency due to the abundant adsorption activity of His-ZIF-90 and the rapid separation of ESM from sample solution. The adsorption behavior of ESM@His-ZIF-90 towards two nitrophenols followed Langmuir isotherm model and pseudo-second-order kinetic model. Notably, the ESM@His-ZIF-90 demonstrated fast adsorption kinetics with adsorption equilibrium achieved in only 10 min. The results of FT-IR, XPS and DFT calculations revealed that the rapid adsorption was attributed to the synergistic effect of π-π EDA, hydrophobic and hydrogen bonding interactions. By coupling ESM@His-ZIF-90-based DME with HPLC-UV, good linearity (R2 ≥ 0.9943) and low limits of detection of 0.25-0.65 μg L-1 were obtained. Finally, the method was successfully applied to the detection of PNP and PNMC in human urine and environmental water, and the method recoveries ranged from 83.0 to 106.1 % with RSDs lower than 7.2 %.

Chemoselective Hydrogenation of Halonitrobenzenes by Platinum Nanoparticles with Auxiliary Co-N4 Single Sites in Sandwiched Catalysts

The chemoselective hydrogenation of halonitrobenzenes to haloanilines is of great importance but remains challenging to simultaneously achieve high catalytic activity, excellent selectivity, and good reusability, especially for ortho-substituted substrates. This is due to the occurrence of hydrogenolysis of halogen groups, as well as the easy migration and aggregation of active species on the catalyst surface during the hydrogenation of nitro groups. In this study, we integrate Pt nanoparticles (NPs) with auxiliary Co-N4 single sites from a porphyrinic metal-organic framework [known as PCN-221(Co)] in a sandwiched nanostructure as a catalyst for the chemoselective hydrogenation of ortho-halonitrobenzenes at 80 °C and 1 MPa H2 in a 50 mL batch microreactor. This sandwiched catalyst achieves 97.3% selectivity for ortho-chloroaniline at nearly complete conversion of ortho-chloronitrobenzene, with an exceptionally high turnover frequency (TOF) of 11,625 h-1 and good reusability over ten cycles, outperforming state-of-the-art heterogeneous supported metal catalysts. Theoretical and experimental investigations reveal that the nitro group in ortho-chloronitrobenzene is preferentially hydrogenated by Pt NPs, while the ortho-chloro group is selectively adsorbed by Co-N4 single sites in PCN-221(Co), preventing its hydrogenolysis and enhancing selectivity for ortho-chloroaniline. Furthermore, the PCN-221(Co) shell in the sandwiched catalyst plays a key role in enriching ortho-chloronitrobenzene and stabilizing the supported Pt NPs, thus leading to high catalytic activity and good reusability. Additionally, at nearly complete conversion of ortho-fluoronitrobenzene and ortho-bromonitrobenzene, this sandwiched Pt catalyst displays 100% selectivity for ortho-fluoroaniline with a TOF of 8680 h-1 and 99.2% selectivity for ortho-bromoaniline with a TOF of 5859 h-1, respectively. When meta- and para-halonitrobenzenes are used as substrates, high activity and excellent selectivity for the corresponding haloanilines are also achieved by the sandwiched Pt catalysts.

Tuning the electronic states of Pd(II) defect-engineered metal-organic framework catalysts for efficient conversion of isocyanides

Recently, defective sites in MOFs have become an important tool for tuning the catalytic performance of MOFs. Herein, we report a heterogeneous catalyst "Pd-UiO-67(N)x" by utilizing the active site of defective MOF to modulate the electronic state of Pd, which demonstrates excellent catalytic performances in the oxidative cyclization reaction of isocyanides with o-aminophenols benefiting from the electron-deficient nature of the Pd species. When the Pd loading in defective Pd-UiO-67(N)x system was decreased to 0.37 mol %, the catalytic efficiency was significantly enhanced and the Pd turnover number (TON) increased to 232, which was 27 and 2.6 times higher than that of homogeneous Pd catalysts and defect-free Pd-UiO-67(N)0, respectively. The open pore structure of d-MOFs supports the adsorption of o-aminophenols. Additionally, the domain-limiting effect of the framework restricts the aggregation of Pd, resulting in good stability of the Pd species, which without significant loss of its activity in five consecutive reaction cycles. This work provides an insight into the improvement of stereoelectronic properties of organometallic catalysts through defect-engineered MOFs.

Pt Nanoparticles Loaded on Bimetallic Porphyrinic MOF for Selective Hydrogenation Reactions

Metal nanoparticles (MNPs) loaded on metal-organic frameworks (MOFs) show promising catalytic performances in various reactions, but finely tuning the electronic properties of MNPs remains challenging. Herein, metal NP-MOF synergy has been finely regulated by incorporating Pt NPs into PCN-224 (FeCo). The as-prepared Pt/PCN-224 (FeCo) exhibited high catalytic activity in the hydrogenation of various carbonyl substrates. Detailed characterizations and mechanistic studies revealed that the Fe/Co sites of the ligands can effectively tune the electronic properties of Pt NPs, which achieved promoted capability to activate H2. The atomic hydrogen (H*) produced by Pt sites mainly migrated to the Co sites to promote the hydrogenation process via hydrogen spillover, thereby enhancing the catalytic activity. This work is devoted to a promising strategy to optimize the catalytic performance of MOF-based nanomaterials by incorporating metal NPs in the thermocatalytic systems.

Fluffy mesoporous Al2O3 supported Ag-In2O3 schottky junction catalysts for selective hydrogenation of CO of α,β-unsaturated aldehydes

Unsaturated alcohols (UOLs) are important fine chemical intermediates. Thus, it is of great significance to design and prepare catalysts for highly selective hydrogenation of CO of α,β-unsaturated aldehydes (UALs). In this paper, a fluffy mesoporous Al2O3-supported Ag-In2O3 catalyst (Ag-In2O3/f-m-Al2O3) was synthesized by employing a two-solvent method, in which Ag and In2O3 form a Mott-Schottky junction and lead to electron transfer from In2O3 to Ag. Electron-rich Ag repels the CC bond owing to "four-electron repulsion", and electron-deficient In2O3 acts as the electrophilic site to adsorb the O atom of the CO bond, thus improving the selectivity towards UOLs. In addition to a larger specific surface area and smaller mass transfer resistance, the fluffy mesopore Al2O3 exhibits a large number of Lewis acid sites, which can further improve UOL selectivity. With the help of Ag-In2O3/f-m-Al2O3, high UOL selectivity can be obtained from UALs containing aliphatic, aromatic and heterocyclic groups. This elaborate design of the catalyst could contribute to the highly selective hydrogenation of UALs to UOLs.

Development of a Zeolitic Imidazolate Framework Based Superhydrophobic Surface with Abrasion Resistance, Corrosion Protection, and Anti-icing

Herein, a superhydrophobic surface was designed and fabricated based on the "lotus effect" construction mechanism. The zeolitic imidazolate framework (ZIF-90) micro-nanoparticles were initially synthesized via a one-pot method, combined with long-chain stearic acid (STA), and subsequently embedded in polyvinyl butyral (PVB) to form a superhydrophobic surface at room temperature. The superhydrophobic surface demonstrated mechanical stability and retained its superhydrophobicity with a water contact angle (CA) greater than 150°, even at a wear distance of 400 cm. The composite coating formed by applying this superhydrophobic surface to magnesium (Mg) alloy exhibited a high corrosion potential (Ecorr = -0.86 V) and a low corrosion current density (icorr = 3.66 × 10-12 A·cm-2) compared to the uncoated Mg substrate (Ecorr = -1.53 V, icorr = 1.14 × 10-4 A·cm-2), indicating that the coating effectively enhances the corrosion resistance of the substrate. Notably, the superhydrophobic composite coating demonstrated corrosion resistance durability with a high charge transfer resistance (Rct = 5.12 × 109 Ω·cm2) after 5 days of immersion in 3.5 wt % NaCl aqueous solution. In addition, the as-prepared superhydrophobic surface also displayed excellent performance in self-cleaning and anti-icing. We believe that this work can facilitate the application of ZIFs on superhydrophobic surfaces and provide a new approach for metal corrosion protection.

Oxygen vacancy-enriched ZIF-8-encapsulated Au nanoparticles for boosting electrochemical dopamine sensing

Rapid and sensitive detection of dopamine (DA) remains a great challenge in biosensing and disease diagnosis. In this work, we proposed a locking in situ reduction series strategy for designing an electrochemical DA sensor. First, an oxygen vacancy-enriched zeolite imidazole framework-8 (ZIF-8) was prepared by facile solvothermal methods, and then Au nanoparticles (Au NPs) were encapsulated within the ZIF-8 (Au@ZIF-8) to obtain an efficient electrochemical DA sensor. The typical porous structure of the ZIF-8 could prevent the aggregation and growth of the Au NPs, thereby improving the activity and stability of the sensor. Under optimal test conditions, the Au@ZIF-8 sensor demonstrated remarkable electrochemical performance for DA detection, with high sensitivity (24.28 μA μM-1 cm-2) in the linear range of 0.5-150 μM and low detection limit (0.003 μM, S/N = 3). Furthermore, the sensor also exhibited good interference resistance and reproducibility. More importantly, DA from bovine serum samples was successfully detected on the Au@ZIF-8 sensor. This study reveals that oxygen vacancy engineering and Au NPs could tune the electronic structure of the sensor and facilitate the adsorption and electrocatalytic oxidation of DA, showing their great potential in the fabrication of biosensors.

Metal nanoparticles encapsulation within multi-shell spongy-core porous microspheres for efficient tandem catalysis

The "one-pot" cascade process involves multiple catalytic conversions followed by a single workup stage. This method has the capability to optimize catalytic efficiency by reducing chemical processes. The key to achieving cascade reactions lies in designing cascade catalysts with well-dispersed, stably immobilized, and accessible noble metal nanoparticles for multiple catalytic conversions. This work presents a strategy for creating long-lasting cascade catalysts by encapsulating Ru and Pd nanoparticles within multi-shell spongy-core porous microspheres (MS-SC-PMs). This cascade catalyst strategy enables the continuous hydrogenation of nitrobenzene to aniline and further to cyclohexylamine, demonstrating both high selectivity and conversion rates. Notably, this approach overcomes the typical challenges associated with noble metal nanoparticles, such as poor stability and recyclability, as it maintains its performance over ten consecutive cycles. Additionally, the MS-SC-PMs have the versatility to encapsulate various metal nanoparticles, providing catalytic versatility, scalability, and a promising avenue for designing long-lasting catalysts loaded with nanoparticles.

3D Covalent Organic Framework Membrane with Interactive Ion Nanochannels for Hydroxide Conduction

Crystalline porous materials, known for their ordered structures, hold promise for efficient hydroxide conductivity in alkaline fuel cells with limited ionic densities. However, the rigid cross-linking of porous materials precludes their processing into membranes, while composite membranes diminish materials' conductivity advantage due to the interrupted phases. Here, we report a self-standing three-dimensional covalent organic framework (3D COF) membrane with efficient OH-transport through its interconnected 3D ionic nanochannels. The large-area, homogeneously connected COF membrane, with an 8 cm diameter and 20 μm thickness, was prepared using an interface polymerization strategy assisted by sacrificial templates of a polyacrylonitrile membrane. At the microscopic level, the introduction of imidazolium salt-building units resulted in a noninterpenetrated structure of 3D COF, creating a 3D interactive continuous hydrophilic channel for OH--conduction. The 3D COF membrane demonstrated high conductivity (169 mS/cm at 80 °C, 100% humidity) and achieved a peak power density of 160 mW/cm2 in H2/O2 single-cell tests. This COF interface polymerization strategy brings new possibilities to address the challenges of porous material membrane formation and is expected to advance their practical applications in the field of ion transport.

Unlocking the catalytic potential of heterogeneous nonprecious metals for selective hydrogenation reactions

Selective hydrogenation has been employed extensively to produce value-added chemicals and fuels, greatly alleviating the problems of fossil resources and green synthesis. However, the design and synthesis of highly efficient catalysts, especially those that are inexpensive and abundant in the earth's crust, is still required for basic research and subsequent industrial applications. In recent years, many studies have revealed that the rational design and synthesis of heterogeneous catalysts can efficaciously improve the catalytic performance of hydrogenation reactions. However, the relationship between nonprecious metal catalysts and hydrogenation performance from the perspective of different catalytic systems still remains to be understood. In this review, we provide a comprehensive and systematic overview of the recent advances in the synthesis of nonprecious metal catalysts for heterogeneous selective hydrogenation reactions including thermocatalytic hydrogenation/transfer hydrogenation, photocatalytic hydrogenation and electrocatalytic reduction. In addition, we also aim to provide a clear picture of the recent design strategies and proposals for the nonprecious metal catalysed hydrogenation reactions. Finally, we discuss the current challenges and future research opportunities for the precise design and synthesis of nonprecious metal catalysts for selective hydrogenation reactions.

Signal Amplification via Nonlinear Femtosecond Laser Filamentation for Trace Metal Ion Detection Using Metal-Organic Framework-Polymer Adsorbents

Signal amplification strategies are essential for enhancing the sensitivity and accuracy of analytical methods. This study introduces an innovative approach that utilizes the nonlinear process of femtosecond laser filamentation as a signal amplifier in combination with metal-organic framework (MOF)-polymer adsorbents. In this method, metal ions adsorbed in the MOF-polymer composite alter the intensity and temporal characteristics of an 800 nm femtosecond laser pulse. These changes significantly impact the spectra produced after filamentation, thus serving as an effective signal amplifier. Using MOF single crystals as metal ion enrichment platforms, we enhance spectral signals and achieve detection limits as low as 0.1 ppb for trace metal ions. The integration of the MOF adsorbent with the extensive spectral modifications induced by femtosecond laser filamentation represents a significant advancement in signal amplification techniques for analytical chemistry and environmental monitoring.

An Acid-Resistant Lanthanide Metal-Organic Framework Based on Tetraphenylethylene as an Electrochemical Nitrite Sensor

Nitrite (NO2-) is attracting increasing attention due to its harmful effect on human health. Thus, it is highly desirable to construct effective electrochemical sensors to detect the presence of NO2-. The majority of electrochemical NO2- detection is focused on alkaline or neutral electrolyte solutions and is rarely reported under acidic conditions. In this work, a tetraphenylethylene (TPE)-based 2D lanthanide metal-organic framework (Ln-MOF), (Me2NH2)[HoIII(tcbpe-F)DMF]•DMF•H2O (1) (tcbpe-F = 4',4‴,4″‴,4″″‴-(ethene-1,1,2,2-tetrayl)tetrakis(3-fluoro-[1,1'-biphenyl]-4-carboxylic acid, DMF = N,N-dimethylformamide)), has been successfully fabricated on carbon paper (CP) by an in situ hydrothermal method. As a NO2- sensor, the fabricated 1 electrode exhibited excellent electrochemical performance in the H2SO4 electrolyte (pH = 1) and offers high sensitivities of 1453.2 and 591.5 μA mM-1 cm-2, with a wide linear detection range of 0.1 μM to 9 M, a low detection limit of 60 nM, excellent specificity even in the presence of various analytes (metal ions, anions, and organic molecules) and real water samples, satisfactory stability, and reproducibility. This is the first report of TPE-based Ln-MOF as a NO2- sensor, and furthermore, a plausible sensing mechanism is confirmed by experiments and theoretical computations.

Mechanochemistry Strategy in Metal/Fe3O4 with High Stability for Superior Chemoselective Catalysis

While noble metal nanoparticles (MNPs) exhibit remarkable performance in heterogeneous catalysis and their incorporation into crystalline materials can fully exploit the combined advantages of both, achieving introduction of nanoclusters during material crystallization, precisely controlling their interactions, and facilitating catalyst recovery remain significant challenges. In this study, Au NPs, Pt NPs, and Pd NPs are supported on magnetic Fe3O4, enabling the modulation of the electronic states of MNPs by adjusting the introduction method. Notably, the catalysts (Pt/Fe3O4, Au/Fe3O4, and Pd/Fe3O4) demonstrate excellent activity in chemoselective reactions: cinnamaldehyde (CAL) hydrogenation (turnover number: 20,135 h-1), nitrobenzene hydrogenation (with 99.9% selectivity for major nitrobenzene derivatives and robust stability at 19 cycles), and 3-nitrophenylacetylene (3-NPA) hydrogenation (yielding up to 98.4% 3-aminophenylacetylene (3-APA)), in stark contrast to the low activity of comparable catalysts. This paper proposes a novel and versatile solid-phase mechanochemistry strategy that achieves precise control over the microenvironment of MNPs while maintaining their inherent activity, thereby offering an effective approach to develop catalysts with high specificity and easy recovery capabilities.

Bismuth Nanoparticles and Single Iron Atoms on Carbon Derived from a Covalent Organic Framework Synergistically Catalyze the Oxygen Reduction Reaction

The utilization of catalysts comprising metal nanoparticle has been beneficial for enhancing the performance of oxygen reduction reaction (ORR). However, the inadequate intrinsic activity of these catalysts still presents a significant challenge, limiting their overall effectiveness. This issue can be addressed by introducing single atoms, which can create a synergistic effect with the nanoparticles to catalyse and thereby improve performance. Nevertheless, the synergistic catalysis of nanoparticles and single atoms is still under investigation. In this study, we fabricated a core-shell structured carbon framework incorporating Fe single atoms and Bi nanoparticles through the pyrolysis of COF and MOF core-shell structures. Introducing Fe single atoms into ZIF-8, with Fe-ZIF-8 as the core and Bi-containing COF as the shell, resulted in higher ORR activity. The catalyst exhibited a half-wave potential of 0.867 V and a high current density of 6.68 mA cm-2 in 0.1 M KOH, which were comparable to those of Pt/C equivalent. This study provides new research concepts for exploring the application of single atoms and nanoparticles in catalytic oxygen reduction reactions through synergistic effects.

Metal-Organic Frameworks (MOFs): Classification, Synthesis, Modification, and Biomedical Applications

Metal-organic frameworks (MOFs) are a new variety of solid crystalline porous functional materials. As an extension of inorganic porous materials, it has made important progress in preparation and application. MOFs are widely used in various fields such as gas adsorption storage, drug delivery, sensing, and biological imaging due to their high specific surface area, porosity, adjustable pore size, abundant active sites, and functional modification by introducing groups. In this paper, the types of MOFs are classified, and the synthesis methods and functional modification mechanisms of MOFs materials are summarized. Finally, the application prospects and challenges of metal-organic framework materials in the biomedical field are discussed, hoping to promote their application in multidisciplinary fields.

High-loading ficin@AuNPs on polymer-UiO-66 surface with enhanced peroxidase-mimetic catalytic activity for colourimetric detection of dopamine

Recently, MOFs@AuNPs composites-based catalysts via anchoring of AuNPs onto metal-organic-frameworks (MOFs) have attracted great attention. However, the influence of the AuNPs loading amounts on the catalytic activity of MOFs@AuNPs composites remains largely unexplored. Here, ficin (Fic) protected AuNPs (Fic@AuNPs) anchored onto the surface of UiO-66-NH2 (UiO) modified with poly(2-vinyl-4,4-dimethyl-2-oxazolidine) (PV) were designed and constructed. The UiOPVFic@AuNPs composites with longer PV chains leading to high-loading Fic@AuNPs exhibited intense peroxidase (POD)-mimetic activity in 3,3'5,5'-tetramethylbenzidine (TMB) oxidation. Further, following the colour-fading, dopamine (DA) was sensitively and selectively monitored in the composites-TMB-H2O2 system. The portable smartphone sensing platform-based colourimetric method had good linearity ranging from 3.34 to 36.7 μM (R2 = 0.995), with a limit of detection of 0.3 μM. This protocol explores high-loading AuNPs on polymer-MOFs composites, providing deep insights into understanding catalytic activity improvements of polymer-MOFs@AuNPs catalysts and revealing their application potential in real biological samples analysis.

Full Selectivity Control over the Catalytic Hydrogenation of Nitroaromatics Into Six Products

A full selectivity control over the catalytic hydrogenation of nitroaromatics leads to the production of six possible products, i.e., nitroso, hydroxylamine, azoxy, azo, hydrazo or aniline compounds, which has however not been achieved in the field of heterogeneous catalysis. Currently, there is no sufficient evidence to support that the catalytic hydrogenation of nitroaromatics with the use of heterogeneous metal catalysts would follow the Haber's mechanistic scheme based on electrochemical reduction. We now demonstrate in this work that it is possible to fully control the catalytic hydrogenation of nitroaromatics into their all six products using a single catalytic system under various conditions. Employing SnO2-supported Pt nanoparticles facilitated by the surface coordination of ethylenediamine and vanadium species enabled this unprecedented selectivity control. Through systematic investigation into the controlled production of all products and their chemical reactivities, we have constructed a detailed reaction network for the catalytic hydrogenation of nitroaromatics. Crucially, using oxygen-isolated characterization techniques is essential for identifying unstable compounds such as nitroso, hydroxylamine, hydrazo compounds. The insights gained from this research offer invaluable guidance for selectively transforming nitroaromatics into a wide array of functional N-containing compounds, both advancing fundamental understanding and fostering practical applications in various fields.

Modulating Electronic States of Cu in Metal-Organic Frameworks for Emerging Controllable CH4/C2H4 Selectivity in CO2 Electroreduction

The intensive study of electrochemical CO2 reduction reaction (CO2RR) has resulted in numerous highly selective catalysts, however, most of these still exhibit uncontrollable selectivity. Here, it is reported for the first time the controllable CH4/C2H4 selectivity by modulating the electronic states of Cu incorporated in metal-organic frameworks with different functional ligands, achieving a Faradaic efficiency of 58% for CH4 on Cu-incorporated UiO-66-H (Ce) composite catalysts, Cu/UiO-66-H (Ce) and that of 44% for C2H4 on Cu/UiO-66-F (Ce). In situ measurements of Raman and X-ray absorption spectra revealed that the electron-withdrawing ability of the ligand side group controls the product selectivity on MOFs through the modulation of the electronic states of Cu. This work opens new prospects for the development of MOFs as a platform for the tailored tuning of selectivity in CO2RR.

Regulating Second-Shell Coordination in Cobalt Single-Atom Catalysts toward Highly Selective Hydrogenation

Manipulating the local coordination environment of central metal atoms in single-atom catalysts (SACs) is a powerful strategy to exploit efficient SACs with optimal electronic structures for various applications. Herein, Co-SACs featured by Co single atoms with coordinating S atoms in the second shell dispersed in a nitrogen-doped carbon matrix have been developed toward the selective hydrogenation of halo-nitrobenzene. The location of the S atom in the model Co-SAC is verified through synchrotron-based X-ray absorption spectroscopy and theoretical calculations. The resultant Co-SACs containing second-coordination shell S atoms demonstrate excellent activity and outstanding durability for selective hydrogenation, superior to most precious metal-based catalysts. In situ characterizations and theoretical results verify that high activity and selectivity are attributed to the advantageous formation of the Co-O bond between p-chloronitrobenzene and Co atom at Co1N4-S moieties and the lower free energy and energy barriers of the reaction. Our findings unveil the correlation between the performance and second-shell coordination atom of SACs.

Close Intimacy between PtIn Clusters and Zeolite Channels for Ultrastability toward Propane Dehydrogenation

Propane dehydrogenation (PDH) serves as a pivotal intentional technique to produce propylene. The stability of PDH catalysts is generally restricted by the readsorption of propylene which can subsequently undergo side reactions for coke formation. Herein, we demonstrate an ultrastable PDH catalyst by encapsulating PtIn clusters within silicalite-1 which serves as an efficient promoter for olefin desorption. The mean lifetime of PtIn@S-1 (S-1, silicalite-1) was calculated as 37317 h with high propylene selectivity of >97% at 580 °C with a weight hourly space velocity (WHSV) of 4.7 h-1. With an ultrahigh WHSV of 1128 h-1, which pushed the catalyst away from the equilibrium conversion to 13.3%, PtIn@S-1 substantially outperformed other reported PDH catalysts in terms of mean lifetime (32058 h), reaction rates (3.42 molpropylene gcat-1 h-1 and 341.90 molpropylene gPt-1 h-1), and total turnover number (14387.30 kgpropylene gcat-1). The developed catalyst is likely to lead the way to scalable PDH applications.

Metalation of metal-organic frameworks: fundamentals and applications

Metalation of metal-organic frameworks (MOFs) has been developed as a prominent strategy for materials functionalization for pore chemistry modulation and property optimization. By introducing exotic metal ions/complexes/nanoparticles onto/into the parent framework, many metallized MOFs have exhibited significantly improved performance in a wide range of applications. In this review, we focus on the research progress in the metalation of metal-organic frameworks during the last five years, spanning the design principles, synthetic strategies, and potential applications. Based on the crystal engineering principles, a minor change in the MOF composition through metalation would lead to leveraged variation of properties. This review starts from the general strategies established for the incorporation of metal species within MOFs, followed by the design principles to graft the desired functionality while maintaining the porosity of frameworks. Facile metalation has contributed a great number of bespoke materials with excellent performance, and we summarize their applications in gas adsorption and separation, heterogeneous catalysis, detection and sensing, and energy storage and conversion. The underlying mechanisms are also investigated by state-of-the-art techniques and analyzed for gaining insight into the structure-property relationships, which would in turn facilitate the further development of design principles. Finally, the current challenges and opportunities in MOF metalation have been discussed, and the promising future directions for customizing the next-generation advanced materials have been outlined as well.

AuNP/MIL-88B-NH2 Nanocomposite for the Valorization of Nitroarene by Green Catalytic Hydrogenation

The efficiency of a catalytic process is assessed based on conversion, yield, and time effectiveness. However, these parameters are insufficient for evaluating environmentally sustainable research. As the world is urged to shift towards green catalysis, additional factors such as reaction media, raw material availability, sustainability, waste minimization and catalyst biosafety, need to be considered to accurately determine the efficacy and sustainability of the process. By combining the high porosity and versatility of metal organic frameworks (MOFs) and the activity of gold nanoparticles (AuNPs), efficient, cyclable and biosafe composite catalysts can be achieved. Thus, a composite based on AuNPs and the nanometric flexible porous iron(III) aminoterephthalate MIL-88B-NH2 was successfully synthesized and fully characterized. This nanocomposite was tested as catalyst in the reduction of nitroarenes, which were identified as anthropogenic water pollutants, reaching cyclable high conversion rates at short times for different nitroarenes. Both synthesis and catalytic reactions were performed using green conditions, and even further tested in a time-optimizing one-pot synthesis and catalysis experiment. The sustainability and environmental impact of the catalytic conditions were assessed by green metrics. Thus, this study provides an easily implementable synthesis, and efficient catalysis, while minimizing the environmental and health impact of the process.

Cu-phen Coordination Enabled Selective Electrocatalytic Reduction of CO2 to Methane

Manipulation of selectivity in the catalytic electrochemical carbon dioxide reduction reaction (eCO2RR) poses significant challenges due to inevitable structure reconstruction. One approach is to develop effective strategies for controlling reaction pathways to gain a deeper understanding of mechanisms in robust CO2RR systems. In this work, by precise introduction of 1,10-phenanthroline as a bidentate ligand modulator, the electronic property of the copper site was effectively regulated, thereby directing selectivity switch. By modification of [Cu3(btec)(OH)2]n, the use of [Cu2(btec)(phen)2]n·(H2O)n achieved the selectivity switch from ethylene (faradaic efficiency (FE) = 41%, FEC2+ = 67%) to methane (FECH4 = 69%). Various in situ spectroscopic characterizations revealed that [Cu2(btec)(phen)2]n·(H2O)n promoted the hydrogenation of *CO intermediates, leading to methane generation instead of dimerization to form C2+ products. Acting as a delocalized π-conjugation scaffold, 1,10-phenanthroline in [Cu2(btec)(phen)2]n·(H2O)n helps stabilize Cuδ+. This work presents a novel approach to regulate the coordination environment of active sites with the aim of selectively modulating the CO2RR.

Construction of Core-Shelled Covalent/Metal-Organic Frameworks for Oxygen Evolution Reaction

Oxygen evolution reaction (OER) is the half-reaction in zinc-air batteries and water splitting. Developing highly efficient catalysts toward OER is a challenge due to the difficulty of removing four electrons from two water molecules. Covalent organic frameworks (COFs) provide the new chance to construct the highly active catalysts for OER, because they have controlled skeletons, porosities, and well-defined catalytic sites. In this work, core-shell hybrids of COF and metal-organic frameworks (MOFs) have first demonstrated to catalyze the OER. The synergetic effects between the COF-shell and MOF-core render the catalyst with higher activity than those from the COF and MOF. And the catalyst achieved an overpotential of 328 mV, with a Tafel slope of 43.23 mV dec-1 in 1 m KOH. The theoretical calculation revealed that the high activity is from the Fe sites in the catalyst, which has suitable binding ability of reactant intermediate (OOH*), and thus contributed high activity. This work gives a new insight to designing COFs in electrochemical energy storage and conversion systems.

Rational Design of NiCo-borate/GO Heterojunction as a High-Performance Supercapacitor Electrode

The bottleneck in the preparation of supercapacitors is how to develop high-energy and high-power-density devices by using appropriate materials. Herein, a novel NixCo3-x-B/GO heterostructure material was synthesized through a simple ultrasonic and precipitation method. The prepared NixCo3-x-B/GO heterostructure exhibits significant improvements in supercapacitor performance than NixCo3-x-B. The presence of GO effectively suppresses the excessive growth and accumulation of NixCo3-x-B; therefore, Ni2.7Co0.3-B/GO exhibits the best performance as an electrode material for supercapacitors: a high specific capacitance (Cm, 1789.72 F g-1@1 A g-1) and excellent rate performance. The asymmetric supercapacitor (ASC) device of Ni2.7Co0.3-B/GO//AC exhibits a Cm of 76.6 F g-1@1 A g-1, a large voltage window of 1.6 V, and a high energy density (ED) of 98.0 Wh kg-1. Furthermore, a flexible, all-solid-state supercapacitor assembled with Ni2.7Co0.3-B/GO as both the positive and negative electrodes demonstrates a Cm of 46.9 F g-1@1 A g-1. Even after multiple folding and bending at various angles, the device maintains excellent performance, showcasing remarkable stability. With a power density (PD) of 479.7 W kg-1, the device achieves a high ED of 60.0 Wh kg-1. This work provides valuable insights into the synergistic effects in electrochemical processes based on heterostructure materials.

The Phase Control of Transition Metallic Elements via Facile Chemical and Physical Syntheses

The crystal phases of metals are important factors to tune the properties of metals, and therefore received extensive attention. Traditionally, phase control is performed within limited numbers of elements by harsh conditions, such as face-centered cubic Fe by high temperature. This review summarizes most reports in metal phase control area, including elements of Fe, Co, Ni, Cu, Ru, Pd, Rh, Os and Au. For every metallic element, the facile phase control methods are systematically introduced, such as epitaxial growth, ball milling, chemical reduction, etc. Their corresponding applications and the mechanisms for phase control are thoroughly discussed.

Ultrafine Ru nanoparticles stabilized by V8C7/C for enhanced hydrogen evolution reaction at all pH

The development of cost-effective electrocatalysts with high efficiency and long durability for hydrogen evolution reaction (HER) remains a great challenge in the field of water splitting. Herein, we design an ultrafine and highly dispersed Ru nanoparticles stabilized on porous V8C7/C matrix via pyrolysis of the metal-organic frameworks V-BDC (BDC: 1,4-benzenedicarboxylate). The obtained Ru-V8C7/C composite exhibits excellent HER performance in all pH ranges. At the overpotential of 40 mV, its mass activity is about 1.9, 4.1 and 9.4 times higher than that of commercial Pt/C in acidic, neutral and alkaline media, respectively. Meanwhile, Ru-V8C7/C shows the remarkably high stability in all pH ranges which, in particular, can maintain the current density of 10 mA cm-2 for over 150 h in 1.0 mol L-1 phosphate buffer saline (PBS). This outstanding HER performance can be attributed to the high intrinsic activity of Ru species and their strong interface interactions to the V8C7/C substrate. The synergistic effect of abundant active sites on the surface and the formed Ru-C-V units at the interface promotes the adsorption of reaction intermediates and the release of active sites, contributing the fast HER kinetics. This work provides a reference for developing versatile and robust HER catalysts by surface and interface regulation for pH tolerance.

Silanol-Assisted High-Yield Nanofabrication of SnO2 Single Crystals with Highly Tunable and Ordered Mesoporosity

Highly ordered mesoporous materials with a single-crystalline structure have attracted broad interest due to their wide applications from catalysis to energy conversion/storage, but constructing them with good controllability and high yields remains a highly daunting task. Herein, we construct a new class of three-dimensionally ordered mesoporous SnO2 single crystals (3DOm-SnO2) with well-defined facets and excellent mesopore tunability. Mechanism studies demonstrate that the silanol groups on ordered silica nanospheres (3DO-SiO2) can induce the efficient heterogeneous crystallization of uniform SnO2 single crystals in its periodic voids by following the hard and soft acid and base theory, affording a much higher yield of ∼96% for 3DOm-SnO2 than that of its solid counterpart prepared in the absence of 3DO-SiO2 (∼1.5%). Benefiting from its permanent ordered mesopores and favorable electronic structure, Pd-supported 3DOm-SnO2 can efficiently catalyze the unprecedented sequential hydrogenation of 4-nitrophenylacetylene to produce 4-nitrostyrene, then 4-nitroethylbenzene, and finally 4-aminoethylbenzene. DFT calculations further reveal the favorable synergistic effect between Pd and 3DOm-SnO2 via moderate electron transfer for realizing this sequential hydrogenation reaction. Our work underlines the crucial role of silanol groups in inducing the high-yield heterogeneous crystallization of 3DOm-SnO2, shedding light on the rational design and construction of various 3DO single crystals that are of great practical significance.

One-pot Construction of Metal Nanoparticles Loaded COF Catalysts for Aqueous Hydrogenation Reactions

The catalysis performance of metal nanoparticles (NPs) will be significantly deteriorated because of their spontaneous agglomeration during practical applications. Covalent-organic frameworks (COFs) materials with functional groups and well-defined channels benefit for the dispersion and anchor of metal ions and the confined growth of metal NPs, working as an ideal platform to compose catalytic systems. In this article, we report a one-pot strategy for the preparation of metal NPs loaded COFs without the need of post-modification. During the polymerization process, the pre-added metal ions were stabilized by the rapidly formed COF oligomers and hardly disturb the construction of COFs. After reduction, metal NPs are uniformly anchored on the COF matrix. Eventually, a wide spectrum of metal NPs, including Au, Pd, Pt, AuPd, CuPd, CuPt and CuPdPt, loaded COFs are successfully prepared. The versatility and metal ions anchoring mechanism are verified with four different COF matrixes. Taking AuPd NPs as example, the resultant AuPd NPs loaded COF materials can selectively decompose ammonium formate and produce hydrogen in-situ, exhibiting over 99 % conversion of hydrodechlorination for chlorobenzenes and nitro-reduction reaction for nitroaromatic compounds under ambient temperature in aqueous solution.

Phosphorus removal from water by the metal-organic frameworks (MOFs)-based adsorbents: A review for structure, mechanism, and current progress

Efficacious phosphate removal is essential for mitigating eutrophication in aquatic ecosystems and complying with increasingly stringent phosphate emission regulations. Chemical adsorption, characterized by simplicity, prominent treatment efficiency, and convenient recovery, is extensively employed for profound phosphorus removal. Metal-organic frameworks (MOFs)-derived metal/carbon composites, surpassing the limitations of separate components, exhibit synergistic effects, rendering them tremendously promising for environmental remediation. This comprehensive review systematically summarizes MOFs-based materials' properties and their structure-property relationships tailored for phosphate adsorption, thereby enhancing specificity towards phosphate. Furthermore, it elucidates the primary mechanisms influencing phosphate adsorption by MOFs-based composites. Additionally, the review introduces strategies for designing and synthesizing efficacious phosphorus capture and regeneration materials. Lastly, it discusses and illuminates future research challenges and prospects in this field. This summary provides novel insights for future research on superlative MOFs-based adsorbents for phosphate removal.

Ultrafine Iridium Nanoparticles Anchored on Co-Based Metal-Organic Framework Nanosheets for Robust Hydrogen Evolution in Alkaline Media

A highly promising electrocatalyst has been designed and prepared for the hydrogen evolution reaction (HER). This involves incorporating well-dispersed Ir nanoparticles into a cobalt-based metal-organic framework known as Co-BPDC [Co(bpdc)(H2O)2, BPDC: 4,4'-biphenyldicarboxylic acid]. Ir@Co-BPDC demonstrates exceptional HER activity in alkaline media, surpassing both commercial Pt/C and recent noble-metal catalysts. Theoretical results indicate that electron redistribution, induced by interfacial bonds, optimizes the adsorption energy of water and hydrogen, thereby enhancing our understanding of the superior properties of Ir@Co-BPDC for HER.

Highly Efficient Iron-Based Catalyst for Light-Driven Selective Hydrogenation of Nitroarenes

Light-driven hydrogenation of nitro compounds to functionalized amines is of great importance yet a challenge for practical applications, which calls for the development of high-performance, nonprecious photocatalysts and efficient catalytic systems. Herein, we report a high-efficiency Fe3O4@TiO2 photocatalyst via a sol-gel and subsequent pyrolysis strategy, which exhibits desirable photothermal hydrogenation performance of nitro compounds to functionalized amines with the excellent selectivity of >90% exceeding those of the state-of-the-art heterogeneous photocatalysts. Our experimental results and theoretical calculations for the first time reveal that Fe3O4 is the major active phase, and the strong metal-support interaction between Fe3O4 and reducible TiO2 further leads to performance improvement, taking advantage of the enhanced photothermal effect and the improved adsorption for the reactant and hydrazine hydrate. Notably, a variety of halonitrobenzenes and pharmaceutical intermediates can be completely converted to functionalized amines with high selectivities, even in gram-scale reactions. This work provides a new insight into the rational design of nonprecious photo/thermo-catalysts for other catalytic reactions.

Metal-Organic-Framework-Based Nanoarrays for Oxygen Evolution Electrocatalysis

The development of highly active and stable electrode materials for the oxygen evolution reaction (OER) is essential for the widespread application of electrochemical energy conversion systems. In recent years, various metal-organic frameworks (MOFs) with self-supporting array structures have been extensively studied because of their high porosity, abundant metal sites, and flexible and adjustable structures. This review provides an overview of the recent progress in the design, preparation, and applications of MOF-based nanoarrays for the OER, beginning with the introduction of the architectural advantages of the nanoarrays and the characteristics of MOFs. Subsequently, the design principles of robust and efficient MOF-based nanoarrays as OER electrodes are highlighted. Furthermore, detailed discussions focus on the composition, structure, and performance of pristine MOF nanoarrays (MOFNAs) and MOF-based composite nanoarrays. On the one hand, the effects of the two components of MOFs and several modification methods are discussed in detail for MOFNAs. On the other hand, the review emphasizes the use of MOF-based composite nanoarrays composed of MOFs and other nanomaterials, such as oxides, hydroxides, oxyhydroxides, chalcogenides, MOFs, and metal nanoparticles, to guide the rational design of efficient OER electrodes. Finally, perspectives on current challenges, opportunities, and future directions in this research field are provided.

Carbon-coated copper nanocrystals with enhanced peroxidase-like activity for sensitive colorimetric determination of 2,4-dinitrophenylhydrazine

Carbon-coated copper nanocrystals (CuNCs) with peroxidase-like activity were hydrothermally prepared by using copper acetate, citric acid (CA) and histidine (His) as the precursors. Various shaped CuNCs, including urchin-like, slab-like and spherical appearance were facilely prepared by addition of different amount of NaNO2 in the precursor solutions. When 3,3',5,5'-tetramethylbenzidine (TMB) was used as the substrate, the CuNCs with urchin-like appearance have greatest peroxidase-like activity and their Michaelis-Menten constant (Km) and the maximum rate constant (νmax) are respectively 8.8 and 1.2 times higher than that obtained from horseradish peroxidase (HRP). The production of reactive oxygen species (ROS) was confirmed by radical quenching and electron spin resonance (ESR) tests. Subsequent studies have found that the CuNCs catalyzed color reaction of TMB can be selectively quenched by the environmental pollutant 2,4-dinitrophenylhydrazine (2,4-DNPH). Thus a new colorimetric method for the determination of 2,4-DNPH with a linear range of 0.60-20 µM was developed and a limit of detection (LOD) as low as 0.166 µM was achieved. The results obtained not only reveal the tunability of the peroxidase-like activity of Cu-based nanomaterials, but also provide a new method for the sensitive determination of environmental contaminate.

Visible-light-induced iron-catalyzed reduction of nitroarenes to anilines

An efficient visible-light-induced iron-catalyzed reduction of nitroarenes to anilines by using N-ethylmorpholine (NEM) as a reductant under mild conditions has been developed. The reaction proceeds with photosensitizer-free conditions and features good to excellent yields and broad functional group tolerance. Preliminary mechanistic investigations showed that this reaction was conducted via ligand-to-metal (NEM to Fe3+) charge transfer and nitro triplet biradical-induced hydrogen atom transfer processes.

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.

Ordered Integration and Heterogenization of Catalysts and Photosensitizers in Metal-/Covalent-Organic Frameworks for Boosting CO2 Photoreduction

ConspectusSolar-driven CO2 reduction into value-added chemicals, such as CO, HCOOH, CH4, and C2+ products, has been regarded as a potential way to alleviate environmental pollution and the energy crisis. In the past decades, numerous pioneered homogeneous catalytic systems composed of soluble photosensitizers (PSs) and catalytic active sites (CASs) have been explored for CO2 photoreduction. Nevertheless, inefficient electron migration based on random collision between CASs and PSs in homogeneous catalytic systems usually causes mediocre performance. Moreover, the relatively poor separation/recycling capability of the homogeneous systems has inevitably reduced their reusability and practicality. The rational combination of PSs and CASs have been proven to play critical roles in the development of highly efficient heterogeneous catalysts to improve their performance, such as anchoring them onto the solid matrixes or connecting them through bridging ligands. However, developing effective assembly strategies to achieve the ordered orientation and uniform heterogenization of PSs and CASs remains a great challenge, mainly due to the lack of crystallinity heterogeneous transformation and structural tailoring ability of traditional solid catalysts. Moreover, due to the lack of assembly and synthesis strategies, many efficient homogeneous photocatalytic systems are still unable to achieve high crystallinity heterogeneous transformation.Metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs) have recently attracted broad interest toward CO2 photocatalysis because of their diverse precursors, well-defined and tailorable structures, abundant exposed CASs and high surface areas, etc. Especially, the highly ordered orientation and uniform combination of PSs and CASs in MOFs and COFs are beneficial for improved light harvesting and charge separation, greatly helping to address the aforementioned challenges. Moreover, the well-defined crystalline structures of MOFs and COFs facilitate the establishment of the structure-activity relationship. Therefore, it is increasingly important to summarize the integration of PSs and catalysts to provide deep insight into MOF/COF-based photocatalysts.In this Account, we summarize the ordered integration of PSs and CASs in MOFs and COFs for CO2 photoconversion and describe the structure-activity relationships to guide the design of effective catalysts. Given the unique structural features of MOFs and COFs, we have emphasized the integration of PSs and CASs to optimize their photocatalytic performance, including the confinement of catalytic active nanoparticles (NPs) into photosensitizing frameworks, co-coordination of PSs and CASs, and ligand-to-metal charge-transfer and anchoring CASs on the secondary building units of the photosensitizing frameworks. The catalytic activity, selectivity, sacrificial agent, and stability of these systems were then discussed. More importantly, MOFs and COFs provide powerful platforms to understand the key steps for boosting CO2 photoreduction and exploring the catalytic mechanism, involving light harvesting, electron-hole separation/migration, and surface redox reactions. Finally, the perspective and challenge of CO2 photoreduction in MOF/COF platforms are further proposed and discussed. It is expected that this Account would provide deep insight into the integration of PSs and catalysts in COFs and MOFs with well-defined structures and afford significant inspiration toward enhanced performance in heterogeneous catalysis.

Enlarging the Ni-O Bond Polarizability in a Phosphorene-Hosted Metal-Organic Framework for Boosted Water Oxidation Electrocatalysis

The emerging lattice-oxygen oxidation mechanism (LOM) presents attractive opportunities for breaking the scaling relationship to boost oxygen evolution reaction (OER) with the direct OLattice-*O interaction. However, currently the LOM-triggering rationales are still debated, and a streamlined physicochemical paradigm is extremely desirable for the design of LOM-defined OER catalysts. Herein, a Ni metal-organic framework/black phosphorene (NiMOF/BP) heterostructure is theoretically profiled and constructed as a catalytic platform for the LOM-derived OER studies. It is found that the p-type BP host can enlarge the Ni-O bond polarizability of NiMOF through the Ni-O bond stretching and Ni valence declining synergically. Such an enlarged bond polarizability will in principle alleviate the lattice oxygen confinement to benefit the LOM pathway and OER performance. As a result, the optimized NiMOF/BP catalyst exhibits promising OER performance with a low overpotential of 260 mV at 10 mA cm-2 and long-term stability in 1 M KOH electrolyte. Both experiment and calculation results suggest the activated LOM pathway with a more balanced step barrier in the NiMOF/BP OER catalyst. This research puts forward Ni-O bond polarizability as the criterion to design LOM-scaled electrocatalysts for water oxidation.

New Function of Metal-Organic Framework: Structurally Ordered Metal Promoter

The remarkable roles of metal promoters have been known for nearly a century, but it is still a challenge to find a suitable structure model to reveal the action mechanism behind metal promoters. Herein, a new function of metal-organic frameworks (MOFs) is developed as an ideal model to construct structurally ordered metal promoters by a targeted post-modification strategy. MOFs as model not only favor clearing the real action mechanism behind metal promoters, but also can anchor one or multiple kinds of metal promoters especially noble metal promoters. Typically, the as-prepared Pd/bpy-UiO-Cu catalysts show high selectivity (>99%) toward 4-nitrophenylethane in 4-nitrostyrene hydrogenation, mainly due to the enhanced interaction between Pd nanoparticles and MOF carriers induced by Cu promoters, thus inhibiting the hydrogenation of 4-nitrophenylethane. This strategy with flexibility and universality will open up a new route to synthesize efficient catalysts with structurally ordered metal promoters.

Surface ligand-assisted synthesis and biomedical applications of metal-organic framework nanocomposites

Metal-organic framework (MOF) nanocomposites have recently gained intensive attention for biosensing and disease therapy applications owing to their outstanding physiochemical properties. However, the direct growth of MOF nanocomposites is usually hindered by the mismatched lattice in the interface between the MOF and other nanocomponents. Surface ligands, molecules with surfactant-like properties, are demonstrated to exhibit the robust capability to modify the interfacial properties of nanomaterials and can be utilized as a powerful strategy for the synthesis of MOF nanocomposites. Besides this, surface ligands also exhibit significant functions in the morphological control and functionalization of MOF nanocomposites, thus greatly enhancing their performance in biomedical applications. In this review, the surface ligand-assisted synthesis and biomedical applications of MOF nanocomposites are comprehensively reviewed. Firstly, the synthesis of MOF nanocomposites is discussed according to the diverse roles of surface ligands. Then, MOF nanocomposites with different properties are listed with their applications in biosensing and disease therapy. Finally, current challenges and further directions of MOF nanocomposites are presented to motivate the development of MOF nanocomposites with elaborate structures, enriched functions, and excellent application prospects.