2D Metal-organic Framework Nanosheets Research Articles

Construction of 2D MOF nanosheets with missing-linker defects for enhanced supercapacitor performance

Metal-Organic Frameworks (MOFs) are highly promising as electrode materials for supercapacitor development due to their large specific surface areas and tunable pore structures. Nevertheless, the intrinsic poor conductivity and suboptimal electrochemical performance of MOFs present substantial challenges. Traditional pyrolysis methods often compromise the inherent characteristics of MOFs. Consequently, a reasonable design of the original MOFs is a promising approach to enhancing its performance. This study commenced with pristine two-dimensional (2D) Ni-BTC (BTC = Trimesic acid) and improved their electrical conductivity and active site accessibility by embedding isophthalic acid (IPA) as missing linkers, resulting in defective Ni-BTC/IPA-x. The physicochemical properties of Ni-BTC/IPA were systematically characterized. The results indicate that defects effectively modulate the electronic structure of the metal center, pore structures, and specific surface areas of MOFs, which is conducive to improving supercapacitor performance. Electrochemical measurements reveal that Ni-BTC/IPA-3 exhibits an exceptional specific capacity of 1209 F g−1 at 0.5 A g−1, demonstrating a rate performance of 70.8 %. Furthermore, hybrid supercapacitor (HSC) devices, incorporating the Ni-BTC/IPA-3, possess an energy density of 30 Wh kg−1 at a power density of 1775.8 W kg−1. These HSC devices successfully power multi-colored light-emitting diodes (LEDs), highlighting their significant potential for practical energy storage applications.

Exfoliation of Metal-Organic Frameworks to Give 2D MOF Nanosheets for the Electrocatalytic Oxygen Evolution Reaction.

The structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond-breaking strategy is demonstrated for synthesizing ultrathin metal-organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs' structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials.

Exfoliation of Metal–Organic Frameworks to Give 2D MOF Nanosheets for the Electrocatalytic Oxygen Evolution Reaction

AbstractThe structure and properties of materials are determined by a diverse range of chemical bond formation and breaking mechanisms, which greatly motivates the development of selectively controlling the chemical bonds in order to achieve materials with specific characteristics. Here, an orientational intervening bond‐breaking strategy is demonstrated for synthesizing ultrathin metal–organic framework (MOF) nanosheets through balancing the process of thermal decomposition and liquid nitrogen exfoliation. In such approach, proper thermal treatment can weaken the interlayer bond while maintaining the stability of the intralayer bond in the layered MOFs. And the following liquid nitrogen treatment results in significant deformation and stress in the layered MOFs’ structure due to the instant temperature drop and drastic expansion of liquid N2, leading to the curling, detachment, and separation of the MOF layers. The produced MOF nanosheets with five cycles of treatment are primarily composed of nanosheets that are less than 10 nm in thickness. The MOF nanosheets exhibit enhanced catalytic performance in oxygen evolution reactions owing to the ultrathin thickness without capping agents which provide improved charge transfer efficiency and dense exposed active sites. This strategy underscores the significance of orientational intervention in chemical bonds to engineer innovative materials.

In Situ Exfoliation Growth Strategy Realizing Controlled Synthesis of 3D to 2D MOF Materials as High-Performance Electrochemical Biosensors.

Two-dimensional (2D) metal-organic framework (MOF) nanosheets with large surface area, ultrathin thickness, and highly accessible active sites have attracted great research attention. Developing efficient approaches to realize the controllable synthesis of well-defined 2D MOFs with a specific composition and morphology is critical. However, it is still a significant challenge to construct thin and uniform 2D MOF nanosheets and resolve the reagglomeration as well as poor stability of target 2D MOF products. Here, an "in situ exfoliation growth" strategy is proposed, where a one-step synthetic process can realize the successful fabrication of PBA/MIL-53(NiFe)/NF nanosheets on the surface of nickel foam (NF) via in situ conversion and exfoliation growth strategies. The PBA/MIL-53(NiFe)/NF nanosheets combine the individual advantages of MOFs, Prussian blue analogues (PBAs), and 2D materials. As expected, the resulting PBA/MIL-53(NiFe)/NF as a glucose electrode exhibits an extremely high sensitivity of 25.74 mA mM-1 cm-2 in a very wide concentration range of 180 nM to 4.8 μM. The present exciting work provides a simple and effective strategy for the construction of high-performance nonenzymatic glucose electrochemical biosensors.

2D Metal–Organic Framework Nanosheets based on Pd‐TCPP as Photocatalysts for Highly Improved Hydrogen Evolution

AbstractIn this report, a 2D MOF nanosheet derived Pd single‐atom catalyst, denoted as Pd‐MOF, was fabricated and examined for visible light photocatalytic hydrogen evolution reaction (HER). This Pd‐MOF can provide a remarkable photocatalytic activity (a H2 production rate of 21.3 mmol/gh in the visible range), which outperforms recently reported Pt‐MOFs (with a H2 production rate of 6.6 mmol/gh) with a similar noble metal loading. Notably, this high efficiency of Pd‐MOF is not due to different chemical environment of the metal center, nor by changes in the spectral light absorption. The higher performance of the Pd‐MOF in comparison to the analogue Pt‐MOF is attributed to the longer lifetime of the photogenerated electron‐hole pairs and higher charge transfer efficiency.

Integrating Photoactive Ligands into Crystalline Ultrathin 2D Metal-Organic Framework Nanosheets for Efficient Photoinduced Energy Transfer.

3D metal-organic frameworks (MOFs) have gained attention as heterogeneous photocatalysts due to their porosity and unique host-guest interactions. Despite their potential, MOFs face challenges, such as inefficient mass transport and limited light penetration in photoinduced energy transfer processes. Recent advancements in organic photocatalysis have uncovered a variety of photoactive cores, while their heterogenization remains an underexplored area with great potential to build MOFs. This gap is bridged by incorporating photoactive cores into 2D MOF nanosheets, a process that merges the realms of small-molecule photochemistry and MOF chemistry. This approach results in recyclable heterogeneous photocatalysts that exhibit an improved mass transfer efficiency. This research demonstrates a bottom-up synthetic method for embedding photoactive cores into 2D MOF nanosheets, successfully producing variants such as PCN-641-NS, PCN-643-NS, and PCN-644-NS. The synthetic conditions were systematically studied to optimize the crystallinity and morphology of these 2D MOF nanosheets. Enhanced host-guest interactions in these 2D structures were confirmed through various techniques, particularly solid-state NMR studies. Additionally, the efficiency of photoinduced energy transfer in these nanosheets was evidenced through photoborylation reactions and the generation of reactive oxygen species (ROS).

Effect of electron transfer of 2D Ti3C2Tx@MOF heterostructure on hydrogen evolution reaction activity

Metal-organic framework (MOF) layers were grown in situ from 2D transition metal carbides (MXenes, Ti3C2Tx) at room temperature to obtain the two-dimensional (2D) Ti3C2Tx@MOF heterostructures with a tightly connected interface. This interface provided more titanium atoms in the low-valence state in comparison to the original Ti3C2Tx, thus facilitating more electron transfer from Ti3C2Tx to MOF-(Fe/Co) nanosheets. The charge density difference and density functional theory results disclosed that Ti3C2Tx could modulate the electronic density around the active sites and lower ΔGH* energy barrier of 2D MOF-(Fe/Co) nanosheets towards the improved hydrogen evolution reaction (HER) activity. The obtained 2D Ti3C2Tx@MOF heterostructures exhibited a much higher HER activity in 1 M KOH electrolyte (with the overpotential of 104 mV at 10 mA/cm2 and Tafel slope of 79 mV/dec) than those of 2D Ti3C2Tx@MOF-TH, 2D MOF nanosheets, and Ti3C2Tx nanosheets. This research provides a basis for developing superior 2D MOFs, which can enhance HER properties through efficient electronic transport at the heterojunction interface.

A fast hemostatic and enhanced photodynamic 2-dimensional metal-organic framework loaded aerogel patch for wound management

Achieving rapid hemostasis and highly effective antibacterial holds significant importance in the early-stage treatment of wounds. In this study, a hybrid aerogel patch comprising carbon quantum dots (CQDs) modified 2-dimensional (2D) porphyrinic metal–organic framework (MOF) nanosheets was designed by incorporating gelatin methacrylate (GelMA) and polyacrylamide (PAM) based matrix. On one hand, CQDs were stably doped onto the surface of the 2D MOF nanosheets, thereby enhancing the photodynamic activity through fluorescence resonance energy transfer (FRET) process. After the preparation of hybrid aerogel patch, the patch loaded with CQDs-doped 2D MOF exhibited excellent photodynamic bactericidal activity against Gram-positive Staphylococcus aureus (>99.99 %) and Gram-negative Escherichia coli (>99.99 %). On the other hand, the hybrid patch with highly porous and absorbent structure can rapidly absorb blood to aggregate clotting components and form a hydration barrier covering the wound to enhance hemostasis. Besides, the hemolysis and cytotoxicity assays demonstrated a good biocompatibility of this designed patch. In summary, this 2D MOF-loaded aerogel patch holds a potential to achieve rapid hemostasis and effective anti-infection in the early-stage treatment of traumatic wounds.

Synthesis of 2D bi-metallic Zn/Cu metal-organic framework integrated graphene nanocomposites for all-solid-state asymmetric supercapacitors

In this work, a novel two-dimensional (2D) bi-metallic metal-organic frameworks (MOFs) consisting of zinc and copper metal centers with 1,3,5-tricarboxylic acid as a chief and efficient organic linker (Zn/Cu-BTC) and its composite with exfoliated graphene nanosheets (EGNSs) have been investigated for supercapacitor applications. The composites were synthesized via facile in-situ solvothermal process. Different spectroscopic, microscopic, and surface analyses confirmed the successful formation of porous electroactive composites, where 2D MOF nanosheets were vertically grown on the EGNS surfaces. In the two-electrode symmetric system, the as-synthesized Zn/Cu-BTC MOF@EGNS electrode achieved an enhanced specific gravimetric capacitance and equivalent volumetric capacitance of 1284.9 F/g and 813.3 F/cm3 at 0.5 A/g. It exhibits high-rate performance and prolonged cycling stability with >90 % retention after 8000 cycles. All-solid-state asymmetric supercapacitor (ASC) device was constructed with Zn/Cu-BTC MOF@EGNS composite and EGNS electrodes, where PVA-KOH membrane served as a separator-cum-electrolyte. The ASC device delivered a satisfactory energy density of 60.55 Wh kg−1 and a maximum power density of 10 kW kg−1 with an admirable cycling stability of 92 % after 10,000 charge-discharge cycles. In the future, this work can encourage manufacturing innovation.

Electrodeposition of gold-platinum nanoparticles on 2D M-TCPP (M = Co, Cu, Zn) for electrochemical monitoring of H2O2 from living cells

Two-dimensional (2D) metal–organic frameworks (MOFs) as supporting nanomaterials to encapsulate or load metal nanoparticles have been widely applied in electrochemical sensing. Therefore, the influences of tetrakis(4-carboxyphenyl) porphyrin-based MOFs (M-TCPP (M = Co, Cu, Zn)) as supporting materials on the electrocatalytic activity were studied. A surfactant-assisted method was employed to facilely synthesize three types of 2D M-TCPP nanosheet MOFs. Polyvinylpyrrolidone was selected as a surfactant for preparing M-TCPP and played a key role in the controlled anisotropic growth of MOF crystals, resulting in the formation of 2D MOF nanosheets. Then, one-step electrodeposition of gold-platinum nanoparticles (AuPt NPs) on the M-TCPP-modified glassy carbon electrode (AuPt/M-TCPP/GCE) was explored for reducing hydrogen peroxide (H2O2). Cyclic voltammetry was applied to investigate the electrocatalytic performance of AuPt/M-TCPP/GCE, and AuPt/Cu-TCPP/GCE exhibited better electrocatalytic characteristics than AuPt/Co-TCPP/GCE and AuPt/Zn-TCPP/GCE. The electrochemical H2O2 sensor displayed a low detection limit of 3.1 nM in the wide concentration range of 0.01 μM to 80 mM. In addition, the proposed sensor showed high stability, good reproducibility, and selectivity. Moreover, HepG2 human liver cancer cells were selected for real-time detection of H2O2 to verify the feasibility of this technology for the evaluation of anticancer drugs. The results showed that Cu-TCPP can be used as an efficient supporting material for enhancing the detection property of electrochemical sensors.

Tuning the Stacking Modes of Ultrathin Two‐Dimensional Metal–Organic Framework Nanosheet Membranes for Highly Efficient Hydrogen Separation

AbstractTwo‐dimensional (2D) metal–organic framework (MOF) membranes are considered potential gas separation membranes of the next generation due to their structural diversity and geometrical functionality. However, achieving a rational structure design for a 2D MOF membrane and understanding the impact of MOF nanosheet stacking modes on membrane separation performance remain challenging tasks. Here, we report a novel kind of 2D MOF membrane based on [Cu2Br(IN)2]n (IN=isonicotinato) nanosheets and propose that synergetic stacking modes of nanosheets have a significant influence on gas separation performance. The stacking of the 2D MOF nanosheets is controlled by solvent droplet dynamic behaviors at different temperatures of drop coating. Our 2D MOF nanosheet membranes exhibit high gas separation performances for H2/CH4 (selectivity >290 with H2 permeance >520 GPU) and H2/CO2 (selectivity >190 with H2 permeance >590 GPU) surpassing the Robeson upper bounds, paving a potential way for eco‐friendly H2 separation.

Tuning the Stacking Modes of Ultrathin Two-Dimensional Metal-Organic Framework Nanosheet Membranes for Highly Efficient Hydrogen Separation.

Two-dimensional (2D) metal-organic framework (MOF) membranes are considered potential gas separation membranes of the next generation due to their structural diversity and geometrical functionality. However, achieving a rational structure design for a 2D MOF membrane and understanding the impact of MOF nanosheet stacking modes on membrane separation performance remain challenging tasks. Here, we report a novel kind of 2D MOF membrane based on [Cu2 Br(IN)2 ]n (IN=isonicotinato) nanosheets and propose that synergetic stacking modes of nanosheets have a significant influence on gas separation performance. The stacking of the 2D MOF nanosheets is controlled by solvent droplet dynamic behaviors at different temperatures of drop coating. Our 2D MOF nanosheet membranes exhibit high gas separation performances for H2 /CH4 (selectivity >290 with H2 permeance >520 GPU) and H2 /CO2 (selectivity >190 with H2 permeance >590 GPU) surpassing the Robeson upper bounds, paving a potential way for eco-friendly H2 separation.

Engineering Functionalized 2D Metal-Organic Frameworks Nanosheets with Fast Li+ Conduction for Advanced Solid LiBatteries.

Solid-state batteries can ensure high energy density and safety in lithium metal batteries, while polymer electrolytes are plagued by slow ion kinetics and low selective transport of Li+ . Metal-organic frameworks (MOFs) are proposed as emerging fillers for solid-state poly(ethylene oxide)(PEO) electrolytes, however, developing functionalized MOFs and understanding their roles on ion transfer has proven challenging. Herein, combining computational and experimental results, the functional group regulation in MOFs can effectively change surficial charge distribution and limit anion movement is revealed, providing a potential solution to these issues. Specifically, functionalized 2D MOF sheets are designed through molecular engineering to construct high-performance composite electrolytes, where the electron-donating effect of substituents in 2D-MOFs effectively limits the movement of ClO4 - and promotes mechanical properties and ion migration numbers (0.36 up to 0.64) of PEO. As a result, Li/Li cells with composite electrolyte exhibit superior cyclability for 1000h at a current density of 0.2mAcm-2 . Meanwhile, the solid LiFePO4 /Li battery delivers highly reversible capacities of 148.8mAh g-1 after 200cycles. These findings highlight a new approach for anion confinement through the use of functional group electronic effects, leading to enhanced ionic conductivity, and a feasible direction for high-performance solid-state batteries.

Nanocomposite polymer blend membrane molecularly re-engineered with 2D metal-organic framework nanosheets for efficient membrane CO2 capture

Membrane gas separation technology is an energy-efficient alternative to the traditional industrial processes for CO2 capture towards the mitigation of global warming. To overcome the inherent performance trade-off behavior of polymeric membranes, many nanoarchitectures have been incorporated for developing high-performance mixed matrix membranes. Yet, a successful nanocomposite membrane design remains challenging, especially for CO2 capture, because of polymer-filler incompatibility and interfacial defects. Herein, 2D Cu-TCPP nanosheets were synthesized and incorporated into Pebax/Poly (ethylene glycol) methyl ether acrylate (PEGMEA) blends to design MMMs with exceptional CO2/N2 separation performance. This synergistic polymer blend after crosslinking, offers a highly accommodating and robust matrix environment for the homogenous distribution of nanosheets. Cu-TCPP particles were also produced as 3D nanoflowers to probe their morphological effect on gas transport. The finely dispersed 2D nanosheets expanded the free volume of the resultant nanocomposite membranes, leading to a significantly enhanced CO2 permeability of up to 1183 Barrer which was 93% higher than the neat polymers, while they also increased the transport pathway tortuosity that contributes to a very high CO2/N2 selectivity of 57.6 at a loading of merely 0.1 wt%. Not only do such separation performances surpassed the Robeson upper bound by a large margin and outcompeted many existing advanced MMM designs, but they also remained stable after long-term operations. By carefully elucidating the gas transport tuning effect of 2D metal-organic framework nanosheets in nanocomposite membranes, this work could help broaden their applicability for other environmentally important molecular separations.

Constructing cactus-like mixed dimensional MOF@MOF as sorbent for extraction of bisphenols from environmental water

Metal-organic frameworks (MOFs) received considerable attention to adsorption and removal of various environmental pollutants because of some inherent advantages. However, it is challenging but meaningful to design and fabricate hierarchical mixed-dimensional MOFs with synergistic effects to enhance the performance for removal and preconcentration of environmental pollutants. Herein, a new hierarchical two-dimensional (2D)-three-dimensional (3D) mixed-dimensional cactus‐like MOF@MOF hybrid material (PCN-134@Zr-BTB) was prepared by in-situ growth of 2D MOF nanosheets (Zr-BTB) on the surface of 3D MOF (PCN-134). The PCN-134@Zr-BTB composites combine the advantages of 2D and 3D MOFs with extensive mesoporous structures and large surface area for effective removal and enrichment of bisphenols (BPs). In comparison with pristine PCN-134 and Zr-BTB materials, the PCN-134@Zr-BTB hybrid material presented excellent adsorption performance for BPs. The adsorption isotherms are consistent with the Langmuir model, and the maximum adsorption capacity of four bisphenols (BPs) ranged from 135.1 mg/g to 628.9 mg/g. The adsorption kinetics are in accordance with the pseudo-second-order model. The recoveries ranged from 72.8% to 108%. The limits of detection were calculated at 0.02–0.03 ng/mL. The enrichment factors were calculated in the range of 310–374. According to FT-IR and XPS analysis, the main adsorption mechanisms are hydrogen bonding and π-π stacking. Nevertheless, this work provides a new and convenient strategy for the preparation of new hierarchical mixed-dimensional MOF@MOF (PCN-134@Zr-BTB) hybrid material for extraction and enrichment of BPs from aqueous matrix.

Trimetallic metal–organic framework nanosheets as nanozymes for the electrochemical sensing of H2O2

A variety of two-dimensional (2D) metal–organic framework (MOF) nanosheets have been discovered with excellent peroxidase-like activity due to their merits of accessible active sites and large surface area. However, few methods can be used for the large-amount production of 2D MOF nanosheets. Herein, we report a simple room temperature solution phase method for the high-yield synthesis of 2D trimetallic MOF nanosheets with three kinds of metal ions as ligands. The as-synthesized NiCoM (M = Cu, Fe, and Zn) nanosheets showed markedly enhanced electrochemical activity due to the synergistic effect. Among these obtained nanosheets, NiCoFe showed the highest electrocatalytic activity, demonstrating that Fe played a dominant role in determining the activities of nanozymes. As a proof-of-concept application, 2D NiCoFe nanosheets are used as modified materials for the electrochemical detection of H2O2. The results showed that the fabricated sensor can detect hydrogen peroxide (H2O2 ) with a detection range of 5.0 μM − 15 mM, a detection limit of 2.1 μM, excellent selectivity and stability. Moreover, the fabricated NiCoFe nanosheet-based electrochemical sensor can be used for the detection of H2O2 in serum samples. Our work provides a scalable method for the large-scale synthesis of 2D trimetallic MOF nanosheets as enhanced nanozymes for various applications.

Layered 2D MOF nanosheets grown on CNTs substrates for efficient nitrite sensing

In this work, we report a ligand-deficient layered cerium-based metal-organic framework (MOF) nanosheets grown on carbon nanotube (CNT) substrates and its application in electrochemical sensors. The construction of layered MOF nanosheet materials is based on CNTs as the backbone and relies on the low ligand-metal ratios which is controlled by the loaded organic ligands on the surface of CNTs, providing a new approach for the application of 2D MOFs in the field of electrochemical sensing. The obtained 2D MOFs possess unique layered structure and hierarchical connectivity channels, providing highly efficient and stable pathways for electron, ion, and mass transport. The synthesized layered 2D CNTs@Ce-MOF nanosheet hybrid material uses Ce as the center ion and electrocatalytic active material for nitrite sensing. This material exhibits excellent nitrite detection performance within two wider linear ranges of 0.65–3.25 μM and 3.25–7000 μM with the sensitivity of 87.65 ± 0.6 μA·μM−1·cm2 and 0.35 ± 0.03 μA·μM−1·cm−2, respectively. The detection limit is estimated to be 0.12 μM according to signal to noise ratio (S/N) = 3. As the result, the prepared sensors possess advantages in aspects of reproducibility, stability, selectivity and responsiveness in comparison to the reported ones.

Pyrene based two-dimensional metal-organic framework nanosheets for targeted chemo-chemodynamic therapy

Metal-organic frameworks (MOFs), as drug delivery carriers, have been extensively studied in biomedical fields. Among them, two-dimensional metal-organic frameworks (2D MOFs) have the advantages of high metal active sites, large specific surface area and easy surface modification. Herein, a novel 2D MOFs nanosheets were constructed by Cu2+ and 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy) under hydrothermal conditions (Cu-MOFs). Then the DOX@Cu-MOFs-HA nanosheets (NSs) were gained through loading doxorubicin (DOX) and modifying with hyaluronic acid (HA), where Cu2+/Cu+ can initiate Fenton-like reaction for chemodynamic therapy (CDT) and HA can actively target tumor cells. In the tumor microenvironment, DOX@Cu-MOFs-HA NSs was gradually degraded to release DOX and Cu2+, where Cu2+ was reduced to Cu+ with glutathione (GSH) to catalyze the conversion of H2O2 to yield highly toxic ROS through a Fenton-like reaction, and DOX acted on the nucleus to induce apoptosis and successfully achieved the combination of chemo-chemodynamic therapy. This strategy provides a new perspective for two-dimensional MOFs NSs in the field of drug delivery.

Size engineering of 2D MOF nanosheets for enhanced photodynamic antimicrobial therapy

Although porphyrin-based metal-organic frameworks (MOFs) have been widely explored as photosensitizers for photodynamic therapy, how the size will affect the light-induced catalytic activity for generation of reactive oxygen species (ROS) still remain unclear. Herein, we first report the size-controlled synthesis of two-dimensional (2D) porphyrin-based PCN-134 MOF nanosheets by a two-step solvothermal method to explore the size effect on its PDT performance, thus yielding enhanced photodynamic antimicrobial therapy. By simply controlling the reaction temperature in the synthesis process, the bulk PCN-134 crystal, large PCN-134 (L-PCN-134) nanosheets with a lateral size of 2-3 μm and thickness of 33.2-37.5 nm and small PCN-134 nanosheets (S-PCN-134) with a lateral size of 160-180 nm and thickness of 9.1-9.7 nm were successfully prepared. Interestingly, the S-PCN-134 nanosheets exhibit much higher photodynamic activity for ROS generation than that of the bulk 3D PCN-134 crystal and L-PCN-134 nanosheets under a 660 nm laser irradiation, suggesting that the photodynamic activity of PCN-134 MOF increases when the size reduces. Therefore, the S-PCN-134 nanosheets show much enhanced performance when used as a photosensitizer for photodynamic antimicrobial activity and wound healing.

Pd nanoparticles decorated ultrathin 2D metal-organic framework nanosheets with enhanced peroxidase-mimic activity and colorimetric assay of glucose.

In addition to size, shape and morphology, enzyme-mimetic property could be efficiently regulated by controlling composition, forming complexes or hybrids, and surface modification. Herein, Pd nanoparticles with an average diameter of 2.52 nm were decorated on ultrathin 2D copper(ii)-porphyrin derived metal-organic framework (MOF) nanosheets by a simple reduction method for catalytic activity regulation. In comparison with other nanozymes, the as-synthesized Pd modified 2D MOF hybrid nanosheets (Pd@Cu-TCPP(Fe)) presented excellent peroxidase-mimic activity, exhibiting an even superior catalytic ability towards H2O2 with a Michaelis-Menten constant as low as 2.33 mM. Based on a cascade reaction between glucose oxidase and Pd@Cu-TCPP(Fe), a colorimetric method for the detection of glucose was established and validated with a wide linear range (0.2-8.0 mM), good recovery (89.5-94.2%) and nice reproducibility (3.65%). All these features guaranteed its excellent ability for glucose determination in human cerebrospinal fluids. This study could offer a valuable reference for constructing novel optical biosensors.