Two-dimensional Metal-organic Framework Nanosheets Research Articles

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.

Surface Electronic Properties-Driven Electrocatalytic Nitrogen Reduction on Metal-Conjugated Porphyrin 2D-MOFs.

Two-dimensional (2D) metal organic framework (MOF) or metalloporphyrin nanosheets with a stable metal-N4 complex unit present the metal as a single-atom catalyst dispersed in the 2D porphyrin framework. First-principles calculations on the 3d-transition metals in M-TCPP are investigated in this study for their surface-dependent electronic properties including work function and d-band center. Crystal orbital Hamiltonian population (-pCOHP) analysis highlights a higher contribution of the bonding state in the M-N bond and antibonding state in the N-N bond to be essential for N-N bond activation. A linear relationship between ΔGmax and surface electronic properties, N-N bond strength, and Bader charge has been found to influence the rate-determining potential for nitrogen reduction reaction (NRR) in M-TCPP MOFs. 2D Ti-TCPP MOF, with a kinetic energy barrier of 1.43 eV in the final protonation step of enzymatic NRR, shows exclusive NRR selectivity over competing hydrogen reduction (HER) and nitrogenous compounds (NO and NO2). Thus, Ti-TCPP MOF with an NRR limiting potential of -0.35 V in water solvent is proposed as an attractive candidate for electrocatalytic NRR.

Two-Dimensional Nickel Porphyrinic Metal-Organic Framework-Modified Electrode for Electrochemical Sensing.

Due to their highly exposed active sites and high aspect ratio caused by their substantial lateral dimension and thin thickness, two-dimensional (2D) metal-organic framework (MOF) nanosheets are currently considered a potential hybrid material for electrochemical sensing. Herein, we present a nickel-based porphyrinic MOF nanosheet as a versatile and robust platform with an enhanced electrochemical detection performance. It is important to note that the nickel porphyrin ligand reacted with Cu(NO3)2·3H2O in a solvothermal process, with polyvinylpyrrolidone (PVP) acting as the surfactant to control the anisotropic development of creating a 2D Cu-TCPP(Ni) MOF nanosheet structure. To realize the exceptional selectivity, sensitivity, and stability of the synthesized 2D Cu-TCPP(Ni) MOF nanosheet, a laser-induced graphene electrode was modified with the MOF nanosheet and employed as a sensor for the detection of p-nitrophenol (p-NP). With a detection range of 0.5-200 μM for differential pulse voltammetry (DPV) and 0.9-300 μM for cyclic voltammetry (CV), the proposed sensor demonstrated enhanced electrochemical performance, with the limit of detection (LOD) for DPV and CV as 0.1 and 0.3 μM, respectively. The outstanding outcome of the sensor is attributed to the 2D Cu-TCPP(Ni) MOF nanosheet's substantial active surface area, innate catalytic activity, and superior adsorption capacity. Furthermore, it is anticipated that the proposed electrode sensor will make it possible to create high-performance electrochemical sensors for environmental point-of-care testing since it successfully detected p-NP in real sample analysis.

The controllable and efficient synthesis of two-dimensional metal-organic framework nanosheets for heterogeneous catalysis.

Two-dimensional (2D) MOFs exhibit unique periodicity in surface structures and thus have attracted much interest in the fields of catalysis, energy, and sensors. However, the expanded production scale of 2D MOFs had remained a great challenge in most previous studies. Herein, a controllable and efficient crystallization method for synthesizing 2D MOF nanosheets using high-gravity reactive precipitation is proposed, significantly improving heterogeneous catalysis efficiency. The two-dimensional ZIF-L nanosheets prepared in a rotating packed bed (RPB) reactor show a smaller lateral and lamellar thickness and a higher BET surface area compared to ZIF-L nanosheets prepared in a conventional stirred tank reactor (STR), with a greatly shortened reaction time. Applying the ZIF-L-RPB nanosheets as a catalyst, the catalytic Knoevenagel condensation as a probe reaction displays a high conversion rate of benzaldehyde (99.3%) within 2 h at room temperature, greatly exceeding that displayed by ZIF-L-STR and other reported catalysts. Furthermore, ZIL-L-RPB nanosheets of only 0.2 wt% enhanced the catalytic activity for the glycolysis of poly(ethylene terephthalate) (PET) with a PET conversion and a monomer yield of 90% in a short period of 15 min at 195 °C and almost completely depolymerized PET with a monomer yield of 94% in 30 min, which was far above that achieved by ZIL-L-STR. These results indicate the promising prospects of a high-gravity reactive precipitation strategy with precise size control in an economical way to prepare high-activity 2D MOF nanosheets for a wide range of heterogeneous catalysis.

Template-controllable rolling circle amplification for dual protein sensitive analysis.

Conjoint analysis of multiple protein biomarkers can improve the accuracy of disease analysis. Rolling circle amplification (RCA) generates different products by designing circular templates, which can subsequently bind with specific probes to generate various fluorescence signals; thus, it has potential for application in the analysis of various protein biomarkers. Current RCA approaches to detect proteins commonly follow an indirect primer-controlled RCA mode. And the molecular beacon probe combines with RCA products through free collision to generate signals, resulting in lower reaction efficiency. Herein, we propose a direct template-controlled RCA mode using nanosheets as carriers and quenchers for fluorescent probes to simultaneously detect two protein biomarkers. A dual functional magnetic bead was first designed to recognize and capture two proteins while releasing two templates for subsequent RCA. RCA products compete with probes loaded on two-dimensional metal-organic framework nanosheets for hybridization, completing the transition from single-stranded to double-stranded DNA. Double-stranded DNA is far from the nanosheets, and the recovered fluorescence signal can be used to evaluate the concentration of target proteins. This method exhibits excellent analytical performance and can successfully achieve the analysis of Tau and AβO in Alzheimer's disease clinical cerebrospinal fluid samples.

Enhancing Photomultiplication in Organic Photodetectors with Two-Dimensional Metal–Organic Framework Nanosheets

Enhancing Photomultiplication in Organic Photodetectors with Two-Dimensional Metal–Organic Framework Nanosheets

Bipolar Molecular Torque Wrench Modulates the Stacking of Two-Dimensional Metal-Organic Framework Nanosheets.

The precise modulation of nanosheet stacking modes introduces unforeseen properties and creates momentous applications but remains a challenge. Herein, we proposed a strategy using bipolar molecules as torque wrenches to control the stacking modes of 2-D Zr-1,3,5-(4-carboxylphenyl)-benzene metal-organic framework (2-D Zr-BTB MOF) nanosheets. The bipolar phenyl-alkanes, phenylmethane (P-C1) and phenyl ethane (P-C2), predominantly instigated the rotational stacking of Zr-BTB-P-C1 and Zr-BTB-P-C2, displaying a wide angular distribution. This included Zr-BTB-P-C1 orientations at 0, 12, 18, and 24° and Zr-BTB-P-C2 orientations at 0, 6, 12, 15, 24, and 30°. With reduced polarity, phenyl propane (P-C3) and phenyl pentane (P-C5) introduced steric hindrance and facilitated alkyl hydrophobic interactions with the nanosheets, primarily resulting in the modulation of eclipsed stacking for Zr-BTB-P-C3 (64.8%) and Zr-BTB-P-C5 (93.3%) nanosheets. The precise angle distributions of four Zr-BTB-P species were in agreement with theoretical calculations. The alkyl induction mechanism was confirmed by the sequential guest replacement and 2-D 13C-1H heteronuclear correlation (HETCOR). In addition, at the single-particle level, we first observed that rotational stacked pores exhibited similar desorption rates for xylene isomers, while eclipsed stacked pores showed significant discrepancy for xylenes. Moreover, the eclipsed nanosheets as stationary phases exhibited high resolution, selectivity, repeatability, and durability for isomer separation. The universality was proven by another series of bipolar acetate-alkanes. This bipolar molecular torque wrench strategy provides an opportunity to precisely control the stacking modes of porous nanosheets.

Synthesis of Two-Dimensional (Cu-S)n Metal-Organic Framework Nanosheets Applied as Peroxidase Mimics for Detection of Glutathione.

Facilely synthesized peroxidase-like nanozymes with high catalytic activity and stability may serve as effective biocatalysts. The present study synthesizes peroxidase-like nanozymes with multinuclear active sites using two-dimensional (2D) metal-organic framework (MOF) nanosheets and evaluates them for their practical applications. A simple method involving a one-pot bottom-up reflux reaction is developed for the mass synthesis of (Cu-S)n MOF 2D nanosheets, significantly increasing production quantity and reducing reaction time compared to traditional autoclave methods. The (Cu-S)n MOF 2D nanosheets with the unique coordination of Cu(I) stabilized in Cu-based MOFs demonstrate impressive activity in mimicking natural peroxidase. The active sites of the peroxidase-like activity of (Cu-S)n MOF 2D nanosheets were predominantly verified as Cu(I) rather than Cu(II) of other Cu-based MOFs. The cost-effective and long-term stability of (Cu-S)n MOF 2D nanosheets make them suitable for practical applications. Furthermore, the inhibition of the peroxidase-like activity of (Cu-S)n MOF nanosheets by glutathione (GSH) could provide a simple strategy for colorimetric detection of GSH against other amino acids. This work remarkably extends the utilization of (Cu-S)n MOF 2D nanosheets in biosensing, revealing the potential for 2D (Cu-S)n MOFs.

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.

Exceptional peroxidase-like activity of an iron and copper based organic framework nanosheet for consecutive colorimetric biosensing of glucose and kanamycin in real food samples.

Two-dimensional metal-organic framework nanosheets are attractive as peroxidase mimicking nanocatalysts due to their rich chemical functional groups, large surface area, high porosity, and accessible active sites. In this study, we synthesized FeCu bifunctional 2D MOF nanosheets using a solvothermal method. Fe and Cu ions were added as metal precursors, while organic amine and acid served as the organic ligands to construct the FeCu-MOF nanosheets. These nanosheets demonstrated robust peroxidase-like catalytic activities and were employed to develop a visual detection system for multiple targets, such as glucose and kanamycin. In the detection mechanism, glucose was oxidized into gluconic acid by glucose oxidase (GOx), leading to the generation of H2O2. When H2O2 is present, the FeCu-MOF NSs demonstrate high intrinsic peroxidase-like activity, which might catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) into a blue-coloured oxTMB product with a strong UV absorption at 654 nm. Subsequently, kanamycin was added to the above sensing system. The kanamycin strongly interacted with the FeCu-MOF NSs through H-bonding and blocked electron transfer, resulting in a colour change of the solution from blue to colourless with a weak UV absorption at 654 nm. Under the optimal conditions, the proposed colorimetric sensor exhibits an excellent linear response to glucose and kanamycin over the 0.25-5 μM and 0.02-0.1 μM ranges, respectively. The proposed colorimetric assay detection limits for glucose and kanamycin were found to be as low as 0.1 μM and 8 nM, respectively, and such a sensor shows excellent selectivity and sensitivity against different potential interferents. Thus, our proposed colorimetric assay was satisfactory when applied to glucose and kanamycin detection in agricultural and livestock husbandry samples.

A bottom-up sonication-assisted synthesis of Zn-BTC MOF nanosheets and the ppb-level acetone detection of their derived ZnO nanosheets

Two-dimensional metal-organic framework nanosheets, as a new member of the two-dimensional family, are attracting increasing research interest in various fields. Herein, a uniform two-dimensional Zn-BTC MOF nanosheet with a thickness of 14 ± 2 nm was synthesized through a simple, efficient, and scalable sonication-assisted bottom-up strategy. The ZnO nanoparticles were used as the Zn source, which can be corroded by H3BTC to form Zn-BTC MOFs under sonication conditions. The morphologies of Zn-BTC MOFs can be modulated from nanosheets to nanorods by changing the content of H3BTC. The crystal growth process is dominated by the thermodynamics of sonication and the stoichiometric ratio of the generated Zn2+ and H3BTC, and the crystal growth mechanism was elaborated by the oriented attachment. Consequently, a chemiresistive gas sensor based on Zn-BTC nanosheet derivatives was fabricated to detect ppb-level acetone. Notably, the experimental detection limit of concentration could reach as low as 100 ppb of acetone due to the functional surface, and the dynamic response linearity reached 99 %. Our work explored a new method of synthesizing two-dimensional Zn-BTC MOF, and the fabricated gas sensing device demonstrated promising potential in gas sensing fields.

Synthesis of ultrathin two-dimensional metal-organic framework nanosheets for lubricant additives

Two-dimension (2D) nano materials are diffusely employed as lubricant additives. In this paper, three kinds of ultrathin 2D metal-organic framework (MOF) nanosheets with different metal ions (Ni2+, Zn2+, and Cu2+) were successfully synthesized by ultrasonic assisted self-assembly under appropriate solvent ratio. Ni-MOF nanosheets as a new additive in 500 N system exhibit the best dispersion stability and lubrication performance, which is related to its maximum absolute value of Zeta potential. Compared with pure 500 N, the best tribological properties were obtained with the addition of 0.1 wt% Ni-MOF nanosheets, reducing friction by 33.2 ± 12.4 % and wear by 98.7 ± 0.14 %. The excellent performance originates from interlayer sliding effect, polishing effect, and tribofilm with concrete structure. The iron oxide particles embedded in the tribofilm play a supporting structrue for the whole tribofilm. The carbonaceous and nitrogenous compounds are filled around the iron oxide particles, which makes tribofilm denser and more smooth. The further friction tests under higher sliding velocity and longer term reveal the potential industrial use of Ni-MOF nanosheets.

Dialytic Synthesis of Two-Dimensional Cu-Based Metal-Organic Frameworks for Gas Separation: Designable MOF-Polymer Interface.

We demonstrate a dialytic strategy for the synthesis of congeneric two-dimensional metal-organic framework (2D MOF) nanosheets with a dialysis membrane using 1,4-benzenedicarboxylic acid (BDC), 1,4-naphthalenedicarboxylic acid (NDC), and 9,10-anthracenedicarboxylic acid (ADC) as organic linkers and copper(II) as a metal precursor, respectively. Polyimide (PI) membranes containing these empty 2D MOF nanosheets exhibit distinct molecular sieve effects. Molecular dynamic simulation results reveal that the structures of MOF-polymer interfaces are designable by modifying the MOF interlayer distance and aperture size, which has significant influences on gas permeability and selectivity. As a result, Cu-NDC/PI with the moderate composite interface structure shows superior performance toward H2/CH4 and CO2/CH4 separations with a selectivity of 199 and 63 over Cu-BDC (121 and 53) and Cu-ADC (135 and 54), respectively.

Surface coatings of two-dimensional metal-organic framework nanosheets enable stable zinc anodes

Aqueous zinc-ion batteries (ZIBs) have been considered as safe and scalable energy storage solutions, but the dendrite and corrosion issues of Zn anodes have hindered their further application. Herein, we demonstrate that two-dimensional metal-organic framework (MOF) nanosheets can act as protective coatings to prevent dendrite formation and hydrogen evolution of Zn anodes. The morphology of MOFs was tuned from octahedral nanoparticles (UiO-67-3D) to nanosheets (UiO-67-2D), leading to significantly enhanced protective performance. UiO-67-2D nanosheets-coated Zn anodes displayed smaller polarization, longer cycling lifetime and lower H2 evolution than those of UiO-67-3D nanoparticles in symmetrical cells, which has been attributed to the higher concentration of surface Zr−OH/H2O to induce uniform Zn deposition and one-dimensional (1D) channels perpendicular to the Zn surface to regulate Zn2+ diffusion. The assembled UiO-67-2D@Zn∥Mn2O3/C full cell shows a high capacity of 240 mAh g−1 at 1 A g−1 and excellent cycling stability.

Ultrathin metal organic framework nanosheets with rich defects for enhanced fluoride removal

Herein, we present a defluoridation approach based on ultrathin two-dimensional metal organic framework (MOF, viz., Ce-DCPBA) nanosheets. The nanosized layers and ultimately exposed metal defects of Ce-DCPBA enable the high-capacity adsorption of fluoride in a wide pH window. Attributed to tailored ligand exchange at metal defects and boron-fluoride complexation, Ce-DCPBA exhibits exceptional selectivity for fluoride with a partition coefficient up to 18.805 L g−1, even in the matrixes with ultrahigh salinity (8 mol/L of nitrate). Negligible interference from other anions, superior adsorption ability and favorable reusability promotes the practical application of Ce-DCPBA for the selective and efficient removal of fluoride from complex environmental samples. These findings furnish a promising strategy for the anesis of fluoride contamination, and illuminate the application potentials and superiorities of ultrathin MOFs-based nanostructures for environmental remediation.

Single-Layer 2D Ni-BDC MOF Obtained in Supercritical CO2 -Assisted Aqueous Solution.

The development of an efficient strategy for fabricating two-dimensional metal-organic framework (MOF) nanosheets with high yield and high stability is desirable. Herein, we demonstrate for the first time that large, single-layer 2D nickel-benzene dicarboxylate (Ni-BDC) MOF nanosheets can be fabricated with the assistance of supercritical (SC) CO2 in a pure aqueous system. Detailed experimental evidence reveals that the SC CO2 molecule can exchange with the lattice-coordinated H2 O molecules, side-on coordinate with the metal Ni1 sites on the Ni-BDC surface, and finally break the interlayer hydrogen bond to exfoliate the bulk Ni-BDC into a 2D MOF. More importantly, a thin SC CO2 layer building up at the water-Ni-BDC interfaces can transform the pristine hydrophilic interface into a super-hydrophobic one. This super-hydrophobic layer at the water-MOF interface can effectively prevent dissociation, thus promoting the stability of Ni-BDC in aqueous system.

Ultrathin Metal-Organic Framework Nanosheets Exhibiting Exceptional Catalytic Activity.

Two-dimensional (2D) metal-organic framework nanosheets (MONs) or membranes are classes of periodic, crystalline polymeric materials that may show unprecedented physicochemical properties due to their modular structures, high surface areas, and high aspect ratios. Yet preparing 2D MONs from multiple components and two different types of polymerization reaction remains challenging and less explored. Here, we report the synthesis of MOF films via interfacial polymerization, which involves three active monomers for simultaneous polycondensation and polycoordination taking place in a confined interface. The well-defined lamellar structure of the MOF films allowed feasible and scalable exfoliation to produce free-standing 2D MONs with high aspect ratio up to 2000:1 and ultrathin thickness (∼1.7 nm). The pore structure was revealed by high-resolution TEM images with near-atomic precision. The imide-linkage of MONs provided superior thermal (up to 530 °C) and good chemical stability in the pH range from 3 to 12. More importantly, the MONs exhibited exceptional catalytic activity and superior reusability for the hydroboration reactions of alkynes, in which the turnover frequency (TOF) reached 41734 h-1, which is 2-4 orders of magnitude greater than that reported for homogeneous and heterogeneous catalysts.

Fabrication of Protonated Two-Dimensional Metal-Organic Framework Nanosheets for Highly Efficient Iodine Capture from Water.

Radioactive iodine (129I and 131I), produced or released from nuclear-related activities, posed severe effects on both human health and environment. The efficient removal of radioiodine from aqueous medium and vapor phase is of paramount importance for the sustainable development of nuclear energy. Herein, a metal-organic framework (MOF) nanosheet with a positive charge was constructed for the capture of iodine for the first time. The as-synthesized ultrathin nanosheets, with a thickness of 4.4 ± 0.1 nm, showed a record-high iodine adsorption capacity (3704.08 mg g-1) from aqueous solution, which is even higher than that from the vapor phase (3510.05 mg g-1). It can be ascribed to the fully interactions between the extensive accessible active sites on the largely exposed surface of 2D MOF nanosheets and the target pollutants, which also gave rise to fast adsorption kinetics with relative high removal efficiencies in the low concentrations, even in seawater. Moreover, a facile recyclability with fast desorption kinetics can also be achieved for the MOF nanosheets. The excellent iodine removal performance in aqueous solution demonstrated that the electrostatic attraction between MOF nanosheets with a positive charge and the negatively charged triiodide (I3-, the dominant form of iodine in aqueous solution) is the driving force in adsorption, which endows the adsorbents with the characteristics of fast adsorption and desorption kinetics. The adsorption mechanism was systematically verified by the studies of ζ potential, Fourier transform infrared, X-ray photoelectron spectroscopy, and Raman spectra.

Silver nanoparticle-decorated 2D Co-TCPP MOF nanosheets for synergistic photodynamic and silver ion antibacterial

Two-dimensional (2D) metal organic framework (MOF) nanosheets have been demonstrated to be promising templates for preparing functional 2D composites. Herein, we report the preparation of silver nanoparticle (Ag NP)-decorated 2D porphyrinic MOF nanosheets (denoted as Ag/Co-TCPP NSs) with a high efficiency for combined antibacterial therapy. The as-prepared Ag/Co-TCPP NSs feature both the advantages of Co-TCPP NSs and Ag NPs, which exhibit excellent antibacterial properties against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria. Under a 660 nm laser irradiation, Ag/Co-TCPP NSs locally generated singlet oxygen (1O2) and promoted Ag NPs to be partly degraded for sustained release of toxic Ag+, achieving a synergistic sterilization effect. This effective strategy for achieving 2D MOF nanosheets with in situ loaded metal nanoparticles provides a guideline to broaden the diverse applications of MOFs and contributes to the development of new intelligent metal-based antibacterial nanomaterials.

Microwave-assisted synthesis of 2D Zr-MOF nanosheets supported gold nanocomposites as efficient catalysts for the reduction of 4-nitrophenol

Two-dimensional metal-organic framework nanosheets (2D MONs) are excellent heterogeneous catalysts owing to their high density and accessible catalytic sites, reduced diffusion pathways for reactants/products, and fast electron transport. Moreover, the employment of 2D MONs as supports to encapsulate noble nanoparticles can not only stabilize the noble nanoparticles, but also significantly improve their catalytic activity through the synergetic effect between 2D MONs and noble nanoparticles. Herein, we reported a microwave-assisted method for the rapid preparation of 2D UiO-67 metal-organic framework nanosheets (named UiO-67 NS). The Au nanoparticles modified UiO-67 nanocomposites (denoted as Au/UiO-67 NS nanocomposites) are formed by the in situ reduction of HAuCl4 in the pores of UiO-67 NS. The Au/UiO-67 NS nanocomposites show excellent catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol, and only 20 equivalent sodium borohydride can completely reduce 10 mM 4-NP in 100 s, thanks to highly exposed Au NPs and reduced diffusion distance. In addition, XPS characterizations showed that the binding energy of Au 4 f in Au/UiO-67 NS nanocomposites displays a 0.48 eV less than that of Au nanoparticles on UiO-67 octahedral microcrystals (denoted as Au@UiO-67 OM), which is believed to be responsible for the enhanced catalytic activity toward the reduction of 4-nitrophenol.