Properties Of MOFs Research Articles

Progress and Strategies of MOFs in Catalyzing Conversion Processes in Lithium‐Sulfur Batteries

AbstractLithium‐sulfur (Li−S) batteries have attracted considerable attention due to their advantages, such as high specific capacity, high energy density, environmental friendliness, and low cost. However, the severe capacity fading caused by shuttle effect of polysulfide needs to be addressed before the practical application of Li−S batteries. Crystalline porous materials including MOFs have generated great interest in energy storage fields especially batteries, because the ordered porous frameworks can offer a fast‐ionic transportation. Nevertheless, the intrinsic low conductivity of MOFs limits their rapid development in lithium‐sulfur batteries. This review mainly discusses the latest research progress on MOF main materials in Li−S batteries. The working principle of Li−S batteries and the classical “adsorption‐catalysis‐conversion” strategy are briefly introduced. Specifically, three modification methods (non‐metal atom doping, single‐atom, and dual‐atom doping modifications) applied in MOF‐based materials are analyzed and summarized, along with their respective mechanisms and advantages and disadvantages. Ligand doping is an effective strategy that can regulate the structure and properties of MOFs, thereby enhancing their catalytic activity and adsorption capacity towards polysulfides. Through ligand doping, key parameters such as the pore size, surface charge, and active site density of MOFs can be controlled, thereby influencing the adsorption and conversion of polysulfides on MOFs surfaces. Furthermore, crucial insights for the rational design of advanced MOF‐based materials for lithium‐sulfur batteries and the exploration of the main challenges and future directions for their application were also discussed.

Mechanochemical “Cage‐on‐MOF” Strategy for Enhancing Gas Adsorption and Separation through Aperture Matching

AbstractPost‐modification of porous materials with molecular modulators has emerged as a well‐established strategy for improving gas adsorption and separation. However, a notable challenge lies in maintaining porosity and the limited applicability of the current method. In this study, we employed the mechanochemical “Cage‐on‐MOF” strategy, utilizing porous coordination cages (PCCs) with intrinsic pores and apertures as surface modulators to improve the gas adsorption and separation properties of the parent MOFs. We demonstrated the fast and facile preparation of 28 distinct MOF@PCC composites by combining 7 MOFs with 4 PCCs with varying aperture sizes and exposed functional groups through a mechanochemical reaction in 5 mins. Only the combinations of PCCs and MOFs with closely matched aperture sizes exhibited enhanced gas adsorption and separation performance. Specifically, MOF‐808@PCC‐4 exhibited a significantly increased C2H2 uptake (+64 %) and a longer CO2/C2H2 separation retention time (+40 %). MIL‐101@PCC‐4 achieved a substantial C2H2 adsorption capacity of 6.11 mmol/g. This work not only highlights the broad applicability of the mechanochemical “Cage‐on‐MOF” strategy for the functionalization of a wide range of MOFs but also establishes potential design principles for the development of hybrid porous materials with enhanced gas adsorption and separation capabilities, along with promising applications in catalysis and intracellular delivery.

MEPO-ML: a robust graph attention network model for rapid generation of partial atomic charges in metal-organic frameworks

Accurate computation of the gas adsorption properties of MOFs is usually bottlenecked by the DFT calculations required to generate partial atomic charges. Therefore, large virtual screenings of MOFs often use the QEq method which is rapid, but of limited accuracy. Recently, machine learning (ML) models have been trained to generate charges in much better agreement with DFT-derived charges compared to the QEq models. Previous ML charge models for MOFs have all used training sets with less than 3000 MOFs obtained from the CoRE MOF database, which has recently been shown to have high structural error rates. In this work, we developed a graph attention network model for predicting DFT-derived charges in MOFs where the model was developed with the ARC-MOF database that contains 279,632 MOFs and over 40 million charges. This model, which we call MEPO-ML, predicts charges with a mean absolute error of 0.025e on our test set of over 27 K MOFs. Other ML models reported in the literature were also trained using the same dataset and descriptors, and MEPO-ML was shown to give the lowest errors. The gas adsorption properties evaluated using MEPO-ML charges are found to be in significantly better agreement with the reference DFT-derived charges compared to the empirical charges, for both polar and non-polar gases. Using only a single CPU core on our benchmark computer, MEPO-ML charges can be generated in less than two seconds on average (including all computations required to apply the model) for MOFs in the test set of 27 K MOFs.

Mechanochemical "Cage-on-MOF" Strategy for Enhancing Gas Adsorption and Separation through Aperture Matching.

Post-modification of porous materials with molecular modulators has emerged as a well-established strategy for improving gas adsorption and separation. However, a notable challenge lies in maintaining porosity and the limited applicability of the current method. In this study, we employed the mechanochemical "Cage-on-MOF" strategy, utilizing porous coordination cages (PCCs) with intrinsic pores and apertures as surface modulators to improve the gas adsorption and separation properties of the parent MOFs. We demonstrated the fast and facile preparation of 28 distinct MOF@PCC composites by combining 7MOFs with 4 PCCs with varying aperture sizes and exposed functional groupsthrough a mechanochemical reactionin 5 mins. Only the combinations of PCCs and MOFs with closely matched aperture sizes exhibited enhanced gas adsorption and separation performance. Specifically, MOF-808@PCC-4 exhibited a significantly increased C2H2 uptake (+64%) and a longer CO2/C2H2 separation retention time (+40%). MIL-101@PCC-4 achieved a substantial C2H2 adsorption capacity of 6.11 mmol/g. This work not only highlights the broad applicability of the mechanochemical "Cage-on-MOF" strategy for thefunctionalization of a wide range of MOFs but also establishes potential design principles for the development of hybrid porous materials with enhanced gas adsorption and separation capabilities, along with promising applications in catalysis and intracellular delivery.

Comparative study of metal-organic frameworks synthesized via imide condensation and coordination assembly.

A series of metal-organic frameworks (1-XDI) have been synthesized by imide condensation reactions between an amine-functionalized pentanuclear zinc cluster, Zn4Cl5(bt-NH2)6, (bt-NH2 = 5-aminobenzotriazolate), and organic dianhydrides (pyromellitic dianhydride (PMDA), naphthalenetetracarboxylic dianhydride (NDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (HFIPA)). The properties of the 1-XDI MOFs have been compared with analogues (2-XDI) prepared using traditional coordination assembly. The resulting materials have been characterized by ATR-IR spectroscopy, acid-digested 1H NMR spectroscopy, elemental analysis, and gas adsorption measurements. N2 adsorption isotherm data reveal modest porosities and BET surface areas (30-552 m2 g-1). All of the new 1-XDI and 2-XDI MOFs show selective adsorption of C2H2 over CO2 while 2-PMDI and 2-BPDI exhibit high selectivity toward C3H6/C3H8 separation. This study establishes imide condensation of preformed metal-organic clusters with organic linkers as a viable route for MOF design.

Module-based machine learning models using sigma profiles of organic linkers to predict gaseous adsorption in metal-organic frameworks

BackgroundMetal-organic frameworks (MOFs) have drawn considerable attention for their potential in adsorption applications, such as gas separation and storage. Machine learning (ML) augmented high-throughput screening approaches have emerged as an effective strategy to expedite the materials search. Traditionally, ML models developed to predict the adsorption properties of MOFs rely on various geometrical and chemical descriptors. While these descriptors are effective, they tend to be specific to each MOF's unique structure, completely omitting the modular nature of MOFs. MethodsA new approach is proposed in this study: a modular descriptor based on the sigma profile of MOF organic linkers. These sigma profiles effectively represent the chemical environment of organic linkers. With these profiles as input features, we train extreme gradient boosting (XGBoost) models to predict the Henry's coefficient (KH) of adsorption for hydrocarbons and acid gases in MOFs. FindingsThe results show that sigma profiles enhance the prediction accuracy and emerge as the most important features for hydrocarbon gases. This study highlights the potential of sigma profiles in developing accurate ML models for identifying optimal MOF adsorbents. Such an approach could also facilitate an inverse design of MOFs with targeted properties.

Cradle‐to‐Gate Environmental Impact Assessment of Commercially Available Metal‐Organic Frameworks Manufacturing

AbstractMetal‐organic frameworks (MOFs) are promising next‐generation crystalline porous materials with exceptional structural, chemical, and application diversity. Since their discovery, the reticular tunability and physiochemical properties of MOFs have been studied and carefully manipulated to make them suitable for a wide variety of applications. After decades of research, these materials are moving from the benchtop to commercial, industrial‐scale production. Although MOFs are now widely explored, the overall environmental impacts of these emerging materials are still underexplored. In this work, the first example of overall assessment of ten industrially produced and widely explored MOFs considering 18 diverse environmental impact categories such as global warming potential, fossil resource scarcity, water consumption, ecotoxicity, etc. via cradle‐to‐gate life cycle assessment is presented. Importantly, this study presents a comprehensive comparison between different synthetic methods of each MOF and compiles the environmental impacts associated only with the individual “synthesis” or “washing” steps. This study highlights the critical importance of using of green solvents over organic to reduce the overall environmental footprint. By identifying the synthetic drawbacks associated with different methods, this work provides a blueprint for the sustainable design and required future development of MOF synthesis.

Efficient adsorption and desorption of elemental mercury by ordered mesoporous cerium oxide nanoparticles derived from Ce-based metal–organic frameworks

Metal oxide-based adsorbents not only exhibit effective elemental mercury (Hg0) removal capacity but also offer suitability for wet desorption, which is a green treatment method to avoid secondary contamination of deactivated adsorbents. Nevertheless, the limited dispersing capacity of the carrier restricts the loading of active substances, hindering further enhancement of adsorption capacity. The pore structure of adsorbent is also a key factor for wet desorption. In this work, we synthesized a hollow cerium-based metal–organic framework (Ce-mesoMOF) as a sacrificial precursor to obtain ordered mesoporous cerium oxide (OM-CeO₂) via a mesoporous genetic pyrolysis-oxidation mechanism. OM-CeO2 inherits the excellent structural properties of mesoporous MOF with better catalytic activity, exhibiting strong adsorption capacity in various atmospheres (97.6 % in pure N2, 98.8 % in N2 + H2S). Wet desorption of Hg compounds and reduction of the active site can be synergized in Na2S2O3 solution. The octahedral structure with an ordered mesoporous shell greatly facilitates the mass transfer process, as evidenced by the strong adsorption capacity and fast kinetic parameters of OM-CeO2. Density functional theory analysis reveals that the conversion reaction of adsorbed Hg has a low energy barrier on the pyrolytic-oxidized OM-CeO2 and the inhibitory effect of reactive S for Hg0 adsorption transforms into a facilitating effect. This study leverages the structural advantages of ordered mesoporous MOFs in the field of Hg adsorption and imparts reactivity through modification for efficient adsorption–desorption.

Combining machine learning and molecular simulation to explore MOF materials that contribute to CF4/N2 separation

High-throughput molecular simulations and machine learning algorithms have been widely used to identify promising metal–organic frameworks for gas separation. However, most studies are limited to screening high-performance materials from existing databases, which fails to fully utilize the predictive function of machine learning. This paper combines genetic algorithms and high-throughput screening to deeply mine anion-pillared MOF (APMOF) performance feature relationships and predict high-performance materials that are not in the database. Considering the actual industrial conditions (CF4/N2 = 10/90), we chose the ratio of CF4:N2 = 1:9 to simulate the adsorption separation of gas mixtures of MOF materials at a temperature of 298 K and a pressure of 1 bar. First, the CF4/N2 separation properties of MOFs in the APMOF library were obtained based on molecular simulations. Then, the filtered data were coded according to the method of “building block classification − structural interval categorization”. Then, the machine learning algorithm was used for model training to obtain a high-precision model. Finally, the tangent adaptive genetic algorithm was used to recombine the genes of the materials, and the new MOF materials were successfully reverse-engineered. The study found that the pore-limit diameter of APMOFs is most conducive to the separation of CF4/N2 by MOFs when the pore-limit diameter of APMOFs is within two times the molecular dynamics diameter of CF4. 134 MOF materials were predicted to have CF4/N2 selectivities exceeding 46.30. The use of organic ligands such as 4,4′-bipyridyl or 1,4-bis(4-pyridyl)benzene (bpb) increases the likelihood of these materials being high-performance for CF4/N2 separation. The combination of computational screening methods and machine learning can expedite the design and development of new high-performance MOFs. This approach can also provide guidance for the synthetic direction and pattern of materials, which can assist experimentalists in their synthesis.

Tunable optical properties of isoreticular UiO-67 MOFs for photocatalysis: a theoretical study.

A theoretical study of the reported photocatalytic systems based on Zr-based MOF (UiO-67) with biphenyl-4,4'-dicarboxylic acid (bpdc) and 2,2'-bipyridine-5,5'-dicarboxylic acid (bpydc) as linkers was performed. Quantum chemical calculations were carried out to understand the optical properties of the materials and to facilitate the rational design of new UiO-67 derivatives with potentially improved features as photocatalysts under ambient conditions. Hence, the effect of the structural modifications on the optical properties was studied considering different designs based on the nature of the linkers: in 1 only the bpdc linker was considered, or the mixture 1 : 1 between bpdc and bpydc linkers (labeled as 1A). Also, substituents R, -NH2, and -SH, were included in the 1A MOF only over the bpdc linker (labeled as 1A-bpdc-R) and on both bpdc and bpydc linkers (labeled as 1A-R). Thus a family of six isoreticular UiO-67 derivatives was theoretically characterized using Density Functional Theory (DFT) calculations on the ground singlet (S0) and first excited states (singlet and triplet) using Time-Dependent Density Functional Theory (TD-DFT), multiconfigurational post-Hartree-Fock method via Complete Active Space Self-Consistent Field (CASSCF). In addition, the use of periodic DFT calculations suggest that the energy transfer (ET) channel between bpdc and bpydc linkers might generate more luminescence quenching of 1A when compare to 1. Besides, the results suggest that the 1A-R (R: -SH and NH2) can be used under ambient conditions; however, the ET exhibited by 1A, cannot take place in the same magnitude in these systems. These ET can favor the photocatalytic reduction of a potential metal ion, that can coordinate with the bpydc ligand, via LMCT transition. Consequently, the MOF might be photocatalytically active against molecules of interest (such as H2, N2, CO2, among others) with photo-reduced metal ions. These theoretical results serve as a useful tool to guide experimental efforts in the design of new photocatalytic MOF-based systems.

Preparation and electromagnetic wave absorption properties of CAU-Al MOF and graphene oxide aerogel composites

The application of microwave technology has penetrated all aspects of life, but also lead to the electromagnetic pollution, therefore the research of high efficiency microwave absorption materials has been widely concerned. In this work, a new type of Al based CAU-10-H MOF was prepared by hydrothermal method. The particles were polyhedral in size of 2 [Formula: see text]m. After high temperature annealing, the interplanar spacing increased with the annealing temperature, and the lattice structure was destroyed at 400°C. CAU-Al/rGO aerogels were prepared by freeze-drying of hydrogels. With the increase of CAU-Al content and the annealing temperature, the carbon crystallinity decreases, and the pores of the aerogels became larger and fluffier. The real parts of permittivity of CAU-Al/rGO aerogels were between 5 and 30, which can be tuned by the annealing temperature and CAU-Al content. For the microwave absorption performance, the CAU-Al/rGO aerogel with a ratio of 3:1 achieved the minimum reflection loss of −37.8 dB at 3 mm. Moreover, the CAU-Al/rGO aerogels showed a wide effective bandwidth, which reached 5.1 GHz under the thickness of 2.5 mm. Therefore, the CAU-Al/rGO aerogels could be used as a kind of broadband microwave absorber with excellent microwave absorption performance.

Enhanced optical and electrochemical properties of FeBTC MOF modified TiO2 photoanode for DSSCs application

In this work, iron based 1, 3, 5-tricarboxylic acid (FeBTC) was prepared via microwave-assisted method and incorporated into TiO2 via ultrasonic assisted method. The TiO2–FeBTC nanocomposites were characterized by XRD, FTIR, Raman, BET, FESEM, HRTEM, TGA, UV‒vis DRS and PL to understand their crystallographic, surface morphology, and optical characteristics. The Raman spectra showed a blue shift of Eg, A1g, and B1g peaks upon incorporation of FeBTC MOF onto TiO2. HRTEM and XRD analysis confirmed a mixture of TiO2 nanospheres and hexagonal FeBTC MOF morphologies with high crystallinity. The incorporation of FeBTC onto TiO2 improved the surface area as confirmed by BET results, which resulted in improved absorption in the visible region as a results of reduced bandgap energy from 3.2 to 2.84 eV. The PL results showed a reduced intensity for TiO2–FeBTC (6%) sample, indicating improved separation of electron hole pairs and reduced recombination rate. After fabrication of the TiO2–FeBTC MOF photoanode, the charge transfer kinetics were enhanced at TiO2–FeBTC MOF (6%) with Rp value of 966 Ω, as given by EIS studies. This led to high performance due to low charge resistance. Hence, high power conversion efficiency (PCE) value of 0.538% for TiO2–FeBTC (6%) was achieved, in comparison with other loadings. This was attributed to a relatively high surface area which allowed more charge shuttling and thus better electrical response. Conversely, upon increasing the FeBTC MOF loading to 8%, significant reduction in efficiency (0.478%) was obtained, which was attributed to sluggish charge transfer and fast electron–hole pair recombination rate. The TiO2–FeBTC (6%) may be a good candidate for use in DSSCs as a photoanode materials for improved efficiency.

Ultrasonic controllable synthesis of sulfur-functionalized metal–organic frameworks (S-MOFs) and their application in piezo-photocatalytic rapid reduction of hexavalent chromium (Cr)

The United Nations’ Sustainable Development Goals (SDGs) are significant in guiding modern scientific research. In recent years, scholars have paid much attention to MOFs materials as green materials. However, piezo catalysis of MOFs materials has not been widely studied. Piezoelectric materials can convert mechanical energy into electrical energy, while MOFs are effective photocatalysts for removing pollutants. Therefore, it is crucial to design MOFs with piezoelectric properties and photosensitivity. In this study, sulfur-functionalized metal–organic frameworks (S-MOFs) were prepared using organic sulfur-functionalized ligand (H2TDC) ultrasonic synthesis to enhance their piezoelectric properties and visible light absorption. The study demonstrated that the S-MOFs significantly enhanced the reduction of a 10 mg/L solution of hexavalent chromium to 99.4 % within 10 min, using only 15 mg of catalyst. The orbital energy level differences of the elements were analyzed using piezo response force microscopy (PFM) and X-ray photoelectron spectroscopy (XPS). The results showed that MOFs functionalized with sulfur atom ligands have a built-in electric field that facilitates charge separation and migration. This study presents a new approach to enhance the piezoelectric properties of MOFs, which broadens their potential applications in piezo catalysis and piezo-photocatalysis. Additionally, it provides a sustainable method for reducing hexavalent chromium, contributing to the achievement of sustainable development goals, specifically SDG-6, SDG-7, SDG-9, and SDG-12.

Anomalous superconductivity in Li/F modified two-dimensional molybdenene

Anomalous superconductivity in Li/F modified two-dimensional molybdenene

High-Level Disordered Metal-Organic Frameworks Synthesized by Interference-Oriented Attachment for Electrochemical Anion Sieve.

Disordered MOFs seamlessly amalgamate the robust stability and pore tunability inherent in crystalline MOFs with the advantages derived from abundant defects and active sites present in amorphous structures. This study pioneers the use of the interference-oriented attachment (IOA) mechanism to meticulously craft the morphology and crystal growth of MIL-101(Cr) (Cr-MOF), resulting in the successful synthesis of a high-level disordered Cr-MOF boasting an enhanced array of active sites and exceptional electrochemical properties. The correlation between disordered structures and the electrochemical properties of MOFs are elucidated using the lattice distortion index and fractal dimension. The high-level disordered MOF electrode showcases a remarkable fluoride sieving effect, outperforming conventional fluoride removal materials with a remarkable fluoride adsorption capacity of 41.04 mgNaF gelectrodes -1. First-principles calculations, in conjunction with relevant experiments, provided further validation that the disordered structure significantly enhances the defluorination performance of the material. This study introduces a novel approach for the direct bottom-up synthesis of high-level disordered MOFs, showcasing their potential for applications in electrochemical water treatment.

Preparation and Application Progress of MOFs

The everyday needs of humanity can no longer be met by traditional materials due to advancements in science and technology. These days, the main objective is to produce materials with increased usefulness, superior performance, and recyclability. Because of their high specific surface area and porosity, easily functionalizable pore structure, and customizable pore structure, metal-organic skeletons (MOFs) represent a novel class of porous materials with a wide variety of applications in the energy, environment, and biomedical sectors. Therefore, this paper summaries the latest research progress in the study of MOFs. Firstly, the paper introduces the basic features of MOFs, including metal centers and organic ligands, and discusses the tunability of these modules for the geometrical and chemical properties of MOFs. Then, the main synthetic methods of MOFs are summarized, including solvothermal synthesis, electrochemical synthesis, and microbiome-assisted synthesis. Finally, the paper also highlights the applications of MOFs in gas storage/separation, biomedicine, and environmental protection. It aims to provide some reference significance for the future development direction of MOFs.

Time-Resolved Spectroscopy for Dynamic Investigation of Photoresponsive Metal-Organic Frameworks.

Photoresponsive MOFs with precise and adjustable reticular structures are attractive for light conversion applications. Uncovering the photoinduced carrier dynamics lays the essential foundation for the further development and optimization of the MOF material. With the application of time-resolved spectroscopy, photophysical processes including excimer formation, energy transfer/migration, and charge transfer/separation have been widely investigated. However, the identification of distinct photophysical processes in real experimental MOF spectra still remains difficult due to the spectral and dynamic complexity of MOFs. In this Perspective, we summarize the typical spectral features of these photophysical processes and the related analysis methods for dynamic studies performed by time-resolved photoluminescence (TR-PL) and transient absorption (TA) spectroscopy. Based on the recent understanding of excited-state properties of photoresponsive MOFs and the discussion of challenges and future outlooks, this Perspective aims to provide convenience for MOF kinetic analysis and contribute to the further development of photoresponsive MOF material.

Advancements of MOFs in the Field of Propane Oxidative Dehydrogenation for Propylene Production.

Compared to the currently widely used propane dehydrogenation process for propylene production, propane oxidative dehydrogenation (ODHP) offers the advantage of no thermodynamic limitations and lower energy consumption. However, a major challenge in ODHP is the occurrence of undesired over-oxidation reactions of propylene, which reduce selectivity and hinder industrialization. MOFs possess a large number of metal sites that can serve as catalytic centers, which facilitates the easier access of reactants to the catalytic centers for reaction. Additionally, their flexible framework structure allows for easier adjustment of their pores compared to metal oxides and molecular sieves, which is advantageous for the diffusion of products within the framework. This property reduces the likelihood of prolonged contact between the generated propylene and the catalytic centers, thus minimizing the possibility of over-oxidation. The research on MOF catalyzed oxidative dehydrogenation of propane (ODHP) mainly focuses on the catalytic properties of MOFs with cobalt oxygen sites and boron oxygen sites. The advantages of cobalt oxygen site MOFs include significantly reduced energy consumption, enabling catalytic reactions at temperatures of 230 °C and below, while boron oxygen site MOFs exhibit high conversion rates and selectivity, albeit requiring higher temperatures. The explicit structure of MOFs facilitates the mechanistic study of these sites, enabling further optimization of catalysts. This paper provides an overview of the recent progress in utilizing MOFs as catalysts for ODHP and explores how they promote progress in ODHP catalysis. Finally, the challenges and future prospects of MOFs in the field of ODHP reactions are discussed.

Tailoring ammonia capture in MOFs and COFs: A multi-scale and machine learning comprehensive investigation of functional group modification.

Our study aims to examine the impact of ligand functionalization on the ammonia adsorption properties of MOFs and COFs, by combining multi-scale calculations with machine learning techniques. Density Functional Theory calculations were performed to investigate the interactions between ammonia (NH3) and a comprehensive set of 48 strategically chosen functional groups. In all of the cases, it is observed that functionalized rings exhibit a stronger interaction with ammonia molecule compared to unfunctionalized benzene, while -O2Mg demonstrates the highest interaction energy with ammonia (15 times stronger than the bare benzene). The trend obtained from the thorough DFT screening is verified via Grand Canonical Monte-Carlo calculations by employing interatomic potentials derived from quantum chemical calculations. Isosteric heat of adsorption plots provide a comprehensive elucidation of the adsorption process, and important insights can be taken for studies in fine-tuning materials for ammonia adsorption. Furthermore, a proof of concept machine learning (ML) analysis is conducted, which demonstrates that ML can accurately predict NH3 binding energies despite the limited amount of data. The findings derived from our multi-scale methodology indicate that the functionalization strategy can be utilized to guide synthesis towards MOFs, COFs, or other porous materials for enhanced NH3 adsorption capacity.

Tribological properties of surface-functionalized Zr-based MOF as a lubricant additive

The development of novel high-performance lubricants is of great significance to reduce energy consumption and save energy. Herein, we report a zirconium-based MOF functionalized with tetradecylphosphonic acid (TDPA-Zr-MOF), as a lubricant additive in soybean oil (SO). The tribological properties of TDPA-Zr-MOF were systematically measured by a four-ball test machine, which showed that soybean oil with TDPA-Zr-MOF exhibit better tribological properties compared with pure soybean oil. The friction coefficient and wear scar diameter are significantly reduced, both of which can be decreased by more than 35%. Based on the analysis of morphology and chemical composition of the worn surface, it is concluded that the excellent anti-friction and anti-wear properties of TDPA-Zr-MOF attributed to rolling effect and protective film effect.