CuBDC Nanosheets Research Articles

Multiplicative rGO/Cu-BDC MOF for 4-nitrophenol reduction and supercapacitor applications

Two-dimensional nanosheets, with their distinct characteristics, are widely used in various applications such as water splitting, supercapacitors, catalysis etc. In this research, we produced Cu-BDC MOF nanosheets by using Cu2O nanotubes for metal ions and H2BDC as the organic linker. We combined these Cu-BDC MOF nanosheets with reduced graphene oxide (rGO) to form a nanocomposite. The collaboration between Cu-BDC MOF and rGO boosts both the catalytic reduction of 4-nitrophenol and the electrochemical capabilities. The conversion of 4-nitrophenol to 4-aminophenol is achieved using sodium borohydride as both a reducing agent and a catalyst. The study explores the impact of different concentrations of 4-nitrophenol and sodium borohydride on catalytic efficiency. The increase in sodium borohydride concentration enhances catalytic efficiency by providing more BH4− ions and electrons for the reduction process. The catalytic reduction process adheres to the Langmuir–Hinshelwood mechanism with apparent pseudo-first-order kinetics. Specifically, Cu-BDC MOF and rGO/Cu-BDC MOF exhibit specific capacities of 468.4 mA h/g and 656.4 mA h/g at a current density of 2 A/g, respectively, while also enhancing the operating voltage window. Therefore, electrodes based on rGO/Cu-BDC MOF nanosheets present a novel approach for environmental remediation and energy storage applications across various fields.

SWCNTs-channeled MOF nanosheet membrane for high-efficient organic solvent nanofiltration

Organic solvent nanofiltration (OSN) has become increasingly important in petrochemical and pharmaceutical industries, demanding superior and robust membranes. 2D MOF nanosheets hold great promise in the preparation of OSN membrane. Nevertheless, the fabrication of defect-free 2D MOF membranes with robust mechanical strength is hampered due to the weak interlamellar interactions between MOF nanosheets. Herein, 2D MOF composite membrane for high-performance OSN application is fabricated through the assembly of copper 1,4-benzene dicarboxylate (CuBDC) nanosheets and NH2-SWCNTs. Within this composite configuration, NH2-SWCNTs can shelter the defects between the adjacent CuBDC nanosheets, rendering CuBDC/CNTs composite membranes precise molecular sieving ability. Meanwhile, the nanochannels created by NH2-SWCNTs with low frictional coefficients on the internal surface promote the permeation of organic solvents. Moreover, the multiple interactions between CuBDC and NH2-SWCNTs improve the mechanical strength of composite membranes. Accordingly, the composite membranes display excellent rejections of dye molecules on the basis of size-sieving mechanism with superior methanol permeance of 1260 L m−2h−1 bar−1, as well as steady congo red rejection at high trans-membrane pressure of 5 bar, demonstrating good pressure resistance of composite membranes. Moreover, the composite membranes exhibit outstanding stability against high-concentration feeds and long-term operation for 50 h, confirming excellent practicality in the purification of dyes from organic solvents. The design approach in this work may inspire the fabrication of other nanosheet-based membranes for high-efficient OSN.

Two morphology distinct fillers with chemical similarity incorporated into Tröger’ base polymers towards enhanced gas separation

Mixed matrix membranes (MMMs) with one class of fillers always require high loadings to maximize gas permeability. The incompatibility between polymers and high content fillers causes non-selective interfacial voids in the MMMs and poor mechanical properties of MMMs. This work adopts two morphology distinct fillers with chemical similarity to achieve improved gas separation performance of Tröger’ base membranes without sacrificing their mechanical properties. The three-dimensional ZIF-8 nanoparticles are beneficial for membrane gas permeability. The addition of low content ZIF-8 nanosheets can greatly improve H2/CH4 and CO2/CH4 selectivities of the membranes. ZIF-8 particles and ZIF-8 nanosheets with similar chemical properties can mix more homogeneously and disperse well in the polymer matrix with expected hydrogen bonding interaction compared to mixed ZIF-8 and CuBDC nanosheets. Eventually, the resulting dual filler MMMs doped with 4 wt% ZIF-8 nanosheets and 10 wt% ZIF-8 nanoparticles have H2/CH4 ideal selectivity of 60 with H2 permeability of 426 Barrer, which is an increase of 18% and 102% over pure membranes, respectively. Moreover, the membrane has a significantly enhanced CO2/CH4 mixed gas selectivity of 68 at sub-ambient temperature, accompanied by temperature-dependent CO2-induced plasticization behavior. Mixing morphology distinct fillers with chemical similarity is proved to be an effective method to prepare a robust MMM at low filler amounts, and the synergistic effect on gas permeability and selectivity endows these dual filler MMMs with great H2/CH4 and CO2/CH4 separation performance.

Fabrication of Two-Dimensional Metal-Organic Framework Nanosheets through Crystal Dissolution-Growth Kinetics.

Controlling the morphology of the metal-organic framework (MOF) for nanosheets is beneficial for understanding their crystal growth kinetics and useful for extending these MOF nanosheets to advanced applications, in particular for gas separation and device integration. However, synthesizing MOF nanosheets with uniform thickness or desirable size still remains challenging. Herein, we provide a crystal dissolution-growth strategy for fabricating dispersible porphyrin MOF nanosheets with lateral dimensions and nanometer thickness. A morphological transition (bulk crystals-nanosheets-bulk crystals) in Zn-TCPP was observed when controlling the crystal growth kinetics by adjusting the reaction parameters (temperature and acidity). These findings encouraged the synthesis of other types of nanosheets (Cu-TCPP, Zn-TCPP (Pd), and Cu-BDC nanosheets). Zn-TCPP (Pd) nanosheets were applied in field-effect transistors and exhibited photoresponse characteristics. This work demonstrates a new strategy for obtaining MOF nanosheets and casts a new light upon fabricating two-dimensional inorganic-organic hybrid materials with controlled thickness.

A lightweight, mechanically strong, and shapeable copper-benzenedicarboxylate/cellulose aerogel for dye degradation and antibacterial applications

• CuBDC nanosheets were loaded on cellulose aerogels by in-situ growth. • The composite aerogel showed good performance in degradation of methylene blue. • The composite aerogel exhibited excellent killing effect towards various bacteria. • Antibacterial mechanism was related to the damage of bacteria envelope integrity. Metal-organic frameworks (MOFs) suffer from low processability and recyclability due to their fragile powder form. Supporting MOFs on the lightweight and porous cellulose aerogels is an efficient way to dramatically extend their practical applications. Herein, a metal–organic framework (MOF) composite material, named as copper-benzenedicarboxylate/cellulose aerogel (CuBDC/CA), was designed and synthesized by one-pot precursor preparation of cellulose aerogels anchored with copper, followed by in-situ growth of CuBDC in the presence of terephthalic acid. The characterizations (scanning electron microscopy with energy-dispersive X-ray, powder X-ray diffraction, Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, stability and mechanical tests) confirmed the successful synthesis of the lightweight (0.0625 ± 0.0010 g/cm 3 for 20% CuBDC/CA), mechanically strong, stable, and porous aerogel composites with well-dispersed CuBDC nanosheets. The aerogel composite showed great potential in wastewater treatment, including dye degradation and antibacterial assays. More than 90% methylene blue could be decomposed by CuBDC/CA in 240 min via the Fenton-like reaction, and the recycling test revealed its good reusability. Moreover, this composite exhibited great antibacterial performance (more than 99.99%) towards commonly used lab strains as well as multidrug-resistant pathogens, including Escherichia coli , Staphylococcus aureus, and Pseudomonas aeruginosa . The screening tests indicated that the mechanism of killing effect was associated with the damage of bacterial envelope integrity. This work has proven that the lightweight and robust MOF/cellulose aerogel is a promising candidate for environmental remediation in practice.

Step by Step Bisacrificial Templates Growth of Bimetallic Sulfide QDs‐Attached MOF Nanosheets for Nonlinear Optical Limiting

AbstractHere, the authors first report a bimetallic sulfide quantum dots (QDs)‐attached metal–organic framework (MOF) nanosheets‐based film from bisacrificial templates. By using a step by step bisacrificial templates strategy, MOF CuBDC precursors (BDC = 1,4‐benzenedicarboxylate) and chalcogenidometalates as the templates can successfully in‐situ assemble Cu2SnS3 (CTS) QDs‐attached CuBDC nanosheets on the functionalized substrate (CTS @ CuBDC film). The obtained CTS QDs possess a uniform size with ≈6.2 nm and are homogeneously dispersed on MOF nanosheets, which results in an improvement of conductivity and represents a semiconductive composite film for optical application. A Z‐scan study under the excitation of a 532 nm laser shows that the CTS @ CuBDC film possesses strong optical limiting (OL) behavior and very low OL thresholds (0.92 J cm−2) as well as large third‐order nonlinear susceptibility (1.9 × 10−6 esu). This work suggests that the step by step bisacrificial templates method is a fascinating and feasible strategy to prepare metal sulfide QDs dispersed MOF hybrid materials, and provides a promising potential candidate for nonlinear optical applications.

Understanding CO2/CH4 Separation in Pristine and Defective 2D MOF CuBDC Nanosheets via Nonequilibrium Molecular Dynamics.

The separation of CO2/CH4 gas mixtures is a key challenge for the energy sector and is essential for the efficient upgrading of natural gas and biogas. A new emerging field, that of metal–organic framework nanosheets (MONs), has shown the potential to outperform conventional separation methods and bulk metal–organic frameworks (MOFs). In this work, we model the CO2/CH4 separation in both defect-free and defective 2D CuBDC nanosheets and compare their performance with the bulk CuBDC MOF and experimental data. We report the results of external force nonequilibrium molecular dynamics (EF-NEMD) for pure components and binary mixtures. The EF-NEMD simulations reveal a pore blocking separation mechanism, in which the CO2 molecules occupy adsorption sites and significantly restrict the diffusion of CH4. The MON structure achieves a better selectivity of CO2 over CH4 compared to the bulk CuBDC MOF which is due to the mass transfer resistance of the methane molecules on the surface of the nanosheet. Our results show that it is essential to consider the real mixture in these systems rather than relying solely on pure component data and ideal selectivity. Furthermore, the separation is shown to be sensitive to the presence of missing linker defects in the nanosheets. Only 10% of missing linkers result in nonselective nanosheets. Hence, the importance of a defect-free synthetic method for CuBDC nanosheets is underlined.

Polyimide based mixed matrix membranes incorporating Cu-BDC nanosheets for impressive helium separation

Incompatibility between particles and polymers has the adverse consequence on the performance of mixed matrix membranes (MMMs).To overcome this problem, MMMs containing Cu-BDC nanosheets with two various polyimides (6FDA-DAM and Matrimid) were fabricated and tested for He separation. High aspect ratio of nanosheets (more than 100) was confirmed by TEM and AFM Analyses. FESEM images of MMMs showed that the nanosheets were uniformly distributed all over the matrices and there was no symptom of micro scale polymer-filler phase void up to 15 wt%. Also due to the interface interaction established between two phases, rigidification of chains happened and resulted in increasing Tg and decreasing FFV of polymers. Addition of particles to matrices led to the permeability of He increased slightly until 9 wt% loading, but it was reduced at 12 and 15 wt%. Actually, the oriented stacking of nanosheets caused the permeability of CH4 and N2 reduced significantly and gave rise to developed ideal selectivities. The best MMMs for both polymers was observed at loading of 15 wt%, so that for 6FDA-DAM based MMM, He/CH4 and He/N2 ideal selectivities enhanced by 2570 and 2320% compared to pure 6FDA-DAM and surpassed the 2008 Robeson upper bound.

Fabrication of mesoporous MOF nanosheets via surfactant-template method for C–S coupling reactions

Abstract Pore size enlargement plays a vital role in the catalytic applications of metal-organic frameworks (MOFs). There is still a big challenge in achieving two-dimension (2D) ultrathin MOF nanosheets with controllable meso-pores, although it has huge demanding. In this work, various kinds of mesoporous MOF nanosheets with uniform meso-pore channels and crystallized microporous frameworks were constructed using surfactants (cetyltrimethyl ammonium bromide, CTAB) as sacrificial templates. CTAB was firstly introduced into MOF nanosheet structure during the formation of MOF nanosheets, and mesopores could be produced by removing CTAB from MOF nanosheets. Remarkably, the integration of ultrathin nanosheets and mesoporous property enables mesoporous CuBDC nanosheets enhanced catalytic activity for C–S cross-coupling reaction, providing a new concept and feasible strategy for highly efficient mesoporous MOF catalyst synthesis.

General Approach to Metal-Organic Framework Nanosheets With Controllable Thickness by Using Metal Hydroxides as Precursors

Metal-organic frameworks (MOFs) nanosheets have attracted great attention in recent years due to their unprecedented properties. However, the synthesis of MOF nanosheets with controllable thickness still remains a challenge. In this work, a series of MOF nanosheets, such as CuBDC (BDC = 1,4-benzenedicarboxylate), CoNDC (NDC = naphthalene‐2,6‐dicarboxylate), CoBPDC (BPDC = biphenyl-4,4’-dicarboxylate), NiBDC and ZnTCPP (TCPP = tetrakis(4-carboxyphenyl)porphyrin) were successfully synthesized by using a metal hydroxide precursor approach. Importantly, the thicknesses of the obtained MOF nanosheets can be well regulated by controlling the conversion rate of the metal hydroxides. As a proof-of-concept application, the obtained CuBDC nanosheets were used as the catalyst for olefin epoxidation, which showed much higher catalytic activity compared to the bulk crystals. This work provides an alternative method for the synthesis of various MOF nanosheets, holding great potential for various promising applications.

2D metal-organic frameworks-derived preparation of layered CuS@C as an efficient and stable electrocatalyst for hydrogen evolution reaction

Given the energy crisis and environmental pollution, it is urgent to design and construct efficient and stable electrocatalyst for the production of clean hydrogen energy. In this work, 2D Cu-contained metal-organic frameworks (Cu-BDC nanosheets) were firstly synthesized using Cu2O cubes as Cu2+ source precursor by a facile and efficient bottom-up method. Subsequently, layered CuS@C were prepared via a sulfidation of Cu-BDC nanosheets as an efficient electrocatalyst for hydrogen evolution reaction (HER). The effects of catalyst structure and chemical composition on the electrocatalytic activity were discussed in detail. Experiment results shows that the optimized layered CuS@C exhibits high HER catalytic activity, affording the current density of 10 mA cm−2 at low overpotentials of 128 mV and Tafel slopes of 44 mV dec−1. The enhanced HER electrocatalytic activity of layered CuS@C may be attributed to structural advantage of 2D Cu-BDC precursors, which endows derived electrocatalyst with high specific surface area and percentages of exposed active sites. Moreover, due to the protection of carbon matrix, as-obtained catalysts show high electrocatalytic stability in acidic, alkaline and neutral mediums, making it a potential candidate as electrodes for the application of production of clean hydrogen energy source.

Self-directed hierarchical Cu3(PO4)2/Cu-BDC nanosheets array based on copper foam as an efficient and durable electrocatalyst for overall water splitting

Overall water splitting is a promising approach to produce sustainable energy. For the practical application of overall water splitting, easy-to-operate catalysts as well as catalysis of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in identical electrolyte are critical. Herein, we report a high-efficiency electrocatalyst with hierarchical Cu3(PO4)2/copper metal-organic framework (Cu3(PO4)2/Cu-BDC) nanosheets array supported by copper foam. In this work, Cu3(PO4)2 nanosheets are firstly prepared on the surface of copper foam by means of in-situ growth method. Subsequently, Cu-BDC nanosheets array are synthesized via self-directed growth. In each step of this reaction, copper ions are all released from the substrate, which is facile and controllable. The effect of reaction temperature and reaction time on the morphology of Cu-BDC was discussed in detail. The optimal electrocatalyst (Cu3(PO4)2/Cu-BDC-150-6 foam) exhibited excellent electrocatalytic performance for OER and HER in 1 M KOH, delivering a current density of 10 mA cm−2 at low overpotential of 241 mV and 145 mV, respectively. Using Cu3(PO4)2/Cu-BDC-150-6 foams as both anode and cathode electrocatalyst in 1 M KOH, a current density of 10 mA cm−2 was achieved at a low cell voltage of 1.56 V. In addition, the Cu3(PO4)2/Cu-BDC foam showed excellent catalytic stability and thus will be promising for application in industrial overall water splitting.

Interactions on External MOF Surfaces: Desorption of Water and Ethanol from CuBDC Nanosheets.

The external surfaces of metal-organic framework (MOF) materials are difficult to experimentally isolate due to the high porosities of these materials. MOF surface surrogates in the form of copper benzenedicarboxylate (CuBDC) nanosheets were synthesized using a bottom-up approach, and the surface interactions of water and ethanol were investigated by temperature-programmed desorption (TPD). A method of analysis of diffusion-influenced TPD was developed to measure the desorption properties of these porous materials. This approach also allows the extraction of diffusion coefficients from TPD data. The transmission Fourier transform infrared spectra, powder X-ray diffraction patterns, and TPD data indicate that water desorbs from CuBDC nanosheets with activation energies of 44 ± 2 kJ/mol at edge sites and 58 ± 1 kJ/mol at external surface and internal and pore sites. Ethanol desorbs with activation energies of 58 ± 1 kJ/mol at internal pore sites and 66 ± 0.4 kJ/mol at external surface sites. Co-adsorption of water and ethanol was also investigated. The presence of ethanol was found to inhibit the desorption of water, resulting in a water desorption process with an activation energy of 68 ± 0.7 kJ/mol.

High-performance nanocomposite membranes realized by efficient molecular sieving with CuBDC nanosheets

Two-dimensional (2-D) CuBDC nanosheets (ns-CuBDC) with high-aspect-ratios were deliberately paired with polymers possessing high free volumes to fabricate high performance gas separation membranes. Owing to the molecular sieving effect of the filler, a small ns-CuBDC loading (2-4 wt%) could significantly improve the CO2/CH4 selectivities of membranes, resulting in performances that surpass the upper bound limit for polymer membranes.