ABSTRACT
Metal-organic frameworks (MOFs) are a class of porous materials that have been gradually applied in the field of supercapacitors, but they still present major challenges due to their inherent instability and poor conductivity. Herein, in order to solve these problems, Ni-based MOFs and their derivative materials with a particular spherical structure were prepared using a special calcination method. This unique structure not only improves the conductivity of the electrode, but also promotes the transport of electrons and ions during the electrochemical energy storage process. The as-prepared Ni-MOF@M-a4 has an amazing specific capacitance (637.78 F g-1) and a relatively low impedance. The fabricated asymmetric supercapacitor (ASC) consisted of Ni-MOF@M-a4 and activated carbon (AC) as positive and negative electrodes, respectively. The specific capacitance of this ASC was 18.14 F g-1. The maximum energy and power densities of the device reached 1.23 W h kg-1 and 175.00 W kg-1, showing good electrochemical performance. In this work, both an innovative strategy for the rational preparation of MOF arrays with good orientation and a special material preparation method are proposed, which have promising application potential in the field of asymmetric supercapacitors.
ABSTRACT
Owing to their high porosity, open metal sites, and huge surface area, metal-organic framework (MOF) materials are commonly employed in iodine adsorption processes. Bimetallic MOFs have drawn a lot of attention since mono-metal MOFs have been unable to keep up with the demand. Bimetallic MOF materials still have drawbacks, including limited adsorption capacity, extended adsorption time, poor stability, and poor selectivity, despite their positive performance in radioactive iodine capture. It has been therefore difficult to develop adsorbents with quick iodine adsorption rates and high iodine adsorption efficiency. This study investigated the adsorption properties of a series of bimetallic MOF-74 materials (Mn-Co-MOF-74, Mn-Zn-MOF-74, and Mn-Ni-MOF-74) for radioactive iodine, as well as their design and synthesis utilizing the reflux approach. It was discovered that the adsorption performance of Mn-Ni-MOF-74 for radioiodine was superior to that of the other two bimetallic MOF-74 materials. Using the bimetallic Mn-Ni-MOF-74 as a precursor, a variety of bimetallic MOF-74 derived carbon compounds (Mn-Ni-CX) were prepared by high-temperature pyrolysis. Simultaneously, the structure of the material and the iodine adsorption characteristics have been thoroughly studied.
ABSTRACT
Metal-organic frameworks (MOFs) are self-assembled constitutive precursors and efficient self-sacrificial templates with metal ions/clusters and organic linkers from which multifunctional materials with carbon nanostructures can be derived. In this study, we synthesized a novel Cu-MOF with Cu(II) as the central metal ion through two ligands, N,N'-bis(pyridin-3-yl)terephthalamide (3-bpta) and fumaric acid (H2FA), which was used as a template for derivatizing carbon-based nanostructured materials of Cu and CuxO through doping with different materials (melamine, urea, and TiO2) in a simple and efficient one-step pyrolysis. The Cu/CuxO-1 catalyst possesses both dark-catalyzed degradation activity and photocatalytic reduction activity during water purification due to the hole-transfer ability between Cu+ and Cu2+ and its inhibition of electron-hole complexation. In the absence of light, force, and cocatalyst, it can also effectively remove azo dyes in water and effectively reduce Cr(VI) under the action of visible light; therefore, Cu/CuxO-1 can be used as a new type of bifunctional material for the removal of pollutants in water, which has a broad prospect.
ABSTRACT
The environmental pollution caused by antibiotics, Fe3+ and MnO4- pollutants is becoming increasingly serious. Polyacrylonitrile (PAN) and polymethyl methacrylate (PMMA) were used and decorated with metal-organic frameworks (MOFs) to fabricated three kinds of nanofibrous membranes (NFMs) with different shapes and sizes were prepared by electrospinning technology using in situ growth method and mixed spinning method. The structures and properties of the above three kinds of NFMs were characterized. Among them, PAN@Co/Mn-MOF-74 NFM prepared by in-situ growth method based on PAN was a kind of nano-fluorescent NFM sensor with uniform structure and good fluorescence performance. It showed unique specificity and excellent sensitivity in the detection of ORN, Fe3+ and MnO4-. Compared with previously reported functionalized MOFs, PAN@Co/Mn-MOF-74 NFM has a lower limit of detection (LOD). This study provides a feasible technical route for the preparation of nano-fluorescent NFMs and the targeted detection of trace metal ions and antibiotics.
ABSTRACT
Double-walled carbon nanotubes (DWCNTs) make up a unique class of carbon nanotubes (CNTs) that are particularly intriguing for scientific research and are promising candidates for technological applications. A more precise level of control and greater yields can be achieved via catalytic chemical vapor deposition (CCVD), which involves the breakdown of a carbonaceous gas over nanoparticles. The addition of molybdenum to the system can increase the selectivity with regard to the number of walls that exist in the obtained CNTs. As reported herein, we have designed and synthesized a novel Co-Mo-MOF, [Co(3-bpta)1.5(MoO4)]·H2O (where 3-bpta = N,N'-bis(3-pyridyl)terephthalamide), and employed the Co-Mo-MOF as a bimetallic catalyst precursor for the CCVD approach to prepare high-quality DWCNTs. The Co-Mo-MOF was employed after being calcined in N2 and H2 at 1100 °C and decomposing into CoO, CoMoO4, and MoO3. Existing CoMoO4 is unaltered after reduction in H2 at 1100 °C, while CoO and MoO3 are converted into Co0 and MoO2, and more CoMoO4 is created at the expense of Co0 and MoO2 without clearly defining agglomeration. Finally, the interaction between metallic Co particles and C2H4 is what initiates the formation of DWCNTs. In-depth discussion is provided in this paper regarding the mechanism underlying the high selectivity and activity of Co-Mo catalysts in regulating the development and structure of DWCNTs. The DWCNTs also offer excellence performance when they are used as water purification agents and as selective sorbents. This work opens a feasible way to use MOFs as a way to produce MWCNTs, thus blazing a new trail in the field of MOF-derived carbon-based materials.
ABSTRACT
In this work, we used Cu(II) ions, a bis-pyridyl-bis-amide ligand [N,N'-bis(4-pyridinecarboxamide)-1,2-cyclohexane (4-bpah)], and an aromatic dicarboxylic acid [1,4-cyclohexanedicarboxylic acid (H2CHDA)] to construct a 1D binuclear Cu-based complex, namely {[Cu3(4-bpah)(CHDA)3(H2O)]·2H2O}n (1). Moreover, we also developed a facile method to synthesize two monometallic/bimetallic-doped materials which were derived from the Cu complex (C-N-1 and C-V-1, which were doped with nitrogen and vanadium, respectively). The as-synthesized derived materials were fully characterized and the iodine sorption/release capabilities were investigated in detail. We performed iodine adsorption experiments on the two monometallic/bimetallic-doped materials and found that C-N-1 and C-V-1 possess highly efficient adsorption activities for the adsorption of iodine from solution. The C-N-1 and C-V-1 complexes exhibited remarkable adsorption capacities of 1141.60 and 1170.70 mg g-1, respectively, for iodine from a cyclohexane solution. Moreover, the dye adsorption properties of C-N-1 and C-V-1 were also investigated in detail. The obtained C-N-1 and C-V-1 exhibit effective dye uptake performances in water solution. The adsorption of Congo red (CR) on a single metal carbon material C-N-1 doped with heteroatoms reached equilibrium within 240 min and reached an adsorption capacity of 1357.00 mg g-1 and the adsorption capacities of C-V-1 for methylene blue (MB), gentian violet (GV), rhodamine B (RhB), and CR at room temperature were found to be 187.60, 190.60 and 108.10 and 1501.00 mg g-1 in 180 min, respectively. By comparison, we found that doping vanadium could play an important role in the adsorption processes. The adsorption capacity of C-V-1 (containing the vanadium in its structure) was relatively higher than that of C-N-1, which indicated that the introduction of non-noble metals may effectively tune the adsorption kinetics activity and the introduction of noble metals can change the surface electronegativity of porous carbon materials, thus leading to significantly improved adsorption capabilities.
ABSTRACT
In this work, a novel three nitro-group-bearing monomer 3,6-dinitro-9-(2-trifluoromethyl-4-nitrophenyl)-carbazole (Car-3NO2 -CF3 ) via a CN coupling reaction between 3,6-dinitro-9H-carbazole (Car-2NO2 ) and 2-chloro-5-nitrobenzotrifluoride is synthesized, and obtained single crystal and single crystal analysis data for this compound. The crystal system of Car-3NO2 -CF3 is monoclinic and it has a P 21/c space group. This new monomer (Car-3NO2 -CF3 ) is also utilized to synthesize a novel azo-linked polymer (Azo-Car-CF3 ). The trifluoromethyl group has polar CF bonds, and thus it is an effective functional group for the capture of iodine. Azo-Car-CF3 has great thermal stability with a mass loss of only 10% at 414 °C, as well as good chemical stability as is demonstrated by its low solubility in common organic solvents such as tetrahydrofuran (THF), acetone, methanol, ethanol, and N,N-dimethylformamide (DMF). The specific surface area of Azo-Car-CF3 can reach as high as 335 m2 g-1 . Azo-Car-CF3 exhibits an excellent capacity for iodine adsorption and can reach up to 1198 mg g-1 in cyclohexane solution, and its adsorption capacity for iodine vapor can get to 2100 mg g-1 . In addition, ethanol can be used to trigger the release of the captured iodine to be easily released from Azo-Car-CF3 .
Subject(s)
Iodine , Polymers , Hydrocarbons, Fluorinated/chemistry , Solvents , EthanolABSTRACT
Photocatalytic degradation of dyes is an extremely difficult but very important issue in the field of environmental protection. Two coordination polymers (CPs) [Cu(3-bpah)(HD)]n (1) and [Cu(3-dpye)0.5(HD)]n (2) [3-bpah = N,N'-bis(3-pyridinecarboxamide)-1,2-cyclohexane, 3-dpye = N,N'-bis(3-pyridinecarboxamide)-1,2-ethane, H2HD = hexanedioic acid] were successfully synthesized by tuning the auxiliary ligands under hydrothermal conditions. CPs 1 and 2 exhibited different compositions because of the different N-donor ligands, and were used as precursors for the preparation of metal oxide heterojunctions. Doping foreign elements into intrinsic CP-based materials is an effective way to enhance their photocatalytic activity, and thus we designed a facile method to synthesize a series of carbon-coated metal oxide heterojunctions which were derived from the two Cu-based CPs (Cu@V-1, Cu@V-2, Cu@Mo-1, Cu@Mo-2, Cu@W-1 and Cu@W-2) in this work for the first time. Benefiting from the formation of a carbon shell and regulation of the electronic structure through doping molybdenum and generating the Mo2C phase, the photocatalytic degradation rates were 94.84% for MB, 76.02% for RhB, 52.29% for MO, and 86.18% for CR after 4 h.
ABSTRACT
A 2D Cu@TiO2 composite with a porous and crystalline structure was successfully synthesized via one-step and low-temperature calcination of a 1D Cu-based coordination polymer (Cu-CP), namely [Cu2(3-dpha)(1,4-NDC)2(H2O)3] n (3-dpha = N,N'-bis(3-pyridyl)adipamide and 1,4-H2NDC = 1,4-naphthalenedicarboxylic acid). Moreover, the Cu@TiO2 membrane was fabricated by a simple filtration of the as-grown Cu@TiO2 composite. Compared with the benchmark TiO2 photocatalyst, the Cu@TiO2 composite material with high specific surface area and reduced photogenerated electron-hole ratio exhibited good photodegradation activity and durability for gentian violet (GV), which could be attributed to the combined effect of co-doping of Cu and TiO2 structure. Furthermore, the ËOH and ËO2 - radicals were predicted to dominate the photocatalytic process. Therefore, this new efficient photocatalyst is a promising candidate for efficient and selective photodegradation of organic pollutants.
ABSTRACT
Metal-organic frameworks (MOFs) have recently emerged as a type of uniformly and periodically atom-distributed precursor and efficient self-sacrificial template to fabricate hierarchical porous-carbon-related nanostructured functional materials. In this work, we used Cu(II) ions and aromatic dicarboxylic acid to construct [Cu3(4,4'-oba)2(µ2-OH)2(H2O)2]n (4,4'-H2oba = 4,4'-oxybisbenzoic acid) as a precursor for the preparation of carbon nanostructures. Doping foreign elements into intrinsic MOF-based nanomaterials is an effective way to enhance the adsorption property and photocatalytic activity; thus, we designed a facile method to synthesize a vanadium-doped mixture of Cu2O and Cu nanoparticles encapsulated in a Cu-MOF-derived carbon nanostructure (C-V-1) in this work for the first time. Benefiting from the protection of the carbon shell and regulation of the electronic structure by doping vanadium and phase-mixing Cu2O and Cu, the adsorption capacities of C-V-1 for MB, RhB, MO, CR and GV at room temperature are 174.13, 147.06, 179.92, 275.90 and 611.81 mg g-1 in 240 min, respectively, while the photocatalytic degradation rates are 88.14% for MB, 79.80% for RhB, 71.31% for MO, and 71.19% for CR after 4 h. In addition, the degradation rate is larger than 99.01% for GV after only 30 min of UV irradiation. This strategy of using a diverse MOF as a structural and compositional material to create a multifunctional composite/hybrid may expand the opportunities to explore highly efficient, fast and robust adsorbents and photocatalysts for water treatment.
ABSTRACT
A novel and unusual 3D luminescent coordination polymer (CP) [Zn2(3-bpah)(bpta)(H2O)]·3H2O (1), where 3-bpah denotes N,N'-bis(3-pyridinecarboxamide)-1,2-cyclohexane and H4bpta denotes 2,2',4,4'-biphenyltetracarboxylic acid, was successfully synthesized via hydrothermal methods from Zn(II) ions and 3-bpah and bpta ligands. The structure of this CP was investigated via powder X-ray diffraction (PXRD) analysis along with single crystal X-ray diffraction. Notably, 1 exhibits remarkable fluorescence behavior and stability over a wide pH range and in various pure organic solvents. More importantly, 1 can become an outstanding candidate for the selective and sensitive sensing of Fe3+, Mg2+, Cr2O72-, MnO4-, nitrobenzene (NB) and nitromethane (NM), at an extremely low detection limit. The changes in the fluorescence intensity exhibited by these six analytes in the presence of 1 over a wide pH range indicate that this polymer can be an excellent luminescent sensor. To the best of our knowledge, 1 is a rare example of a CP-based multiresponsive fluorescent sensor for metal cations, anions, and toxic organic solvents.
ABSTRACT
To research the effect of structural diversity on citrate-based coordination polymers (CPs), citric acid (H4cit) was selected to combine with Cu(ii) under hydrothermal conditions. A new CP [Cu2(cit)(H2O)2] (1) was synthesized and structurally characterized. The title complex shows a 3D 2,4,6-connected topology with the point symbol of {43·63}{44·66·85}{4}. Inspired by the decomposition and functional molybdenum component, 1 was used as a catalyst precursor to synthesize a carbon-based material (C-1) and a C@Mo material (C-Mo-1) by the chemical vapor deposition (CVD) method and characterized in detail. The selective removal of a contaminant (Congo red) by complex 1, C-1 and C-Mo-1 in the aqueous phase was also comparatively investigated.
ABSTRACT
The synthesis of multi-walled carbon nanotubes (MWCNTs) was carried out over different Ni-loaded metallic oxide catalyst nanoparticles and under different reduction times to control the outside diameter of the nanotubes. Moreover, high-purity, free-standing membranes were fabricated by a simple filtration of the as-grown MWCNTs. Furthermore, the dye-adsorption properties of the nanotubes depended on the diameter of the carbon nanotubes (CNTs). The adsorption isotherms and kinetics of anionic dyes could be described by Freundlich and pseudo-second-order models, respectively. Thermodynamic studies suggested that the adsorption processes were spontaneous and exothermic. This work provides new insights into the synthesis and application of MWCNTs with the selective adsorption properties of carbon-based materials for the removal of organic dyes.