查看更多>>摘要：Metal-organic frameworks (MOFs), known as highly ordered crystalline hybrid structures, are the products of coordination polymerization of transition metals and organic ligands. MOFs are best known for their extensive specific surface area, hierarchically porous and tailorable ID, 2D, or 3D micro-and nanostructure, and acceptable biocompatibility. Because of the multiplicity of metallic and organic units used in MOFs synthesis, tailor-made MOFs can be synthesized to be served as building blocks of advanced biological materials and systems. Recently, synthesis of green MOFs has received much more attention for nanobiomedicine usage. We review herein synthesis and biomedical application of green MOFs by analyzing their components, including green solvents, ligands, linkers, auxiliary linkers, and sustainable organic precursors. First, MOFs were classified in terms of their general toxicity level and biological behavior by considering the chemistry of ligands, linkers, and green organic precursors. Second, applications of bio-MOFs and nano-MOFs in medicine were categorized. Third, chemistry of green MOFs used as pro-drug and their potential and effects related to bioimaging, drug delivery, and multimodal therapeutics were systematically reviewed and discussed. Fourth, concluding remarks and challenging aspects of future developments of bio-MOFs and nano-MOFs were underlined.
查看更多>>摘要：Covalent organic frameworks (COFs) are promising for catalysis, adsorption, separation, etc. owing to unprecedented combination of the large surface area, high crystallinity, tunable pore size, and unique molecular architecture of COFs. Just because of the above-mentioned merits, COFs can be ideal support for quite a few kinds of small materials with unstable nature, such as nanoparticles, ions, quantum dots, single atoms and so on. With COF support, those species can not only exist stably, but also readily be applied in various fields. Herein, the recent advances in the design and synthesis of COF-support hybrids for various applications are presented. Also, future research directions and perspectives are discussed for the development of efficient COF-support hybrid materials.
查看更多>>摘要：In this work, a series of hydrolyzed polymers of intrinsic microporosity (PIMs) membranes were successfully synthesized under alkaline conditions. Positron annihilation lifetime measurement is employed to analyze the pore structure of the hydrolyzed PIMs. In the original PIM-1, there are two kinds of pores, i.e. micropores with radius of 4.32 A and ultramicropores with radius of 2.58 A. The size of all the pores shows a continuous decrease with increasing hydrolysis time, which is confirmed by the reduced chain-to-chain spacing in the hydrolyzed PIMs measured by X-ray diffraction. Meanwhile, the fractional free volume also shows decrease after the hydrolysis process, while the relative number of ultramicropores increases. Benefiting from the smaller pore size in the hydrolyzed PIMs membrane, the gas molecules with smaller size (such as CO2) can be separated more efficiently. The selectivity of CO2/CH4 of hydrolyzed PIMs reaches up to 30.05 with a relatively high CO2 permeability of 140.58 Barrer, which exceeds the Robeson's 1991 upper bound. Our results indicate that the hydrolyzed polymers of intrinsic microporosity membranes are promising candidates for gas separation membrane in the future.
查看更多>>摘要：With the continuous occurrence of oil-spill accidents, superhydrophobic materials demonstrate tremendous potential in oil-water separation. In this research work, SiO2 nanospheres with surface mercapto groups were prepared by the condensation reaction of 3-mercaptopropyltriethoxysilane (KH590) and hydroxyl groups on the surface of silica (SiO2) particles. Subsequently, HTPB-coated SiO2 superhydrophobic particles were obtained through the thiol-ene click chemistry reaction between the SiO2 nanospheres and the hydroxyl terminated polybutadiene (HTPB). Depending on the polar attraction between the terminal hydroxyl groups of HTPB and the hydroxyl groups on the surface of SiO2, SiO2 nanospheres could be firmly coated with HTPB. Fortunately, stable and durable superhydrophobic lipophilic SiO2 particles (Si-HTs) was obtained. Because of the existence of micro-nano structures, the resultant Si-HTs could easily float on the oil-water surface, and effectively absorb oil solvents more than 4 times its own weight with an ultrahigh separation efficiency above 99%. Even under strong acid and strong alkali conditions or in the seawater environments, the Si-HTs were afforded with effective oil-absorption capability and high recyclability over 20 times. Consequently, the Si-HTs prepared show great potential as a superhydrophobic nanoparticle for low-cost, high-efficiency and environmentally friendly oil-water separation.
查看更多>>摘要：Gobbinsite (GOBZ) is rare zeolite with a disordered framework cation distribution, which is likely beneficial to Cd(II) fixation. This study developed a simple hydrothermal crystallization route to synthesize the novel GOBZ using natural halloysite nanotubes minerals (HNTS). In micropore and mesoporous of BET data analysis, a large number of HNTS microporous structures transformed into GOBZ mesoporous structures, which could greatly facilitate the adsorption ability of GOBZ. The XPS and FTIR exhibited the mesoporous coordination and the interaction of different hydroxyl functional groups, is the main adsorption mechanism to strengthen the Cd(II) fixation capacity. Liu isotherms described well of the adsorption of Cd(II), indicating the process was heterogeneous and multilayers simultaneously. General order kinetics assumed that the adsorption occur accompanied by a chemical reaction on GOBZ. Reusability of GOBZ show that it has good recycling performance and application value in Cd(II) adsorption. The TEM and XRD showed that the adsorption of Cd(II) affected the elemental composition, surface morphology and internal structure of GOBZ, which contributed to in-situ formation of phillipsite-Ca, otavite, garronite and gmelinite-Na. Above all, hydrothermal crystallization (GOBZ technology) can provide viable options for the removal of toxic metal pollution, showing the prospect of clay minerals in the removal.
查看更多>>摘要：The loading dependence of self-diffusion coefficient (Ds), diffusion selectivity (s_(diff)), and structural properties of pure CH4, H2S, and dieir mixtures in MIL-47(V) material were investigated using Molecular Dynamics (MD) simulations. The preferential adsorption sites of gas molecules in the lattice, as well as the molecular structure of gases were determined using Radial Distribution Functions (RDFs). The diffusion behavior of gas molecules diffusing in the lattice was further investigated utilizing the 2D probability density plots and free energy profiles derived by the Histogram Sampling mediod. Furthermore, the findings of our computational study are examined and compared to previous research.
查看更多>>摘要：Improving photocatalytic properties of semi-conductor materials and Band-gap engineering are a major challenge. Herein, we report, a successful immobilization of tungsten oxide and tungstite on the surface of micro-porous silica by simple one-step method. The surface area decreased from 607 to 588 m~2/g after immobilization due to the loading of tungsten oxide species on silica pores. While, the band-gap energies were found to be 2.21, 2.41 eV for SiO2/WO3 and SiO2/WO3-C, respectively. Thereafter, the photocatalytic activity of the composites was studied through the oxidative degradation of sulfamethazine under UV-visible light irradiation, SiO2/WO3 exhibited relatively good stability and reusability after four cycles of photocatalytic experiment in respect to the calcinated sample. The high photocatalytic activity and recyclability of the non-calcinated sample are attributed to the presence of water molecules in tungstite structure, assuming that tungsten oxide species are bonded to microporous silica via hydrogen bond interaction.
查看更多>>摘要：Divalent Nickel cations were incorporated in two commercial zeolites (Na-A zeolite and Na-X zeolite) by a process of ionic exchange marginally affecting structure, morphology and porosity of the host materials, as verified by XRD, HRTEM and physisorption measurements. Comparable amounts of magnetic ions were introduced (4.80 wt% in Na-A zeolite and 6.20 wt% in Na-X zeolite), as checked by AAS and TGA. Magnetic measurements were done between 2 and 300 K using a SQUID magnetometer up to 70 kOe. The initial susceptibility follows the Curie-Weiss law with Curie temperatures 9 of 10.3 and 11.5 K. The effective magnetic moments on Ni~(2+) ions suggest almost complete quenching of the angular momentum. No long-range magnetic order is found below 8; however, FC/ZFC magnetization curves indicate the formation of superparamagnetic clusters of magnetic ions with blocking temperature of about 6.5 K in both zeolites. Cluster size, average number of clustered ions, effective anisotropy of clusters are evaluated. A comprehensive picture of all magnetic effects taking place over the whole temperature range is drawn by combining magnetic, structural and morphological data.
查看更多>>摘要：3D-mesoporous KIT-6 supported highly dispersed Pd nanocatalysts (Pd/KIT-6) are prepared via inorganometallic chemical adsorption (ICA) and sonochemical reduction for dodecahydro-N-ethylcarbazole (H12-NEC) dehydrogenation. First, Si-O~--Na~+ is obtained through the reaction between NaOH and silanol groups (Si-OH) on the surface of KIT-6. Then, Pd(NH3)4~(2+) is adsorbed by Si-O~--Na~+ to obtain (Si-CO2-Pd(NH3)4~(2+) by ICA. Finally, Pd-EU/K6 is obtained through the reduction of (Si-O~-)2-Pd(NH3)4~(2+) using ultrasound-assisted isopropanol without adding any stabilizer. The Pd dispersion of Pd-EU/K6 is as high as 97%, which is mainly attributed to the ICA between Pd(NH3)4~(2+) and Si-O~--Na~+. The Si-O-Pd on Pd-EU/K6 is formed through Pd coordination with O in Si-OH and acetone from isopropanol reduction, which stabilizes the Pd nanoparticles. Pd-EU/K6 shows excellent catalytic H12-NEC dehydrogenation performance with a dehydrogenation efficiency of 97.4% at 180 °C for 6 h and a TOF of 7.08 min~(-1), which is attributed to its ultrahigh metal dispersion and favorable textural properties. The dehydrogenation efficiency of Pd-EU/K6 is maintained above 95% after 10 cycles.
Jelena RuparDanica Bajuk-BogdanovicMaja Milojevic-Rakic
11页
查看更多>>摘要：Here, we propose a novel, electrochemical preparation of in situ N-doped alginate-based carbon precursors with monodispersed zinc ions. Obtained carbons were evaluated by spectroscopic (FTIR, Raman and XPS), textural (N2 physisorption), microscopic (TEM) and elemental (SEM-EDS) descriptors to establish their distinctive features originating from different synthetic procedures. Carbons characteristics were assessed in view of several carbonization temperatures applied for their preparation from alginate precursors, and individual and joint effect of zinc and nitrogen on the precursor. Obtained Zn monodispersion, emphasizes the significance of electrochemical preparation, allowing increasing temperature to induce changes from its ionic form to carbonate and oxide, while at 800 °C ZnO further reduces and evaporates. Since homogeneously dispersed Zn species acts as porosity evolving agent during carbonization, a substantial surface area is developed, in the range 718-1056 m~2 g~(-1). Textural properties revealed that the use of rivanol as an N-doping agent shields carbon scaffold from porosity overdevelopment. The alginate-based carbons are probed as electrode materials for supercapacitors and surface/textural properties connected to electrochemical results. Controlled electrochemical dispersion of zinc and, in situ N-doping with rivanol, developed a bio-based material of excellent capacitance (265 F g~(-1) @5 mV s~(-1)) and stability. This study reflects key features in material design necessary for engineering upcoming supercapacitors.
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