Controllable synthesis of FeMn bimetallic ferrocene-based metal-organic frameworks to boost the catalytic efficiency for removal of organic pollutants

A series of FeMn bimetallic ferrocene-based metal-organic frameworks (FeMn-Fc-MOFs) with various molar ratios of Fe and Mn (1:9, 2:8, 4:6, 6:4) were successfully synthesized using a simple hydrothermal synthesis method and employed as an efficient activator on persulfate (PS) activation for water decontamination. Characterizations demonstrated that Fe and Mn were smoothly introduced into ferrocene-based MOFs and various molar ratios of Fe:Mn had some influence on crystallinity and surface structure of FeMn-Fc-MOFs. Within 120 min, Fe₄Mn₆-Fc-MOFs demonstrated the best catalytic activity among the different molar ratios, and acid orange 7(AO7) degradation rate was up to 92.0%. In addition, electrochemical experiments revealed that Fe₄Mn₆-Fc-MOFs possessed superior electron transfer capability than other FeMn-Fc-MOFs, leading to better catalytic performance. Moreover, quenching tests and electron paramagnetic resonance (EPR) detection indicated that hydroxyl radicals and sulfate radicals were both responsible for AO7 decomposition. Notably, the redox cycle of Fe(II)/Fe(III) and Mn(II)/Mn(IV) was discovered in the Fe₄Mn₆-Fc-MOFs/PS system, which was considered as the limiting process for the cleavage of the O-O bond in PS to generate active radicals. Ultimately, the Fe₄Mn₆-Fc-MOFs exhibits an excellent universality and good cycling stability for 5 continuous runs. This paper broadens the application of ferrocene-based MOFs on heterogeneous PS activation in environmental catalysis.

Self assembled three dimensional β-Cu2V2O7 hierarchical flower decorated porous carbon: An efficient electrocatalyst for flutamide detection in biological and environmental samples

The serious situation mandates the use of anticancer drugs, which protect people all over the world from the growth of prostate cancer. In particular, excessive dosage and erroneous discharge of flutamide concentration cause make environmental pollution on the surface of the wastewater. In this study, the highly sensitive and selective electrochemical approach based on copper vanadium oxide decorated porous carbon (denoted as β-Cu₂V₂O₇/PC) composite modified glassy carbon electrode (GCE) has been developed and it was applied for sensitive detection of anticancer drug flutamide (FTM). Moreover, using the co-precipitation method, the flower-like β-Cu₂V₂O₇ hierarchical microstructure was synthesized, and through the wet chemical process, the β-Cu₂V₂O₇/PC composite was obtained. The resultant product was characterized by XRD, FTIR, RAMAN, XPS and structural morphology established by FESEM analysis. Besides that, the electrochemical characterization and properties were analyzed by cyclic voltammetry (CV) and amperometric (i-t) techniques. The β-Cu₂V₂O₇/PC/RDGCE had two linear ranges at 0.01-2.11 μM and 2.31-30.81 μM. The lower limits of detection and sensitivity were found at 0.62 nM (S/N = 3), and 24.33 μA μM^-1 cm^-2 respectively. The practicability test was applied for the determination of FTM in urine, blood serum and environmental aquatic fluid with satisfactory recovery obtained.

Flower-Like Superstructures: Structural Features, Applications and Future Perspectives

Mimicking natural objects such as flowers, is an objective of scientists not only because of their attractive appearance, but also to understand the natural phenomena that underpin real world applications such as drug delivery, enzymatic reactions, electronics, and catalysis, to name few. This article reviews the types, preparation methods, and structural features of flower-like structures along with their key applications in various fields. We discuss the various types of flower-like structures composed of inorganic, organic-inorganic hybrid, inorganic-protein, inorganic-enzyme and organic compositions. We also discuss recent development in flower-like structures prepared by self-assembly approaches. Finally, we conclude our review with the future prospects of flower-like micro-structures in key fields, being biomedicine, sensing and catalysis.

Graphene oxide wrapped Cu3V2O7(OH)2 · 2H2O nanocomposite with enhanced electrochemical performance for lithium-ion storage

Transition metal oxides (TMOs) are widely accepted as one of the alternatives for the graphite anode in lithium-ion batteries (LIBs) owing to the high specific capacity and facile synthesis of nanoscale materials facilitating fast ionic transfer. However, the lower electronic conductivity always impedes the application of TMOs. Herein, we report a graphene oxide wrapped layer-structured Cu₃V₂O₇(OH)₂ · 2H₂O nanocomposite (CVO/GO) synthesized via an in situ co-precipitation method. It is corroborated that the introduction of GO not only provides more active sites for lithium-ion storage, but also improves the charge transfer rate of the electrode, issuing an enhanced electrochemical performance. As expected, the CVO/GO nanocomposite exhibits an ultrahigh specific capacity of 870 mA h g^-1 at 0.1 A g^-1 compared with CVO nanoparticles. Even at a high current density of 5 A g^-1, a specific capacity of 158 mA h g^-1 could be achieved for the CVO/GO nanocomposite.

In-situ preparation of hierarchical flower-like TiO2/carbon nanostructures as fillers for polymer composites with enhanced dielectric properties

Novel three-dimensional hierarchical flower-like TiO₂/carbon (TiO₂/C) nanostructures were in-situ synthesized via a solvothermal method involving calcination of organic precursor under inert atmosphere. The composite films comprised of P (VDF-HFP) and as-prepared hierarchical flower-like TiO₂/C were fabricated by a solution casting and hot-pressing approach. The results reveal that loading the fillers with a small amount of carbon is an effective way to improve the dielectric constant and suppress the dielectric loss. In addition, TiO₂/C particles with higher carbon contents exhibit superiority in promoting the dielectric constants of composites when compared with their noncarbon counterparts. For instance, the highest dielectric constant (330.6) of the TiO₂/C composites is 10 times over that of noncarbon-TiO₂-filled ones at the same filler volume fraction, and 32 times over that of pristine P (VDF-HFP). The enhancement in the dielectric constant can be attributed to the formation of a large network, which is composed of local micro-capacitors with carbon particles as electrodes and TiO₂ as the dielectric in between.

F-TiO2/P(VDF-HFP) hybrid films with enhanced dielectric permittivity and low dielectric loss

Self-assembly flower-like TiO₂ particles (F-TiO₂) were synthesized as fillers and the resulting F-TiO₂/P(VDF-HFP) composites exhibited enhanced dielectric properties.

Novel chemical synthesis and characterization of copper pyrovanadate nanoparticles and its influence on the flame retardancy of polymeric nanocomposites

In this work, copper pyrovanadate (Cu3V2O7(OH)2(H2O)2) nanoparticles have been synthesized by a simple and rapid chemical precipitation method. Different copper-organic complexes were used to control the size and morphology of products. The morphology and structure of the as-synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectrum, electron dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), differential thermal analysis (DTA) and photoluminescence (PL) spectroscopy. The influence of copper pyrovanadate nanostructures on the flame retardancy of the polystyrene, poly vinyl alcohol and cellulose acetate was studied. Dispersed nanoparticles play the role of a magnetic barrier layer, which slows down product volatilization and prevents the flame and oxygen from the sample during decomposition of the polymer. Cu3V2O7(OH)2(H2O)2 is converted to Cu3V2O8 with an endothermic reaction which simultaneously releases water and decrease the temperature of the flame region.

Significantly Enhanced Dielectric Performance of Poly(vinylidene fluoride-co-hexafluoropylene)-based Composites Filled with Hierarchical Flower-like TiO₂ Particles

In this study, we report a feasible strategy for fabricating high-dielectric-constant polymer composites for applications in energy storage devices and embedded capacitors. Hierarchical flower-like TiO2 particles were prepared via a facile solvothermal process and incorporated into the P(VDF-HFP) matrix. The temperature and frequency dependent dielectric properties of flower-like TiO2/P(VDF-HFP) composites as well as commercial TiO2/P(VDF-HFP) composites were investigated. The results reveal that the flower-like TiO2 particles are more effective in increasing the dielectric constant of P(VDF-HFP) when compared with commercial TiO2. Typically, the dielectric constant of the P(VDF-HFP) composite filled with 20 vol % flower-like TiO2 reaches 83.1 at 100 Hz, in contrast to 43.4 for the composite filled with 20 vol % commercial TiO2 and 11.3 for pristine P(VDF-HFP). Also, the flower-like TiO2-filled composites exhibit similar characteristic breakdown strengths to their commercial TiO2-filled counterparts. The significant improvement in the dielectric constant could be attributed to the enhancement of Maxwell-Wagner-Sillars polarization, which originates from the sophisticated morphology of flower-like TiO2 particles.

3D hierarchical ZnOHF nanostructures: synthesis, characterization and photocatalytic properties

Hierarchical nanoflake-assembled ZnOHF nanoflowers have been synthesized via a hydrothermal route by using (NH₄)₂SiF₆ as fluoride source.

A general strategy to fabricate simple polyoxometalate nanostructures: electrochemistry-assisted laser ablation in liquid

Polyoxometalate nanostructures have attracted much attention because of significant technical demands in applications such as catalysts, sensors, and smart windows. Therefore, researchers have recently developed many methods for the synthesis of these nanomaterials. However, these techniques have many visible flaws such as high temperatures or high pressure environments, various templates or additives, demanding and complicated synthesis procedures as well as the presence of impurities in the final products. We therefore propose a general strategy for the fabrication of particular polyoxometalate nanostructures by electrochemically assisted laser ablation in liquid (ECLAL). These polyoxometalates are usually simple as they typically contain two metals and are not soluble in water. This approach is a green, simple, and catalyst-free approach under an ambient environment. Apart from these merits, this novel technique allows researchers to choose and design interesting solid targets and to use an electrochemical approach toward the fabrication of polyoxometalate nanostructures for the purpose of fundamental research and for potential applications. Using the synthesis of Cu(3)Mo(2)O(9) nanorods as an example, we substantiate the validity of the proposed strategy. For the fabrication of Cu(3)Mo(2)O(9) nanostructures, we chose molybdenum as a solid target for laser ablation in liquid copper electrodes for the electrochemical reaction and water as a solvent for the ECLAL synthesis. We successfully fabricated Cu(3)(OH)(2)(MoO(4))(2) nanorods with magnetic properties. Interestingly, we obtained well-defined Cu(3)Mo(2)O(9) nanorods by annealing the Cu(3)(OH)(2)(MoO(4))(2) nanostructures at 500 °C. Additionally, the basic physics and chemistry involved in the ECLAL fabrication of nanostructures are discussed.