Morphology Of Microspheres Research Articles

Electrosprayed Chitosan-Copper Complex Microspheres with Uniform Size.

Chitosan-based nano- and microspheres have shown great potential in a broad range of applications, including drug delivery, bone tissue engineering, wastewater treatments, etc. The preparation of uniformly sized spheres with controlled morphology and microstructure is still a challenge. This work investigates the influence of cupric ions (Cu2+) on the size, shape, morphology and stability of electrosprayed chitosan–copper (CHT–Cu2+) complex microspheres, using chitosans with different degrees of deacetylation. The dynamic viscosity of CHT–Cu2+ solutions was measured by Höppler viscometer, while attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used for the identification of dried microspheres. The size, shape and morphology of microspheres were analyzed by light microscope and scanning electron microscopy (SEM), while stability of dried microspheres was evaluated in different buffer solutions. The volume ratio of wet and dry microspheres was assessed based on the estimated diameter of microspheres. The higher concentration of Cu2+ ions resulted in a decrease in viscosity of CHT–Cu2+ solutions and volume ratio of prepared microspheres. Changes in the intensities and wave numbers of absorption bands of amino and hydroxyl groups, amide I and amide II suggested that the nitrogen and oxygen atoms in chitosan are coordinating the cupric ions. Micrographs obtained by light microscope and SEM showed that all prepared samples are spherical. The increase of cupric ions concentration changed the topography of microspheres and decreased their size. These results indicated the successful electrospraying of CHT–Cu2+ microspheres with uniform size and good stability in aqueous medium.

PH-Responsive Hollow Polymeric Microspheres from Irradiated Cyclic Ether Aqueous Solution

Smart hollow polymeric microspheres have been widely applied in various fields such as controlled release, drug delivery, catalysis, and so on. Herein, a facile, green and one-step template-free method is introduced for preparing pH-responsive hollow polymeric microspheres via gamma irradiation of cyclic ether aqueous solution. The hollow polymeric microspheres are synthesized by radiation-induced polymerization and following the self-assembly and self-organization of amphiphilic polymer with cyclic ethers as monomers in water. SEM, TEM, micro-FTIR, and NMR confirmed the morphology and structures of the resultant microspheres. The confocal laser scanning microscope was used to investigate the stimuli-responsiveness and release behavior of hollow microspheres using 1-pyrene carboxaldehyde as a hydrophobic molecule model. The well-defined hollow polymeric microspheres with an average diameter of ca. 2.6 μm or 1.6 μm were prepared directly from dicyclohexal-18-crown-6 or tetraphydropyrane aqueous solution, respectively. The prepared hollow microspheres exhibit obvious pH stimuli-responsiveness and can release the encapsulated hydrophobic molecules when pH is higher than 5.0. Moreover, the reversible morphology transition between hollow microspheres and micelles makes the prepared hollow polymeric microspheres potentially suitable for a wide range of applications, including removal of dyes, oil field engineering, and biomedical fields.

A novel method for extraction, quantification, and identification of microplastics in CreamType of cosmetic products

The objective of this study was to develop an accessible and accurate analysis method for microplastics that have been unintentionally added to cream cosmetic products. An experiment was performed on three cleansing creams in rich and viscous formulations. A spiked sample was prepared by adding polyethylene (PE) microspheres to the cleansing creams. After removing cosmetic ingredients from the creams using chemical digestion, damage to the PE microspheres was identified using Fourier transform infrared (FT-IR) spectroscopy. Field emission scanning electron microscopy (FE-SEM) images were obtained before and after digestion and used to characterize the morphology of the PE microspheres. The highest digestion efficiency was obtained using a chemical digestion method consisting of heating and stirring a sample in a 10 wt% KOH solution at 55 °C and 300 rpm for 5 days and did not damage the PE microspheres. The Nile red (9-diethylamino-5H-benzo[α]phenoxazine-5-one) staining method was effective in identifying small microplastics (< 106 μm). The optimal staining conditions are 5 μg/ml Nile red in n-hexane for green wavelengths.

Bile salts adsorption on dextran-based hydrogels

Dextran-based gels bearing two types of pendant N, N-dimethyl-N-alkyl-N-(2-hydroxypropyl) ammonium chloride groups with different alkyl chain length substituents (C2 and C12/C16, respectively) at the quaternary nitrogen were synthesized and structural characteristics of the compounds were studied by elemental analysis, potentiometric titration, FTIR and NMR spectroscopy. The morphology and size of polymeric microspheres were examined by SEM and their swelling behavior in water was also investigated. The hydrogels were evaluated as sorbents for sodium cholate (NaCA) and sodium deoxycholate (NaDCA) in water and 10 mM NaCl solutions. Different isotherm models (nearest-neighbor-interaction, Langmuir, Freundlich, Dubinin-Raduskevich, Sips and Hill) were used to elucidate the adsorption mechanism and established the characteristics of the most efficient polymeric sorbent. The maximum adsorption capacity of the gels was highly controlled by gel hydrophobicity which enhanced gel-bile salt affinity but decreased binding cooperativity. Swelling porosity, ionic strength and ligand lipophilicity were other factors that also affected the adsorption process. The hydrogel having 25 mol% pendant dodecyl groups retained the maximum amount of bile salts (1051 mg NaCA/g and 1138 mg NaDCA/g). All hydrophobically modified hydrogels revealed a better affinity and strength of binding compared to commercial Cholestyramine®.

Effects of Ce–Dy rare earths co-doping on various features of Ni–Co spinel ferrite microspheres prepared via hydrothermal approach

The effects of Ce–Dy co-doping on the crystal structure, optical, dielectric, magnetic properties, and hyperfine interactions of Ni–Co spinel ferrite microspheres synthesized hydrothermally have been studied. A series of ferrites with the general formula Ni0.5Co0.5CexDyxFe2-2xO4 were synthesized with x values ranging from 0.00 to 0.10. The phase, crystallinity, and morphology of ferrite microspheres were analyzed by X-ray powder diffractometry (XRD), scanning and transmission electron microscopes (SEM and TEM), respectively. The structural analyses of the synthesized ferrite microspheres confirmed their high purity and cubic crystalline phase. The Diffuse reflectance spectroscopic (DRS) measurements were presented to calculate direct optical energy band gaps (Eg) and is found in the range 1.63 eV - 1.84 eV. 57Fe Mossbauer spectroscopy showed that the hyperfine magnetic field of tetrahedral (A) and octahedral (B) sites decreased with the substitution of Dy3+-Ce3+ ions that preferrentially occupy the B site. The impact of the rare-earth content (x) on the magnetic features of the prepared NiCo ferrite microspheres was investigated by analyzing M-H loops, which showed soft ferrimagnetism. The magnetic features illustrate a great impact of the incorporation of Ce3+-Dy3+ ions within the NiCo ferrite structure. The saturation magnetization (Ms), remanence (Mr), and coercivity (Hc) increased gradually with increasing Ce–Dy content. At x = 0.04, Ms, Mr, and Hc attain maximum values of about 31.2 emu/g, 11.5 emu/g, and 512.4 Oe, respectively. The Bohr magneton (nB) and magneto-crystalline anisotropy constant (Keff) were also determined and evaluated with correlation to other magnetic parameters. Further increase in Ce3+-Dy3+ content (i.e., x ≥ 0.06) was found to decrease Ms, Mr, and Hc values. The variations in magnetic parameters (Ms, Mr, and Hc) were largely caused by the surface spins effect, the variations in crystallite/particle size, the distribution of magnetic ions into the different sublattices, the evolutions of magneto-crystalline anisotropy, and the variations in the magnetic moment (nB). The squareness ratios were found to be lower than the predicted theoretical value of 0.5 for various samples, indicating that the prepared Ce–Dy substituted NiCo ferrite microspheres are composed of NPs with single-magnetic domain (SMD). Temperature and frequency-dependent electrical and dielectric measurements have been done to estimate the ac/dc conductivity, dielectric constant, and tangent loss values for all the samples. The ac conductivity measurements confirmed the power-law rules, largely dependent on Ce–Dy content. Impedance analysis stated that the conduction mechanisms in all samples are mainly due to the grains-grain boundaries. The dielectric constant of NiCo ferrite microspheres give rise to normal dielectric distribution, with the frequency depending strongly on the Ce–Dy content. The observed variation in tangential loss with frequency can be attributed to the conduction mechanism in ferrites, like Koop's phenomenological model.

Preparation of chitosan microspheres as carrier material to controlled release of urea fertilizer

This study aimed to investigate the effects of volume ratio in the continuous phase and the dispersed phase (CP/DP) and stirring speed on yield, water absorption, particle size, morphology surface, and cumulative release of nitrogen from the chitosan microsphere. The chitosan microsphere preparation method was emulsion cross-linking with glutaraldehyde saturated toluene (GST) as the cross-linking agent. Urea was mixed with chitosan solution and put into the oil. It was then stirred to form an emulsion. Glutaraldehyde saturated toluene (GST) was added slowly, followed by 2 ml glutaraldehyde, stirred continuously for 2 h. The formed chitosan microsphere was eventually washed and dried to be analyzed. The yield obtained was about 87.01%-96.71%, the water absorption was 79.77%–89.25%, and the diameter size of chitosan microspheres was from 153.66 ± 26.35 μm to 179.39 ± 34.95 μm. The chitosan microspheres morphology were good sphericity even though there were irregular size. Cumulative release analysis was obtained from 32.38%–37.69% by release mechanism such as anomalous behavior (non-Fickian kinetics)

Formation of nanosheets-assembled porous polymer microspheres via the combination effect of polymer crystallization and vapor-induced phase separation

A facile and versatile route is demonstrated to fabricate nanosheets-assembled porous polymer microspheres via the ingenious combination of polymer crystallization promoted by high temperature and vapor-induced phase separation (VIPS). Water vapor which permeates into the polymer solution promotes the precipitation of hydrophobic polyacrylonitrile (PAN). High temperature promotes PAN crystallization and assembling into hierarchical porous microspheres (about 1–3 μm). Interestingly, the addition of polyethyleneimine (PEI) functioning as nucleation sites and steric stabilizer can also promote PAN crystallization owing to their strong interactions. In this protocol, polymer composition, preparation temperature, solvent type and solution concentration are critical to determine the final morphologies of porous microspheres. This versatile strategy for fabricating nanosheets-assembled porous microspheres can be extended to other semi-crystalline/crystalline polymers, which could hopefully be applied in drug delivery, energy storage, separation,and purification, etc.

Poly(1,5-anthraquinonyl sulfide)/reduced graphene oxide composites towards high Li and Na storage both in half- and full-cells

Conjugated carbonyl compounds with high theoretical capacity, low cost, structural flexibility and abundant resources are potential cathodes in metal-ion batteries (lithium-LIBs, sodium-SIBs, kalium-KIBs). Regrettably, their inherent drawbacks of high solubility and low electrical conductivity limit their further application. Herein, different mass ratios of reduced graphene oxide wrapped poly (1,5-anthraquinonyl sulfide) (PAQS/rGO) composites were prepared through a calcination-treatment process aiming at decreasing the dissolution and enhancing the conductivity. XRD, FTIR and Raman analysis confirmed the successful synthesis of PAQS. XRD analysis also confirmed the conversion of GO to rGO. Four-probe test results showed that the conductivity of composites increased as the rGO ratio increased. SEM images showed that PAQS/rGO composites presented microsphere morphologies. Profiting from the enhanced conductivity and limited dissolution in electrolyte, the PAQS2 (the mass ratios of PAQS and rGO is 10:2) composite exhibited outstanding performance both in half- and full-batteries. In LIBs/SIBs, PAQS2 exhibited reservable discharge capacities of 121 and 115 mAh g−1 at 50 mA g−1 after 200 and 400 cycles, respectively. In PTPAn/PAQS2 all-organic Li/Na-ion batteries, reservable charge/discharge capacities of 42.1/39 and 42.1/40.4 mAh g−1 were retained at 50 mA g−1 after 200 cycles, respectively. Ex-situ FT-IR analysis further performed the redox reaction of carbonyl groups during charging and discharging.

Formation of micro/nanoparticles and microspheres from polyesters by dispersion ring‐opening polymerization

AbstractThe micro/nanoparticles and microspheres of polyesters derived from the heterocyclic monomers of lactide (L,L or D,L), ε‐caprolactone, and glycolide have received significant interest as drug carriers for biomedical applications. This review focuses on the recent advances in the study of polyester‐based micro/nanoparticles and microspheres derived from the dispersion ring‐opening polymerization (ROP) of heterocyclic monomers, and/or self‐assembly of polyester macromolecules, and/or dialysis of polyester solution in water‐miscible organic solvents against water. The dispersion polymerization of heterocyclic monomers in the presence of non‐polar miscible solvents and amphiphilic polymer surfactant leads to the formation of polyester particles with a narrower size distribution. The use of the polymer surfactant is crucial in controlling the diameter, morphology, and stability of the polyester particles formed during the ROP. The polymer surfactant acts as a stabilizer and is bound to the polyester particles strongly and irreversibly to control the size and morphology of polyester microspheres. The properties of polyester particles are varied by controlling the number average diameter and diameter polydispersity index. Hence, in this article, we review different synthetic strategies developed for the formation of polyester based particles with controlled diameter of distribution and the factors influencing its formation such as structure of the polymer surfactant, critical micelle concentration of the surfactant, type of radical initiator/monomer used, reaction parameters, etc. The article also describes methods developed for transforming the polyester microspheres into the water for better biocompatibility and encapsulation of bioactive compounds, drugs, and proteins into the polyester particles and their potential release at the targeted specific site are reviewed.

Design and Evaluation of Novel Sustained-Release Floating Microspheres for Oral Delivery of Ciprofloxacin Hydrochloride

Background: Ciprofloxacin (CIP) is a broad-spectrum antibiotic, used to treat various bacterial infections. Administration of conventional oral dosage forms of CIP is associated with multiple challenges such as short residence time of the drug in the gastrointestinal tract which could reduce bioavailability and effectiveness of the drug. This study aimed to design and develop novel floating microspheres for the sustained release of CIP in the stomach over 24 hours after oral administration, besides evaluating the effect of different variables on the characteristics of developed microspheres. Methods: Microspheres were developed by the solvent-evaporation method utilizing cellulose acetate and polyvinyl alcohol, then characterized for physicochemical properties including bulk density, buoyancy, and entrapment efficacy. The drug-excipient compatibility was evaluated by Fourier-transform infrared spectroscopy and the Scanning electron microscopy was used to observe the morphology of microspheres. The effects of the drug to polymer ratio, polymer concentration, and the pace of stirring through the preparation process, on the size and release rate were also evaluated. Results: Morphology analysis indicated round-shape microspheres with a mean particle size between 66-344 µm. The polydispersity index of prepared formulations was determined to be in the range of 0.129 to 0.230. It was observed that at higher polymer concentrations the drug release rate from microspheres decreased while the mean particle size increased. Increasing the drug to polymer ratio and decreasing the stirring speed increased the mean particle size. All formulations showed more than 70% cumulative drug release in the prolonged period of 24 h while remaining buoyant in the meantime. The formulations followed Higuchi and Korsmeyer-Peppas kinetics and release the drug by diffusion mechanism. Conclusions: Based on the results obtained from in vitro release study besides floating properties the prepared microspheres could be considered suitable for enhanced sustained-release of CIP following the oral administration.

Investigation of the Physical Properties and Clinical Application of Embosphere Microspheres

Background: The aim of this study was to understand physical characteristics of Embosphere microspheres for the clinical use of microsphere chemotherapy embolization of liver cancer. Methods: The morphology of Embosphere microspheres in different states, including static, oscillating, and in a magnetic field was observed with the naked eye. Ninety-five patients diagnosed with primary hepatocellular carcinoma (HCC) were separated into 3 groups based on the types of embolic material as follows: 32 cases of sole microspheres, 34 cases of iodinated oil (17 cases with additional application of gelatin sponge particle), and 29 cases of iodinated oil + Embosphere microspheres. Results: The diameter of the microspheres ranged from 100 to 300 μm, with a sedimentation rate υ = 0.0375 cm/s in physiological saline. The diameter of microspheres ranged from 300 to 500 μm, with a sedimentation rate υ = 0.1875 cm/s. The swelling rate of microspheres was 90%. Microspheres showed nondirectional movement in a 1.5- or 3.0-T magnetic field during magnetic resonance imaging. A volumetric ratio of 1:1.4–1:1.5 between microspheres and contrast agent resulted in optimal suspension properties. Microspheres appeared circular with a smooth surface upon water adsorption. Microsphere embolism was observable in blood vessels of pathological sections. The surface of microspheres can adsorb 5-fluorouracil and arsenic trioxide. There are statistically significant differences in local-regional tumor control conditions among patients treated with sole microspheres, iodinated oil, and iodinated oil + microspheres during transarterial chemoembolization. Conclusions: Embosphere microspheres can be used to embolize patients with rupture and hemorrhage of HCC. Embosphere microsphere embolization is superior to iodinated oil and iodinated oil + microsphere for HCC.

Formulation and Evaluation of Ranitidine Hydrochloride Loaded Floating Microspheres for the Treatment of Gastric Ulcer

The study was aimed to prepare gastro retentive floating microsphere of Ranitidine Hydrochloride by Ionotropic Gelation technique and solvent evaporation technique by using the different carriers’ ratios (Carbopol 934, Chitosan, and sodium alginate). Both natural and synthetic polymers have been used to prepare floating microspheres and evaluated the relevant parameters. There was no drug and carrier interactions assessed from FTIR. Depending upon the ratio, the percentage yield was found between 58.33% to 90.38%. in all formulations. The surface morphology of microspheres was characterized by SEM and it was discrete, spherical in shape with rough outer surface and showed free flowing properties. The mean particle size of microspheres significantly increases with increasing polymer concentration and the range between 99.92±1.221 to 168.23±1.963 µm. Among all the formulations, RF3 showed high drug entrapment efficiency (87.52%). The percentage in-vitro buoyancy of the floating microspheres was in the range of 66.92% to 81.52%. The in-vitro drug release study revealed that RF3, RF6 and RF9 Formulations having 89.97%,92.91%,93.68% drug released at the end of dissolution studies respectively. It could be concluded that the developed floating microsphere of Ranitidine Hydrochloride can be used for prolonged release in stomach. Therefore improving the bioavailability and patient compliance.

Preparation and piezoelectric catalytic performance of HT-Bi2MoO6 microspheres for dye degradation

HT-Bi2MoO6 microspheres were prepared by hydrothermal method and applied in piezoelectric catalytic degradation of dye. The crystallinity, morphology, optical property, and the surface chemical state of Bi2MoO6 catalyst were characterized by XRD, SEM, UV–vis and XPS techniques, respectively. The effects of catalyst preparation method, catalyst amount, dyes type and reaction conditions were investigated on the piezoelectric catalytic performance. The highest degradation ratio of 98.9% was achieved with 10 mg of HT-Bi2MoO6 catalyst after 45 min of piezoelectric catalytic vibration. In addition, a possible piezoelectric catalytic mechanism over HT-Bi2MoO6 catalyst has been proposed by active species trapping experiment. ·O2− and h+ are suggested to be the main active species in the piezoelectric catalytic process. These research results show that the HT-Bi2MoO6 catalyst with flower-like microspheres morphology consisting of nanosheets can effectively transform mechanical energy into electrical energy by vibration to generate reactive species for the degradation of dyes.

Analysis of Safety and Effectiveness of Sodium Alginate/Poly(γ-glutamic acid) Microspheres for Rapid Hemostasis.

Most preventable deaths after trauma are related to hemorrhage and occur early after injury. Timely hemostatic treatment is essential to minimize blood loss and improve survival. Among the various treatment methods, the most economical and effective is to use a hemostatic agent. A powdered hemostatic agent can be used for wounds of any shape or depth with high compactness and excellent accumulation effect. Herein, we chose the natural, hydrophilic polymer poly(γ-glutamic acid) (γ-PGA) to form composite hemostatic microspheres with sodium alginate (SA), which show good biocompatibility, water absorptivity, and viscosity. The morphology and structure of the hemostatic microspheres were determined using Fourier transform infrared spectroscopy and scanning electron microscopy. The overall safety, hemolysis, pyrogenic, and intradermal irritation tests were examined. The relationship between hemostatic pressure and hemostatic time during microsphere use was also measured. The hemostatic effect was analyzed with a liver, spleen, and femoral artery bleeding model. The composite microspheres were well tolerated in vivo and exhibited better hemostatic effects in animal experiments than a microporous polysaccharide powder compound. Research results showed that SA/γ-PGA microspheres are materials with good hemostatic effect, high safety, and great potential in clinical applications.

Study on the polystyrene plastic degradation in supercritical water/CO2 mixed environment and carbon fixation of polystyrene plastic in CO2 environment

Through the degradation of organic waste, the carbon can be extracted and converted into syngas with calorific value, and the CO2 generated can also be used after fixed. In this work, the gasification of polystyrene (PS) in supercritical water with CO2 was studied in the temperature range of 400 °C−700 °C and time range of 0–30 min. In addition, PS containing only carbon and hydrogen can react with CO2 to generate CO in CO2 atmosphere. Therefore, the degradation of PS plastics in CO2 atmosphere was also studied. The results showed that PS plastic was hardly gasified at 400 °C, and as the temperature rose, the liquid composition changed. In supercritical water, under certain feedstock conditions, reacting for 20 min, the carbon conversion efficiency of PS plastic reached 47.6% at 700 °C. Under all CO2 atmosphere conditions in this experiment, the highest proportion of CO2 consumed by PS degradation was 12.5%. Moreover, the higher the temperature, the smaller the average diameter of carbon microspheres in the solid product. The morphology of carbon microsphere was also related to the reaction time, and the main change came from the gasification of carbon microspheres and the precipitation and adhesion of carbon element in liquid product.

A vacancy-free sodium manganese hexacyanoferrate as cathode for sodium-ion battery by high-salt-concentration preparation

Sodium manganese hexacyanoferrate (MnPBA) is attracting wide attention as an ideal low-cost cathode material for sodium-ion batteries (SIBs) because of high specific capacity, three-dimensional open framework, and low cost. However, some issues, including high [Fe(CN)6]4- vacancy concentration, a large amount of structural water in lattice, and nano-scale particles, hinder the practical application. Here, the effects of coprecipitation process under high-salt-concentration solution were systematically investigated to prepare a vacancy-free MnPBA with micro-spherical particle morphology. The sample (PBAT-80), prepared at ageing temperature of 80 °C for ageing time of 20 h, achieved high yield of 100 g L−1 (w/v = weight of production / liter of solution) and theoretical reversible capacity of 170 mAh g−1. Moreover, the relationship between crystallinity and thermal stability of MnPBAs was further investigated and the different storage mechanisms of distinct water molecules were identified. These results will be attractive for commercial applications of SIBs in large-scale energy storage systems.

Comparative Evaluation of Physical Characteristics and Preclinical Data of a Novel Monodisperse Polycaprolactone Microspheres Filler

Demand for dermal fillers has been increasing gradually over the past decade. Polycaprolactone (PCL) fillers, a biodegradable polymer, not only naturally maintain the volume of the skin, but also stimulate collagen production by microsphere. However, inflammation can be caused by several factors such as large diameters, non-uniformity, uneven surfaces and non-spherical shapes of microspheres in use. Thus, a filler using microspheres with a uniform diameter of more than 20μm and spherical shape was developed. The main purpose of this study was to evaluate the efficacy and safety of newly monodisperse polycaprolactone microspheres fillers, IVL-F001 with smaller microsphere size and better morphology against a conventional commercial PCL filler. The morphology and diameters of microsphere included in IVL-F001 and the PCL filler were analyzed, and the viscoelasticity and inject ability of both fillers were examined. After intradermal injection to hairless mice, the durability and efficacy of both fillers were evaluated through PRIMOSLITE and Folliscope for 24 weeks. Histology was performed to assess the biocompatibility, inflammation, and collagen synthesis. Microspheres of IVL-F001 demonstrated a narrow size distribution with average diameter of 34.16μm and distribution of 4.11. The level of injection force was low and the elasticity (G') was high compared to the licensed PCL filler. In the histopathological evaluation, IVL-F001 had significantly lower inflammatory reactions and higher collagen synthesis compared to the licensed PCL filler. These data indicated that IVL-F001 has lower inflammatory reaction and improved persistence compared with commercial PCL filler. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Morphology and properties of hollow glass microspheres. Part 4. On the kinetics of the destruction of hollow glass microspheres under the action of hydrostatic pressure and methods for increasing their strength

The kinetics of destruction of hollow glass microspheres (HGM) of various size groups is investigated. It is shown that removing a certain part of large-diameter microspheres from the initial batch by sieving can significantly increase the specific strength of the remaining HGM.

Imine‐Induced Metal‐Organic and Covalent Organic Coexisting Framework with Superior Li‐Storage Properties and Activation Mechanism

Due to the adjustable structure and the broad application prospects in energy and other fields, the exploration of porous organic materials [metal-organic polymers (MOPs), covalent organic frameworks (COFs), etc.] has attracted extensive attention. In this work, an imine-induced metal-organic and covalent organic coexisting framework (Co-MOP@COF) hybrid was designed based on the combination between the amino units from the organic ligands of Co-MOP and the aldehyde groups from COF. The obtained Co-MOP@COF hybrid with layer-decorated microsphere morphology exhibited good electrochemical cycling performance (a large reversible capacity of 1020 mAh g-1 after 150 cycles at 100 mA g-1 and a reversible capacity of 396 mAh g-1 at 500 mA g-1 ) as the anode for Li-ion batteries. The coexisting framework structure endowed the Co-MOP@COF hybrid with more surface area exposed in the exfoliated COF structure, which provided rapid Li-ion diffusion, better electrolyte infiltration, and effective activation of functional groups. Therefore, the Co-MOP@COF hybrid material achieved an enhanced Li storage mechanism involving multi-electron redox reactions, related to the CoII center and organic groups (C=C groups of benzene rings and C=N groups), and furthermore improved electrochemical performance.

Hierarchically Nanostructured ZnO with Enhanced Photocatalytic Activity

Hierarchical nanostructures of ZnO are integrated architectures comprising well-ordered nanoscale subunits and excellent photocatalytic properties. In this study, synthesis of ZnO nanoparticles using methods such as co-precipitation, hydrothermal, thermal decomposition, and electrochemical precipitation yielded microsphere, nanorod, pyramid, and nanopetal-like morphologies, respectively. The catalysts obtained were characterized using XRD, IR, SEM-EDX, UVDRS, TGA, PL, and Zeta potential analysis. The XRD spectra confirmed that all the different morphologies of ZnO have hexagonal wurtzite structures The photocatalytic activity of these nanostructures was determined using a dye degradation study on a model pollutant Methylene Blue (MB) under simulated visible light. The kinetic study of the dye degradation reveals that it obeys pseudo-first-order kinetics with a maximum rate constant of 0.01503 min−1. The nanorod structured ZnO particles prepared by the hydrothermal method showed the best catalytic activity.