Melamine-based metal-organic frameworks for high-performance supercapacitor applications.

Melamine-based metal-organic frameworks (MOFs) for high-performance supercapacitor applications are described in this paper. Melamine (Me) is employed as an organic linker, and three metal ions cobalt, nickel, and iron (Co, Ni, Fe) are used ascentral metal ions to manufacture the desired MOF materials (Co-Me, Ni-Me, and Fe-Me). While melamine is an inexpensive organic linker for creating MOF materials, homogenous molecular structures can be difficult to produce. The most effective technique for expanding the molecular structures of MOFs through suitable experimental optimization is used in this work. The MOFs materials are characterized using standard techniques. The kinetics of the materials' reactions are investigated using attenuated total reflectance. X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (P-XRD), Fourier transform infrared (ATR-FT-IR) spectroscopy, and Brunauer-Emmett-Teller (BET) studies verified the development of the MOFs structure. The surface morphology of the produced materials is investigated using field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), and atomic force microscopy (AFM). The elements found in MOFs are studied via XPS analysis, energy dispersive X-ray diffraction (EDX), mapping, and mapping. The materials' absorption characteristics were examined by the use of UV-visible absorption spectroscopy. The thermal stability of the materials is examined by thermogravimetric analysis (TGA); these materials are more stable, according to the findings, even at high temperatures. The electrochemical investigation determines the specific capacitance of the materials. The specific capacitance of Co-Me, Ni-Me, and Fe-Me in 3 M KOH electrolyte is 1267.36, 803.22, and 507.59F/g @ 1 A-1, according to the three-electrode arrangement. The two-electrode device maximizes power and energy density by using an asymmetrical supercapacitor in a 3 M KOH electrolyte. The power and energy densities of Co-Me, Ni-Me, and Fe-Me are 3650.63, 2813.21, and 6210.45 W kg-1, and 68.43, 46.32, and 42.2 Wh kg-1, respectively. According to the materials stability test, the MOFs are highly stable after 10,000 cycles. Preliminary results suggest that the materials are suitable for usage in high-end supercapacitor uses.

A Review on Electrospun Nanofiber Composites for an Efficient Electrochemical Sensor Applications.

The present review article discusses the elementary concepts of the sensor mechanism and various types of materials used for sensor applications. The electrospinning method is the most comfortable method to prepare the device-like structure by means of forming from the fiber structure. Though there are various materials available for sensors, the important factor is to incorporate the functional group on the surface of the materials. The post-modification sanction enhances the efficiency of the sensor materials. This article also describes the various types of materials applied to chemical and biosensor applications. The chemical sensor parts include acetone, ethanol, ammonia, and CO2, H2O2, and NO2 molecules; meanwhile, the biosensor takes on glucose, uric acid, and cholesterol molecules. The above materials have to be sensed for a healthier lifestyle for humans and other living organisms. The prescribed review articles give a detailed report on the Electrospun materials for sensor applications.

Boosting Fenton's Oxidation Reaction by a Food Waste-Derived Catalyst for Oxidizing Organic Dyes: Synergistic Effect of Complex Iron Oxides and the Layer Carbon Structure.

The constant increase in the human population drives the demand for food supply and thereby increasing the food wastage dramatically all over the world. Especially, around 60% of banana biomass has been generated as inedible domestic waste. Herein, we successfully employed banana waste as a catalyst for Fenton's oxidation reaction. The biomass-derived catalysts were subjected to various characterization techniques such as XRD, ATR-FTIR, confocal Raman spectroscopy, and XPS, XRF, BET, SEM, and TEM analyses. The XRD results revealed that, after carbonization of the dried banana bract material, a perloffite-like metal oxide phase was formed due to the aerial oxidation reaction. Characterization results of Raman and ATR-FTIR confirm that the carbonized catalyst possesses a layer-like structure with different types of functional groups. The calcium, magnesium, potassium, sodium, and iron are the dominating metal species in the resultant material, which was evident from the XRF and EDAX analyses. The carbonized banana bract catalyst is successfully utilized for the Fenton's oxidation reaction at neutral pH. The experimental results showed that the degradation efficiency of the fresh catalyst was 95% in 4 h of reaction time, and the stability of the catalyst was retained up to nine consecutive cycles. The high activity of MB, methylene blue, is mainly attributed to the strong interaction between oxy functional groups of the catalyst and MB molecule as compared to RhB. Further, the calculated efficiency of the hydrogen peroxide was found to be 99% and the self-decomposition of hydrogen peroxide by the formed metal oxides was highly limited.

L-Lysine-Modified pNIPAm-co-GMA Copolymer Hydrogel for pH- and Temperature-Responsive Drug Delivery and Fluorescence Imaging Applications.

The development of dual-stimuli-responsive hydrogels attracts much research interest owing to its unique stimuli-responsive characteristics. In this study, a poly-N-isopropyl acrylamide-co-glycidyl methacrylate-based copolymer was synthesized by incorporating N-isopropyl acrylamide (NIPAm) and a glycidyl methacrylate (GMA) monomer. The synthesized copolymer, pNIPAm-co-GMA was further modified with L-lysine (Lys) functional units and further conjugated with fluorescent isothiocyanate (FITC) to produce a fluorescent copolymer pNIPAAm-co-GMA-Lys hydrogel (HG). The in vitro drug loading and dual pH- and temperature-stimuli-responsive drug release behavior of the pNIPAAm-co-GMA-Lys HG was investigated at different pH (pH 7.4, 6.2, and 4.0) and temperature (25 °C, 37 °C, and 45 °C) conditions, respectively, using curcumin (Cur) as a model anticancer drug. The Cur drug-loaded pNIPAAm-co-GMA-Lys/Cur HG showed a relatively slow drug release behavior at a physiological pH (pH 7.4) and low temperature (25 °C) condition, whereas enhanced drug release was achieved at acidic pH (pH 6.2 and 4.0) and higher temperature (37 °C and 45 °C) conditions. Furthermore, the in vitro biocompatibility and intracellular fluorescence imaging were examined using the MDA-MB-231 cell line. Therefore, we demonstrate that the synthesized pNIPAAm-co-GMA-Lys HG system with temperature- and pH-stimuli-responsive features could be promising for various applications in biomedical fields, including drug delivery, gene delivery, tissue engineering, diagnosis, antibacterial/antifouling material, and implantable devices.

Thermoplastic Starch Composites Reinforced with Functionalized POSS: Fabrication, Characterization, and Evolution of Mechanical, Thermal and Biological Activities.

Rapid advancements in materials that offer the appropriate mechanical strength, barrier, and antimicrobial activity for food packaging are still confronted with significant challenges. In this study, a modest, environmentally friendly method was used to synthesize functionalized octakis(3-chloropropyl)octasilsesquioxane [fn-POSS] nanofiller. Composite films compared to the neat thermoplastic starch (TS) film, show improved thermal and mechanical properties. Tensile strength results improved from 7.8 MPa to 28.1 MPa (TS + 5.0 wt.% fn-POSS) with fn-POSS loading (neat TS). The barrier characteristics of TS/fn-POSS composites were increased by fn-POSS by offering penetrant molecules with a twisting pathway. Also, the rates of O2 and H2O transmission were decreased by 50.0 cc/m2/day and 48.1 g/m2/day in TS/fn-POSS composites. Based on an examination of its antimicrobial activity, the fn-POSS blended TS (TSP-5.0) film exhibits a favorable zone of inhibition against the bacterial pathogenic Staphylococcus aureus and Escherichia coli. The TS/fn-POSS (TSP-5.0) film lost 78.4% of its weight after 28 days in natural soil. New plastic materials used for packaging, especially food packaging, are typically not biodegradable, so the TS composite with 5.0 wt.% fn-POSS is therefore of definite interest. The incorporation of fn-POSS with TS composites can improve their characteristics, boost the use of nanoparticles in food packaging, and promote studies on biodegradable composites.