Toward Low-Cost and Sustainable Supercapacitor Electrode Processing: Simultaneous Carbon Grafting and Coating of Mixed-Valence Metal Oxides by Fast Annealing

There is a rapid market growth for supercapacitors and batteries based on new materials and production strategies that minimize their cost, end-of-life environmental impact, and waste management. Herein, mixed-valence iron oxide (FeOx) and manganese oxide (Mn3O4) and FeOx-carbon black (FeOx-CB) electrodes with excellent pseudocapacitive behavior in 1 M Na2SO4 are produced by a one-step thermal annealing. Due to the in situ grafted carbon black, the FeOx-CB shows a high pseudocapacitance of 408 mF cm−2 (or 128 F g−1), and Mn3O4 after activation shows high pseudocapacitance of 480 mF cm−2 (192 F g−1). The asymmetric supercapacitor based on FeOx-CB and activated-Mn3O4 shows a capacitance of 260 mF cm−2 at 100 mHz and a cycling stability of 97.4% over 800 cycles. Furthermore, due to its facile redox reactions, the supercapacitor can be voltammetrically cycled up to a high rate of 2,000 mV s−1 without a significant distortion of the voltammograms. Overall, our data indicate the feasibility of developing high-performance supercapacitors based on mixed-valence iron and manganese oxide electrodes in a single step

Multilayer Thin Films on Fine Particles

The tunable construction of multilayer thin-film-based particulate has opened up new horizons in materials science and led to exciting new developments in many scientific areas during the past two decades. Indeed, to utilize the synergistic properties of thin film coatings and the core particles, the thin film immobilized on fine particles can be a promising approach. The interaction between the thin films and the core fine particles results in adjustable properties of the coated particles. Therefore, such coated systems have been considered as an important class of emerging powder technology for a wide range of applications. Namely, multilayer structural features can lead to designing a highly active and selective catalytic systems. In addition, multilayer-coated nano/micro particles (NMPs) can be employed in the development of many new properties, ease of functionalization, conjugation of biomolecules, etc. Such structure with multilayer coatings can also revolutionize the energy storage and conversion systems

Trace Detection of Diphenhydramine by Adsorption on a Microelectrode at Flow Injection System by Fast Fourier Transform Continuous Cyclic Voltammetry

A continuous cyclic voltammetric study of diphenhydramine at gold micro electrode was carried out. Some investigations were also done to find the effects of various parameters on the sensitivity of the proposed method. The experiments were performed under the following conditions: pH = 2, the scan rate = 40 V/ s (v), accumulation potential = 500 mV (E), and accumulation time = 0.2 s (t). The drug in phosphate buffer (pH = 2.0) is adsorbed at optimized condition on the surface of electrode, giving rise to change in the current of well-defined oxidation peak of gold in the flow injection system. The proposed detection method is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. Signal-to-noise ratio has significantly increased by application of discrete Fast Fourier Transform (FFT) method, background subtraction and twodimensional integration of the electrode response over a selected potential range and time window. The linear concentration range was from 4.0 × 10–7 to 1.0 × 10–11 mol dm–3 (r = 0.9987) with a limit of detection and quantitation 5 × 10–12 and 4 × 10–11 mol dm–3, respectively. The method has the requisite accuracy, sensitivity, precision and selectivity to assay diphenhydramine in tablets

Curing epoxy with ethylenediaminetetraacetic acid (EDTA) surface-functionalized CoxFe3- xO4 magnetic nanoparticles

In this work, the bulk and surface composition of Fe3O4 supermagnetic nanoparticles were modified for efficient epoxy curing. The bare, ethylenediaminetetraacetic acid (EDTA) capped, and cobalt (Co)-doped EDTA capped Fe3O4 nanoparticles were synthesized electrochemically. The crystalline structure and phase information, surface capping, morphology and magnetization behavior of nanoparticles were studied by X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM) and vibrating sample magnetometer (VSM), respectively. A low amount of the prepared nanoparticle (0.1¿wt.%) was used in preparation of epoxy nanocomposites. Nonisothermal differential scanning calorimetry (DSC) under different heating rates was performed to study the potential of nanoparticles in curing epoxy resin with an aliphatic amine. The heat release data on nanocomposites suggest that EDTA capped Co-doped Fe3O4 considerably improved the curing reaction between epoxy resin and the curing agent. Calculations based on Cure Index approved qualitatively a shift from Poor to Good cure by concurrent lattice and surface modifications of magnetic nanoparticles. It is bielived that the approach used in this work can pave the way to enhance curability of epoxy nanocomposites by the combined modification of bulk and surface of nanoparticlesPostprint (author's final draft

Novel method for determination of trace amounts of citalopram in tablets by fast fourier continuous cyclic voltammetry at au microelectrode in flowing solutions

In this work, fast Fourier transform continuous cyclic voltammetric technique for the monitoring of ultra trace amounts of citalopram in a flow-injection system has been presented. The potential waveform, consisting of the potential steps for cleaning, stripping and potential ramp, was continuously applied on an Au disk microelectrode (with a 12.5 µm in radius). The proposed detection method has some advantages, the greatest of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, this is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. The method was linear over the concentration range of 7 - 116 pg mL-1 (r = 0.9960) with a limit of detection and quantitation 2.3 and 7 pg mL-1, respectively. The method has the requisite accuracy, sensitivity, precision and selectivity to assay citalopram in tablets. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the citalopram were considered. The proposed method was applied to the determination of citalopram in a pharmaceutical preparation

A new homatropine potentiometric membrane sensor as a useful device for homatropine hydrobromide analysis in pharmaceutical formulation and urine: a computational study

Homatropine (Equipin, Isopto Homatropine) is an anticholinergic medication that inhibits muscarinic acetylcholine receptors and thus the parasympathetic nervous system. It is available as the hydrobromide or methylbromide salt. In this study, a potentiometric liquid membrane sensor for simple and fast determination of homatropine hydrobromide in pharmaceutical formulation and urine was constructed. For the membrane preparation, homatropine-tetraphenylborate complexes were employed as electroactive materials in the membrane. The proposed sensor presents wide linear range (10-5-10-1 mol L-1), low detection limit (8×10-6 mol L-1), and fast response time (ca. 10 s). Validation of the method shows suitability of the sensors for applicability in the quality control analysis of homatropine hydrobromide in pharmaceutical formulation and urine