جستجوی مقالات مرتبط با کلیدواژه "electrode" در نشریات گروه "شیمی"

In recent decades, there has been a continuous rise in the worldwide demand for electrochemical electrodes, driven by their established advantages such as rapidity, cost-effectiveness, user-friendly nature, and practicality in comparison to alternative electrochemical methods. However, despite these advancements, there remains a pressing need to tailor electrode preparation methods to accommodate the diverse requirements of the pharmaceutical industry. A newly developed electrochemical method was described to produce three stable probes to measure tamoxifen citrate by a coated protective layer formed from ZnO nanocomposite polymer. This modified layer was prepared by drop-casting a solution of ethaline: oxaline: water on a polymer membrane. The modified membrane exhibited potential by less than 0.22 mV for 24 days. Different analytical measurements were examined to determine the optimization proposed electrode; it was found that the addition of polymer nanocomposite metals polymer mixed with deep eutectic solvents prompted high probe efficiency used for poor solubility drugs in water. The Nernstian slope was found to be good agreement measurements in Polyvinyl Pyrrolidine (PVP) electrode around 59.71±0.60 mV/decade while other electrodes slightly decreased at 58.88±0.23 mV/decade for Poly Ethylene Glycol (PEG) and 60.20±0.15 mV/decade recorded for polyvinylchloride (PVC) electrode. Tamoxifen samples in tablet form were found to be acceptable and accurate determinations in new electrochemical technique dependent on the preparation of different nanocomposite ZnO polymer molecules, with trace added of (1.5%, 2.0%, and 2.5%) weight percentage deep eutectic solvent water mixtures (DESs) as supporting permeation during hydrophobic membranes attributed to partition and pores mechanisms helped to ion pair diffusion.

A unique sensitive electrochemical Molecularly Imprinted Polymer (MIP) sensor was fabricated using a Glassy Carbon Electrode (GCE) in phosphate buffer solution (pH 7.0) and cyclic voltammetry in the presence of dipicolinic acid (DPA) as a template molecule. In addition, gold nanoparticles (AuNPs) were used to modify the electrode's surface. AuNPs were roughly spherical in shape and irregular in distribution. The diameter of the nanoparticles was in the range of 14-30 nm. The cyclic voltammograms confirmed that the MIP-modified electrode had higher sensitivity than the non-modified electrode due to the presence of specific binding sites. The analysis of AuNPs/MIP modified electrodes in the presence of various similar compounds, such as Dinicotinic acid, Glucose, Ascorbic acid, and Phenylalanine confirmed the applicability of modified electrodes for recognition of DPA. High selectivity and sensitivity were achieved using the AuNPs/MIP modified electrode for the detection of DPA in the concentrations of 0 and 10-2 M, with a low detection limit of 1.58 × 10-8 M and response time 20 s. The fabricated sensor was selective, sensitive, controllable, and easy to operate without the need for any toxic or dangerous by-products.

A high urea compound in human blood is indicated for kidney disease, urinary tract stones, and even bladder tumors. It is necessary to take several preventive measures, starting with detecting the urea compound. This study presents the preparation of a working electrode based on graphite-TiO2 (G/TiO2) composites immobilized into a glass tube for sensing urea compound under an electrochemical system. The G/TiO2 composites were successfully synthesized through a physical mixing method and then immobilized into a glass tube for fabricating a working electrode to sense the urea compound under the cyclic voltammetry (CV) technique. The material characterization results show that the nano-TiO2 powder is composed of irregular polycrystalline and amorphous, revealing a broad pattern with low intensity. However, the effect of amorphous materials on the expansion of the nano-sized XRD TiO2 pattern is negligible. In addition, the morphological analysis of graphite has a very tight layer of flakes with a smooth and uniform surface. At the same time, the G/TiO2 composites are also granule-shaped that attached to the graphite surface, identified to cover part of the graphite surface. Under the electrochemical performance test, the excellent composition of TiO2 modifier is 0.5 g mixed into graphite to sense urea compound by using CV technique under a scan rate of 0.5 V.s-1 with 0.1M K3[Fe(CN)6] (+0.1M NaNO3) electrolyte solution. We obtain a standard deviation of 0.361403514 and a detection limit of 0.005976905 mg.L-1 with RSDr and PRSDr values of 5.51% and 3.13%, respectively. The performance of the electrodes over 25 days showed a significant effect on stability over 10 days.

In this work, we investigated the applicability of the clay-modified carbon paste electrode (CPE-clay) in the detection of paracetamol (PAR), using two electrochemical methods differential pulse voltammetry (DPV) and cyclic voltammetry (CV) in the range between 20 and 400 mV in a Britton Robinson buffer solution (pH 7). The voltammetric technical behavior of PAR is studied where a sensitive anodic and cathodic peak has been appeared at about 0.4 V and 0.2 V (vs. Ag/AgCl/3 M KCl) successively. These peaks were recorded from the reversible redox of PAR at the CPE-clay surface. The proposed technical (DPV, CV) exhibits remarkably an electro-catalytic success for PAR redox. The current response of the catalytic peaks obtained by DPV depended linearly on the concentration of PAR in the range between 1.0 × 10-6 and 1.0 × 10-3 mol L-1 with a detection limit of 5.27 × 10-9 mol L-1. Subsequently, the relative standard deviation (RSD) at 1.0 × 10-4 mol L-1 PAR concentration was 3.8% for nine replicates. The proposed electrode has been successfully used for PAR detection in the human blood sample.

The temperature and the electrode thickness are among the important parameters which affect the performance of photovoltaic cells. Based on a diffusion model defined in the literature, these effects have been investigated by using MATLAB. This model is mainly characterized by the diffusion of electrons in the semiconductor porous film (TiO2). As a result, the increase of temperature has no effect on the density of the photocurrent. Moreover, when the thickness increases, the current density increases but after a certain value (15 µm) it decreases. The increase of the thickness results to a decrease in power and fill factor (FF), due to the internal resistance of the cell. In addition, the power conversion efficiency (PCE) is proportional to the temperature, as well as the thickness, except that the PCE starts to decrease from a certain value of the thickness (d = 5 µm). The simulation shows that the optimal electrode thickness is 5 µm.

Spinel magnesium Cobaltite (MgCo2O4) nanoparticles with a crystalline size in the range of ∼16 nm were prepared by a simple co-precipitation technique with NaOH as a precipitant. The formation of spinel MgCo2O4 phase was confirmed by X-ray diffraction (XRD) pattern. Scanning electron microscope (SEM) images showed that aggregated nanoplates. The electrochemical performance of modified MgCo2O4 electrodes was investigated with 2M of tetrabutylammonium perchlorate (TBA) electrolyte. The cyclic voltammetry (CV) results revealed that the MgCo2O4 electrode reached the highest specific capacitance of 390 °F/g at a scan rate of 5mV/s. The excellent electrochemical performance was absorbed due to the electrochemical faradaic redox reactions related to the intercalation/de-intercalation of the tetrabutylammonium cation (TBA+) and MgCo2O4 lattice, and brings an additional pseudocapacitive contribution. The present work proves that the prepared magnesium cobaltite can serve as advanced electrode material for next generation organic electrolyte supercapacitors.

An electrochemical sensor was fabricated by strontium ferrite (SrFe) nanostructure modified carbon paste electrode (SrFeME). This electrode showed good catalytic effect on oxidation of amino acid tyrosine (Tyr) in voltammetric studies. It can improve the anodic peak current of Tyr significantly and also decrease the oxidation overpotential of this amino acid. The peak current increased by two times and the overpotential is decreased more than 110 mV. The enhancing of oxidation signal of Tyr at modified electrode is related to the improving the electron transfer rate at these nanoparticles and increasing the active surface area of the modified electrode by the nanoparticles. This electrode was used as an electrochemical sensor for the measurement of Tyr by differential pulse voltammetry. The anodic peak current was linearly related to Tyr concentration in the range from 0.8 μM to 300.0 μM and the detection limit was calculated as 0.15 μM (S/N = 3). The presence of ascorbic acid, dopamine, glucose and a number of ions could not affect the Tyr measurement. Finally, the proposed sensor was successfully used for measurement of Tyr in real samples.

Ketotifen (KET)–selective electrode of both conventional polymer membrane and coated graphite types, based on incorporation of ketotifen–tetraphenyl borate (KETTPB) ion-pair have been constructed. The influences of membrane composition, temperature, pH of the test solution, ionic strength and foreign ions on the electrode performance were investigated. The electrode showed a Nernstian concentration range 1.0×10-5 to 1.0×10-2 M and 5.0×10-6 to1.0×10-2 M with a slope of 57.5±1.07 and 59.0±0.9 mV per decade and lower limit of determination are 1.0×10-5 M and 5.0×10-6 M for conventional and coated graphite types, respectively. The electrodes display a good selectivity for ketotifen with respect to a number of common foreign inorganic and organic species. The response not affected by pH between 2.0 and 4.9. The electrode was successfully used for determination of ketotifen both in pure solution and in pharmaceutical preparation. The solubility product of the ion-pair and also the formation constant of the precipitation reaction leading to the ion-pair formation were determined conductometrically.