Analytical & Bioanalytical Electrochemistry
Volume:14 Issue: 7, Jul 2022

A peculiar feature of catalytic wave (or catalytic peak), appearing in voltammograms of a surface regenerative electrode mechanism (surface EC’ mechanism), in which an irreversible reduction of substrate “Y” to its final form “Z” is mediated by an adsorbed redox couple Ox/Red, is studied theoretically under conditions of square-wave voltammetry. This phenomenon, also known under the term ‘split-wave’ in cyclic voltammetry, appears when the rate of electron transfer step at the electrode surface is fast and comparable to the rate of chemical regenerative reaction. The effect of the kinetics of chemical regenerative step to the features of simulated square-wave voltammograms is studied for systems featuring quasi reversible and fast electron transfer steps. We present a relevant set of theoretical data, while we focus on conditions under which the two peaks in square-wave voltammetry can be resolved. An experimental observation of this phenomenon, which occurs in a very limited kinetic region, provides a basis to propose a simple methodology for assessing the rate constant of catalytic reaction.

n this work, the gem-dichlorocyclopropane allylcarveols Carb_8-Carb_10 namely: 1-allyl-5-(2,2-dichloro-1-methylcyclopropyl-2-methylcyclohex-2-en-1-ol, 1-(but-3-en-2-yl)-5- (2,2-dichloro-1-methylcyclopropyl)-2-methylcyclohex-2-en-1-ol and 5-(2,2dichloro-1-methyl cyclopropyl)-1-((2,2-dichloro-1-methylcyclopropyl)methyl)-2 methylcyclohex-2-en-1-ol were synthesized from R-(-)-Carvone (the major constituent of spearmint oil) derivatives. In this synthesis, we used the technique of liquid-liquid phase transfer catalysis. These compounds were evaluated as corrosion inhibitors of steel in 1 M HCl by gravimetric methods. The acquired results prove that the inhibitory efficiency increases with concentration. The temperature effect on the corrosion behavior of steel in 1 M HCl in the presence and absence of inhibitors at 1×10-2 mol/l was studied in the temperature range of 313–343 K, the activation parameters of the corrosion reaction were calculated using the Arrhenius equation, and the transition state equation. The adsorption of this compound on Mild Steel surface obeys Freundlich’s adsorption isotherm. In the theoretical computations, we used the Density Functional Theory (DFT) and Monte Carlo simulations to find the best spatial configuration of inhibitors on the steel surface.

This study improved three potentiometric sensors for measuring the drug trazodone hydrochloride. The constructive sensors were designed for the preparation of electro-active plasticized membranes representative of ion-association complexes. Trazodone cation and phosphomolybdate acid anions used a plasticized poly(vinyl chloride) membrane sensor acting as an electro-active material in a plasticized polyvinyl chloride electrode. The sensors showed agreement at near-Nernstian responses for trazodone hydrochloride-phosphotungstic acid-di-butyl phthalate and trazodone hydrochloride-phosphotungstic acid-o-Nitro phenyl octyl ether with lower detection limits of approximately 2.8×10-6 mol.L-1 and 1.1×10-6 mol.L-1, while the slopes were found to be around 55.00 and 51.70 mV/concentration decade. The pH ranges were approximately 2.0-7.5, 2.5-8.0, and 3.0-8.0 for trazodone hydrochloride-phosphotungstic acid-di-butyl phthalate, trazodone hydrochloride-phosphotungstic acid-o-Nitro phenyl octyl ether and trazodone hydrochloride-phosphotungstic acid-di-butyl phthalate, respectively. The sensor hydrochloride-phosphotungstic acid-di-butyl phthalate showed small values of the slope near the 31.20 mV/concentration decade, while the detection limit was around 5.0×10-6 mol.L-1. The three sensors indicated a high selectivity for the TRZ drug over several inorganic cations for different drug formulation samples. The dissolution profiles showed good relationships when plotted for use in the proposed sensor at optimum electrode conditions. The investigated sensors can be applied for the direct determination of TRZ in some pharmaceutical preparations, and can be used for the investigation of many TRZ tablets.

The research and progress in electrochemical nitrite sensing are continuously increasing and have a great choice of interest by researchers and scientists. Therefore, understanding the topics of interest and expanding the network of collaborations are necessary to advance the research development towards integrated and beneficial efforts. This bibliometric study aims to use the VOSviewer to evaluate the global research trends in the fields of electrochemical nitrite sensing area based on the publication of the journal name, keyword co-occurrences, co-authorship, and country. A total of 387 journal articles published between 2000 to 2021 were analyzed using the Scopus database. Since 2000, the data shows that the studies released tend to increase year by year. The most productive countries are China, India, and United States. In conclusion, water pollution, pollution detection, ligands, layered semiconductors, heavy metals, and carbon black have the potential to be a hotspot for future research in this field.

The Li-Ti-O-coated LiNi0.5Co0.2Mn0.3O2 (LTO@NCM) cathode materials are synthesized via an in situ co-precipitation method followed by the lithiation process and thermal annealing. The Li-Ti-O coating layer is designed to strongly adhere to the core-material with diffusion pathways for Li+ ions. Measurements and analysis of structure, morphology and electrochemical properties have been applied. X-ray diffraction patterns showed the existence and conversion of lithium titanium oxide (Li-Ti-O labeled as LTO). Electrochemical tests suggest that compared with pristine NCM, The LTO layer works both as an excellent Li ion conductive layer and as a protective coating layer against the attack of HF in the electrolyte, and remarkably improves the cycling performance at higher charged state and rate capability of the LTO@NCM composite material. 3.0 wt.% LTO-coated NCM (LTO3) material exhibited higher capacity retentions of 94.8% than that of the bare one (58.2%) and nickel-riched cathodes (90-91%) after 100 cycles at cut-off charge voltages of 4.3V at 1C rate.

Epithelial sodium channel (ENaC) proteins are proportional to sodium intake and clinically associated with hypertension. The selectivity of aptamer-based electrochemical biosensor for ENaC detection has been developed in this study, and the stability of the cerium oxide modified electrode was reported. The concentration of ENaC was measured using differential pulse voltammetry of [Fe(CN)6]4−/3- redox system. The aptasensor based on the bioconjugate of ENaC aptamer with gold nanoparticle (AuNP) using streptavidin-biotin linker, and immobilized on the screen-printed electrode-CeO2. The ENaC aptamer selectivity was tested for other proteins that might be present in the urine sample, and the stability of the modified SPCE was studied throughout storage of SPCE-CeO2-aptamer. The limit of detection of ENaC protein with this aptasensor was obtained of 0.110 ng mL-1, in the linear range of concentrations 0.05–3.0 ng mL-1. The percentage of selectivity of the aptamer to ENaC compared to creatinine and potassium channel proteins was 79.08%. The cerium oxide modified SPCE/aptamer bioconjugate is stable up to one year of storage. The developed aptasensor is simple and can be miniaturized to determine the ENaC concentration in urine for the realization of a point-of-care device for the early detection of hypertension.