Electrolyte Solution Research Articles

Synthesis of Cu doped Ba(OH)2 thin film by SILAR method for supercapacitor electrode application

Abstract An economically suitable successive ionic layer adsorption and reaction (SILAR) method has been used to deposit 0.25, 0.50 and 0.75 wt% copper doped barium hydroxide on stainless steel (SS) substrate. X-ray diffraction analysis shows the orthorhombic crystal structure of Cu doped Ba(OH)2 electrode. FTIR analysis reveals the chemical bonds present in the sample. The energy-dispersive x-ray spectroscopy (EDAX) and x-ray photo electron spectroscopy (XPS) measurements have been performed to confirm Cu doping into Ba(OH)2. The electrochemical properties of Cu doped Ba(OH)2 electrode have been analysed by cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) techniques. The 0.50 wt% Cu doped barium hydroxide electrode exhibits the highest specific capacitance (Csp) of 356.12 F g−1 (59.55 mF cm−2) at 1 mV s−1 scan rate in 1 M Na2SO4 electrolyte solution. This electrode also shows ~ 85% capacitance retention up to 8000 cycles. A symmetric device has also been fabricated by using two electrodes. This device shows energy and power densities of 1.13 Wh Kg-1 and 279.7 W Kg-1 respectively. This cyclic retention and capacitive behaviour of Cu-doped Ba(OH)2 shows its utility as an energy storage material in the near future.

Electrostatic Aspect of the Proton Reactivity in Concentrated Electrolyte Solutions.

Water-in-salt electrolytes with a surprisingly large electrochemical stability window of ≤3 V have revived interest in aqueous electrolytes for rechargeable lithium-ion batteries. However, recent reports of acidic pH measured in concentrated electrolyte solutions appear to be in contradiction with the suppressed activity of the hydrogen evolution reaction (HER). Therefore, the fundamental thermodynamics of proton reactivity in concentrated electrolyte solutions remains elusive. In this work, we have used density functional theory-based molecular dynamics (MD) simulations and the proton insertion method to investigate how the HER potential shifts in concentrated LiCl solutions under both acidic and alkaline conditions. Our results show that the intrinsic HER activity increases significantly with the salt concentration under acidic conditions but remains relatively constant under alkaline conditions. Moreover, by leverage over finite-field MD simulations, it is found that a determining factor for the HER activity is the Poisson potential of the liquid phase, which increases in concentrated electrolyte solutions with comparable values from both density functional theory and point-charge models.

An optical flow battery enabled by trap-engineered nanophosphors

Flow batteries represent a promising technology for storing electrical energy in circulating electrolyte solutions that contain redox-active chemicals. Inspired by the redox flow battery, in this paper we describe the concept and implementation of an optical flow battery, which stores photon energy in circulating nanophosphor colloids. Similar to the redox flow battery, the optical flow battery enables the conversion between photon energy and chemical energy in a rechargeable manner, facilitating distributed energy storage by decoupling energy and power. We characterized basic cell attributes and performance metrics of this prototype optical flow battery in the context of common assessment methods for conventional redox flow batteries. We envision that this optical flow battery may provide a useful tool for solar energy storage, light delivery in live animals, and light-based therapy, diagnosis, and surgery in medicine.Graphical

Interfacial properties of aqueous ionic liquids on graphene surface in supercapacitors

It is expected to improve the energy density of supercapacitors by applying ionic liquids (ILs) with wide voltage window as electrolyte and graphene high specific surface area as the electrode. Due to the hygroscopic nature of ILs, some water presenting in ILs electrolyte is found to be easy stacked near the positive electrode and effect the supercapacitors’ performance. In this work, acetonitrile (ACN) was taken to add into the ILs electrolyte to solve this problem, and the interfacial properties of aqueous ACN-ILs on charged graphene surface in supercapacitors was investigated from microscopic perspective. The effect of ACN content and charge density was also discussed. The results show that the addition of ACN not only increases the wettability of aqueous ILs on graphene surfaces, but also significantly inhibits the aggregation of water molecules on the positive electrode surface and reduces the aggregation degree of anions and cations in the electrolyte solution, particularly within hydrophilic ILs systems. In addition, cyclic voltammetry experiments confirmed that the electrochemical window of aqueous ILs was improved with addition of ACN. This study provides a significant foundation for further promoting the application of ILs as electrolyte in supercapatiors.

Electrochemical detection of amine neurotransmitters is drastically different in buffer solutions, in vivo, and cell culture systems

Detection of neurotransmitters requires high sensitivity and temporal resolution, favoring electrochemical techniques for the sensing mechanism. However, electrochemical detection of amine neurotransmitters is highly dependent on electrode surface condition and thus, results obtained in clean buffer solutions are not directly applicable to the real measurement environment in vivo or in vitro. In these more complex electrolyte solutions, the presence of antioxidants and surface-adsorbing molecules drastically alters the redox characteristics of amine neurotransmitters, their precursors and metabolites. Accordingly, we surveyed their redox characteristics in the phosphate buffered saline (PBS), cerebrospinal fluid (CSF) and cell culture medium, with high-sensitivity electrodes made of single-walled carbon nanotube network.The concentration of surface-fouling molecules was lowest in the PBS and highest in the culture medium. Accordingly, electrochemical reaction kinetics were facile in the PBS and sluggish in the culture medium. Surprisingly, analyte molecular structure had much more importance in the CSF compared to other electrolytes, however the reaction kinetics remained to be generally slower in the CSF compared to when measured in the PBS.Whereas the CSF also contains L-Ascorbic acid and uric acid that are electrochemically active interfering molecules, they are either completely absent or can be omitted in the in vitro setting. On the contrast, the culture medium contains substantially higher concentration of surface-adsorbing molecules that causes more significant fouling of electrode and thus loss of sensitivity. As the in vitro brain-on-a-chip applications are rapidly being adopted, direct comparison of these different experimental settings was essential to understand their implications for electrochemical sensors.

Facile Preparation of Composite Coatings with Incorporated 13X Zeolite and CeO2

One-step methods for the formation of efficient thin-film catalysts for wastewater treatment under the sunlight spectrum is a topic of interest for many research groups. This article reports on the facile preparation of photocatalytic coatings by plasma electrolytic oxidation processing from 0.01 M sodium tungstate electrolyte solution containing both 13 X zeolite and CeO2. Obtained coatings are characterized with respect to their surface morphology, chemical and phase composition, and possible application as photocatalysts in photodegradation of organic pollutants. All prepared coatings contain elements originating from both substrate and electrolyte solution. Addition of 1 g/L of 13X zeolite and CeO2 in various concentrations to electrolyte solution results in increased photodecomposition of model organic pollutant. The highest photodegradation under simulated sunlight is observed for coatings formed in 0.01 M sodium tungstate with addition of 1 g/L of 13 X zeolite and 1 g/L of CeO2, reaching 50% after 6 h of irradiation.

Electrostatic Interaction of Dielectric Particles in an Electrolytic Solution

On the basis of the Poisson-Boltzmann equation the electrostatic interaction between two charged dielectric spherical particles in a symmetric electrolyte solution is considered. The interaction forces between particles of the same radius under the condition of uniform charge distribution on their surfaces in the absence of an external field have been calculated by the finite element method. The dependence of the electrostatic repulsion forces between the particles on the magnitude of the particle charges and the dielectric permittivities of the particle materials and the surrounding medium has been analyzed.

Surface potentials of conductors in electrolyte solutions.

When we place conducting bodies in electrolyte solutions, their surface potential Φs appears to be much smaller in magnitude than the applied one Φ0 and normally does not obey the classical electrostatic boundary condition of a constant potential expected for conductors. In this paper, we demonstrate that an explanation of these observations can be obtained by postulating that diffuse ions condense at the "wall" due to the reduced permittivity of a solvent. For small values of Φ0, the surface potential responds linearly. On increasing Φ0 further, Φs augments nonlinearly and then saturates to a constant value. Analytical approximations for Φs derived for these three distinct modes show that it always adjusts to salt concentration, which is equivalent to a violation of the constant potential condition. The latter would be appropriate for highly dilute solutions but only if Φ0 is small. Surprisingly, when the plateau with high Φs is reached, the conductor surface switches to a constant charge density condition normally expected for insulators. Our results are directly relevant for conducting electrodes, mercury drops, colloidal metallic particles, and more.

Manipulating Aggregate Electrochemistry for High‐Performance Organic Redox Flow Batteries

Organic molecule in solutions is the energy storage unit in the organic redox flow batteries (ORFBs), of which the aggregation is acknowledged pivotal but has been rarely investigated. By establishing a pyridinium library, the manipulation over the aggregation in solutions is investigated at the molecular level. Both theoretical calculations and physiochemical methods are used to characterize the aggregate’s structure, and salient findings are as follows. First, the singly‐reduced monoradicals simultaneously aggregate in a concentrated solution, which is driven by the solvation effect, orbital overlap and dispersion interaction. Second, the aggregation can be manipulated by the molecular engineering strategy and counteracted by introducing either electrostatic repulsive force or twisted geometry. Third, the monoradical’s aggregation yields a decrease in the molecular singly occupied molecular orbital energy level and a linear scaling relationship with its thermodynamic potential. As a result, the increase in the concentration lowers the battery’s voltage, which counteracts its effort to increase the battery’s energy density. The anti‐aggregation is proven effective in breaking the scaling relationship and accordingly, a molecular strategy to manipulate aggregate electrochemistry is developed. This work provides physical insights into the electrolytic solution and chemical strategy for optimizing the flow battery.

Organic redox flow batteries in non-aqueous electrolyte solutions.

Redox flow batteries (RFBs) are gaining significant attention due to the growing demand for sustainable energy storage solutions. In contrast to conventional aqueous vanadium RFBs, which have a restricted voltage range resulting from the use of water and vanadium, the utilization of redox-active organic molecules (ROMs) as active materials broadens the range of applicable liquid media to include non-aqueous electrolyte solutions. The extended voltage range of non-aqueous media, exceeding 2 V, facilitates the establishment of high-energy storage systems. Additionally, considering the higher cost of non-aqueous solvents compared to water, the objective in developing non-aqueous electrolyte solution-based organic RFBs (NRFBs) is to efficiently install these systems in a compact manner and explore unique applications distinct from those associated with aqueous RFBs, which are typically deployed for grid-scale energy storage systems. This review presents recent research progress in ROMs, electrolytes, and membranes in NRFBs. Furthermore, we address the prevailing challenges that require revolution, encompassing a narrow cell voltage range, insufficient solubility, chemical instability, and the crossover of ROMs. Through this exploration, the review contributes to the understanding of the current landscape and potential advancements in NRFB technology and encourages researchers and professionals in the energy field to explore this emerging technology as a potential solution to global environmental challenges.

The process of electrolyte-plasma cathode exfoliation of graphite

We discussed the development of cathodic electrochemical exfoliation of graphite, accompanied by a plasma discharge with a voltage of 200V DC, in an aqueous solution of various electrolytes. The method of cathodic electrochemical exfoliation of graphite has established itself as a promising eco-friendly industrial method for producing nanographite with subsequent grinding by ultrasound into low-layer graphene (FLG). Cathodic exfoliation allows selective doping of nanographite oxygen atoms.

Effect of Melamine on the Oxygen Reduction Reaction in the n(111)-(111) Series of Pt3Co

Abstract Enhancement of the oxygen reduction reaction (ORR) activity is an important subject for the development of fuel cells. In this study, we prepared the n(111)-(111) series of Pt3Co single crystal electrodes using an induction heating furnace and investigated the ORR in 0.1 M HClO4 using the rotation disk electrode (RDE). The specific activity of the ORR (j k) increased monotonously with increasing terrace width n on the n(111)-(111) series of Pt3Co, showing the highest activity on Pt3Co(111). The value of j k of Pt3Co(111) was 59-fold higher than that of Pt(111) at 0.95 V(RHE). This trend was different from those of the same series of Pt, Pt3Co, and Pt3Ni reported previously. Furthermore, the ORR activity was improved on all electrodes by adding melamine to the electrolytic solution. Melamine was preferentially adsorbed at the terrace edge. Pt3Co(553) n = 5 showed the highest activity. The values of j k at 0.95 V(RHE) were 23- and 3.3-fold higher than those of Pt(553) n = 5 and Pt3Co(553) n = 5 without melamine modification, respectively. The durability of Pt3Co(553) n = 5 with melamine was improved 8.0-fold. Graphical Abstract

A Powtoon Animation Video Development Utilizing a Scientific Approach for Teaching Electrolyte and Non-electrolyte Solutions

Students often experience difficulty learning chemistry because the concepts are abstract and complex and require deep understanding. Therefore, innovation in learning is needed. Educational media is crucial for fostering this innovation. This research aims to develop educational materials on Powtoon animation that utilize a scientific approach to instruct on electrolyte and non-electrolyte solutions and evaluate their efficacy. The method applied was ADDIE model covering five steps, i.e. Analysis, Design, Development, Implementation, and Evaluation. The study involved three peer reviewers, experts in media and materials, five high school chemistry teachers, and thirteen students. Data were collected through questionnaires that were analyzed qualitatively and quantitatively with validated instruments. The result is an interactive learning video in HD mp4 format covering electrolyte and non-electrolyte solutions. The product obtained a score of 82.5% and 95% by material and media experts, respectively, and was categorized as valid. Assessments by teachers and students show scores of 82,5% and 94.4% in a very good category. This Powtoon animation video serves as an alternative and potential medium for teaching chemistry on this topic in the classroom.

Electrochemical Corrosion Resistance of Al2O3–YSZ Coatings on Steel Substrates

Ceramic materials as coatings are known to have very good corrosion resistance properties compared to metallic or organic coatings, regardless of environmental conditions. The following samples were used for the experiments: an initial steel substrate and Al2O3 + YSZ (12.5%; 25% and 37.5% wt) atmospheric plasma spray-coated samples. The open circuit potential showed similar average values for all samples coated with ceramic layers, which were slightly higher than the potential of the original uncoated sample. The corrosion current densities (icorr) of all plasma jet sputter-coated systems were very similar and significantly lower than those of the original material. Corrosion rates were much lower in the coated systems due to the chemical inertness of the ceramic coatings, particularly alumina- and zirconia-based coatings. It was observed that ceramic layers improve the corrosion resistance of the metallic material, especially at higher percentages of YSZ in the plasma spray-deposited complex layer. The porosity of the sputter-deposited layers reduced their corrosion resistance due to the contact between the electrolyte solution and the metal substrate created by the interconnection of the pores. The complex equivalent electrical circuit chosen for the analysis of the values led to results in accordance with the experimental parameters.

Revolutionizing copper pipe durability: Shielding against corrosion with graphene oxide through electrophoretic application

This research endeavors to utilize electrophoretic deposition (EPD) to coat copper (Cu) pipes with graphene oxide (GO) nanosheets, aiming to bolster their resistance against corrosion. To achieve this, a stable aqueous colloidal suspension of GO was meticulously prepared via liquid exfoliation in deionized water. This suspension served as an electrolytic solution for EPD. The EPD process involved the meticulous application of varied operational parameters such as deposition time, applied voltage, and GO nanosheet concentration to facilitate anodic deposition on the copper pipe’s surface. To gauge the efficacy of the GO coating, evaluations were conducted to assess adhesive force and stabilization using specialized coating adhesion scratch testing equipment. Further analysis of the resulting film on the Cu pipe was executed employing X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). These methods provided detailed insights into the characteristics and properties of the GO material post-deposition. The study yielded noteworthy outcomes, revealing the achievement of a uniform, unbroken, and consistent coating film on the Cu pipe. This was accomplished by employing specific parameters as 60 s of deposition time, a GO concentration of 0.5 mg/mL, and a voltage of 20 V. Impressively, when subjected to a corrosive solution containing 3.5% sodium chloride, the corrosion protection exhibited a remarkable twofold enhancement compared to untreated copper tubing, boasting an efficiency (η) of 90.48%. These findings suggest that the Cu pipe, coated with GO using the EPD technique, holds significant promise for utilization in demanding industrial settings susceptible to corrosion challenges.

Facile synthesis of CuCo2O4@CdS nanoheterostructure for asymmetric supercapacitor

The abundant active sites, high theoretical capacitance, and cost-effective synthesis of transition metal oxides@sulfides (TMOs@TMSs) have made them a highly desirable choice as active electrode materials for supercapacitors. This study demonstrated the successful fabrication of a CuCo2O4@CdS nanoheterostructure electrode using a simple and economical co-precipitation method The morphology, physicochemical properties, and electrochemical behavior of this electrode were subsequently studied. The synthesized CuCo2O4@CdS nanoheterostructure was characterized using Infrared Fourier-transform spectroscopy, X-ray diffraction, Raman spectroscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, High-resolution transmission electron microscopy, N2 adsorption/desorption isotherms and atomic force microscopy. The electrochemical performance was studied using cyclic voltammetry, impedance spectroscopy, and galvanostatic charge-discharge (GCD) measurements with a 6 Molar KOH aqueous electrolytic solution. Results from powder X-ray diffraction pattern and energy dispersive X-ray revealed the formation of CuCo2O4@CdS nanoheterostructure. Furthermore, SEM images showed the formation of more spherical structures in nanoheterostructure. The results of optical measurements of thin films were analyzed, which showed an increase in the energy gap (Eg) of CuCo2O4 nanoparticles when combined with cadmium sulfide (CdS). Additionally, the intensity of photoluminescence of the CuCo2O4@CdS nanoheterostructure was lower compared to the pure nanoparticles. Moreover, the newly synthesized CuCo2O4@CdS nanoheterostructure showed a specific capacitance of 257.5 F g−1 at a current density of 0.5 A g−1 via a three-electrode galvanostatic charge-discharge system, respectively. In the asymmetric device, the supercapacitor yielded an optimum energy density and power density of 19.6 Wh kg−1 and 700 W kg−1 at 1 A g−1 current density, respectively. Although the capacitance retention was maintained at nearly 85.2 % after 4000 cycles at a current density of 3 A g−1.

Experimental confirmation of the bactericidal action of the domestic antiseptic “Anolit” in surgical practice

Background. Antimicrobial resistance is one of the most serious threats to modern clinical medicine. Despite the significant successes of modern pharmacology, the search for effective antiseptics that can influence wound processes continues. In our study, an experimental study of the effect of Anolit solution on pathogenic microorganisms Pseudomonas aeruginosa and Proteus mirabilis was conducted.The aim. To evaluate the antimicrobial activity of the domestic antiseptic “Anolit” against gram-negative pathogens of nosocomial infections using the example of P. aeruginosa and P. mirabilis.Methods. To assess the quality of the effect of “Anolit” on the studied colonies of microorganisms, experimental studies were performed in vitro. The bacteriological study was carried out in three stages using the Koch method.Results. “Anolit” is a modern antiseptic agent with a pronounced antimicrobial effect based on the electrolysis of aqueous solutions. Its ability to lyse pathogenic microorganisms (P. aeruginosa and P. mirabilis) has been confirmed by experimental research.Conclusion. The bactericidal effect of “Anolit” on the growth of gram-negative bacteria is shown, proving its high antimicrobial efficacy.

An Acid-Resistant Lanthanide Metal-Organic Framework Based on Tetraphenylethylene as an Electrochemical Nitrite Sensor.

Nitrite (NO2-) is attracting increasing attention due to its harmful effect on human health. Thus, it is highly desirable to construct effective electrochemical sensors to detect the presence of NO2-. The majority of electrochemical NO2- detection is focused on alkaline or neutral electrolyte solutions and is rarely reported under acidic conditions. In this work, a tetraphenylethylene (TPE)-based 2D lanthanide metal-organic framework (Ln-MOF), (Me2NH2)[HoIII(tcbpe-F)DMF]•DMF•H2O (1) (tcbpe-F = 4',4‴,4″‴,4″″‴-(ethene-1,1,2,2-tetrayl)tetrakis(3-fluoro-[1,1'-biphenyl]-4-carboxylic acid, DMF = N,N-dimethylformamide)), has been successfully fabricated on carbon paper (CP) by an in situ hydrothermal method. As a NO2- sensor, the fabricated 1 electrode exhibited excellent electrochemical performance in the H2SO4 electrolyte (pH = 1) and offers high sensitivities of 1453.2 and 591.5 μA mM-1 cm-2, with a wide linear detection range of 0.1 μM to 9 M, a low detection limit of 60 nM, excellent specificity even in the presence of various analytes (metal ions, anions, and organic molecules) and real water samples, satisfactory stability, and reproducibility. This is the first report of TPE-based Ln-MOF as a NO2- sensor, and furthermore, a plausible sensing mechanism is confirmed by experiments and theoretical computations.

Correlating Ionic Conductivity to Structure and Dynamics of Li-Ion Battery Electrolyte Systems: Raman Spectroscopy, Dielectric Relaxation Measurements, and Streak Camera Solvation Data Analysis.

A correlation between ionic conductivity and electrolyte solution structure and dynamics was explored by performing electrolyte concentration- and temperature-dependent measurements of conductivity, viscosity, and dielectric relaxation (DR) in solutions of lithium bis(trifluoromethane)sulfonimide (LiTFSI) in triethylene glycol dimethyl ether (also known as triglyme, G3). In addition, an electrolyte concentration-dependent Raman spectroscopic study and ultrafast dynamic fluorescence Stokes shift measurements of solvation of a dissolved solute by employing a streak camera detection technique were carried out. Measured conductivities (σ) and the average DR times (⟨τDR⟩) were found to be partially decoupled from the solution viscosities (η) and obeyed the relation, σ or ⟨τDR⟩-1 ∝(η/T)-p, with p = 0.6-0.75 for σ and p = 0.2-0.45 for ⟨τDR⟩-1. Raman data indicated the formation of ion pairs and ionic aggregates in these solutions, while the measured glass transition temperature increased with LiTFSI concentration. Conductivities (σ) showed a nonlinear concentration dependence but increased linearly with the solution static dielectric constants (εs). The latter may be explained by considering the temperature effects on complex electrolyte species and the subsequent solution dielectric behavior. Interestingly, an inverse power-law dependence of σ on the measured DR or solvation time scales, σ ∝ (τx)-m, with m = 1.2-1.9, was observed. This dependence may be explained by considering that the same environmental friction regulates both the ion diffusion and the medium polarization relaxation. The control of a slow process (ion translation) by relatively faster medium dynamics (dipolar rotation), although quite fascinating for the present system, warrants further experimental scrutiny for other electrolyte systems relevant to battery applications.

Investigation of oxidation-reduction processes of nickel hydroxide precipitation and their carbothermical reduction.

Most of the known methods for the chemical production of nickel nano- and microparticles, nickel oxides and hydroxides use various reducing agents and solvents, which are often toxic to the environment. As a rule, these methods are energy-consuming, lengthy and multi-stage, requiring complex equipment. Therefore, the development of a simple and "green" process for the synthesis of nickel-containing particles, including those with magnetic properties, remains one of the priority tasks. In this paper, a new physicochemical method for oxidation-reduction contact deposition of nickel(II) hydroxide nano-microparticles on the surface of magnesium particles from aqueous solutions of nickel-containing electrolyte is proposed. This method is based on the local corrosion of microgalvanic cells' formation with predominant hydrogen depolarization. The proposed method was used to obtain nickel(II) hydroxide samples and study their morphology using SEM, as well as their phase composition using XRD analysis. It has been proven that the shape and structure of the resulting Ni(OH)2 particles depend on the contact deposition conditions: depending on the surface state of the magnesium particles as a reducing agent, it is possible to obtain both plate-shaped α/β-Ni(OH)2 particles and three-dimensional β-Ni(OH)2 "flowers" with different degrees of crystallinity.