Chronocoulometry Measurements Research Articles

Magneto-electrochemical method for chiral recognition of amino acid enantiomers.

Chiral recognition of enantiomers with identical mirror-symmetric molecular structures is important for the analysis of biomolecules, and it conventionally relies on stereoselective interactions in chiral chemical environments. Here, we develop a magneto-electrochemical method for the enhanced detection of chiral amino acids (AAs), that combines the advantages of the high sensitivity of electrochemiluminescent (ECL) biosensors and chirality-induced effects under a magnetic field. The ECL difference between L- and D-enantiomers can be amplified over 35-fold under a field of 3.5 kG, and the chiral discrimination can be achieved in dilute AA solutions down to the nM level. The field-dependent ECL and chronocoulometry measurements suggest that chiral AAs can lock the spins on their radicals and thus enlarge the ECL change under applied magnetic fields (magneto-ECL, MECL), which explains the field-enhanced chiral discrimination of AA enantiomers. Finally, a detailed protocol is demonstrated for the identification of unknown AA solutions, in which the species, chirality and concentration of AAs can be determined simultaneously from the 2D plots of the ECL and MECL results. This work benefits the development of field-assisted detection methods and represents a promising and universal strategy for the comprehensive analysis of chiral biomolecules.

Ferrimicrobium acidiphilum Exchanges Electrons With a Platinum Electrode via a Cytochrome With Reduced Absorbance Maxima at 448 and 605 nm.

Ferrimicrobium acidiphilum is a Gram-positive member of the Actinobacteria phylum that can respire aerobically or anaerobically with soluble Fe(II) or Fe(III), respectively, in sulfuric acid at pH 1.5. Cyclic voltammetry measurements using intact F. acidiphilum at pH 1.5 produced fully reversible voltammograms that were highly reproducible. The maximum current observed with the anodic peak was considerably less than was the maximum current observed with the cathodic peak. This difference was attributed to the competition between the platinum electrode and the soluble oxygen for the available electrons that were introduced by the cathodic wave into this facultative aerobic organism. The standard reduction potential of the intact organism was determined to be 786 mV vs. the standard hydrogen electrode, slightly more positive than that of 735 mV that was determined for soluble iron at pH 1.5 using the same apparatus. Chronocoulometry measurements conducted at different cell densities revealed that the intact organism remained in close proximity to the working electrode during the measurement, whereas soluble ionic iron did not. When the cyclic voltammetry of intact F. acidiphilum was monitored using an integrating cavity absorption meter, the only small changes in absorbance that were detected were consistent with the participation of a cellular cytochrome with reduced absorbance peaks at 448 and 605 nm. The cytochrome that participated in the exchange of electrons between the intact organism and extracellular solid electrodes like platinum was the same cytochrome whose oxidation was previously shown to be rate-limiting when the organism respired aerobically on extracellular soluble iron.

Fabrication of WO3 electrochromic devices using electro-exploding wire techniques and spray coating

Electrochromic devices (ECDs) play an important role in smart window applications for blocking heat from sunlight. Tungsten trioxide (WO3) is one of the best candidates for making electrochromic films. Current manufacturing processes are, however, costly, have long processing time, and often use non-eco-friendly precursors. Here an alternative facile method integrating electro-exploding wire and spray coating techniques is demonstrated for applications in large size ECDs. The electro-exploding wire technique is used to synthesize WO3 nanomaterials (NMs) in deionized water. The varied size distribution of WO3 NMs is achieved by changing the exploding voltage. The NMs are characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The exploding voltage of 36 V is selected to generate WO3 NMs in a wide size distribution for making porous WO3 films. Subsequently, spray coating is used to disperse WO3 NM suspension on the ITO/glass substrate to form an electrochromic film. The films are characterized by scanning electron microscopy (SEM) and by cycle voltammetry, chronoamperometry, and chronocoulometry measurements in dilute sulfuric acid. The WO3 NM films prepared at a high exploding voltage and a high substrate temperature present a higher electrochemical stability. Considering porosity and electrochemical stability, WO3 NMs exploded at 36 V are used to prepare WO3 films on substrates heated at 300 °C. The electrochromic WO3 film can be operated for over 1000 cycles. We demonstrate an ECD with an area of 15 × 15 cm2 and propose a way to make large size ECDs with low cost and eco-friendly processes.

Electrochemical behavior of N-Nitrosodiphenylamine and its determination in synthetic urine samples using a graphite-polyurethane composite electrode

In this paper, the electrochemical determination of the N-nitrosodiphenylamine was proposed comparing the voltammetric response of two non-modified carbon electrodes: a glassy carbon (GCE) and a solid graphite-polyurethane composite (GPUE). The surfaces of the electrodes were characterized by atomic force microscopy. The electroactive areas of GCE and GPUE were 0.040 and 0.068 cm2, respectively, calculated from chronocoulometry measurements using K4Fe(CN)6 as probe and the integrated form of Cottrell Equation. Cyclic voltammograms obtained for N-nitrosodiphenylamine using both electrodes indicated anodic and cathodic peaks (vs. Ag/AgCl (3.0 mol L−1 KCl), in agreement with the literature. At GCE, the electrochemical reduction of the molecule is a diffusion-controlled process, whereas at GPUE some degree of adsorption was also observed. Square wave and differential pulse voltammetry were explored in order to optimize the best analytical performance for the quantification of the molecule. Under optimal conditions, linear range (sensitivity and limit of detection) for GCE and GPUE of 8.02 to 46.6 μmol L−1 (1.09 μA L μmol−1 cm−2 and 4.54 μmol L−1) and of 2.51 to 17.5 μmol L−1 (5.50 μA L μmol−1 cm−2 and 0.270 μmol L−1) were obtained, respectively. Considering higher sensitivity and lower detection limits values, the GPUE was selected for the quantification of N-nitrosodiphenylamine in synthetic urine samples. The developed method presented a competitive detection limit compared to other sensors reported in the literature, considering the use of a non-modified electrode, with low cost of fabrication, easiness of surface renovation, and sustainability.

The electrochemical phase behaviour of chemically asymmetric lipid bilayers supported at Au(111) electrodes

Chemically asymmetric phospholipid bilayers supported on Au(111) surfaces have been studied with differential capacitance and chronocoulometry measurements. The bilayers were prepared using Langmuir-Blodgett deposition, followed by Langmuir-Schaeffer deposition using a different molecule. Combinations of three phospholipids with common hydrocarbon tail groups were compared: dimyristoyl phosphatidyl choline (DMPC), dimyristoyl phosphatidyl ethanolamine (DMPE) and dimyristoyl phosphatidyl serine (DMPS). DMPC and DMPE are zwitterionic and DMPS is anionic in the electrolyte used. The asymmetric bilayers containing DMPS gave distinct electrochemical responses depending on whether the DMPS was deposited first, onto Au, or second, onto another lipid, indicating that asymmetry was maintained over the timescale of the experiment. The results for DMPE and DMPC combinations suggest similar headgroup conformations in the two bilayers. The relationship between the location of the charged molecule and the electrochemical properties is complex but in all cases, DMPS tends to raise bilayer capacitance and DMPE tends to lower capacitance. These observations can be explained by the relatively higher solvation of the charged DMPS molecules and tight packing of DMPE molecules, which leads to exclusion of solvent from the bilayer.

Influence of the Nb2O5 doping on the electrochemical properties of V2O5 thin films

Aiming to improve electrochromic properties of vanadium pentoxide (V2O5) new niobium-doped vanadium pentoxide (V2O5:Nb2O5) thin films were obtained by combining sol–gel method with dip-coating technique. The sols were synthesized by reacting vanadium (V) oxytripropoxide and niobium ethoxide (V) with 2, 5, and 10mol% of Nb sol concentrations as precursors. The films were deposited on a FTO conducting glass substrates and heat treated at 300°C. Cyclic voltammetry characterization of V2O5 and V2O5:Nb2O5 films revealed two cathodic and two anodic peaks that fused in one with increase of scan rate up to 50mV/s. Chronoamperometry showed that the doped samples are more stable than undoped ones. Chronocoulometry measurements proved that the best values of charge density of about 80 mC/cm2 was obtained for the film doped with 5mol% of Nb sol. UV–Vis spectroscopy confirmed 47% transmittance difference at 633nm between colored and bleached states of doped sample, which was 6% more than for undoped one. The characterization of the Nb intercalated V2O5 deposits was done combining energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), proving a possibility of synthesis of structured niobium intercalated vanadium oxides. Moreover, scanning electron microscopy (SEM) morphology and atomic force microscopy (AFM) topography analyses evidenced uniform and smooth surface of the films with more granules on the surface of the doped sample and the RMS values of 9.66 and 3.45nm for V2O5:Nb2O5 and V2O5 film, respectively. V2O5:Nb2O5 electrochromic films have shown improved electrochemical stability and transmittance difference between colored and bleached values, when compared to pure vanadia films.

Anodic Behavior of the Aluminum Current Collector in Imide-Based Electrolytes: Influence of Solvent, Operating Temperature, and Native Oxide-Layer Thickness.

The inability of imide salts to form a sufficiently effective passivation layer on aluminum current collectors is one of the main obstacles that limit their broad application in electrochemical energy-storage systems. However, under certain circumstances, the use of electrolytes with imide electrolyte salts in combination with the aluminum current collector is possible. In this contribution, the stability of the aluminum current collector in electrolytes containing either lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) or lithium fluorosulfonyl-(trifluoromethanesulfonyl) imide (LiFTFSI) as conductive salt was investigated by electrochemical techniques, that is, cyclic voltammetry (CV) and chronocoulometry (CC) in either room-temperature ionic liquids or in ethyl methyl sulfone. In particular, the influence of the solvent, operating temperature, and thickness of the native oxide layer of aluminum on the pit formation at the aluminum current collector surface was studied by means of scanning electron microscopy. In general, a more pronounced aluminum dissolution and pit formation was found at elevated temperatures as well as in solvents with a high dielectric constant. An enhanced thickness of the native aluminum oxide layer increases the oxidative stability versus dissolution. Furthermore, we found a different reaction rate depending on dwell time at the upper cut-off potential for aluminum dissolution in TFSI- and FTFSI-based electrolytes during the CC measurements; the use of LiFTFSI facilitated the dissolution of aluminum compared to LiTFSI. Overall, the mechanism of anodic aluminum dissolution is based on: i) the attack of the Al2 O3 surface by acidic species and ii) the dissolution of bare aluminum into the electrolyte, which, in turn, is influenced by the electrolyte's dielectric constant.

Suppression of Aluminum Current Collector Dissolution by Protective Ceramic Coatings for Better High-Voltage Battery Performance.

Batteries based on cathode materials that operate at high cathode potentials, such as LiNi0.5 Mn1.5 O4 (LNMO), in lithium-ion batteries or graphitic carbons in dual-ion batteries suffer from anodic dissolution of the aluminum (Al) current collector in organic solvent-based electrolytes based on imide salts, such as lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). In this work, we developed a protective surface modification for the Al current collector by applying ceramic coatings of chromium nitride (Crx N) and studied the anodic Al dissolution behavior. By magnetron sputter deposition, two different coating types, which differ in their composition according to the CrN and Cr2 N phases, were prepared and characterized by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and their electronic conductivity. Furthermore, the anodic dissolution behavior was studied by cyclic voltammetry and chronocoulometry measurements in two different electrolyte mixtures, that is, LiTFSI in ethyl methyl sulfone and LiTFSI in ethylene carbonate/dimethyl carbonate 1:1 (by weight). These measurements showed a remarkably reduced current density or cumulative charge during the charge process, indicating an improved anodic stability of the protected Al current collector. The coating surfaces after electrochemical treatment were characterized by means of SEM and XPS, and the presence or lack of pit formation, as well as electrolyte degradation products could be well correlated to the electrochemical results.

Electroanalytical Investigation of 2,2′,7,7′‐Tetrakis(diphenylamino)‐9,9′‐spirobifluorene

Two voltammetric techniques, cyclic voltammetry (CV) and chronocoulometry (CC), were used to investigate the redox characteristics of an organic semiconductor, 2,2′,7,7′‐tetrakis(diphenylamino)‐9,9′‐spirobifluorene (spiro‐TAD). The electron‐transfer characteristics of spiro‐TAD, including the formal oxidation potentials (E o′), diffusion coefficients (D o), and electron‐transfer rate constants (k o′), were estimated by a combination of CV and CC measurements. The energy of the highest‐occupied molecular‐orbital could also be found from the quantitative relationship between the oxidation potential and the ionization energy.

Size-fitting effect for hybridization of DNA/mercaptohexanol mixed monolayers on gold.

In this article we proposed a simple hexagonal model for exploring the hybridization of thiol-modified probe DNA self-assembled monolayers (SAMs) on gold with target DNA molecules in solution. The size-fitting coefficient d(c)/d(t) from the model was used to discuss the principle for DNA optimal hybridization, where d(c) was the channel diameter among three adjacent probe DNA molecules on gold and dt was the gyration diameter of the target DNA molecules in solution. Experimentally we investigated the hybridization effect (hybridization efficiency H(E) and hybridization density H(D)) of thiol-modified probe DNA (DNA base amount m = 15, 25 or 35)/mercaptohexanol (MCH) mixed SAMs on gold in 1 M electrolyte solution by chronocoulometry (CC) and electrochemical impedance spectroscopy (EIS). The surface coverage Γ(m) of the probe DNA on gold was adjusted by changing the mixed concentration ratio of probe DNA with MCH (C(DNA)/C(MCH)) in the assembly solution. Results indicated that with the increase of C(DNA)/C(MCH), H(E) decreased gradually; H(D) first increased and then decreased, which arrived at the biggest at C(DNA)/C(MCH) = 1 for all the probe DNA/MCH mixed SAMs (m = 15, 25, 35). The optimal Γ(m) for achieving the biggest H(D) in DNA hybridization decreased with the increase of m from 15 to 35. The experimental conclusions obtained by CC and EIS measurements verified each other. Combining the simple model with our experimental results, we ascertained that d(c)/d(t) decreased with the increase of m, which showed a good linear relationship. These conclusions provided an important reference and guidance for controllably constructing DNA sensors with optimal performance.

2′-Anthraquinone-Conjugated Oligonucleotide as an Electrochemical Probe for DNA Mismatch

We previously prepared the oligonucleotides (ODNs) conjugated to an anthraquinone (AQ) group via one carbon linker at the 2'-sugar position. When these modified ODNs bind to cDNA sequences, the AQ moiety can be intercalated into the predetermined base-pair pocket of a duplex DNA. In this paper, 2'-AQ-modified ODNs are shown to be an excellent electrochemical probe to clarify the effect of a mismatch base on the charge transfer (CT) though DNA. Two types of DNA-modified electrodes were constructed by assembly of disulfide-terminated 2'-AQ-ODN duplexes onto gold electrodes. One type of electrodes (system I) contains fully matched base pairs or a single-base mismatch in duplex DNA between the redox center and the electrode. The other (system II) consists of the mismatch but at the outside of the redox center. The modified electrodes were analyzed by cyclic voltammetry to estimate the CT rate through duplex DNA. In system I, the CT rate was found to be approximately 50 s (-1) for the fully matched AQ-ODN duplexes, while the CT rates of the mismatched DNA were considerably slower than that of the fully matched DNA. In system II, the AQ-ODN duplexes showed almost similar CT rates ( approximately 50 s (-1)) for the fully matched DNA and for the mismatched DNAs. The detection of a single-base mismatch was then performed by chronocoulometry (CC). All the DNA duplexes containing a mismatch base in system I gave the reduced electrochemical responses when compared to the fully matched DNA. In particular, the mismatched DNAs including G--A mismatch can be differentiated from fully matched DNA without using any electrochemical catalyst. We further tested the usefulness of single-stranded (ss) AQ-ODN immobilized on a gold electrode in the electrochemical detection of a single-base mismatch through hybridization assay. The ss-AQ-ODN electrodes were immersed in target-containing buffer at room temperature, and the CC measurements were carried out to see the changes in the integrated charge. Within 60 min, the mismatched DNA was clearly distinguishable by the CC differences from the fully matched target. Thus, the electrochemical hybridization assay provides an easy and convenient detection for DNA mutation that does not require any extra reagents, catalyst, target labeling, and washing steps.

Redox Behavior of Phenyl-Terpyridine-Substituted Artificial Oligopeptides Cross-Linked by Co and Fe

This work presents the synthesis and characterization of metalated oligopeptide duplex assemblies composed of artificial oligopeptides bearing tethered phenyl terpyridine ligands that are coordinated to Co(II) and Fe(II) ions. The metals cross-link the oligopeptide strands, forming duplex structures. UV-vis spectrophotometric titrations that monitor the absorbance of the metal complexes' characteristic MLCT bands demonstrate stoichiometric metal chelation. Anodic peaks in the cyclic voltammograms of these molecules are consistent with one-electron oxidative reactions without strong coupling between the metal complexes. In separate chronocoulometry measurements, the diffusion coefficients of the metal complexes decrease with increasing oligopeptide length, suggesting the primary products are metal-linked oligopeptide duplex assemblies. Larger metalated oligopeptides adsorb to electrode surfaces during cyclic voltammetry and yield irreversibly adsorbed electroactive films with thicknesses that depend on the number of voltage cycles. Electrochemical and spectroelectrochemical investigations of the films on Pt and ITO electrodes show that the electron transfers in the adsorbed films are chemically reversible but are kinetically quasi-reversible.

Electrochemical properties of hydrogenase on glass carbon electrodes modified with carbon nanotubes

Hydrogenase (H2 ase) purified from phototropic bacteriumThiocapsa roseopersicina was coassembled with carbon nanotubes (CNTs) on glass carbon electrodes. Both oxidized CNTs and Nafion-CNT composites were used to modify the electrodes. The pure H2 are formed dot-like domains, while the oxidized CNT-H2 ase and Nafion-CNT-H2 ase composites formed wire-like and large closely packed aggregates, respectively. The reductive potentials for the [4Fe-4S]2+/1+ clusters of H2ase were at about −500, −650, and −700 mV (vs Ag/AgCl) for the electrodes modified with pure H2ase, Nafion-SWNT-H2ase, and Nafion-MWNT-H2ase composites, respectively. Potential step chronocoulometry measurements indicated a larger charge-transfer diffusion coefficient between the H2ase and electrodes when the CNTs were co-assembled with H2ase, suggesting that the CNTs can not only act as a supporting layer to immobilize enzymes, but also act as a highly conductive wire throughout the films.

Novel Electrochromic Displays Using Monodisperse Viologen‐Modified Porous Polymeric Microspheres

AbstractSummary: In order to achieve a reasonable response time in an electrochromic display, viologen‐modified porous polymeric microspheres of various porosities have been used as substrates. Porous microspheres are prepared using seeded polymerization in the presence of a porogen. Based on ionic conductivity and the chronocoulometry measurements, it is confirmed that the electrolyte content increases, and the resistance of the polymer particles in the device decreases as the specific surface area of the porous particles increases. This results in a rapid response time of 270 ms.Schematic representation of the viologen‐modified porous polymeric microspheres in the manufactured ECD device (A). Images of the device (B) in the OFF state (left) and in the ON state (right).magnified imageSchematic representation of the viologen‐modified porous polymeric microspheres in the manufactured ECD device (A). Images of the device (B) in the OFF state (left) and in the ON state (right).

Electrochemical quartz crystal nanobalance and chronocoulometry studies of phenylalanine adsorption on Au

The interfacial adsorption behaviour of the amino acid, phenylalanine (Phe), was studied at a polycrystalline Au surface in 0.05 M KClO 4 using cyclic voltammetry, chronocoulometry (CC) and electrochemical quartz crystal nanobalance (EQCN) frequency measurements. The frequency was observed to decrease with increasing concentration of Phe, indicating that the frequency measurements were following analyte adsorption directly. Both CC and EQCN frequency measurements showed a two-stage adsorption process, consistent with the molecule being adsorbed in the horizontal position at negative potentials, but rearranged to the more upright position at potentials more positive to the potential of zero charge. From the slopes at the onset of each of these two regions in plots of change in mass from the EQCN frequency measurements versus the surface charge density from CC measurements, the calculated molar mass corresponded to that of Phe displacing adsorbed water molecules for EQCN measurements made with small bulk concentrations of Phe (i.e., <1 × 10 −4 mol L −1). The adsorption process from CC measurements for Phe, described using the Henry adsorption isotherm, gave Gibbs energies of adsorption (Δ G ADS) ranging from −18 to −35 kJ mol −1 over the potential range of −0.6 to 0.6 V. The observed decrease in frequency of the EQCN measurements with additions of aliquots of amino acid and the substantial Δ G ADS values suggests that Phe adsorbs onto the surface via chemisorption. Surface concentrations (1.2 × 10 −10 mol cm −2) were in excellent agreement between the EQCN and CC measurements for small bulk concentrations of Phe (4.0 × 10 −5 mol L −1), in very good agreement with previously published results at the Au(1 1 1) surface. Thus, for small bulk concentrations of analyte, these electrochemical techniques complement one another to enhance our knowledge of the behaviour of thin organic films at electrode surfaces.

Electrochemical Investigation of Metal-Free and Nickel-Containing Porphyrazines Carrying Eight Tosylaminoethylthia Groups

In this study, the electrochemical properties of metal-free and nickel-containing porphyrazines with eight tosylaminoethylthia groups were investigated using cyclic voltammetry, double potential step chronoamperometry, double potential step chronocoulometry, and controlled potential coulometry. Cyclic voltammetry measurements showed that both compounds exhibit two quasi-reversible and an irreversible reduction waves. The first electron transfer reaction was followed by an irreversible chemical reaction, the second one by a reversible chemical reaction for both species. The electrode processes of metal-free and nickel-containing porphyrazines are diffusion controlled, but the double potential step chronocoulometry measurements indicated that the nickel porphyrazine is adsorbed at the electrode. However, a small adsorption current has no significant effect on the mass transport mechanism of the system. Diffusion coefficients of both compounds were determined by both cyclic voltammetric and chronocoulometric measurements. The diffusion coefficients of the reduced forms of the porphyrazines were found to be smaller than those of the neutral forms.

Adsorption of 2-methyl-2-butanol on bismuth single crystal planes

Cyclic voltammetry, impedance and chronocoulometry have been employed for a quantitative study of 2-methyl-2-butanol ( tert-PenOH) adsorption at the bismuth single crystal plane ∣ aqueous Na 2SO 4 solution interface. The adsorption characteristics of tert-PenOH, obtained from the impedance and chronocoulometry measurements, are in reasonable agreement within the limits of surface charge densities −16< σ<2 μC cm −2. The adsorption characteristics (Gibbs energy of adsorption −Δ G° A; limiting Gibbs adsorption Γ max; limiting potential shift of zero charge E N; molecular interaction parameter a, etc.) of tert-PenOH depend on the crystallographic structure of the electrode surface. Comparison of the adsorption parameters for n-propanol ( n-PrOH), n-butanol ( n-BuOH), tert-butanol ( tert-BuOH), tert-PenOH and n-hexanol ( n-HexOH) shows that the adsorption activity and other parameters depend on the length and structure of the hydrocarbon radical of the organic compound studied. The adsorption activity of tert-PenOH increases in the order of Bi planes (001)<(111)<(01 1 ̄ ) as the interfacial density of the planes increases. The limiting Gibbs adsorption Γ max and the molecular interaction parameter a decrease in the order of planes (001)≥(111)>(01 1 ̄ ) . Very low Γ max and E N values for the Bi(01 1 ̄ ) plane indicate that tert-PenOH molecules probably have a flat orientation on the chemically most active Bi(01 1 ̄ ) single crystal plane. Comparison of the adsorption characteristics for the Bi ∣ tert-PenOH interface with the data for Au single crystal planes [8,9,12] and Hg [14,25] is given.

Cathodic Generation and Oxidation of Lead Zintl Ion Pb94- in Potassium Iodide Solutions in Liquid Ammonia

The electrochemical reduction of lead and oxidation reaction of the resulting Pb94- Zintl ions have been studied in 0.1 and 1.0 M KI solutions in liquid ammonia at −70 °C. The reduction process is a complicated multistep reaction. Under certain conditions the oxidation of Pb94- occurs as a simple, electrochemically irreversible reaction for which the limiting current is diffusion controlled. The diffusion coefficient of Pb94- was determined from a combination of chronoamperometry measurements on a 25 μm Pt ultramicroelectrode and chronocoulometry measurements on a 1 mm Pb disk electrode. The chronocoulometric method for the determination of Pb94- determination is presented and used to determine the actual Pb94- concentrations in the electrochemical cell. Side effects, which accompany the reduction and oxidation reactions, have also been studied and the ways to avoid them presented.