Galvanic Cell Research Articles

Preparation of Coating on the Titanium Surface by Micro-Arc Oxidation to Improve Corrosion Resistance

In this paper, two kinds of micro-arc oxidation (MAO) coatings on TA2 with different thickness were prepared by controlled oxidation time and then were characterized for their composition, crystalline structure, and surface morphology. The effect of MAO treatment on electrochemical corrosion behaviors of TA2 in 3.5% NaCl solution were studied by the electrochemical measurements including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves. The results indicate that the electrochemical behavior of MAO coating is related to the coating structure. OCP can be used to evaluate the porosity of MAO coating. More positive OCP indicates coating with lower porosity and larger resistance obtained from EIS. The MAO treatment can significantly enhance the corrosion resistance of TA2, but the thickness increase of MAO coating could not further improve the corrosion resistance. In addition, because of the increase in effective surface area, the MAO treatment may enhance the cathode action of TA2 when the galvanic cell is composed of TA2 and other more negative metal, which in turn promotes the corrosion of negative metal.

Single ion activity coefficients of chloride ions in aqueous sodium chloride and magnesium chloride estimated potentiometrically based on ionic liquid salt bridge at 298 K

The single ion activity coefficients of Cl-,γCl-, in aqueous NaCl and MgCl2 solutions have been estimated at 25 °C potentiometrically by use of galvanic cells with ionic liquid salt bridge consisting of tributyl(2-methoxyethyl) phosphonium bis(pentafluoroethanesulfonyl) amide. With increasing the ionic strength, Im, the γCl- decreases monotonously up to ca. 1 and 1.5 mol kg−1 for NaCl and MgCl2 solutions, respectively.The observed monotonous decrease is distinctively different from the leveling-off of the values greater than 0.5, previously reported, and is in agreement with the prediction by the Franekel’s Debye-Hückel-Smaller-ion Shell (DH-SiS) model that shows no minimum in γCl- versus Im curves in both NaCl and MgCl2 solutions. Quantitatively, the measured γCl- values are consistently smaller than those predicted by the DH-SiS model.

The Galvano-Fenton process: Experimental insights and numerical mechanistic investigation applied to the degradation of acid orange 7

In the present study, the kinetics of degradation of acid orange 7 (AO7) by the Galvano-Fenton process is assessed experimentally and simulated numerically in order to figure out the mechanism of generation and consumption of free radicals with this novel advanced oxidation process. 10 mg/L of the azo dye are degraded during 20 min by combining a copper-iron Galvanic cell to Fenton mechanism at pH 3. The electrochemical and electrolytic reactions are approached following two scenarios, whose the more complex includes the cathodic and anodic reactions, the Fenton scheme and the formation of ferric and ferrous irons complexes and salt as well as the reactivity of sulfate ions. The numerical results demonstrated a high correlation coefficient of 93.5% with experimental results using this latter scenario, while the identified pathways of generation and consumption of HO• and SO4•−, considering their contribution to the initiation reactions of the chain mechanism of AO7 degradation, demonstrated a significant participation of SO4•−. The sensitivity of the process to the corrosion current was examined numerically over the range 0.3 to 1 mA, the results exhibited the achievement of a steady state for the molar concentrations of HO• and SO4•−. This observation was explained by the continuous release of Fe2+ catalyst in the Galvano-Fenton process, in contrast with the classic Fenton scheme. The comparison of both Galvano-Fenton and classic Fenton processes in one hand, and Galvano-Fenton and electro-Fenton processes in the other hand, was further investigated and discussed numerically.

Excellent dye degradation performance of FeSiBP amorphous alloys by Fenton-like process

Amorphous alloys are being newly applied in wastewater treatment because of their unique atomic packing structure. They possess excellent degradation efficiency, stability and reusability. In this work, Fe80Si10B10 and Fe83Si5B8P4 amorphous ribbons exhibited advanced catalytic performance for the degradation of Methyl Blue (MB) and Rhodamine B (RhB) dyes, and the color removal reach nearly 100% within 11 min for both the dyes. Compared with the Fe80Si10B10 amorphous ribbon, the Fe83Si5B8P4 ribbon showed higher degradation efficiency due to its lower reaction activation energy, higher electron transfer ability and higher Fe content, and the formation of the galvanic cell between the strong Fe–P bonds and the weak Fe–B bonds. It also exhibited high stability and reusability. The degradation efficiency was improved when the appropriate concentration of H2O2 is added. As regards the pH, high degradation efficiency was observed in acidic MB solution, but it decreased as the pH increased up to pH 7. The application of the electro–Fenton–like process is discussed, which can effectively improve the degradation performance in a nearly natural solution. This study presents a high efficiency low-cost catalyst for synthetic dye degradation and expands the functional applications of Fe-based amorphous alloys.

Tubular laminated composite structural battery

This paper introduces a polymer-matrix composite-based structural lithium-ion battery system with tubular morphology. Its shape and closed cross-section, fabricated during the autoclave process, allow for high electrochemical performance by controlling the electrode distance and battery environment. To prevent the degradation of the organic liquid electrolyte within this continuous resin polymer system, extra components such as thermoplastic hot melt film, a double glass load-bearing separator, aluminum film, and polydimethylsiloxane were implanted. The electrochemical properties of this manufactured multi-functional structural battery design, named the tubular laminated composite battery (TLCB), were tested with a galvanic cell testing machine. The initial specific capacity of TLCB was found to be approximately 120–130 mAh/g with good cycling performance and steady coulombic efficiency. Furthermore, mechanical load resistance and correlation with electrochemical performance were also assessed under the four-point bending load condition. These results show that the TLCB has the potential to operate as a subsidiary energy storage for future electric vehicle systems with a certain level of structural specific capacity and load-bearing properties.

Prediction of formation probability of rare earth uranates inside nuclear reactor fuel from the determined oxygen potential using a solid oxide galvanic cell

Phase diagrams of the Pr–U–O and Er–U–O systems were established from the Gibbs energy formation obtained using a galvanic cell.

Mechanistic origin of the time-dependence of the open-circuit voltage of a galvanic cell involving a ternary or higher compound.

It has previously been predicted [H.-I. Yoo and M. Martin, Phys. Chem. Chem. Phys., 2010, 12, 14699] and observed [E. Kim, et al., Solid State Ionics, 2013, 235, 22] that the open-circuit voltage U of a galvanic cell, involving a ternary or higher compound with more than one kind of mobile ionic carrier, is path- and time-dependent upon imposition or removal of the mobile components' chemical potential differences, in contradistinction to the cell involving a binary compound. This has been attributed [H.-I. Yoo and M. Martin, Phys. Chem. Chem. Phys., 2010, 12 14699; J.-Y. Yoon, et al., Solid State Ionics, 2012, 213, 22] to the decoupled redistributions of multiple mobile components or multi-fold relaxation. We hereby experimentally demonstrate with SrTi0.982Al0.018O3-Δ, known to have an appreciable water solubility depending on temperature, that introduction of a secondary ionic carrier H+ in addition to the native O2- indeed renders the otherwise time-independent U time-dependent; and that this phenomenon may, thus, be employed to probe the presence of a secondary ionic carrier, e.g., H+ in addition to the primary O2- in BaTi0.982Al0.018O3-Δ whose water solubility is yet to be known. The temporal behavior of U of SrTi0.982Al0.018O3-Δ subjected to the two fixed chemical potential differences, ΔμO and ΔμH, is precisely delineated in terms of two-fold relaxation of H and O, yielding their chemical diffusivity values, and consequently, the ambiguity with the EMF-method to determine the ionic transference numbers of a multinary compound is cleared away.

A facile synthesis of high entropy alloy nanoparticle-activated carbon nanocomposites for synergetic degradation of methylene blue.

Nanocomposites of CoCrFeMnNi high entropy alloy nanoparticle–activated carbon (HEA NPs–AC) were prepared by a facile and controllable impregnation–adsorption method. The HEA NPs–AC showed excellent catalytic performance in the degradation of methylene blue (MB) without any peroxide addition. Besides, their reaction rate is also competitive among single-element and other catalysts. The outstanding efficiency is attributed to the coupling effects of the solid-solution structure of HEA NPs, and the large specific surface area and substantial reaction channels of AC. Moreover, the HEA NPs embedded in distinctive porous architectures accelerate the electron transfer and the mass transport as nanoscale galvanic cells in active bond breaking of MB. The nanocomposites of HEA NPs–AC are distinguished by containing non-noble metals and having high catalytic performance due to the synergetic degradation, providing a better alternative for efficient metal catalysis.

Application of nano electrode Ag/AgCl on potentiometric sensor based on molecularly imprinted polymer (MIP) to verify caffeine

Caffeine of Molecularly Imprinted Polymer (MIP) has been synthesized by the cooling-heating method and to obtain sensor material to detect caffeine. The caffeine is verified through a potentiometric method based on galvanic cells involving anodes and cathodes. MIP of caffeine that has been made function as a cathode or working electrode and the modified of the Ag/AgCl reference electrode that made by reducing the AgCl membrane to nano size (44.45 nm) function as an anode. Then the modified Ag/AgCl reference electrode performance test is compared to the standard AgCl reference electrode. The result has shown the modified Ag/AgCl reference electrode produces linearity of the calibration curve in testing caffeine solutions with a concentration range of 0.1 ppm to 5.0 ppm. Based on the result of the modified Ag/AgCl reference electrode’s test range, we got the linearity coefficient value of 0.9993, with a slope of 0.9693 and an intercept of 0.1306. Generated accuracy calculation resulted in a value of 98.85% and a precision of 0.951%. The result of the lower limit of detection (LoD) was at a concentration of 0.2 ppm and the limit of quantification (LoQ) at a concentration of 0.4 ppm. Thus, it concluded that the modified Ag/AgCl reference electrode has the same or equivalent capability as a standard electrode.

Кристаллофизическая модель ионного переноса в монокристаллах супериоников Ba-=SUB=-1-x-=/SUB=-La-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=- и Ca-=SUB=-1-x-=/SUB=-Y-=SUB=-x-=/SUB=-F-=SUB=-2+x-=/SUB=-

Based on the electrophysical and structural data, a crystallophysical model of ion transfer in superionic conductors Ba1-xLaxF2 + x and Ca1-xYxF2 + x (space group Fm3m) is proposed, in which the charge carriers are mobile interstitial ions Fmob-, formed as a result of heterovalent substitutions of fluorite fragments [M14F64] (M = Ca, Ba) into structural clusters [M8R6F69] (R = La, Y). Single crystals of solid solutions Ca1-xYxF2 + x (0.02≤ x≤0.16) and Ba1-xLaxF2 + x (x = 0.31) were obtained by directional crystallization of the melt. The mobilities of ionic carriers in isostructural superionics Ba0.69La0.31F2.31, Ca0.84Y0.16F2.16, Pb0.67Cd0.33F2, and Pb0.9Sc0.1F2.1 are compared. Crystals Ba1-xLaxF2 + x and Ca1-xYxF2 + x with improved conductometric and mechanical characteristics are promising for replacing the traditional CaF2 electrolyte in galvanic cells for thermodynamic research of chemicals.

Insights into fluidic endogenous magnetism and magnetic monopoles from a liquid metal droplet machine

Magnetism and magnetic monopoles are among the most classical issues in physics. Conventional magnets are generally composed of rigid materials and may face challenges in extreme situations. Here, as an alternative to rigid magnets, we propose, for the first time, the generation of fluidic endogenous magnetism and construct a magnetic monopole through tuning with a liquid metal machine. Based on theoretical interpretation and conceptual experimental observations, we illustrate that when liquid metals, such as gallium alloy, in a solution rotate under electrical actuation, they form an endogenous magnetic field inside. This explains the phenomenon where two such discrete metal droplets can easily fuse together, indicating their reciprocal attraction via the N and S poles. Furthermore, we reveal that a self-fueled liquid metal motor also runs as an endogenous fluidic magnet owing to the electromagnetic homology. When aluminum is added to liquid gallium in solution, it forms a spin motor and dynamically variable charge distribution that produces endogenous magnetism inside. This explains the common phenomena where reflective collision and attractive fusion between running liquid metal motors occur, which are partially caused by the dynamic adjustment of their N and S polarities, respectively. On this basis, more experimental approaches capable of generating dynamic electrical fields also work for the same target. Finally, we propose that such a fluidic endogenous magnet could lead to a magnetic monopole and four technical routes to realize this are suggested. The first involves matching the interior flow of liquid metal machines. The second is the superposition between an external electric effect and the magnetic field. The third route involves composite construction between magnetic particles and a liquid metal spin motor. Finally, chemical methods, such as via galvanic cell reactions, are proposed. Overall, the present theory and identified experimental evidence illustrate the role of a liquid metal machine as a fluidic endogenous magnet and highlight promising methods for the realization of magnetic monopoles. A group of unconventional magnetoelectric devices and applications could therefore be possible in the near future.

Use of Potentiometric Titration for the Study of Thermodynamic Properties of UCl <sub>4</sub> and UO <sub>2</sub> in Fused LiCl-KCl Eutectic

The interaction between uranium oxygen-free and oxygen ions in molten LiCl-KCl eutectic (LKE) at 773 K was studied to investigate the chemical and electrochemical properties of U 4+ and O 2- ions by potentiometric titration method. Combining theoretical and experimental data, the E - p O 2- Pourbaix diagram for stable uranium compounds has been constructed. The stable states of U(IV) in molten LiCl-KCl salt at 773 K were UO 2 and UCl 4 during the concentration of oxygen ions reaches equivalent point α =2.39. The calculated values of the activity coefficient of UCl 4 and UCl 3 were 5.05×10 - 5 and 1.01×10 - 3 , respectively. This is indicated that U(III) ions are less active than U(IV) ions probably due to the formation of strong complexes with the chloride ions. Tungsten cathode was used to deposit metal uranium, and the equilibrium potentials vs. the Ag/AgCl reference electrode are -1.5005 V and -2.5305 V separately by using the emf of the galvanic cell. The potential of urnium ions in the melt was changed linearly with the concentration function of oxygen ions ( p O 2- ). According to the titration reaction, solid UO 2 was formed in the range 0 < α < 2.39. The equilibrium between UO 2 and U (IV) ions was described by the equation: E =3.678+0.0383´ p O 2- , by which the stability constant of UO 2 can be calculated. Meanwhile, the equilibrium of UO 2 with U(III) is as shown in the formula: E =2.107+0.154´ p O 2- .

Thermodynamic Properties: Determination of the (NaCl + l-Proline + H2O) Ternary System Based on Potentiometric Measurements at T = (293.2, 303.2 and 313.2) K

In this work, the thermodynamic properties of the ternary (NaCl + l-proline + H2O) system are reported, based on the potentiometric technique. The potentiometric measurements were carried out by using self-made ion selective electrodes (ISE) on the galvanic cell of type Na-ISE | NaCl (mB), l-proline (mA), H2O | Ag/AgCl in various series of the l-proline aqueous solution (mA = 0.2227, 0.4571, 0.7043 and 0.9651) mol·kg−1 and NaCl in pure water over NaCl molalities ranging from (0.01 to 4.00) mol·kg−1 at T = (293.2, 303.2, and 313.2) K and p = 101.3 kPa. Correlation of the experimental data was performed based on the Pitzer model as modified by Esteso et al. (MP). The MP parameters obtained were used to calculate the natural logarithm of the ratio of l-proline activity coefficients in NaCl and water mixtures to l-proline activity coefficients in pure water ( $$\ln ({{\gamma_{{\text{A}}} } \mathord{\left/ {\vphantom {{\gamma_{{\text{A}}} } {\gamma_{{\text{A}}}^{0} }}} \right. \kern-\nulldelimiterspace} {\gamma_{{\text{A}}}^{0} }})$$ ), osmotic coefficients (φ), excess Gibbs energy (GE/RT) and water activity (aw) for different series of l-proline molality. The NaCl transfer Gibbs energy and McMillan–Mayer parameters were also calculated for the system. Good consistency was found between the MP and McMillan–Mayer model parameters.

Solvent-Dependent Thermoelectric Performance of PC-=SUB=-70-=/SUB=-BM

Based on the electrophysical and structural data, a crystallophysical model of the ionic transport in superionic conductors Ba1-xLaxF2+x and Ca1-xYxF2+x (space group Fm¯3m), in which the charge carriers are mobile interstitial ions F− resulting from heterovalent substitutions of fluorite fragments of [M14F64] (M = Ca, Ba) by structural clusters of [M8R6F69] (R = La, Y). Single crystals of Ca1-xYxF2+x (0.02&lt;x&lt;0.16) and Ba1-xLaxF2+x (x = 0.31) solid solutions were obtained by directed crystallization of the melt. The mobility of ionic carriers in isostructural superionics Ba0.69La0.31F2.31, Ca0.84Y0.16F2.16, Pb0.67Cd0.33F2, and Pb0.9Sc0.1F2.1 are compared. Crystals of Ba1-xLaxF2+x and Ca1−xYxF2+x with improved conductometric and mechanical characteristics are promising active to replace the traditional CaF2 electrolyte in galvanic cells for thermodynamic research of chemicals.

Ecological projects from the perspective of economic and environmental impacts– a case study of galvanic cell manufacturer

Ecological projects from the perspective of economic and environmental impacts– a case study of galvanic cell manufacturer

Galvanic corrosion of zero-valent iron to intensify Fe2+ generation for peroxymonosulfate activation

Zero-valent iron (ZVI) usually activates peroxymonosulfate (PMS) through the generation of Fe2+ from the self-corrosion of ZVI in a Fenton-like reaction. However, the generation rate of Fe2+ forms the reaction rate-limiting step. Against this, a microscopic Fe-graphitic carbon galvanic cell array (GCA) was created to intensify the PMS activation process. The synergistic effect between a ZVI anode and a graphitic carbon cathode accelerated the generation of Fe2+ via ZVI galvanic corrosion to significantly increase the PMS activation performance. Distinctive short-circuiting of the anode and cathode in GCA effectively enhanced the galvanic corrosion. The electrochemical behavior of GCA was characterized in detail to elucidate the PMS activation mechanism. The microscopic Fe-graphitic carbon galvanic cell array provided a promising pathway for pollutant remediation.

MODELING TEACHING IN STUDY OF GALVANIC CELLS: UPPER-SECONDARY SCHOOL CONTEXT

Besides improving students' understanding of scientific concepts, chemistry teaching should also improve students' ability of applying concepts to solve problems. The research aims to explore the effects of modeling teaching on students’ proficiency in solving galvanic cell problems. This research used a quasi-experimental design, and the independent variable of the research was the teaching method. Forty-five students in the experimental class received modeling teaching, and 48 students in the control class received lecture-style teaching. The dependent variable was the performance level of the student's ability to solve the problem of the galvanic cell, which was evaluated using the galvanic cell proficiency assessment tool. The research results show that the students in the experimental class were significantly more proficient in solving galvanic cell problems than those in the control class. The results of unstructured interviews assisted in illustrating the role of modeling teaching in improving the proficiency of students in solving galvanic cell problems, and students in the experimental class had positive views on modeling teaching. Keywords: galvanic cells, modeling teaching, problem solving, proficiency level

Elucidation of the Synergistic Effect of Dopants and Vacancies on Promoted Selectivity for CO2 Electroreduction to Formate.

Sn-based materials are identified as promising catalysts for the CO2 electroreduction (CO2RR) to formate (HCOO- ). However, their insufficient selectivity and activity remain grand challenges. A new type of SnO2 nanosheet with simultaneous N dopants and oxygen vacancies (VO -rich N-SnO2 NS) for promoting CO2 conversion to HCOO- is reported. Due to the likely synergistic effect of N dopant and VO , the VO -rich N-SnO2 NS exhibits high catalytic selectivity featured by an HCOO- Faradaic efficiency (FE) of 83% at -0.9 V and an FE of > 90% for all C1 products (HCOO- and CO) at a wide potential range from -0.9 to -1.2 V. Low coordination Sn-N moieties are the active sites with optimal electronic and geometric structures regulated by VO and N dopants. Theoretical calculations elucidate that the reaction free energy of HCOO* protonation is decreased on the VO -rich N-SnO2 NS, thus enhancing HCOO- selectivity. The weakened H* adsorption energy also inhibits the hydrogen evolution reaction, a dominant side reaction during the CO2RR. Furthermore, using the catalyst as the cathode, a spontaneous Galvanic Zn-CO2 cell and a solar-powered electrolysis process successfully demonstrated the efficient HCOO- generation through CO2 conversion and storage.

(Invited) Porous Structure Produced By Metal-Assisted Etching of Silicon

Metal-assisted etching of silicon can produce porous silicon and silicon nanowires by simply immersing metal-modified silicon in a hydrofluoric acid solution without electrical bias [1]. Such etching proceeds by a local galvanic cell mechanism consisting of local anodic dissolution of silicon and local cathodic reduction of an oxidizing agent, such as oxygen [2, 3] or hydrogen peroxide, on catalytic metal. The structure of porous silicon is widely controlled from nanometer to sub-millimeter scale in pore size and from straight to an ants’ nest like in pore morphology by changing etching conditions [1-3]. We fabricate various porous structures on silicon wafers, and apply them to antireflection of solar cells and autocatalytic electroless formation of metal-nanorods and metal films on silicon surfaces. The structure of porous silicon is easily controlled in the nanometer scale with changing etching conditions such as kind, size, and distribution of metal catalysts, kind and concentration of oxidizing agent, intensity of photoillumination, and etching time. Recently, we found that general corrosion occurred on the top surface of the silicon substrate around the metal particles even under the dark condition [4]. The general corrosion depended on the metal species and it was explained by the formation and dissolution of a mesoporous layer.[1] Z. Huang, N. Geyer, P. Werner, and U. Gösele, Adv. Mater., 23, 285 (2011).[2] S. Yae, Y. Kawamoto, H. Tanaka, N. Fukumuro, and H. Matsuda, Electrochem. Comm., 5, 632 (2003).[3] S. Yae, M. Tashiro, M. Abe, N. Fukumuro, H. Matsuda, J. Electrochem. Soc., 157, D90 (2010).[4] A. Matsumoto, H. Son, M. Eguchi, K. Iwamoto, Y. Shimada, K. Furukawa, and S. Yae, RSC Adv., 10, 253 (2020).

Electrochemical removal of sulfide ions and recovery of sulfur from sulfide ions containing wastes

In this work a two-compartment galvanic cell with two graphite rod electrodes and two types of cation exchange membranes: namely the Nafion membrane and synthetic fabric membrane is tested in treating sulfide containing wastes and recovery of elemental sulfur. The cell reactions are sulfide oxidation at the anode and chromium (VI) reduction at the cathode. The effect of different parameters such as external resistance, initial concentration of K2Cr2O7 solution, H2SO4 concentration, and initial concentration of Na2S, the pH of the solution, NaCl concentration, and temperature of the solution is investigated. The cell performance as a reactor and as an energy converter is expressed in terms of % sulfide removal and current-voltage plots, respectively. Depending on the effects of the aforementioned factors, the optimal conditions that give the highest performance were determined, and then the cell was tested on real wastes from refinery processing at those conditions. The cell showed high selectivity in sulfide removal and sulfur recovery with almost no interference with other contaminants.