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Electro-osmotic drainage technology is especially suitable for low-permeability clay soil. The electrode–clay interface is believed to play a crucial role in electro-osmosis. Previous documents have highlighted the importance of the electrochemical processes at the electrode–clay interface, but few studies exist with respect to the influencing mechanisms. Therefore, the influencing mechanisms of the electrochemical processes on the electrode–clay interface have been thoroughly studied herein, both theoretically and experimentally. An interfacial resistance model in the electro-osmotic system is proposed based on the interfacial kinetic reactions of metal electrodes and graphite electrodes according to electrochemical theory. The reliability of the proposed model is demonstrated by chamber tests. The proposed model states that the most critical factor influencing interfacial resistance is the current density on the electrode surface. Other crucial influencing factors for interfacial resistance include the electrode material, surface status, pH of the pore solution, soil void ratio, conductive properties and adsorption properties. [ABSTRACT FROM AUTHOR]

The transfer of electrons from V to Ti in the Ti-C-V bond leads to an upward shift of the d-band center of V, which enhances the adsorption of V on the intermediate LiO 2 , fundamentally improving the electrocatalytic performance of TiVC. [Display omitted] Lithium-oxygen (Li-O 2) battery possesses high theoretical energy density of ∼ 3500 Wh kg−1, yet the sluggish kinetics of oxygen redox reactions hinder its practical application. Herein, TiVC bimetallic MXene solid solution is prepared as the efficient electrocatalyst for Li-O 2 battery. The results of experiment and theoretical calculations reveal that through the formation of Ti-C-V bond in TiVC, electrons transfer from V site to Ti site enhances electron delocalization of V sites, which causes the upshift of d band center of V site and strengthens the adsorption of intermediate products (LiO 2) on TiVC electrode surface. Due to the strong adsorption of intermediates, the film-like Li 2 O 2 can be formed on TiVC electrode via the surface-adsorbed pathway, which ensures the full contact between the electrode and discharged product and thus facilitates the charge transfer between TiVC electrode and oxygen species during charge process. As a consequence, the TiVC based Li-O 2 battery exhibits superior electrochemical performance including large discharge capacity (12780 mAh/g) and extended cycling stability (422 cycles) at the current density of 300 mA g−1. [ABSTRACT FROM AUTHOR]

In this work, the influence of bias and electric field intensity on the electrochemical migration of SAC305 solder alloy is investigated using a self-designed in-situ thin electrolyte film device. The results indicate that when the bias is 0.5 V, a compact passivation film forms on the sample surface, effectively inhibiting dendrite growth. When the applied bias reaches 0.75 V, it is observed that specific corrosion products are generated between the two plates, and the occurrence of dendritic growth phenomena is still absent. Dendrite development is observed when a bias voltage of 1 V is applied. Regarding the electrode reactions, when the applied bias falls below 1.5 V, a notable polarization resistance is encountered in the anode reaction. In this case, the cathode reaction primarily entails the process of oxygen reduction. As the applied voltage climbs to 1.5 V, the anodic potential shows an increase, leading to a reduction in the polarization resistance of the anodic process that determines the rate of the electrochemical reaction. At this time, the cathode potential exhibits a comparatively negative value, leading to the progressive occurrence of the hydrogen evolution process. Additionally, the influence mechanism of bias on ECM is also proposed.

Atmospheric carbon dioxide (CO2) concentration has reached record levels due to excessive anthropogenic CO2 emissions from massive industrial productions. Renewable-energy-driven CO2 electroreduction is an effective method of directly converting CO2 into various value-added chemicals or materials without subsequent geological disposal treatment. Owing to their promising thermal stability, wide electrochemical window, tunable oxo-basicity, and nontoxic nature, molten salt electrolytes endow intrinsic advantages, such as fast CO2 absorption and selective electrochemical transformation, among different electrolyte species, wherein advanced carbon materials, CO, and hydrocarbons can be generated at relatively high current densities. Herein, we review the recent advances in molten salt CO2 capture and electrochemical transformation (MSCC-ET) technologies, including reaction mechanisms, CO2 absorption kinetics, electrode reaction kinetics, and product selectivity. This review highlights feasible strategies for regulating nanostructures, carbon product crystallinity, energy efficiency, overall CO2 conversion efficiency, and MSCC-ET adaptability toward practical flue gases. Moreover, suitable cost-effective inert anode candidates for the oxygen evolution reaction are discussed. [ABSTRACT FROM AUTHOR]

Electrophoresis of particles by applying an electric field to a colloidal suspension allows simultaneous manipulation and shaping of particles. A film forming process utilizing the electrophoretic phenomenon of charged particles in a liquid is called “electrophoretic deposition (EPD)” and is used for powder coating. The main difference between the EPD process and other colloidal processes is the coexistence of electrode reactions, ie electrochemical reactions that occur at the interface between the electrode and the electrolyte solution. The applied electric field in the EPD method plays an important role not only in the electrophoresis of charged particles but also in controlling the coagulation mechanism and film quality. This paper introduces the principle of the EPD process considering the electrode reaction and an example of the functional film formation process. [ABSTRACT FROM AUTHOR]

Electroosmotic flow (EOF) is a universal phenomenon in most microfluidic systems when an external electric field exists along charged channel walls. The mechanism of ion transport and fluid flow in such systems has been extensively studied, largely based on simplified models without consideration of electrode reactions and water dissociation. To study the effects of these electrochemical reactions, we build an electrokinetic model with full consideration of these processes, namely electrochemistry (EC) model, and compare its performance with that of the traditional electrokinetic (EK) model. Our results show that electrode reactions alter the electric potential and reduce the current, causing a significant reduction in EOF velocity. These potential changes and EOF reduction are driven almost entirely by electrode reactions, because the difference between the results from the EC model and those from the EK model with potential adjustment induced by chemical reactions is slight. In addition, the participation of ions in electrode reactions leads to notable alterations in their concentration within the microchannel and significant pH change, which are ignored in the traditional EK model. It is found that at a typical applied electric field of 50 V/cm, the EOF velocity in the EC model is 63% of that in the EK model. This difference in velocity decreases to only 4.0% as the EK model considers electric potential shifts caused by electrode reactions. In the microchannel, the Cl− concentration drops by approximately 50% while the OH− increases, leading to a pH growth 3.5. The results presented in this work can improve the understanding of electrode effects on the physicochemical properties of EOF systems, providing essential guidance for manipulating fluid flow and amphoteric molecular transport in various microfluidic systems. [ABSTRACT FROM AUTHOR]

Lithium-oxygen (Li-O 2 ) battery with large theoretical energy density (≈3500 Wh kg -1 ) is one of the most promising energy storage and conversion systems. However, the slow kinetics of oxygen electrode reactions inhibit the practical application of Li-O 2 battery. Thus, designing efficient electrocatalysts is crucial to improve battery performance. Here, Ti 3 C 2 MXene/Mo 4/3 B 2-x MBene superlattice is fabricated its electrocatalytic activity toward oxygen redox reactions in Li-O 2 battery is studied. It is found that the built-in electric field formed by a large work function difference between Ti 3 C 2 and Mo 4/3 B 2-x will power the charge transfer at the interface from titanium (Ti) site in Ti 3 C 2 to molybdenum (Mo) site in Mo 4/3 B 2-x . This charge transfer increases the electron density in 4d orbital of Mo site and decreases the d-band center of Mo site, thus optimizing the adsorption of intermediate product LiO 2 at Mo site and accelerating the kinetics of oxygen electrode reactions. Meanwhile, the formed film-like discharge products (Li 2 O 2 ) improve the contact with electrode and facilitate the decomposition of Li 2 O 2 . Based on the above advantages, the Ti 3 C 2 MXene/Mo 4/3 B 2-x MBene superlattice-based Li-O 2 battery exhibits large discharge specific capacity (17 167 mAh g -1 ), low overpotential (1.16 V), and superior cycling performance (475 cycles)., (© 2024 Wiley‐VCH GmbH.)

A facile and effective one‐step in‐situ technique for the synthesis of layered two‐dimensional metallic vanadium sulfide‐reduced graphene oxide (VS2/rGO) nanocomposite (NComp) hasbeen described and their electrocatalytic properties towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have been studied. From transmission and scanning electron microscopy analyses, it was observed that the layered two‐dimensional VS2 nanoparticles successfully grew over the layered graphene matrix. The as‐synthesized NComp displayed excellent electrocatalytic activities towards ORR with a four‐electron transfer pathway, and OER in alkaline medium. The synthesized nanocatalyst exhibits lower ΔE value (0.75 V) as compared to other literature values, high catalytic current density (−6.26 mA cm−2 for ORR) with a lower Tafel slope (59 mV dec−1), as compared to Pt/C, and lower overpotential (η=0.31 V at 10 mA cm−2 for OER) with a smaller Tafel slope (68 mV dec−1) than those of RuO2. Moreover, it displays high electrochemically active surface area, long‐term stability in alkaline medium and good resistance to the methanol crossover effect. The enhanced bifunctional electrocatalytic properties of the synthesized nanocatalyst may be owing to the synergistic effect of combining VS2 and rGO, which improves the surface area, adsorption of reaction intermediates, active sites density, and electrical conductivity. Along with the high stability of the hybrid NComp, these advantages provide immense promise for triggering breakthroughs in fuel‐cell electrocatalysis. [ABSTRACT FROM AUTHOR]

This work investigates the reaction characteristics of the anode and cathode by overpotential analyses in 100 cm2 class planar anode-supported SOFCs. The reactant gas addition (RA) technique was applied to analyse the overpotential, which uses the reactant gas flow rate and partial pressure as parameters due to their variation upon adding a reactant species to an electrode. The anodic overpotential was determined to be made up of mass transfer-induced overpotentials of H 2 and H 2 O species. The H 2 O species account for the majority of the anodic overpotential at the measured current range i.e., 0–150 mA cm−2. Thus, the anodic reaction is under an extreme H 2 O-induced mass-transfer resistance compared with H 2. The RA method showed that the cathodic overpotential was mainly due to a deficiency of O 2 species in the mass transfer through the gas phase rather than the solid phase. Furthermore, both cathodic and anodic overpotentials depended on gas flow rate and utilisation, indicating a significant gas-phase mass transfer effect. • Anode is the gas phase mass transfer controlling processes of H 2 and H 2 O. • Overpotential due to the water deficiency is dominant at the anode. • Cathode is the mass transfer controlling process of O 2 species at the gas phase than the solid phase. • Reactant gas addition method reveals overpotential of each reactant gas species. [ABSTRACT FROM AUTHOR]

The uniqueness of DC deep-well ground electrodes (DWGEs) lies in their low area requirements. However, the gas produced by DWGEs during electrolysis may cause more severe exhaust problems than those caused by conventional electrodes. To investigate the influence of different electrode materials on the gas evolution of DWGEs, an innovative U-shaped experimental platform is proposed for the separate collection of cathode and anode gases. The metal–electrolyte contact interface in a DWGE project was simulated, and gas evolution experiments were performed on three typical ground electrode materials. The gas evolution rates of the electrode materials when operate as cathodes and anodes were obtained. Polarization curves were used to compare the corrosion rates of the three materials and evaluate the effects of these rates on the gas evolution rates of the materials. The results revealed that when operated as anodes, mixed metal oxide (MMO) and high-silicon cast iron produced oxygen, whereas carbon steel did not. Furthermore, the evolution of O2 in MMO was faster than that in high-silicon cast iron. When operated as cathodes, the three materials generated hydrogen, and carbon steel exhibited the slowest H2 evolution rate. The current distribution in the different gas evolution processes was summarized. The supplied current was used as the reaction current of metal corrosion and for gas generation. Under the same current, quicker corrosion corresponded to a lower amount of gas evolution for a material. [ABSTRACT FROM AUTHOR]

The potential for electrochemical conversion of bio-oil was overlooked for a long period due to the poor electrical conductivity and unclear reaction mechanism. This study aimed to provide an insight into bio-oil of electrochemical conversion mechanism and product distribution. In this study, using walnut shell bio-oil with enhanced electrical conductivity by ammonium carbonate as raw material, electrolysis experiments were carried out using different electrolysis times by constant current method (20 mA) in H-type electrolytic cell at a stable temperature (0 °C). The results showed that phenols, aldehydes, and lignin were copolymerized; meanwhile, unsaturated fatty acids such as oleic acid underwent decarbonylation and decarboxylation. The hydrogen-releasing electrode reaction also occurred at the cathode during the conversion process. Besides, the properties of products were characterized by elemental analysis, GC-TCD/FID, GC/MS, 1H NMR, FTIR, and TG-FTIR. Solid products were of possibility for application in new materials owing to containing copolymers with lignin structure, and gas products could be utilized as gas fuels with the combustible gas (H2, CO, CH4, and olefins) content as 79.24%. [ABSTRACT FROM AUTHOR]

Deep well grounding electrodes (DWGE) have small occupied areas. The number of sub-ground electrodes is less than that of traditional vertical grounding electrodes. Thus, the former has a favorable development prospect. However, given that the active part of a DWGE is buried in the deep earth, DWGE faces more complex gas exhaust problem than shallow-buried grounding electrodes. To research the gas evolution characteristics of DWGE, a U-shaped gas evolution experimental platform that can collect anode and cathode gases separately is designed. Carbon steel material is used as the electrode, and experiments have been conducted on water and saturated coke on the basis of the designed platform and a 30-m DWGE test. The results show that the operating environment and mode (anodic/cathodic) affect gas evolution. When inside water, only the reaction of Fe dissolution occurs at the anode, and Fe is transformed into Fe2+ while hydrogen evolution and oxygen consumption reactions occur simultaneously at the cathode. When in saturated coke, the gas production at the cathode increases with ampere-hours, thereby changing the contact resistance between the electrode and the coke and forming a “bubble resistance”, then leading to a gas block. The test result of a 30 m well at 100 A further verifies the experimental results of the designed platform and confirms that a vent pipe plays a role in practical use.

A method for operating membrane capacitive deionization (MCDI) systems without electrode reactions at a high cell potential was studied. The charge supplied to the cell was controlled to suppress Faradaic reactions. The maximum allowable charge (MAC) that can be supplied to a carbon electrode without electrode reactions was measured to be 58 C/g. Adsorption experiments were conducted while supplying a charge of 55 C/g (95% of the MAC value) in constant-current (CC) and constant-voltage (CV) mode. The cell potential increased to 1.42 V in CC (1.43–4.29 mA/cm2) mode, but the concentration and pH of the effluent were kept constant. In addition, the effluent pH was stable in CV (1.25–2.0 V) mode. The salt adsorption capacities and charge efficiencies were approximately 15.5 mg/g and 92%, respectively, regardless of the current densities and cell potentials applied to the cell. With increasing cell potential, the concentration polarization in the feed stream was intensified, resulting in an increase in cell resistance. It was thought that electrode reactions did not occur at a high cell potential because of the high voltage drop due to the cell resistance. The higher the cell potential (or current density) is, the faster the desalination rate in MCDI operation. It is expected that this operation method applying the MAC concept will contribute to the stable operation of MCDI systems and an improvement in desalination performance. Image 1 • A stable operation method for MCDI systems at high cell potentials was proposed. • Faradaic reactions were suppressed by controlling the charge supplied to the cell. • The MCDI desalination performance was stable regardless of cell potential. • The voltage drop due to cell resistance increased with increasing cell potential. [ABSTRACT FROM AUTHOR]

Highlights • MAC was defined as the maximum charge that can be supplied to a carbon electrode without electrode reactions. • Faradaic reactions in MCDI were analyzed by the instantaneous charge efficiency. • No electrode reactions were observed in the MCDI operation below the MAC value. • The MCDI operation above the MAC value caused a decrease in desalination performance due to electrode reactions. Abstract We have studied a new method to operate a membrane capacitive deionization (MCDI) without electrode reactions by controlling the total charge (TC) supplied to the MCDI cell. The MCDI experiments were carried out by varying the TC (45–90 C/g) at a high cell potential. When approximately 59 C/g of charge was supplied to the carbon electrode, the electrode reaction began. Thus the MAC value, which is the maximum charge supplied to the carbon electrode at the point where the electrode reactions begin, was determined to be 59 C/g. The carbon oxidation reaction occurred when 59–83 C/g of charge was supplied. At 83 C/g or more, the water oxidation reaction proceeded at a rapid rate, resulting in a drastic decrease in the charge efficiency. No electrode reactions were found during the MCDI operation at a TC value lower than the MAC value. When the MCDI system was operated at a TC higher than the MAC, however, the effluent pH and concentration changed as the adsorption and desorption process was repeated, resulting in deterioration of the desalination performance. It was verified that the electrode reactions can be easily controlled by adjusting the TC supplied to the MCDI cell. [ABSTRACT FROM AUTHOR]

Abstract A new standard metric has been developed to express the actual adsorption capacity of the carbon electrode in consideration of the electrode reactions. The adsorption experiments were carried out by changing the cell potentials (0.6–1.6 V) in the MCDI unit cell. The point at which the electrode reactions occur was determined from the change in instantaneous charge efficiency during the adsorption process. Then, the total charge supplied to the carbon electrode at this point was defined as the maximum allowable charge (MAC). The MAC values were constant at 59 C/g irrespective of cell potentials. In addition, the salt adsorption capacity (S A C M A C ) and the charge efficiency at MAC were approximately 16 mg/g and 91%, respectively, regardless of the cell potentials. Furthermore, the equivalent circuit analysis for the MCDI cell revealed that Faradaic reactions rarely occur at the MAC. The MAC is the maximum charge that can be supplied to the carbon electrode without electrode reactions. It is also unaffected by the cell components and operating conditions of the MCDI cell. Therefore, the MAC is expected to be a useful metric to objectively express the actual adsorption capacity of the carbon electrode. Graphical abstract Image 1 Highlights • The total charge supplied until Faradaic reactions occurred is defined as MAC. • The MAC values of the carbon electrode were constant regardless of the cell potentials. • The desalination performances at MAC were constant irrespective of the cell potentials. • MAC can be a useful metric to describe the adsorption capacity of carbon electrodes. [ABSTRACT FROM AUTHOR]

Highlights • Electrolyte with a thickness less than grain size was fabricated by cost-effective method. • Bamboo-structured thin electrolyte effectively reduces ohmic resistance of protonic ceramic fuel cell. • Electrode reactions were analyzed by distribution of relaxation time method. • Surface diffusion of an adsorbed oxygen to the triple phase boundaries at cathode is the most probable rate determining step. Abstract High-performance and cost-effective fabrications should be simultaneously achieved for practical applications of fuel cells. Unfortunately, protonic ceramic fuel cells, which are considered next-generation solid oxide fuel cells operating at lower temperatures (≤600 °C), do not satisfy the requirements. While thin electrolyte and rapid reactions at electrode/electrolyte interfaces are crucial for cell performance, the thickness of the electrolyte via cost-effective ceramic processes is still not satisfactory (currently capable of >10 μm) and the electrode reaction(s) are yet to be clarified. Here we demonstrate the fabrication of a columnar-structured thin electrolyte (∼2.5 μm) of BaCe 0.55 Zr 0.3 Y 0.15 O 3-δ , in which no perpendicular grain boundaries exist against the current direction, through a low-cost screen printing method. A high open-cell voltage of 1.10 V ensures that the thin electrolyte is sufficiently dense for gas-tightness, thereby achieving an extraordinary maximum power density of 350 mW/cm2 at 500 °C. The electrode reactions are investigated by distribution of relaxation time method based on electrochemical impedance spectroscopy as a function of oxygen partial pressure and hydrogen partial pressure at 500 °C, suggesting that the reaction step corresponding to the surface diffusion of an adsorbed oxygen to the triple phase boundaries at the cathode is most probably the main contributor to the overall polarization resistances. [ABSTRACT FROM AUTHOR]

The double perovskite oxides La 2-x NiMnO 6-δ (x = 0.0, 0.1, 0.2, 0.3) are evaluated as potential cathodes for intermediate temperature solid oxide fuel cells. The effects of La-deficiency on the crystal structure, high temperature thermal and electrical properties, and catalytic activity for oxygen reduction reaction are comprehensively investigated. La 2-x NiMnO 6-δ crystallizes in monoclinic structure with the space group P 2 1 /n. The cell volume expands with the increase of La-deficiency. The highest electrical conductivity of 25 S cm −1 is found for La 1.8 NiMnO 5.71 at 800 °C in air. Introducing La 3+ deficiency greatly improves the amount of chemical adsorbed oxygen species on material surface, which promotes the oxygen reduction reaction of La 2-x NiMnO 6-δ cathode. The optimum composition, La 1.8 NiMnO 5.71 exhibits the lowest area specific resistance of 0.21 Ω cm 2 at 700 °C in air. Meanwhile the peak power density of the anode-supported single cell with La 1.8 NiMnO 5.71 cathode reaches 0.6 W cm −2  at 700 °C. The electrochemical impedance spectra measurements combining with distribution of relaxation times analysis prove that the charge transfer process is the rate-limiting step of the ORR reaction. [ABSTRACT FROM AUTHOR]

Abstract: Bicinchoninic acid (BCA) is widely used for determining the valence state of copper in biological systems and quantification of the total protein concentration (BCA assay). Despite its well‐known high selectivity of Cu(I) over Cu(II), the exact formation constants for Cu(I)(BCA)23− and Cu(II)(BCA)22− complexes remain uncertain. These uncertainties, affect the correct interpretations of the roles of copper in biological processes and the BCA assay data. By studying the voltammetric behaviors of Cu(I)(BCA)23− and Cu(II)(BCA)22−, we demonstrate that the apparent lack of redox reaction reversibility is caused by an adsorption wave of Cu(II)(BCA)22−. With the adsorption wave identified, we found that the Cu(I)/Cu(II) selectivity of BCA is essentially identical to another popular ligand, bathocuproinedisulfonic acid (BCS). Density functional theory calculation on the geometries of Cu(I)(BCA)23− and Cu(II)(BCA)22− rationalizes the preferential Cu(I) binding by BCA and the strong adsorption of the Cu(II)(BCA)22− complex at the glassy carbon electrode. Based on the shift in the standard reduction potential of free Cu(II)/Cu(I) upon binding to BCA, we affirm that the formation constants for Cu(I)(BCA)23− and Cu(II)(BCA)22− are 1017.2 and 108.9, respectively. Therefore, BCA can be chosen among various ligands for effective and reliable studies of the copper binding affinities of different biomolecules. [ABSTRACT FROM AUTHOR]

This work compares the electrode reaction mechanisms of 100 cm2 class molten carbonate cells (MCCs) operated in electrolysis cell (EC) and fuel cell (FC) modes using a reactant gas addition (RA) method. The RA method reveals essential information on an electrode reaction mechanism by measuring the overpotential of an electrode resulting from adding a reactant. The hydrogen electrode (HE) is revealed to be under a gas-phase mass transfer-controlled process in both modes. In addition, the HE overpotential at an inlet composition of H 2 : CO 2 : H 2 O = 0.3: 0.3: 0.4 atm is caused mainly by H 2 species in FC mode, while CO 2 contributes the majority in EC mode due to the production of H 2 and consumption of CO 2 by the water–gas shift reaction. On the other hand, most of the oxygen electrode (OE) overpotential is contributed by O 2 species in both modes. The overpotential induced by O 2 species was larger in FC mode than EC mode because EC mode generates O 2 and provides less mass transfer resistance of O 2 species in the liquid phase. The addition of CO 2 to the OE raised overpotential in both modes. The overpotential was especially large in FC mode due to the reduced O 2 partial pressure and relatively low in EC mode because of O 2 generation. Therefore, the total overpotential in EC mode is less than in FC mode. [ABSTRACT FROM AUTHOR]