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Fe-based amorphous alloys are an eco-friendly alternative to Ni- and Co-based amorphous alloys, which are not sustainable. Herein, amorphous Fe–P alloys were electrodeposited from an eco-friendly aqueous electrolyte. The influence of bath temperature on the electrochemical behaviour during Fe–P alloy deposition was investigated using linear-sweep voltammetry, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The morphology, P content and phase structure were characterized via scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and differential scanning calorimetry. The electrochemical corrosion behaviour in 3.5 wt% NaCl solution was studied using potentiodynamic polarization curves and EIS spectra. The results showed that an increase in bath temperature leads to a positive shift in the inductive co-deposition potential and increases the reaction rate. At bath temperatures of 20–60°C, the P content in deposits varied in the range of 17.07–21.13 wt% and the phase structure was amorphous. Although the amorphous alloys lacked crystalline defects, the P content had a marginal effect on the corrosion properties, whereas the surface morphology significantly influenced the corrosion properties. The amorphous Fe–P alloys fabricated in this study exhibit superior corrosion properties to almost all electrodeposited amorphous alloys reported in the literature, demonstrating their potential for corrosion protection. [ABSTRACT FROM AUTHOR]

Cyclic voltammetry (CV) is one of the most important electrochemical research methods; however, many instrumental analysis textbooks only briefly discuss CV operating principles. The electrode reaction processes are not discussed in-depth; consequently, students can lack the necessary skills to interpret CV curves. This study analyzed the electrode processes to determine the changes in the concentration of electroactive materials at the electrode/interface. Furthermore, the characteristics of the CV curve and the effect of concentration and scanning speed on the CV curve are also described. Finally, the philosophical principles contained in CV are discussed. This study can provide reference information for both peer teaching and student learning. [ABSTRACT FROM AUTHOR]

The relationship between interface structure (e. g., the facet of the solid phase and the configuration of solvation) and the reactivity of the corresponding electrode is a critical issue in electrochemistry. Compared to macroscopic electrode measurements, electrochemical methods established on the single‐particle scale have advantages in establishing the structure‐property relationship. In recent years, great achievements have been made in electrochemical energy storage and electrocatalysis that allow the evolution and kinetics of electrodes to be understood by employing single‐particle measurements. This concept aims to provide an overview of the update of single‐particle measurements in related electrochemical processes. Furthermore, the challenges and prospects for the development and application of single‐particle measurements are also discussed. [ABSTRACT FROM AUTHOR]

For clarifying the electrochemical deposition mechanism of corrosion-resistant aluminum coating on surface of cast iron , the aluminum coating was electrodeposited on cast iron surface in AlCl3-[EMIM]Cl ionic liquid, and the deposition electrode process and nucleation growth mechanism of aluminum electrochemical coating on surface of cast iron were studied by cyclic voltammetry and chronoamperometry. Subsequently, aluminum coating was prepared by constant current density electrodeposition, and the effect of the current density and deposited time on the corrosion resistance of cast iron deposited with aluminum coating was investigated by the AC impedance, polarization curve and salt spray test methods. Results showed that the precipitation overpotential of aluminum on the surface of cast iron was close to zero. The deposition was dominated by the mass transfer process, and the nucleation confirmed with three-dimensional instantaneous nucleation model. Comparing the cast iron sample, the self corrosion potential of the cast iron sample deposited aluminum coating shifted negatively, and the corrosion current also became smaller than that of cast iron. Moreover, the deposition current density was the decisive factor affecting the corrosion resistance of cast iron. With the increase of current density, the corrosion resistance of cast iron increased. The corrosion current value of the cast iron sample deposited aluminum coating under constant current density 30 mA/cm2 was lower one order than that of the cast iron substrate. The aluminum coating deposited for 20 min possessed small crystal grains and excellent corrosion resistance.

Innovation of highly active cathode is of great significance to the development of protonic ceramic fuel cells (PCFCs). Herein, tailoring oxygen vacancies in Zn-doped Ba 0·95 La 0·05 FeO 3−δ (BLFZ) perovskite is proved to be beneficial for promoting the formation of proton defects. Hydration ability of the triple conducting BLFZ perovskites is confirmed by electrical conductivity relaxation (ECR). The results demonstrate that BLFZ exhibits a proton surface exchange coefficient of 1.34 × 10−3 cm s−1 at 600 °C, which greatly extends active sites from the electrolyte/cathode interface to the entire electrode. Mechanism and process elementary steps of the oxygen reduction reaction (ORR) of BLFZ-BaCe 0.7 Zr 0·1 Y 0.1 Yb 0.1 O 3−δ (BCZYYb) are detailedly studied. It is found that the rate-determining step of ORR is surface dissociative adsorption of oxygen on BLFZ-BCZYYb cathode. A maximum power density of 673 mW cm−2 at 700 °C is achieved and BLFZ-BCZYYb based single-cell shows no obvious degradation at 600 °C for 200 h. The good performance is ascribed to the rapid proton diffusion of BLFZ-BCZYYb composite electrode by regulating the oxygen vacancies. • Zn-doped Ba 0·95 La 0·05 FeO 3−δ (BLFZ) increases the formation of oxygen vacancies. • The hydration ability of BLFZ is confirmed by electrical conductivity relaxation. • BLFZ exhibits a proton surface exchange coefficient of 1.34 × 10−3 cm s−1 at 600 °C. • The rate determining step of oxygen reduction reaction of cathode is revealed. [ABSTRACT FROM AUTHOR]

The corrosion and the kinetics of electrode processes on a St3 steel with a superhydrophobic coating based on laser texturing of the surface and subsequent hydrophobization with fluorooxysilane (wetting angle is 165° ± 2° and roll angle is 3° ± 1°) in a highly mineralized chloride medium (50 g/L of NaCl) without and in the presence of hydrogen sulfide as an additive (400 mg/L) are studied. The influence of the duration of exposure of electrodes in solution (0.25–96 h) on the kinetics of electrode processes and the corrosion rate of steel is considered. The superhydrophobic coating on steel without hydrogen sulfide decreases the corrosion rate by a factor of 67, 13, and 2 after 0.25, 24, and 48 h exposure in a chloride solution. The cathodic process slows down in time and the anode process accelerates; this is especially important in the case of electrodes with a hydrophobic coating. The steel with a superhydrophobic coating in the presence of hydrogen sulfide in a chloride solution has more than an order of magnitude low corrosion rate compared to unprotected samples during 96 h exposure of electrodes. In this case, there is a decrease in anodic reaction rate and an increase in cathodic one in comparison with a solution without hydrogen sulfide. The corrosion process proceeds under anodic control. [ABSTRACT FROM AUTHOR]

The electrochemically mediated amine regeneration (EMAR) for CO 2 capture presents a promising CO 2 capture approach. However, there is a lack of systematic research on the EMAR electrode process, particularly regarding the diffusion of Cu2+ and [Cu-Am]2+, the characteristics of electrode reactions, and the impact of desorbed CO 2 bubbles on electrode process. In this work, we investigated the Cu-EDA based EMAR process by the combination of electrochemical measurements and multi-physics simulation. The experimental results revealed that the anode process is controlled by both mass transfer and charge transfer process, while the mass transfer process in the cathode process is the rate-controlling step. A lower anode copper loading and a higher cathode copper loading are conducive to the EMAR process. A reasonable simplification method for the electrode process was proposed by referencing the equilibrium reactive model results of Cu(II)–EDA–CO 2 –H 2 O system. A multi-physics model was constructed using COMSOL software, which coupled the Tertiary Nernst-Planck model and the Bubbly Flow model to simulate the complex electrode process and its effectiveness has been verified. Simulation results show that the formation of CO 2 bubbles has a negative impact on the electrode process, while the disturbance caused by the bubbles may have a certain promotion effect on the electrode process. The CO 2 desorption and the desorption rate is greatly affected by the the applied potential, and the desorption energy consumption mainly keeps a linear relationship with the applied potential. This work supposes to provide an effective guidance for the improvement of the vital electrodes process of the EMAR system. [Display omitted] • Combined experimental and computational method is used to study electrode process. • A chemistry equilibrium model of Cu(II)–EDA–CO 2 –H 2 O was developed. • A model simplification method for the complex electrode process is proposed. • A multi-physics model for the EMAR system is implemented in COMSOL. [ABSTRACT FROM AUTHOR]

With the expanding applications, concerns about the charging safety of lithium-ion batteries (LIBs) have become more significant. In this paper, the constant-current (CC) overcharge electrode process of pouch LiCoO2/graphite batteries are analyzed at 0.25 C, and then, a self-protection mechanism for decreasing the overcharge risk of batteries is evaluated. As for the batteries passing the safety test, their typical overcharge behaviors show the battery voltage and temperature begin to dramatically increase to about 5.2 V and 65 °C from about 155% state of charge (SOC) and then decrease slowly after a short fluctuating period. The element analysis of two electrodes and separator reveals that besides the well-known metal lithium, cobalt precipitation pierces the separator and subsequently forms an internal micro-short circuit at about 155% SOC to consume the charge energy and subsequently avoid the overcharge explosion and ignition. As a conclusion, a self-protection mechanism based on an internal micro-short circuit model, which is closely related with the deposited electric lithium and cobalt and the separator porosity, is proposed and experimentally verified. These results offer an idea and method to decrease the CC overcharge risk of LIBs and can advance the safe application of LIBs. [ABSTRACT FROM AUTHOR]

• The application of scanning probe microscopy in interfacial electroanalysis is reviewed. • The interfacial reaction mechanism in energy systems is discussed in-depth. • The detection of the electric double layer and space charge layer is summarized. The electrochemical reaction mainly occurs at the electrode/electrolyte interface in the electrochemical system. For a fundamental insight into the interfacial reaction mechanism, in situ/operando analysis of the interfacial evolution at the microscale is essential. Scanning probe microscopy (SPM), noted for its high spatial resolution, real-time imaging, and multifunctional detection, is considered as one of the most important in situ analytical tools for the electrochemical interfaces from the atomic/molecular scale to the nanoscale. This review first introduces the brief principles of typical SPM, such as scanning tunneling microscopy, atomic force microscopy, and scanning electrochemical microscopy. The applications of in situ SPM in surface and interface analysis for electrochemical energy systems, including electrocatalysts and energy storage batteries, are then presented. In addition, in situ detection of the electric double layer and space charge layer is further discussed. Challenges and future developments in the field are proposed in the outlook. [ABSTRACT FROM AUTHOR]

A review emphasized on the electro-desulfurization mechanism of sulfides as cathodes or anodes in molten salts. [Display omitted] • The research advance of metal or alloy prepared by molten salt electro-desulfurization is reviewed for the first time in this paper. • This review provides a comprehensive insight into the electrode reaction mechanism of various metal sulphides in molten salts. • The challenges in molten salt electro-desulfurization technology are summarized and the future research direction is pointed out. Sulfide is one of the most abundant minerals in the earth's crust and a major raw material for metal extraction. The traditional pyrometallurgy or hydrometallurgy process is relatively lengthy, and will produce CO 2 and SO 2 with greater hazards for environment. Electro-desulfurization is a metal extraction method developed in the past 20 to 30 years, which is considered to be an environmentally friendly and simple process. In electro-desulfurization process, sulfide is used as electrode and raw material, and molten salt is used as electrolyte. Metal and elemental sulfur are extracted at the cathode and anode respectively after current is introduced, meanwhile CO 2 and SO 2 are not produced. In this paper, the recent research of electro-desulfurization in molten salts is summarized, including the electrode reaction process when sulfide is used as cathode or anode, electrolytic products and factors affecting current efficiency and energy consumption. It is expected to provide suggestions for future direction and enhance the theoretical support for the clean development of sulfides through the comprehensive analysis of molten salt electro-desulfurization process. [ABSTRACT FROM AUTHOR]

Keywords: electrocatalysis; electrochemical energy storage; electrochemistry; electrode process; single-particle measurements EN electrocatalysis electrochemical energy storage electrochemistry electrode process single-particle measurements 1 1 1 02/03/23 20230201 NES 230201 In recent years, single-particle measurements have been applied to electrochemical energy storage as well as electrocatalysis and have led to great achievements in understanding the evolution and kinetics of electrodes. Frontispiece: Single-Particle Measurements: A Powerful Method for Investigating Electrochemical Reactions Electrocatalysis, electrochemical energy storage, electrochemistry, electrode process, single-particle measurements. [Extracted from the article]

LiFePO/C was prepared via solid state reaction and characterized with X-ray powder diffraction and charge-discharge test. As-prepared LiFePO/C has a triphylite structure and exhibits an excellent rate capability and capacity retention. Electrochemical impedance spectroscopy (EIS) was applied to investigate LiFePO/C (0< x<1) electrode on temperature variation. The valid equivalent circuit for EIS fitting was determined which contains an intercalation capacitance for Li+ ion accumulation and consumption in the electrode reaction. The surface layer impedance needs to be included in the equivalent circuit when LiFePO/C is deeply delithiated at a relatively high temperature. EIS examination indicates that a temperature rise leads to a better reversibility, lower charge transfer resistance, higher exchange current density J0 and greater Li+ ion diffusion coefficient for the LiFePO/C electrode process. The Li ion concentration in LiFePO/C is potential to impact the Li ion diffusion coefficient, and a decrease in the former results in an increase in the latter. [ABSTRACT FROM AUTHOR]

Internal spacing of electrodes is a key point for controlling electron-transfer (ET)-related phenomena. However, their disordered porous structures often prevent the observation of microscopic effects. It hampers the development of modern electrochemical theories. The development of model porous electrodes therefore provides an ideal platform to discover intriguing fundamental principles of electrode processes. We developed a new synthetic strategy for all-oxide monolithic ruthenium dioxide (RuO 2 )/antimony-doped tin oxide (ATO) electrodes with a controlled hierarchically porous structure and oxide-oxide heterojunction. The use of the obtained RuO 2 /ATO electrodes as model electrodes suppressed influences related to different mass diffusion efficiencies between electrodes with heterojunctions of different types. Then, we showed unconventional oxide-oxide heterojunction effects, improving reversible Li + -coupled electron-transfer properties using model electrodes constituted of various nanostructured (nano-) RuO 2 on porous ATO. In addition to the superior electrochemical properties of the nano-RuO 2 /ATO heterojunction, the quasi-two-dimensional (2D) RuO 2 /ATO heterojunction led to improved specific capacity at a high rate and longer cycle life. We anticipate that this oxide-oxide heterojunction effect and developed all-oxide model porous electrodes can provide a path to develop advanced reversible energy storage devices.

Kinetic isotope effect (KIE) is a common physicochemical effect to elucidate complicated microscopic reaction mechanism in biological, chemical and physical systems. In particular, the exchange of hydrogen to deuterium is a standard approach to investigate kinetics and pathways of a wide spectrum of key reactions involving proton transfer. However, KIE in electrocatalysis is still challenge. One main reason is because of high sensitivities of electrochemical systems to impurities. Aiming to establish an appropriate approach to observe KIE in electrocatalysis, we investigated KIE in oxygen reduction reaction with platinum electrodes, which is well-known to be sensitive to impurity, by comparing electrochemical properties in fully deuterated ultrapure electrolytes and high purity but not ultrapure grade solutions. This experimental plan is based on the fact that D 2 O is usually used in electrochemical systems without additional purifications to reach an ultrapure grade. In the conclusion, the KIE in electrode processes in these systems can be strongly influenced by a purity of a deuterated electrolyte, especially in the case of alkaline conditions. Therefore, additional purifications of D 2 O is indispensable to study KIE in electrocatalysis. This work shows a method to observe a reliable KIE in electrocatalysis, and therefore, provides a general approach to investigate complicated electrode processes. • Ultrapure heavy water is key for kinetic isotope effect (KIE) measurements in electrocatalysis. • KIE in alkaline solutions are strongly affected by impurities. • Additional purification to obtain Milli-Q grade heavy water is indispensable to measure reliable KIE. [ABSTRACT FROM AUTHOR]

An EC-CE-C 4 D flow system was applied to the investigation of electrocatalytic processes by monitoring carboxylic acids formed during the electro-oxidation at various potentials of primary alcohols (mixture of 1 mmol/L of ethanol, n-propanol, n-butanol and n-pentanol) in acidic, neutral and alkaline media. The electro-oxidation was carried out on gold and platinum disk electrodes (3 mm of diameter) in a thin-layer electrochemical flow cell. Products were sampled 50 μm apart from the electrode directly into the capillary. All the generated carboxylates were determined in near real time (less than 2 min) by CE-C 4 D in counter-flow mode, with Tris/HCl buffer solution (pH 8.6) as BGE. Long sequences of 5-min experiments were run automatically, exploring the applied potential, electrolysis time and solution composition. Electro-oxidation at 1.5 V (versus Ag/AgCl quasi-reference) during 50 s in acidic medium was found appropriate for both Pt and Au electrodes when the determination of alcohols after derivatization is intended. A noteworthy selectivity effect was observed on the Au electrode. The signal corresponding to pentanoate is similar on both electrodes while the signal of ethanoate (acetate) is four times larger on gold than on platinum. The carboxylate signals were lower in alkaline medium (below the determination limit on Pt) than in acidic and neutral media. On gold, the formation of carboxylates was anticipated (0.85 V in alkaline medium versus 1.40 V in neutral medium). The automatic online monitoring of electrochemical processes by EC-CE-C 4 D holds great potential to investigate ionic/ionizable intermediates/products of new electrocatalysts and/or alternative fuels., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The material choice for efficient electrocatalysts is limited because it is necessary to be highly active as well as highly stable. One direction to solve this issue is to understand elementary steps of electrode processes and build an unconventional strategy for a conversion of inert and, therefore, stable materials into efficient catalysts. Herein, we propose a simple concept for obtaining catalysts from inert and hence stable materials by forming their heterojunctions, namely, covering inert Au with corrugated carbon-nitrogen-based two-dimensional porous frameworks. It shows more than 10 times better activity for the hydrogen evolution reaction than for the pure Au surface, and it also demonstrates the high catalytic activity for the oxygen reduction reaction (ORR) via an effective four-electron reduction mechanism, which is different from the usual two-electron reduction typical for ORR on Au surfaces. This activity induced by formation of a heterojunction was analyzed by a conjugation of computational and experimental methods and found to originate from alternative efficient reaction pathways that emerged by the corrugated porous framework and the Au surface. This work provides not only the method for creating active surface but also the knowledge on elementary steps of such complicated multielectron transfer reactions, thereby leading to intriguing strategies for developing energy conversion reactions based on materials which had never been considered as catalysts before.