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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]

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]

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]

The effect of oxygen partial pressure on anode reaction of steam electrolysis using SrZrCeYO (SZCY-541) proton conducting electrolyte was investigated by AC impedance measurement in this work. The anode reaction was enhanced by increasing oxygen partial pressure, and this result was opposite to the expectation from the conventional anode reaction (water splitting reaction). The increase in the electrode reaction conductivity with oxygen chemical potential was proportional to $$ {P_{{\mathrm{O}}_2}}^{1/4} $$ at 600 °C and at higher oxygen partial pressure region of 700 and 800 °C, suggesting the possibility that the enhancement is caused by the increase in hole concentration on the electrolyte surface near the anode. [ABSTRACT FROM AUTHOR]

A LiFePO/C sample was prepared via solid state reaction and characterized with X-ray powder diffraction, scanning electron microscopy and charge-discharge test. Conductive carbon and highly crystallized LiFePO were embedded in each other to form the as-prepared LiFePO/C, which exhibited an excellent rate capability and capacity retention. The LiFePO/C electrode reaction was investigated by the method of medium scan rate cyclic voltammetry (CV) under temperature variation. The limit values for the CV redox peak potentials of the LiFePO/C electrode scanned at different rates were obtained by curve fitting. The reversibility of the LiFePO/C electrode was studied and found to be both scan rate and temperature dependent. A higher temperature led to a higher critical CV scan rate for a reversible LiFePO/C electrode. In the electrode process, a higher temperature resulted in a smoother Fe/Fe redox reaction, better reversibility, lower R, smaller charge transfer resistance and higher Li ion diffusion coefficient at the cathode of the LiFePO/C. [ABSTRACT FROM AUTHOR]

Gravity electrode is an electrode system, which is operated in a high gravity field arising from centrifugal force, and allows us to measure the change in the partial molar volume between product and reactant ions in an electrode reaction. In this paper, in the presence of a large amount of supporting electrolyte, the partial molar volume of each active ion in equilibrium state is first formulated on the basis of thermodynamics. Then, the change in the partial molar volume applicable to gravity electrode is derived. Therefore, it is possible to validate the equation obtained for gravity electrode by the thermodynamic measurement. [ABSTRACT FROM AUTHOR]

The reliability of the measurement of the change in partial molar volume between product and reactant ions measured by gravity electrode (GE) was examined by the thermodynamic measurement of pycnometer (PM). Since the PM method requires an experimental equation of the apparent molar volume to calculate the partial molar volumes of the individual ions, the most suitable experimental equation must be first determined. As a test reaction for the experiment, oxidation of ferrocyanide (FERO) ion to ferricyanide (FERI) ion was adopted. After fitting several experimental equations to the data of the apparent molar volumes by the PM method, the calculated changes in the partial molar volume were compared with the data of the GM method. Then, it is concluded that the polynomial with a degree of 3 of the logarithm of the molality of the FERO ion suggests the most suitable equation. As a result, the reliability of the GE method was also experimentally validated. [ABSTRACT FROM AUTHOR]

The formation of copper nanoparticles in a KU-23 15/100 sulfocation-exchanger was studied. It was demonstrated that the formation of copper as assemblies from nanoparticles with sizes of 3 to 10 nm during chemical synthesis is determined by the nature of the polymer and does not depend on the amount of metal precipitated. The percolation threshold of electron conductivity, which determines the formation of electrochemical activity of nanocomposites, was discovered. It was determined that the electroreduction of molecular oxygen takes place on the surface and in the subsurface zone of a nanocomposite grain, the size of which is determined by the local concentration of metal particles in the ion-exchanger phase. [ABSTRACT FROM AUTHOR]

Reverse electrodialysis (RED) is a method for directly extracting electrical energy from salinity gradients, especially from sea and river water. For the commercial implementation of RED, the electrode system is a key component. In this paper, novel electrode systems for RED were compared with existing systems on safety, health, environment, technical feasibility and economics. Systems with inert DSA-type electrodes and a NaCl–HCl supporting electrolyte with the reversible Fe2+/Fe3+ redox couple or the [Fe(CN)6]4–/Fe(CN)6]3– couple achieved the highest ranking. Improvements of the electrode system are also discussed like the use of special stable metal electrodes, graphite electrodes, other reversible redox couples, capacitive electrodes and electrolytes with carbon particles. [ABSTRACT FROM AUTHOR]

Two electrochemical systems based on sol-gel silica matrix impregnated with organic solvent were prepared and studied. The first one is composed of tetramethylorthosilicate based material filled with ferrocene solution in polar solvent: propylene carbonate. Electrodes are immersed in this solid electrolyte during all stages of sol-gel process. Despite of the lack of the extra added salt, by using ultramicroelectrode, undistorted electrochemical signal corresponding to the electrooxidation of the ferrocene was obtained. Its diffusion coefficient within the sol-gel matrix depends on the time elapsed after gelation and it is not much below that in salt solution in the same solvent. The second system is based on graphite dispersion in hydrophobic sol-gel silicate matrix. This material was filled with mixture of liquid butylferrocene and hexadecane. After immersion in aqueous salt solution it serves as working electrode. The electrochemical signal corresponding to the electrooxidation of the butylferrocene within organic phase was obtained. Probably the electrode process occurs at three phase (carbon/organic phase/aqueous phase) junction and it is accompanied by anion transfer through the liquid-liquid interface. [ABSTRACT FROM AUTHOR]

The electrochemical behaviour of the Np3+/Np couple in the LiCl–KCl eutectic salt was investigated by electromotive force measurements, cyclic voltammetry and chronopotentiometry in the temperature region between 723 and 823 K. The standard redox potential of the Np3+/Np couple vs Ag/AgCl (1.00 wt %) was measured and given by the equation, ENp = −2.0298 + 0.000706 T, where E is in V and T in K. The electrode reaction of the Np3+ /Np ° = −2.0298 + 0.000706 T, where E is in V and T in K. The electrode reaction of the Np3+/Np couple was almost reversible under the conditions studied. The diffusion coefficient of Np3+, DNp 3+, in the LiCl–KCl eutectic melts between 723 and 823 K was represented by the equation, DNp 3+ = 2.22 × 10−6 − 6.88 × 10−9 T + 5.60 × 10−12 T2 cm2 s−1. The adsorption and desorption peaks of Np at the Mo working electrode caused by underpotential deposition were also observed in the cyclic voltammograms, and the work function of Np was evaluated as 3.04 eV by peak analysis of the cyclic voltammograms. [ABSTRACT FROM AUTHOR]

The oxygen dissolution in metallic zirconium has been investigated by electrochemical and X-ray techniques. The mechanism of the zirconium oxidation process is proposed. It is shown that during the first stage of the process, oxygen dissolves in the metal matrix acting as an electron donor. The region of oxygen solid solutions in zirconium reaches 25 at.% oxygen. After oxygen saturation of the metal surface the second stage starts; zirconium oxides form. [ABSTRACT FROM AUTHOR]

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