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This work shows the technical feasibility to obtain uranium tetrafluoride through an electrochemical mercury cell. This technique represents a custom scaling-up methodology from our previous studies to obtain UF4 using the dropping mercury electrode cell. The UF4 products were obtained from natural UF6 gas, which was hydrolyzed to obtain a 50 g/L UO2F2 solution. The electrolysis cell was made using a mercury reservoir, to reach UF4 production rates of 1 Kg UF4/day. This custom design allowed a stable UF4 production thanks to the mercury cathode, which do not permit the accumulation of solid products in its surface. The cell was tested using current densities from 5.000 to 17.500 A/m2 and temperatures from 25 to 65 °C. The maximum current efficiency achieved under these conditions was 80%. The UF4 powders possessed spherical morphology, with diameters between 20 – 80 μm. Compared to the SnCl2 precipitation, this process did not allow preferential growth of the precipitates. This improved the compaction of the UF4 – Mg powders mixtures, with densities between 3.0 – 3.5 g/cm3. The purity of the UF4 products was over 98%.

A technology for cyclic generation of hydrogen and oxygen using electrodes made of variable valency material that does not need the use of separating ion-exchange membranes is presented. The technological solution enables to fabricate electrolyzers for uninterrupted producing high-pressure hydrogen with reduced energy intensity of the production. The total work for compressing 1 m3 of hydrogen and 0.5 m3 of oxygen has been estimated. Results of investigation of influence of discrete supply of DC current to the electrolysis cell, in order to improve the processes of gas evolution and to simplify the power systems of the electrolysis plant, have been considered. There is also considered an electrolysis installation equipped with a thermosorption compressor in which LaNi5 is used as a hydride-forming compound. The comparative characteristics of the developed electrolyzer and the currently used hydrogen generators are given.

To promote the viability of commercial solid oxide fuel cell (SOFC), developing novel oxygen electrodes with high electrochemical activity is essential. Herein, a series Ruddlesden-Popper oxides, Sr3−xLaxFe2O7−δ (SLFx), are successfully synthesized and evaluated as potential cathode materials for SOFC. The oxygen desorption behavior, electrochemical activity and oxygen reduction reaction (ORR) kinetics of the SLFx cathodes are systematically discussed. The Sr2.9La0.1Fe2O7−δ (SLF10) cathode exhibits highest oxygen vacancy concentration and excellent electrocatalytic performance, as evidenced by a low polarization resistance of 0.14 Ω cm2 and high maximum power density of 0.77 W cm−2 at 700 °C. From electrochemical impedance spectra and distribution of relaxation times analysis, the oxygen adsorption/desorption process is the rate-limiting step toward ORR at the cathode interface. Furthermore, SLF10 shows considerable polarization overpotentials in both SOFC and solid oxide electrolysis cell (SOEC) modes, indicating that SLF10 is a promising bifunctional electrode for electrocatalytic oxygen reaction.

We describe the generation of bulk nanobubbles using electrolysis of aqueous alkaline, neutral, or acidic electrolytes. The technique can be used in either an undivided electrolytic cell to generat...

The work aims to develop digital control and management systems of copper electrolytic refining processes when addressing energy efficiency issues. Thermal imaging scanners can be used to monitor the process state of an electrolytic cell. In this regard, the experience in the automation and control systems of OJSC Novgorod Metallurgical Plant was considered. Mathematical research methods and a stochastic model developed in the MatLab software were used. This model was applied at the Lao Cai copper-smelting plant (Vietnam). The proposed algorithm is based on the temperature variation in electrolyte depending on the heating of cathode and anode sections during short circuits due to dendritic growth, as well as process disturbance time. The algorithm was developed using the Visual BasicScript programming languages. The temperature rise in short circuit areas was recorded using a thermal imaging scanner immediately after the colour change of the cathode surface. It was shown that the duration of a short circuit depends on the amount of sludge deposited in an electrolytic cell. The sludge formed following the destruction of intergrown dendrites contains precious metals. The developed measures, along with those of digitisation, are necessary for effective management, taking into account the functional and kinetic characteristics of the copper refining process. The proposed solutions and control algorithms will allow remote access systems with augmented reality elements when creating a digital twin. This will reduce the specific power consumption by 20 –25% while decreasing the number of electrode short circuits. Controlling the composition and level of electrolyte and sludge will reduce material losses and maintain the concentration of noble metals in the electrolyte. To improve the control quality of automation during the electrolytic production of cathode copper, a number of technical measures were proposed that provide additional points of control to expand the process database. Furthermore, the proportion of manual periodic measurements of process parameters is reduced.

Water electrolysis is a process that can produce hydrogen in a clean way when renewable energy sources are used. This allows managing large renewable surpluses and transferring this energy to other sectors, such as industry or transport. Among the electrolytic technologies to produce hydrogen, proton exchange membrane (PEM) electrolysis is a promising alternative. One of the main components of PEM electrolysis cells are the bipolar plates, which are machined with a series of flow distribution channels, largely responsible for their performance and durability. In this work, AISI 316L stainless steel bipolar plates have been built by additive manufacturing (AM), using laser powder bed fusion (PBF-L) technology. These bipolar plates were subjected to ex-situ corrosion tests and assembled in an electrolysis cell to evaluate the polarization curve. Furthermore, the obtained results were compared with bipolar plates manufactured by conventional machining processes (MEC). The obtained experimental results are very similar for both manufacturing methods. This demonstrates the viability of the PBF-L technology to produce metal bipolar plates for PEM electrolyzers and opens the possibilities to design new and more complex flow distribution channels and to test these designs in initial phases before scaling them to larger surfaces.

A free-standing catalyst electrode for urea electrolysis was synthesized by electroless plating of NiCoB alloy onto a flexible carbon felt. The synthesized NiCoB@C catalyst exhibited porous and partially amorphous metallic structure depending on its composition, as analysed by XRD, XPS, and TEM; thus, NiCoB@C catalyst showed a high catalytic activity for urea oxidation reaction as well as hydrogen evolution reaction. The required cell voltage in the electrolysis cell with NiCoB@C as anode and cathode was as low as 1.34 V for the current densities 10 mA cm−2. Similar performance of the urea electrolysis for H2 production using 0.33 M urea and a fresh urine in 1 M KOH was observed. The result indicated that NiCoB could be incorporated on to carbon felt by electroless plating, and it could be used as free-standing bifunctional electrodes for urea electrolysis using urea as well as urine.

As a new type of energy conversion device, solid oxide electrolysis cell (SOEC) has attracted much attention in recent years because of its advantages such as high efficiency and unlimited capacity. At present, SOEC mainly has such issues as the element diffusion or delamination at oxygen electrode/electrolyte interface under high oxygen partial pressure, which limits its operation lifetime. In this paper, La1-xCaxFeO3-δ materials without Sr and Co were prepared by glycine-nitrate combustion method as SOEC oxygen electrodes. It is found that La0.6Ca0.4FeO3-δ (LCF64) has excellent electrical conductivity and has a coefficient of thermal expansion matching with SSZ electrolyte. The hydrogen electrode supported single cells with structure of LCF64-GDC (6:4) | GDC | SSZ | NiO-SSZ active layer | NiO-YSZ transition layer | NiO-YSZ supported layer were prepared by tape casting and co-firing method showed good electrochemical performance in SOEC mode. The electrolysis current density is 457.46 mA cm-2 with 60% H2O-H2 atmosphere and 1.3 V applied voltage at 800 °C. During the constant voltage (1.3V) electrolysis process, the SOEC showed an acceptable stable current density of approximate 280 mA cm-2 for more than 60 h.

Electrochemical ammonia (NH3) production, an alternative to the energy-intensive Haber process, has been extensively studied based on the basis of N2 fixation; a high-yield production is hindered b...

Water treatment sludge from coagulation process in Indonesia is generally directly discharged into rivers. This condition may negatively affect the environment and human health. The high concentration of aluminum in the sludge can be potentially recovered as alum coagulant. Laboratory-scale electrolysis using cation exchange membrane (CEM) has proven to increase purity of recovered alum. The use of CEM for alum recovery in a pilot-scale can be used to estimate investment, operation, and maintenance costs in its application. This study aims to examine effectiveness of the pilot-scale electrolysis using CEM for alum recovery from water treatment sludge. The electrolysis cell used plate acrylic material with a batch recirculation reactor system. Feed tank capacity was 5 L with electrolysis cell volume of 400 mL. The cross-sectional area of the electrode was 48 cm2. The electrolysis was operated for 10 h. The electric currents used in this study were 400, 600, and 800 mA. Conductivity, pH, total dissolved solids, aluminum, iron, and manganese were measured every hour, as well as concentrations of zinc, lead, chromium, and copper at the initial and end of electrolysis. Results showed that optimum current density was 12.5 mA/cm2 with alum recovery efficiency of 68.06% at specific energy consumption of 53.47 kWh/kg. The recovered alum was free from organic impurities, and the main metal component was aluminum with high percentage (91.23%). The electrolysis effectiveness in alum recovery was influenced by the ratio of electrode area and electrolysis cell volume, operation time, and current density.

Summarization: This study describes the fabrication of ultrafast laser-induced periodic nanostructures on Nickel sheets and their use as cathodes in alkaline electrolysis. For the first time, to the best of our knowledge, laser-nanostructured Ni sheets were used as cathode electrodes in a custom-made electrolysis cell at actual, Hydrogen producing conditions, and their efficiency has been compared to the untreated Nickel sheets. The electrochemical evaluation showed higher Jpeaks, lower overpotential, and enhanced double-layer capacitance for the nanostructured electrode. A decrease in the Tafel slope was also found for the nanostructured electrode. The hydrogen production efficiency was found to be 3.7 times larger for the laser-nanostructured Nickel electrode, which was also confirmed by current-time measurements during electrolysis. Also, a novel approach is proposed to improve the stability of the current density during electrolysis and, therefore, the hydrogen production process by about 10%. Presented on: International Journal of Hydrogen Energy

Metal nanoparticles anchored on perovskite through in situ exsolution under reducing atmosphere provide catalytically active metal/oxide interfaces for CO2 electrolysis in solid oxide electrolysis cell. However, there are critical challenges to obtain abundant metal/oxide interfaces due to the sluggish diffusion process of dopant cations inside the bulk perovskite. Herein, we propose a strategy to promote exsolution of RuFe alloy nanoparticles on Sr2Fe1.4Ru0.1Mo0.5O6−δ perovskite by enriching the active Ru underneath the perovskite surface via repeated redox manipulations. In situ scanning transmission electron microscopy demonstrates the dynamic structure evolution of Sr2Fe1.4Ru0.1Mo0.5O6−δ perovskite under reducing and oxidizing atmosphere, as well as the facilitated CO2 adsorption at RuFe@Sr2Fe1.4Ru0.1Mo0.5O6−δ interfaces. Solid oxide electrolysis cell with RuFe@Sr2Fe1.4Ru0.1Mo0.5O6−δ interfaces shows over 74.6% enhancement in current density of CO2 electrolysis compared to that with Sr2Fe1.4Ru0.1Mo0.5O6−δ counterpart as well as impressive stability for 1000 h at 1.2 V and 800 °C.

A promising strontium and cobalt-free ferrite Pr1-xCaxFeO3-δ (PCF, x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) has been synthesized successfully by glycine-nitrate combustion method and used as the air electrode of solid oxide electrolysis cell (SOEC) for steam electrolysis. The crystal structure and electricity conductivity of PCF are investigated in detail. According to the conductivity test, Pr0.6Ca0.4FeO3-δ (PCF64) with higher conductivity is selected as the air electrode to preparing the single cell with structure of PCF64|GDC|SSZ|YSZ-NiO. Under SOFC mode, the maximum power density of the single cell is 462.93 mW cm−2 at 800 °C with hydrogen as fuel. Under SOEC mode, the current density reaches 277.14 mA cm−2 and the corresponding hydrogen production rates is 115.84 mL cm−2 h−1 at 800 °C at 1.3 V. In the 10 h short-term stability test, the cell shows good electrolysis stability.

The cathode of solid oxide electrolysis cell (SOEC) is used as a place for fuel gas electrolysis/co-electrolysis, and its performance significantly affects the efficiency of electrolysis. La0.75Sr0.25Cr0.5Mn0.5O3-δ (LSCM) is a potential SOEC cathode material due to its excellent redox stability and catalytic ability for fuel gas. An electrolyte-supported LSCM/YSZ/LSCM symmetrical cell and LSCM/YSZ/LSCF full cell were prepared and evaluated for high temperature steam electrolysis, carbon dioxide electrolysis and co-electrolysis. Under the applied voltage, both the symmetrical electrolysis cell and the full electrolysis cell can effectively electrolysis CO2 and H2O. During the experiment, by changing the operating conditions, the influence of different temperatures, concentration of CO2 and H2O, and applied voltage was studied to evaluate the electrochemical performance of SOEC. In order to further verify the long-term performance of SOEC, constant voltage was applied for co-electrolysis of CO2 and H2O. During the entire electrolysis process, the SOEC showed a stable current density of 0.1A·cm-2 under the applied voltage 1.5 V for more than 24 h.

The electrochemical production of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (ORR) can realize the customer-oriented onsite synthesis of H2O2 in a green and sustainable method. The ongoing challenge that needs to be solved is the fabrication of robust electrocatalysts of excellent performance. In this work, C60 was selected as a precursor due to its uniform structure and abundant pentagon rings. Thanks to the strong interaction between C60 and thiophene, after heteromolecule assembly in the liquid reaction and subsequent reconstruction of the carbon topological structure in solid calcination, C60 was successfully transformed into polyhedral carbon micro-nano shells (PCMNS) with an effective pore structure for the first time, which exhibited excellent capacity for production of H2O2 via two-electron ORR, especially in neutral media. In addition to the high onset potential (0.49 V vs reversible hydrogen electrode (RHE)) and low Tafel slope (72 mV dec-1), its selectivity reached >90% within the potential range of 0.30-0.45 V and maintained >80% after constant potential electrolysis for 10 h. The yield rate of H2O2 was 1102.5 mmol gcat-1 h-1, determined by an H-type electrolytic cell, which was one of the highest values of metal-free carbon-based ORR electrocatalysts ever reported. Such excellent two-electron ORR performance of PCMNS was attributed to its abundant accessible active sites and hierarchical pore structures.

The quantitative description and theoretical research on the stability of the electromagnetic field interfacial wave in aluminum electrolysis cells are the key to achieving high energy efficiency and operational safety. The magneto-hydrodynamics equations were established based on the theory of electromagnetics and hydrodynamics and applied to a 500-kA cell. The Fourier series expansion and finite element methods were used for modeling and simulation of interfacial stability. Detailed analysis was conducted on wave mode coupling regimes by custom code in MATLAB. Based on the characteristics of total modulus, a modal analysis method was proposed to clarify how anode–cathode distance (ACD) and length-width ratio of cells affected interfacial stability. The results indicate that the stability is enhanced as the increase of ACD for a 500-kA electrolysis cell and the critical ACD is derived as 0.041 m, which is preferable for stabilizing the cell and reducing energy consumption.

Mathematical modeling is the main tool for optimizing the operation of aluminum electrolytic cells. It helps to get answers to important questions to developers of complex systems in the aluminum industry. It contributes to the intensification and improvement of these systems development in the quality with minimal resources and time. One of the main parameters characterizing the process of aluminum electrolysis is the current efficiency, an output indicator that evaluates the efficiency of the aluminum electrolytic cells. The paper proposes to use modeling regression equations for automatic control of the electrolyte temperature according to the statistical parameters of voltage fluctuations. It helps to control the technological process of electrolysis with correction for the melt temperature quickly. The authors propose a mathematical model of the thermal regime of an aluminum electrolytic cell based on an estimation of the relationship between the melt temperature and the main indicators of the electrolysis process (melt temperature and composition, concentration of dissolved alumina, cryolite ratio, anode-cathode-distance (ACD) and voltage fluctuation parameters.

Biogas refining system including methanation reactor and proton-conducting electrolysis cell has been proposed and investigated based on the simulation including mass and heat balance analysis. Based on the calculation results, carbon deposition was predicted to still occur at the cathode outlet even with the gas humidification when a conventional oxide-ion conducting electrolyte is applied to the electrolysis cell due to the enhanced carbon activity caused by oxide-ion transport from the cathode to the anode. In the case of the proton-conducting electrolyte applied solid oxide electrolysis cell, proton transport from the anode to the cathode was found to mainly promote reverse water-gas shift reaction and methanation reaction without any carbon deposition. Even though the calculation results should be verified by comparing with experimental results, the numerical study suggested that the biogas refining system combined with p-SOEC is a promising technology for generating carbon-neutral methane with a strongly suppressed risk of carbon deposition.

Solid oxide fuel cells (SOFCs) are expected to become widespread as an energy conversion technology that can directly produce electrical energy from fuel. Solid oxide electrolysis cells (SOECs) are essentially SOFCs operating in reverse to produce fuel from electricity. The exchange current density is one of the most important parameters to simulate SOEC/SOFC. In this study, experimental data was evaluated as apparent exchange current density and the effects of SOEC/SOFC operation and different electrode materials were discussed.

A high temperature solid oxide electrolysis cell (SOEC) for electrolysis of water is paired with a H-SOEC for hydrogen compression (EHC). SOEC and EHC have been integrated into an electrochemical network (ECN) in a flow-series configuration and then simulated and analyzed. Adding heat and minimizing area specific resistance (ASR) would be highly desirable for further developing highly-efficient SOEC+EHC ECN’s. It is important to note there is a maximum possible heat generation rate with a given ASR when operated below the thermoneutral point. There is a maximal heat addition rate for optimal efficiency of the SOEC, and it is not at thermoneutral. Many developers have expressed interest in the thermal management of electrolyzer cells and in the possible existence of such an optimum. It is important to understand in general that heat removal can allow an increased hydrogen production rate over the thermoneutral path at constant temperature. For this reason, the SOEC+EHC ECN was simulated over a range of currents and ASR’s to determine the heat addition or removal required. If the internal resistance of an SOEC could be lowered sufficiently via the development of new, high-performing materials, the efficiency of hydrogen production could be very high, especially when supplementary heat is provided from solar or other waste heat sources such as nuclear or coal power plants. It is remarkable that a quarter to a third of the energy for the combined high-temperature electrolysis and hydrogen compression system could be provided by solar, nuclear, or coal.

Solid oxide electrolyzer is expected to be an energy storage device using renewable energy to produce useful fuels. Recently there are strong interests on co-electrolysis of CO2-H2O for producing H2/CO syngas, and even for directly producing liquid fuel or hydrocarbon feedstocks. Further increase in activity and stability of the fuel electrode are required for practical application. In this study, CO2 and CO2-H2O electrolysis were investigated using CuFe2O4 (CFO), La0.6Sr0.4Fe0.8Mn0.2O3 (LSFM) and their composites as cathodes. LaGaO3 based oxide was used for electrolyte and Ba0.6La0.4CoO3 was used for anode. It was found that mixing CFO and LSFM was effective for remarkable improvement of the cell performance in co-electrolysis. Effect of varying CO2/H2O ratio in feed gas was also investigated and the product was always enriched with H2 in comparison with the preset CO2/H2O feed gas due to water-gas-shift reaction (WGS reaction, CO + H2O → CO2 + H2). Since the chemical equilibrium of WGS is thermodynamically preferred to H2 production as decreasing operating temperature, temperature dependence of the co-electrolysis performance using CFO-LSFM composite cathode was also studied. The results indicate that the electrolysis performance was decreased, while the H2 product was increased with decreasing operation temperature. However, considering the cell durability, lowering the operating temperature or the applied electrolysis current density (or working voltage) would be preferable. Degradation of electrolysis performance was also discussed by impedance analysis. Overall, the use of the composite oxides as cathode gives very promising electrochemical performance achieved with excellent Faraday’s efficiency (> 95% of theoretical value), operation stability and reversibility in co-electrolysis.

Solid oxide electrolysis cells (SOECs) convert electrical energy to chemical energy stored in H2 and/or CO and has a great potential to become a key enabling technology in the transition towards renewables. The key challenges for the successful commercialization of SOEC are the limited long-term durability and cost. To ensure high production rate and hence reduce the investment cost, operation at high current densities needs to be considered. Conventional Ni/yttria stabilized zirconia (YSZ) fuel electrode supported SOEC cells demonstrate acceptable long-term durability when operated at below 1 A/cm2, with a number of tests running for years. These cells suffer however severe degradation when operated at above 1 A/cm2, where the major degradation phenomena are reported to be delamination of the oxygen electrode, crack formation in the YSZ electrolyte, depletion of Ni in the active Ni/YSZ electrode, deterioration of the Ni-YSZ interface, and formation of ZrO2 nano-particles on Ni surface. A large part of the cell resistance increase is associated with the Ni/YSZ electrode. By introducing Ce0.8Gd0.2O2- d (CGO) nanoparticles into the Ni/YSZ electrode via solution infiltration, we were able to reduce the cell degradation (evaluated based on cell voltages of 0-1000h) from 699 mV/1000h to 66 mV/1000h when operating the cells at 800 oC and 1.25 A/cm2. The CGO nano-particles facilitate the steam splitting reaction at the Ni/YSZ triple phase boundaries (TPB), reduce the electrode polarization and effectively mitigate the microstructural deterioration typically seen in the non-modified Ni/YSZ electrodes. The remaining 66 mV/1000h degradation is mainly associated with formation of a poorly conducting CeAlO3 phase, which is a reaction product between Al2O3 as the sintering aid and the CGO particles on the Ni grains. An effort to break down the CeAlO3 phase was explored, though not successful. Testing the cell with modified Ni/YSZ electrode was extended to one year. A steam supply failure at 4000 h caused certain damage to the cell and resulted in a higher degradation rate in the second half of the one-year test. A counter-balance strategy was successfully tried out by increasing the cell operating temperature to 830 oC eventually. The test was successfully terminated after reaching one year, with cell voltages of 1124 and 1468 mV at the beginning and end of the test, corresponding to an average degradation rate of 40 mV/kh. The current work shows high potential for modifying conventional SOEC cells for use in high current density electrolysis applications.

The spatial distribution of current and temperature plays important role in the electrochemical performance of Solid Oxide Electrolysis Cells (SOECs). Many numerical predictions of current and temperature distribution have been reported, whereas experimental investigations were rare. In this research, we are applying a electrode-segmentation [1] method to investigate the spatial current and temperature variation in a cathode-supported microtubular SOEC. The electrode-segmentation method shows a remarkable current variation among the segments. The current densities of the midstream and downstream segments are smaller than the upstream segment with an increased cell voltage, implying that the cell suffers from water starvation. Besides, the temperature at each segment increases with the voltage increase. The largest current in the upstream segment is observed, which agrees with the largest temperature rise there. The largest temperature gradient happens between the upstream and midstream segments. References Aydin, T. Koshiyama, H. Nakajima, T. Kitahara, Journal of Power Sources, 279, 218-223 (2015).

A significant contributor to carbon and air-pollutant emissions is the steel industry, which is responsible for 2.8 Gt of CO2 annual emissions and accounts for a quarter of industrial CO2 emissions. A significant and valuable by-product of steelmaking is coke oven gas (COG), which is produced from coke-making via high-temperature dry distillation of coal in the absence of oxygen. COG typically consists of 55-60 vol% hydrogen (H2), 23-27 vol% methane (CH4), 5-8 vol% carbon monoxide (CO) and impurities such as H2S and tars [1]. Every ton of coke produced yields 300-360 m3 of COG and an estimated 650 Mt of COG is produced in the steelmaking industry worldwide each year, with up to 50 % re-utilised within steelmaking [2]. However, the rest is flared, contributing to carbon emissions and wasting valuable and useful gases. In this paper, co-electrolysis of simulated COG (CH4/H2 30/70 vol%) with carbon dioxide using a commercially available solid oxide fuel cell (SOFC) was investigated at 750 °C. The electrochemical performance of an anode supported button cell was characterised using open circuit potential measurements, current-voltage curves and electrochemical impedance spectroscopy. The product gas composition was analysed using quadrupole mass spectrometry (QMS). The QMS measurements show that CH4 was initially converted at the open circuit potential into synthesis gas (H2/CO) via dry reforming of CH4 and the reverse water gas shift reaction, yielding a gas mixture composed of 39.2 vol% H2, 38.3 vol% CO2, 22 vol% CO and low levels of unconverted CH4 (see figure). Increasing the voltage from the OCP to 1.4 V caused the CO2 to decrease and the CO to increase, yielding a gas mixture consisting of 42.6 vol% H2, 26.7 vol% CO2 and 29.5 vol% COincreased the synthesis gas content (H2 + CO) of the output gases by 44% relative to the OCP, with the levels of H2 produced increasing by 9% over this voltage range. In addition, the level of unconverted CH4 increased slightly, indicating that the CO2 conversion processes were competing with catalytic dry reforming of CH4. Possible reaction mechanisms are discussed. The I-V and EIS measurements established that cell electrical performance was increased by addition of CO2 through dry reforming and also improved diffusion of the fuel gases through the anode. The effects of COG fuel variability have also been investigated and show that increasing the CH4/H2 ratio from 10/90 vol% to 40/60 vol% of the COG increased the syngas production by 92%. The I-V curve and EIS measurements show that increasing the CH4/H2 ratio decreased the electrical performance of the cell due to prevalent carbon deposition. This work presents a method of efficiently utilising CO2 and suggests SOFC co-electrolysis of COG is an effective way to increase the usefulness and value of this waste gas stream. References: [1] Czachor M, Laycock C, Carr S, Maddy J, Lloyd G, Guwy A,. Co-electrolysis of simulated coke oven gas using solid oxide electrolysis technology. Energy Conversion and Management, 2020;225:113455. 10.1016/j.enconman.2020.113455 [2] Gao R, Zhang C, Kwak G, Lee Y, Chang S. Techno-economic evaluation of methanol production using by-product gases from iron and steel works. Energy Conversion and Management, 2020;213:112819. 10.1016/j.enconman.2020.112819 Figure. The effect of increasing the voltage on the composition of the anode output gases of an anode-supported cell under a 2:2 fuel/CO2 ratio. The fuel composition was 30/70 vol% CH4/H2. The cell temperature was 750 °C. Figure 1

Thin foil based porous transport layers (PTLs) that contain highly structured pore arrays have shown promise as anode PTLs in proton exchange membrane electrolysis cells. These novel PTLs, fabricated with advanced manufacturing techniques, produce thin, tunable, multifunctional layers with reduced flow and interfacial resistances and high thermal and electric conductivities. To further optimize their design, it is important to understand their fundamental impact on the transport of protons, electrons, and liquid/vapor mixtures in the electrode. In this work, we develop a two-dimensional multiphysics model to simulate the coupled electrochemistry and multiphase transport in an electrolysis cell operated with the novel PTL architecture. The results show that larger pores improve access of water to the anode catalyst layer, which is beneficial for both the oxygen evolution reaction and membrane hydration. Larger pore sizes also improve oxygen gas transport from the catalyst layer, because generated oxygen gas is forced to travel in-plane through the anode catalyst layer until it reaches a pore opening that is connected to a channel. The discussed results confirm that the proposed thin foil based PTLs are fundamentally different from conventional PTLs, such as felts or layered meshes. The model developed in this work also provides generalizable insight into fundamental PEMEC phenomena, such as the competition between liquid and gas phase transport, membrane hydration and water management, and nonuniform electrochemical reactions, which are processes relevant to all PEMEC designs.

To keep optimally connected, all electrolysis cell elements is one of the most important design criteria. The optimal distribution of the clamping points is crucial to increasing cell performance. In this work, the compression pressure distribution inside of a 25 cm2 PEM electrolysis cell was evaluated, using different materials: Teflon®, Viton®, ethylene propylene diene monomer rubber (EPDM), and nitrile rubber. Sealing material evaluation was performed taking as performance indicators: total compressed area (%) and compression pressure, for different torques applied. Pressure distribution was obtained by using pressure-sensitive films, analyzing the distribution of pressure points from three-dimensional plots (3D), and quantifying intensities of the images obtained. Results showed that pressure points distribution depends on the stiffness and thickness of the gasket materials. For a tightening torque of 3.70 N m, a pressure of 2.23 MPa is obtained with 85% of the membrane area compressed using nitrile rubber-EPDM gaskets.

Hydrogen production via solid oxide electrolysis cell (SOEC) is world widely concerned with the new energy revolution. The SOEC performance must be enhanced for the practical application. In this study we report a high-performance Ce0.9Co0.1O2-δ-LSM-YSZ (CC-LSM-YSZ) oxygen electrode, in which Ce0.9Co0.1O2-δ nanoparticles are loaded on LSM-YSZ scaffold and characterized by XRD, SEM, O2-TPD and H2-TPR. Under 50% absolute humidity (A.H), the cell with 1CC-LSM-YSZ, 2CC-LSM-YSZ, 3CC-LSM-YSZ and 4CC-LSM-YSZ oxygen electrode delivers a current density of 0.63, 0.94, 1.14 and 1.26A cm−2 at 1.3 V, which is 1.7, 2.5, 3.0 and 3.3 times higher than the blank LSM-YSZ cell, respectively. The hydrogen generation rate of the 4CC-LSM-YSZ cell is as high as 873 m L cm−2 h−1 under 70% A.H. The DRT results demonstrate the accelerated charge transfer reaction on LSM-YSZ-Ce0.9Co0.1O2-δ oxygen electrode. LSM-YSZ-Ce0.9Co0.1O2-δ has the potential for the application of oxygen electrode in SOEC technology.

The adverse effects of global warming and climate change have driven the exploration of feasible routes for CO2 capture, storage, conversion and utilization. The processes related to CO2 conversion in high-temperature electrochemical devices (HTEDs) using dense ceramic membranes are particularly appealing due to the simultaneous realization of highly efficient CO2 conversion and value-added chemical production as well as the generation of electricity and storage of renewable energy in some cases. Currently, most studies are focused on the two processes, CO2 electrolysis and H2O/CO2 co-electrolysis in oxygen-conducting solid oxide electrolysis cell (O-SOEC) reactors. Less attention has been paid to other meaningful CO2-conversion-related processes in HTEDs and systematic summary and analysis are currently not available. This review will fill the gap and classify the CO2-conversion-related processes in HTEDs reported in recent years into four types according to the related reactions, including assisted CO2 reduction to CO, H2O and CO2 co-conversion, dry reforming of methane and CO2 hydrogenation. Firstly, an overview of the fundamentals of HTED processes is presented, and then the related mechanism and research progress of each type of reactions in different HTEDs are elucidated and concluded accordingly. The remaining major technical issues are also briefly introduced. Lastly, the main challenges and feasible solutions as well as the future prospects of HTEDs for CO2-conversion-related processes are also discussed in this review.

The urea solution electrolysis has become more attractive than water splitting, because it not only produces clean H2 via the cathodic hydrogen evolution reaction (HER) with lower cell voltage, but also treats sewage containing urea through anodic urea oxidation reaction (UOR). However, lack of efficient electrocatalysts for HER and UOR has limited its development. Herein, hairy sphere -like Ni9S8/CuS/Cu2O composites were synthesized on nickel foam (NF) in situ by a two-step hydrothermal method. The Ni9S8/CuS/Cu2O/NF exhibited good electrocatalytic activity for both HER (−0.146 V vs. RHE to achieve 10 mA cm−2) and UOR (1.357 V vs. RHE to achieve 10 mA cm−2). Based on the bifunctional properties of Ni9S8/CuS/Cu2O/NF, a dual-electrode urea solution electrolytic cell was constructed, which only needed a low voltage of 1.47 V to reach a current density of 10 mA cm−2, and displayed a good stability during a 20-h test. In addition, the reason for the good catalytic activity of Ni9S8/CuS/Cu2O/NF was analyzed and the UOR mechanism was discussed in detail. Our research shows that Ni9S8/CuS/Cu2O/NF is a very promising low-cost dual-function electrocatalyst, which can be used for high-efficiency electrolysis of urea solution to produce hydrogen and treat wastewater.

The Hydroxygen as an additive to the gasoline is used in the present experimental investigation for reducing the fuel consumption and conserve the fast depleting fossil fuel without any engine modification. The Hydroxygen was produced from the developed electrolytic cell and the power of the alternator through the battery was used. The power to the electrolytic cell was controlled by circuit. During the experiment, the voltage and current across the electrolytic cell was measured by introducing the other circuit and data was collected. The experiment was conducted on Discover bike engine with constant Hydroxygen gas flow of 600 ml per hour to the engine intake manifold. Performance and exhaust gas emission parameters were measured by keeping 0.6 mm and 0.8 mm electrodes gap of spark plug (EGSP). Overall performance and emission was found to be optimum for 0.6 mm EGSP with Hydroxygen addition with the maximum relative decrease in brake specific fuel consumption 50.43%, increase in brake power and brake thermal efficiency (ƞ%) are 77.20% and 101.76% respectively, the maximum relative decrease in carbon monoxide, un burned hydrocarbon and nitrogen oxide are 96.96%, 90.29%, and 81.73% respectively.

Pressure assisted flash sintering was used to process Mn-Co-Cu based spinel coatings, electrophoretically deposited on a Crofer22APU interconnect. This method resulted in highly dense coatings, heat-treated for only a short duration ( 200 °C/min). The high heating rate promoted Cu modified Mn-Co spinel and limited the formation of a Cr-oxide scale on the Crofer22APU substrate. Flash sintering was found to be a promising and time efficient sintering technique to overcome some of the issues related to low coating density and oxide scale formation in solid oxide electrolysis cell conditions.

Solid oxide cells (SOCs) can switch between fuel cell and electrolysis cell modes, which alleviate environmental and energy problems. In this study, the La0.3Sr0.7Fe0.9Ti0.1O3-δ (LSFTi 91) perovskite is innovatively used as a symmetric electrode for solid oxide electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs). LSFTi 91 exhibits a pure perovskite phase in both oxidizing and reducing atmospheres, and the maximum conductivity in air and 5% H2/Ar is 150 and 1.1 S cm-1, respectively, which meets the requirement of the symmetric electrode. The polarization resistance (Rp) at 1.5 V is as low as 0.09 Ω cm2 in the SOEC mode due to the excellent CO2 adsorption capacity. The current density can reach 1.9 A cm-2 at 1.5 V and 800 °C, which is the highest electrolytic performance in the reported single-phase electrodes. LSFTi 91 also exhibits eminent oxygen reduction reaction and hydrogen oxidation reaction (ORR and HOR) activities, with Rp of 0.022 and 0.15 Ω cm2 in air and wet H2, respectively. The peak power density of SOFC could reach 847 mW cm-2 at 800 °C. In addition, good reversibility is confirmed in the cyclic operation of SOFC and SOEC.

As an energy-intensive industry, the chlor-alkali process has caused numerous environmental issues due to heavy electricity consumption and pollution. Chlor-alkali industry has been upgraded from mercury, diaphragm electrolytic cell, to ion exchange membrane (IEM) electrolytic cells. However, several challenges, such as the selectivity of the anodic reaction, sluggish kinetics of alkaline hydrogen evolution, degradation of membranes, the reasonable design of electrolytic cell structure, remain to be addressed. For these reasons, this paper mainly reviews the research progress of the chlor-alkali industry from materials to devices, including hydrogen evolution anode, chlorine evolution cathode, IEM, and electrolytic cell system. Finally, the research directions and prospects in the chlor-alkali industry are proposed for its further improvement.

Purpose Alternating current (AC) corrosion is a type of corrosion that occurs in buried pipelines under AC stray current interference, which can increase the hydrogen embrittlement sensitivity of pipelines. However, rare research works have been conducted on the hydrogen permeability characteristics of pipeline steel under AC stray current interference. The purpose of this paper is to study hydrogen permeation behavior of X80 steel under AC stray current interference. Design/methodology/approach In this paper, the hydrogen permeation behavior of X80 steel under AC interference is studied by AC hydrogen charging experiment in a dual electrolytic cell. The relationship between hydrogen evolution rate and hydrogen permeation flux is studied using the gas collection method. The difference between AC hydrogen permeability and direct current (DC) hydrogen permeability is also discussed. Findings The anodic dissolution caused by AC corrosion promotes the chemical desorption reaction of the adsorbed hydrogen atoms on the surface, reducing the hydrogen atom absorption ratio by 70%. When the AC is smaller than 150░ A/m2, the hydrogen permeation process is controlled by the hydrogen atom generation rate, and the hydrogen permeation flux increases with the increase in hydrogen atom generation rate. When the AC exceeds 400░ A/m2, the hydrogen permeation process is controlled by the absorption ratio. The hydrogen permeation flux decreases with the decrease in the absorption ratio. Under AC interference, there is a maximum hydrogen permeation flux that linearly correlates to the H+ concentration in the solutions. Originality/value The high-strength steel is very sensitive to hydrogen embrittlement, and X80 steel has been widely used in oil and gas pipelines. To date, no research has been conducted on the hydrogen permeation behavior of pipeline steel under AC interference, and the hydrogen permeability characteristics of pipeline steel under AC interference are not clear. The research results of this paper are of great significance for ensuring the intrinsic safety of high-strength pipelines under AC stray current interference.

CeO2-based surface modification is established as an effective strategy for improving the electrochemical performance of solid oxide electrolysis cells (SOECs), but the relevant mechanism has not been fully explored yet. Here, we employ focused ion beam-scanning electron microscopy to examine the microstructural evolution of bare nickel-based yttrium-stabilized zirconia (Ni/YSZ) electrode (reference cell) and Gd-doped CeO2 (CGO)-infiltrated Ni/YSZ electrode (optimized cell) before and after 100-h durability test. The initial current density of the optimized cell was 1.16 A cm−2 (at 1.3 V), which was 1.5 times larger than that of the reference cell. The voltage of the reference cell degraded dramatically due to a 1.16% reduction in the volume fraction of Ni, while the optimized cell showed a negligible degradation with a minor change in the volume fraction of Ni. It was confirmed that CGO nanoparticles formed a protective layer on the Ni surface during the electrolysis process, which prevented further evaporation of Ni. Overall, the infiltration of CGO into traditional Ni/YSZ electrode prevented decrease in the triple-phase boundary density and reduced the resistance by providing additional active sites for hydrogen evolution reaction. We believe that this work provides an efficient strategy for developing high-performance and long-term stable SOECs.

In this research, a novel Microbial reverse-electrodialysis electrolysis struvite-precipitation cell (MRESC) was developed for energy recovery through struvite (MgNH4PO4·6H2O) crystallization and hydrogen production concurrently in a single process without any electrical-grid energy consumption. This hybrid system can effectively transfer the salinity gradient energy to electrical energy as a driving force to produce hydrogen gas coupled with struvite recovery and organic wastewater degradation. A MRESC containing 10 pairs of RED cells, supplied solutions typical of high concentration (600 mM NaCl) and low concentration (12 mM NaCl) at 1.0 mL/min, was operated in the fed-batch mode. The rates of hydrogen production and struvite crystallization were determined to be 0.71 m3-H2/m3-Van/d and 7.62 g/m2/h, respectively. The gas produced was >92% H2. The Coulombic efficiency was close to or above 100% with a COD removal of 84 ± 6%, and an overall energy efficiency of 28%. The morphology and structure of the main component of accumulated crystal at the cathode were verified by a scanning electron microscope with energy dispersive spectroscopy (SEM-EDS) and X-ray diffraction. These results showed that the MRESC system could be used as an effective bioelectrochemical method for energy recovery in the form of pure hydrogen gas and struvite simultaneously.

Among perovskite anodes in solid oxide electrolysis cell (SOEC), Ba0·5Sr0·5Co0·8Fe0·2O3-δ (BSCF) has gained much attention due to its dominantly high performance. However, the BSCF still suffers from chemical instability. In this study, the B-site of BSCF is partially substituted by a higher valence Ta5+ (5, 10, 15 and 20 mol%) to improve its structural stability - Ba0·5Sr0·5(Co0·8Fe0.2)1-xTaxO3-δ (BSCFTax, 0 ≤ x ≤ 0.20). It is found that doping with higher valence Ta5+ increases both chemical stability and electrochemical performance of BSCF. Although the BSCFTa0.10 shows the lowest oxygen vacancies indicating by the ratio of adsorbed oxygen vacancies (Oadsorbed) to lattice oxygen (Olattice), the electrochemical performance increases. The decrease in Co3+/Co4+ ratio results in increasing electronic conductivity in the anode. It is likely that proper amount of Ta5+ doping provide a balance between ionic and electronic conductivity in the anode and improved electrochemical performance. The symmetrical half-cells with electrolyte support (BSCFTa/YSZ/BSCFTa) are fabricated to determine the area specific resistance (ASR) and activation energy of conduction - BSCFTa0.10 shows the best performance. Cathode-supported Ni-YSZ/YSZ/BSCFTa0.10 also shows higher durability than Ni-YSZ/YSZ/BSCF (operating at current density −0.45 A cm−2 in electrolysis mode, 80 h, 800 °C and H2O to H2 ratio of 70:30).

Gold nanoparticles were deposited on fluorine-doped tin oxide (Au/FTO) with the mean particle size controlled by the deposition precipitation method. A two-electrode electrochemical cell with the s...

Solid oxide cells (SOCs) are mutually convertible energy devices capable of generating electricity from chemical fuels including hydrogen in the fuel cell mode and producing green hydrogen using electricity from renewable but intermittent solar and wind resources in the electrolysis cell mode. An effective approach to enhance the performance of SOCs at reduced temperatures is by developing highly active oxygen electrodes for both oxygen reduction and oxygen evolution reactions. Herein, highly conductive Sm3+ and Nd3+ double-doped ceria (Sm0.075Nd0.075Ce0.85O2-δ, SNDC) is utilized as an active component for reversible SOC applications. We develop a novel La0.6Sr0.4Co0.2Fe0.8O3 -δ (LSCF)-SNDC composite oxygen electrode. Compared with the conventional LSCF-Gd-doped ceria oxygen electrode, the LSCF-SNDC exhibits ∼35% lower cathode polarization resistance (0.042 Ω cm2 at 750 °C) owing to rapid oxygen incorporation and surface diffusion kinetics. Furthermore, the SOC with the LSCF-SNDC oxygen electrode and the SNDC buffer layer yields a remarkable performance in both the fuel cell (1.54 W cm-2 at 750 °C) and electrolysis cell (1.37 A cm-2 at 750 °C) modes because the incorporation of SNDC promotes the surface diffusion kinetics at the oxygen electrode bulk and the activity of the triple phase boundary at the interface. These findings suggest that the highly conductive SNDC material effectively enhances both oxygen reduction and oxygen evolution reactions, thus serving as a promising material in reversible SOC applications at reduced temperatures.

We prepared a highly active and stable cathode catalyst for a solid oxide electrolysis cell (SOEC), decorated with in situ exsolved Fe nanoparticles (NPs) socketed on La1.2Sr0.8Mn0.4Fe0.6O4−α (R.P.LSMF), toward the CO2 electrolysis reaction to produce CO selectively. This catalyst was derived from the perovskite structure of La0.6Sr0.4Mn0.2Fe0.8O3−δ (LSMF) by simple annealing in a H2 atmosphere and showed high current densities of 2.04, 1.43, and 0.884 A cm−2 at 850, 800, and 750 °C, respectively, at a voltage of 1.5 V with corresponding total polarization resistance values of 0.205, 0.326, and 0.587 Ω cm2, respectively, at an open circuit voltage. The highly improved performance should be ascribed to the in situ exsolved Fe NPs anchored on Ruddlesden–Popper oxide and to the increased contents of oxygen vacancies in R.P.LSMF. More importantly, this active catalyst also exhibited a stable voltage profile for 100 h operation at an constant current density of 1.8 A cm−2, suggesting that the catalyst Fe–R.P.LSMF proposed in this study is a highly promising candidate for use in an efficient SOEC cathode for CO2 electrolysis processes.

The ionic conductivity of the interlayer in the intermediate temperature solid oxide electrolysis cell (IT-SOEC) affects the polarization resistance of the oxygen electrode. Improving the ionic conductivity of the interlayer can improve the performance of the oxygen electrode. In this work, the ionic conductivity of a samarium-doped ceria (SDC) interlayer is improved by doping the transition metal oxide Fe2O3. The experimental results show that the oxygen electrode polarization resistance of the symmetrical cell based on the SDC-Fe2O3 interlayer is 0.09 Ω cm−2 at 800 °C and under the open circuit voltage, which is obviously lower than that of the symmetrical cell based on an SDC interlayer (0.22 Ω cm−2). Besides, the electrolysis current of the SOEC based on the SDC-Fe2O3 interlayer is 0.5 A cm−2 at 800 °C and 1.5 V, which is higher than that of the SOEC based on the SDC interlayer (0.3 A cm−2). The above results show that improving the ionic conductivity of the SDC interlayer in the SOEC by doping Fe2O3 can reduce the polarization resistance of the oxygen electrode and enhance the performance of the SOEC. Thus, this work provides an effective way for improving the performance of the SDC interlayer in the IT-SOEC.

Design and fabrication of high-efficiency electrocatalysts are important to generate hydrogen via urea electrocatalysis with the minimum required energy. In this study, in situ growth of a branch-like Mo-doped Ni3S2 nanoforest on Ni foam was achieved through a facile one-pot hydrothermal process. The as-obtained catalyst exhibited excellent activity and robust durability because of its unique hierarchical nanostructures and doping-optimized electronic structural configuration, and required merely 1.33 V (vs. RHE) and 90 mV (overpotential) to attain a current density of 10 mA cm−2 for the urea oxidation reaction (UOR) and hydrogen evolution reaction (HER), without any noticeable loss in activity even after 120 h of operation. On the basis of the experimental results and theoretical calculations, it was confirmed that the incorporation of Mo in Ni3S2 altered the morphology and electronic structure of the catalyst; hence, more active sites were exposed and the Gibbs adsorption energy of the intermediates in the UOR was optimized. Notably, the overall urea electrolysis cell could afford a low voltage of 1.45 V (vs. RHE) to attain a current density of 10 mA cm−2 and showed excellent durability over 120 h. The findings from this study provide new insights into efficient electrocatalysts for urea electrolyzers, which hold great potential in electrochemical energy conversion and sewage treatment applications.

An operando characterization of electrode materials under electrochemical reaction conditions is important for their further development. X-ray absorption spectroscopy (XAS) presents a unique opportunity in this regard as the absence of a vacuum chamber in this technique makes it possible to collect spectroscopy data using user-designed operando cells. In the current study, the design and performance of an operando XAS cell are evaluated for characterizing solid oxide electrolysis cell working electrodes under a reaction environment that mimics high-temperature ammonia production conditions from H2O and N2. Sr2FeMoO6−xNx (SFMON)-type double perovskite oxides were used as the cathode materials in these experiments. The operando cell contained a sample stage with a turnable head so that XAS data can be collected at different angles between the electrode and the X-ray beam with an accuracy of 0.5°. The mechanism to adjust the angle of incidence of the beam on the sample allows control over the depth of penetration of the X-ray photons into the electrode. At low angles, it becomes possible to collect surface sensitive data, which is of great importance as the electrochemical processes are believed to take place on the surface of the electrodes. Sr K-edge and Fe K-edge XAS collected at 2° and 45° angles showed that these the oxidation state changes occurring in these elements are different in the near-surface region compared to the bulk of the electrode. Such an ability to distinguish between the surface and bulk properties of the electrode during real reaction environment will help to understand the underlying phenomena better, which will enable electrode design targeted towards the reactions of interest.

An electrochemical micromachining (EMM) removes material via anodic dissolution. Several parameters affect their machining rate as well as accuracy. Analyzing these parameters and their effects via experiments is very rigorous and time-consuming. The simulation study helps in better prediction of the parameters as well as saves time. In this paper, different parameters and their effects are analyzed during machining. A three-dimensional model is formed by making an electrolytic cell with a tungsten carbide micro-drill tool as a cathode and SS-316L as the anode surface with sodium chloride as an electrolyte. From the simulation results, it is found that on increasing the voltage and concentration of the electrolyte, material removal rate (MRR) increases. The current density decreases on increasing the interelectrode gap (IEG). A non-uniform behavior of current density is observed during EMM. The simulation results for the effect of voltage and concentration of the electrolyte over MRR is validated with the experiments. The deviation of simulation results from the experimental results is around 15%.

To improve the thermal stability and intrinsically sluggish kinetics of oxygen electrode reactions in solid oxide fuel cells (SOFCs) and reversible protonic ceramic cells (RPCCs) at intermediate temperatures, a novel layered swedenborgite structure Y0.8Er0.2BaCo3.2Ga0.8O7+δ (YEBCG) catalyst is introduced as an alternative to perovskite materials that contain cobalt. The thermal expansion coefficient of YEBCG is 8.41 × 10−6 K−1, which is relatively well matched to the state-of-the-art proton-conducting and oxygen-ion-conducting electrolytes. The chemical bulk diffusion and surface exchange coefficients of YEBCG are 7.12 × 10−4 and 8.01 × 10−3 cm2 s−1, respectively, at 650 °C, which leads to much faster action than with state-of-art perovskite structured materials at intermediate temperatures. The maximum power densities of YEBCG cells are notably high, reaching 0.77 and 0.83 W cm−2 at 650 °C in SOFC and protonic ceramic fuel cell modes, respectively. Under electrolysis, the YEBCG cells achieve outstanding current densities of −0.61 and −4.42 A cm−2 at 500 and 700 °C, respectively, under an applied voltage of 1.4 V. Furthermore, the RPCC with YEBCG present no degradation over an entire 1000 h in fuel cell and electrolysis cell modes. These results demonstrate the excellent properties, including good durability, of the YEBCG air electrode when used in high performance SOFCs and RPCCs.

The development of three-dimensional electrode substrates is a strategy for designing powerful electrolysis cells for hydrogen production combined with electrochemical oxidation of various refractory organic compounds. Herein, to achieve highly effective and low-cost anodic treatment of pollutants and simultaneous cathodic hydrogen evolution in a single electrolysis cell containing sulfate-laden wastewater, we fabricated carbon-coated TiC nanoarrays (C@TiC NAs) as efficient three-dimensional (3D) electroactive supports. The anodes prepared via the deposition of boron-doped diamond (BDD) on 3D C@TiC NAs (BDD@TiC NAs) exhibited 1.9-fold higher efficiency for benzoic acid degradation and 4.4-fold higher peroxydisulfate (PDS) generation than the conventional plate type BDD electrode. Moreover, with multi-activity assessment using 8 organic substances, the BDD@TiC NAs enabled successful anodic treatment of all tested refractory organics and the kinetic rate did not depend on the substrate type. For the cathode, Pt nano-dots (NDs) coated on C@TiC NAs (Pt@C@TiC NAs) can be simply prepared via salt coating and subsequent thermal reduction. Uniformly decorated Pt NDs with a low mass loading of 0.029 mg cm−2 on C@TiC NAs showed the same hydrogen evolution reaction performance as that of a commercial Pt plate. When a single electrolysis cell was configured using BDD@TiC NAs and Pt@C@TiC NAs, the cell performance surpassed that of a conventional ideal electrolysis cell (flat BDD//Pt plate) in all efficiency aspects: degradation of benzoic acid, sulfate radical generation, and hydrogen production.

Solid oxide electrolysis cell (SOEC) is a promising electrochemical device with high efficiency for energy conversion and storage. In this work, La1.5Sr0.5Ni1-xMnxO4+δ (LSNMx) (x = 0, 0.1, 0.25, 0.5, 0.75) Ruddlesden-Popper oxides are synthesized via the conventional solid-state method and evaluated as potential air electrodes for SOEC. The effects of substituting Mn for Ni on the crystal structure, oxygen content, thermal expansion behavior, electrical conductivity, and electrochemical performance are comprehensively investigated. XRD results show that the solid-solution concentration of Mn in LSNMx cannot exceed 0.5. The X-ray photoelectron spectroscopy of O1s suggest that Mn doping increases the concentration of oxygen vacancy. The polarization resistance (Rp) of LSNMx (x = 0, 0.1, 0.25, 0.5) exhibits a significantly decreasing tendency with increasing Mn content. LSNM0.5 shows the lowest Rp value of 0.488 Ω cm2 at 800 °C and is reduced by as much as 81.1% in comparison with that of the LSN electrode. A current density of 500 mA cm−2 at 1.4 V is obtained for the LSNM0.5 air electrode with 70% CO2 + 30% CO feed gas on the fuel electrode in a fuel electrode-supported single cell at 800 °C. This current density shows an increase of approximately 85.2% compared with that of the un-doped LSN electrode. The stability test of the half-cell shows that the LSNM0.5 air electrode is relatively stable after anodic polarization at 500 mA cm−2 and 800 °C in air for 145 h. Thus, the Mn-doped LSNM0.5 Ruddlesden-Popper material is a promising air electrode for SOEC.

Electrosynthesis of chemicals in parallel with hydrogen production exhibits distinct advantages: energy saving and generation of two value-added products. In this work, we first design an asymmetric neutral–acidic electrolytic cell by coupling the silver oxidation reaction (AOR) in a neutral anode chamber with the hydrogen evolution reaction (HER) in an acid cathode chamber. When the anode electrolyte contains a certain amount of chloride ions, AgCl particles can be steadily synthesized close to, but not in contact with, the silver electrode at a fixed voltage. This electrolytic cell requires a voltage of only 1.1 V to drive 10 mA cm−2. In order to simplify the system and reduce the cost, a symmetric acid membrane-free electrolytic cell is designed; this cell requires a voltage of only 0.95 V to drive 10 mA cm−2 and 1.37 V to drive 250 mA cm−2 when a silver rod and graphite rod are used as the anode and cathode, respectively. Besides high purity H2 generation at the cathode, the anode product is pure AgCl and its size can be controlled by changing the voltage. The Faraday efficiency is close to 95% for both H2 and AgCl generation.

Development of electrochemical pathways to convert CO2 into fuels and feedstock is rapidly progressing over the past decade. Here we present a comparative cradle-to-gate life cycle assessment (LCA) of one and two-step electrochemical conversion of CO2 to eight major value-added products; wherein we consider CO2 capture, conversion and product separation in our process model. We measure the carbon intensity (i.e., global warming impact) of one and two-step electrochemical routes with its counterparts – thermochemical CO2 utilization and fossil-fuel based incumbent synthesis routes for those eight products. Here we show that due to inevitable carbonate formation or CO2 crossover in one-step CO2 electrolysis using neutral pH membrane electrode assembly, the two-step electrosynthesis pathways (i.e., CO2 to CO in solid oxide electrolysis cell followed by CO electroreduction in alkaline flow cell) would be distinctively compelling through the lens of climate benefits. This analysis further reveals that the carbon intensity of electrosynthesis products is due to significant energy requirement for conversion (77–83% of total energy consumption for gas products) and product separation (30–85% of total energy consumption for liquid products) phases. Global warming impact of electrochemical route is highly sensitive to the electricity emission intensity and is compelling over incumbent routes only when coupled with low emission intensity ( 20 wt%. It is our hope that this analysis will guide the CO2 electrosynthesis community to target achieving these technological goals, such that when coupled with low-carbon electricity, electrochemical route would bring climate benefits in near future.

Ni–Fe-alloy-foam supported solid oxide electrolysis cell with an arrangement of nickle and Sc0.1Ce0.005Gd0.005Zr0.89O2 (Ni-SCGZ) cathode, SCGZ electrolyte and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) anode is successfully fabricated by the sequence wet-chemical coating. The multi-layer cathode with a gradient of thermal expansion coefficient (TEC) is deposited on the alloy-foam support. Two-step firing processes are applied including cathode pre-firing (1373 K, 2 h) and electrolyte sintering (1623 K, 4 h) using slow heating rate enhanced with compressive loading. The fabricated cell shows current density of −0.95 Acm−2 at 1.1 V with H2O:H2 = 70:30 and 1073 K, providing hydrogen production rate at 4.95 × 10−6 mol s−1. However, performance degradation was observed with the rate of 0.08 V h−1, which can be ascribed to the delamination of BSCF anode under operating at high current density.