Electrolytic Method Research Articles

Assessing potential of high temperature reactor facilities of Russian design for near-term deployment of hydrogen production

In frames of the work, a pilot comparative multi-criteria evaluation of several options for the production of hydrogen using the energy of nuclear reactors was carried out. Technical and economic models of hydrogen production by methods of steam methane reforming, high-temperature and low-temperature electrolysis using nuclear reactors as a source of thermal and electrical energy have been developed. Russian projects of high-temperature gas-cooled reactors and existing VVER-type NPPs are considered. An approach to a comparative multi-criteria evaluation of options for hydrogen production using the energy of nuclear reactors is proposed. The proposed approach has been tested by comparing several variants of hydrogen production. When evaluating the values of the criteria, data obtained from open sources, with the help of developed economic models and expert assessments, were used. As a result, the considered variants of hydrogen production were ranked using several metrics and sets of criteria weights. The sensitivity analysis of metric values and option ratings to changes in the main criteria showed a sufficient sustainability of the multi-criteria analysis carried out.

Facile synthesis of mesoporous ncCoW powder via electrodeposition; characterization and its efficient application on hydrogen generation and organic pollutants reduction

The electrolytic deposition method, which generates a high-purity powder, is one of the most promising, easy-to-use, and rapid techniques to produce nanopowder. In the current study, an electrolytic solution was suggested to easily synthesize ultrafine mesoporous CoW nanopowder. The W content is in the range of 1.5-7.5 %, based on the operating circumstances. XRD patterns show that the powder annealed at 873 K consists mainly of cubic Co3O4 and CoO phases, in addition to a small amount of monoclinic CoWO4 phases. TEM analysis of the resultant powder's particle size indicated an average value of 4.0 nm. In tests to reduce organic pollutants like p-NP, the hydrolysis of SB using the nanopowder as a catalyst released a lot of hydrogen. The p-NP and dye reduction kinetics conformed to a pseudo-first-order model. The higher W% in the prepared CoW powder can improve the catalytic efficiency of dye reduction and accelerate the process. The recyclability and stability of catalysts explore that the powder shows promising efficiency toward significant applications in industrial catalysis and dye reduction.

Electrochemical Coupling Reactions Using Non‐Transition Metal Mediators: Recent Advances

AbstractIndirect electrolysis method using appropriate mediators enables numerous chemical reactions. The general principles of mediators were described herein with a particular focus on non‐transition metal mediators. Recent representative examples of bond formation reactions by indirect electrolysis are summarized and discussed here.

An innovative adaptive hybrid prediction model based on deep learning methods (CEEMDAN-GRU) for green hydrogen production, In case study: Turkey

Due to global warming, countries have turned to renewable and clean energy sources. Among these sources, they have started to prefer hydrogen energy and green hydrogen production as the cleanest type of energy in producing hydrogen energy. In this study, an innovative adaptive hybrid forecasting model based on deep learning was proposed to be used in green hydrogen production forecasting. The energy required for the electrolysis method used in hydrogen production was planned to be provided by wind energy. A new perspective was introduced in determining hydrogen production with the proposed model. In particular, the wind regime in 9 provinces selected for the case study was determined and the most suitable wind turbine power for the system was calculated according to this regime by applying the decomposition method to wind speeds, the most important input of wind energy. Depending on the determined turbine powers, the amount of hydrogen that can be produced was estimated. In the prediction process, 70 % of the data was used as training data (24528), 5 % as validation data (1752) and 25 % as test data (8760). The highest accuracy rate obtained in hydrogen energy forecasting among the selected provinces is 92.045 %. The lowest error and the highest regression rates (The root mean square error (RMSE): 0.600, Mean absolute percentage error (MAPE): 0.100 and the coefficient of determination (R2): 0.990) in wind speed prediction were realized in İzmir province. The highest wind turbine power was calculated as 225 kW.

Nanofluids and Ionic Fluids as Liquid Electrodes: An Overview on Their Properties and Potential Applications

The current review work focuses on recent developments in the exploration of electroactive nanofluids, ionanofluids, and ionic liquids acting as liquid electrodes. The nanofluids used for this purpose are composed of organic or aqueous electrolytes as base fluids with the addition of nanoparticles in pure, oxidized, or hybrid forms. On the other hand, the ionic liquids are formed by adding a solution, which can be an acid, a base, or a salt, in water. The electrochemical properties, such as electrical conductivity and capacitance, of these innovative fluids are discussed thoroughly, along with their influencing factors, such as the nature and concentration of the included nanoparticles, the type of base fluids, and the operating temperature. Moreover, this overview summarizes the fundamental applications of electroactive nanofluids, ionanofluids, and ionic liquids in various possible flow-cell configurations and electrolysis methods, along with the associated feasibility factors. Additionally, this survey of scientific papers on the matter enabled the listing and evaluation of general aspects related to the usage of electroactive nanofluids, ionanofluids, and ionic liquids. Finally, it addresses the main problems associated with such types of fluids and outlines the primary prospects for further research and utilization of electroactive nanofluids, ionanofluids, and ionic liquids in diverse scientific and technological fields.

Enhancing Hydrogen Production through Integration of Electrolysis and Photocatalysis in a Cell

We present a new method for hydrogen production that combines photocatalysis and electrolysis in a cell. TiO2 was doped with Ni and nitrogen to form Ni-TiO2 and N-Ni-TiO2 photocatalysts. XRD, UV-Vis, and SEM techniques were used to characterize the resulting samples. The Ni-TiO2 and N-Ni-TiO2 samples had anatase structures with energy gaps of 2.77 eV and 2.03 eV, respectively. A 50-watt UV lamp with a wavelength of 254 nm was used as the photon source. Our results indicate that this method produces more hydrogen than the sum of hydrogen generated by separate electrolysis and photocatalysis methods. The N-Ni-TiO2 sample produced the highest yield of HHO gas among the Ni-TiO2 and TiO2 p.a samples. The underlying mechanisms responsible for this improvement, including the role of the Ni and nitrogen doping, are discussed and analyzed.

Convergent Paired Electrolysis for the Synthesis of Pyrazolyl‐Substituted Tetrahydroisoquinolines

AbstractA convergent paired electrolysis method for the synthesis of 1‐pyrazolyl‐substituted tetrahydroisoquinolines has been developed. The reaction proceeded without any transition metal catalyst and chemical oxidant. The desired products could be isolated in high yields (80–99%) in 60–80 minutes. The Faradaic efficiency was 108% and gram‐scale synthesis (84%) could be carried out. Mechanistic studies revealed that the C−N bond formation process might mainly involve a nucleophilic addition reaction.

Effect of Current, Voltage, Temperature, and Time Variations on Thickness of Steel using Electroplating Process

The use of low carbon steel is categorized as one of the supporting materials in industrial and technological developments because it has high ductility and toughness. However, low carbon steel has limitations in terms of corrosion resistance. There are several ways to increase corrosion resistance in steel. One of them is by providing a layer of protection on the steel surface. The steel plating method used is the electrolysis method or electroplating method. This study aims to determine the influence of variations in current, voltage, temperature, and time on the thickness of the coating formed on steel. The steel plating process is carried out by electroplating process where the coating material or anode is Nickel (Ni) with dimensions (60 mm x 30 mm x 0,1 mm). In comparison, the coated object or cathode is SK5 steel with dimensions (50 mm x 20 mm x 0,3 mm). The aim of this study is to investigate the effect of Current, Voltage, Temperature, and Time Variations on the thickness of steel using electroplating processes. Moreover, all factors will be optimised to achieve the best thickness for steel. Consequently, the corrosion resistance of SK5 can be significantly improved by increasing its thickness. The current variations were used 1A, 2A, 3A, and 4A; voltage variations were used 3V, 6V, 9V, and 12V; temperature variations were used 30°C, 40°C, and 50°C; and times variations were used 0 m, 5 m, 10 m, and 20 m. Based on the results of research that has been carried out on all samples, it is concluded that current, voltage, temperature and time affect the thickness of the sample in the electroplating process. The current, voltage, temperature and time values are linearly related to the thickness resulting from the electroplating process.

Rapid preparation of high efficiency hydrogen evolution catalyst with hydrophilicity

The electrolytic water method is an outstanding hydrogen production process because of its high stability and no restriction. A low-priced and efficient catalyst for electro-deposition of Ni–Co microspheres and nanoclusters on carbon steel (Ni–Co/CS) has been prepared by the dynamic hydrogen bubble template. In the 6 M KOH solution, Ni–Co/CS only requires an overpotential of 48 mV to provide a current density of 50 mA cm−2. At the same time, it also has a large electrochemically active specific surface area (ECSA) and a hydrophilic surface. In addition, the study about the influence of carbon steel (CS) on Ni–Co coatings and the comparison experiment for different base materials has been completed. The results prove that CS is an excellent base material for hydrogen production. It can help the Ni–Co catalyst to have a stable electrolysis in 6 M KOH for 500 h. The above properties of Ni–Co/CS catalyst make it a new choice of hydrogen production by electrolysis of water in practical applications.

Facile four-electrode electrolytic synthesis of defective PtPd/graphene with low Pt content for hydrogen evolution reaction and ethanol oxidation reaction

The fabrication of low-Pt loading and cost-efficient electrocatalysts still remains a challenge. In this work, a defective PtPd alloy with ultralow Pt content loaded on graphene (PtPd/G-40) is prepared by electrolytic synthesis method. During electrolysis, the formation of PtPd precursors and the exfoliation of graphite are achieved at the anode and cathode of the cell, respectively. The as-prepared PtPd/G-40 shows excellent electrocatalytic activity and stability toward hydrogen evolution reaction (HER) and ethanol oxidation reaction (EOR). Its mass activity is 29.7 times (at −100 mV) and 1.5 times higher than that of commercial Pt/C for HER and EOR, respectively. The ligand effect generated by formation of PtPd alloy and strain effect caused by abundant defects optimize the electronic structure of active Pt, which enhances its intrinsic activity and reduces the activation energy for HER and EOR. This facile synthetic approach generates a new type of graphene supporting defective metal alloy nanostructures as potential electrocatalysts for advanced energy conversion applications.

Electrochemical exfoliation of phosphorus doped carbon dots with dual-emission originating from carbon core and surface states

Carbon dots have attracted significant attention due to their versatile and excellent photoelectric properties; however, the origins and underlying mechanism remain a subject of debate especially for dual-emission CDs. Here, novel dual-emission CDs have been exfoliated from graphite rods via an electrochemical method in a dihydrogen phosphate electrolyte. The CDs possess a very narrow blue emission band in the short wavelength region and a broad cyan emission band in the long wavelength range, which are attributed to carbon core state and surface state from phosphorus atom doping, respectively. Interestingly, the former shows excitation-dependent behavior, but the latter is excitation-independent. Thus, as the excitation wavelength increases, the blue emission band is gradually closing to the cyan one and coalesce into a broad peak at the excitation wavelength of 420 nm. The variations of both emission intuitively illustrate the role transition between a core state and the doped surface state at different excitation wavelengths, which offer a real sample for the study of transition between emissive states. Our findings provide novel and fundamental insights on the fluorescence mechanism of CDs with dual-emission.

A novel hybrid electrode materials for supercapacitors based on polyelectrolyte chitosan complex

In this work, hybrid materials based on polyelectrolyte complexes of chitosan with cobalt and nickel oxycompounds on the stainless steel surface were obtained using the non-stationary electrolysis method. Morphology, structure and elemental composition of the hybrid materials were studied. The X-ray phase analysis method allowed us to find that the main phase of the obtained hybrid materials is cobalt hydroxyisocyanate Co(OCN)0.6(OH)1.4(H2O)0.6. The electrochemical characteristics of the hybrid materials obtained were studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) in an alkaline electrolyte. The specific capacitance was 479 F∙g−1 at the current density of 1 A∙g−1. The calculated energy density and power density of the cell was 0.055 W∙h∙kg−1 and 116 W∙kg−1, respectively. The results of long-term cycling allow us to conclude that the hybrid material is characterized by sufficient stability with capacity retention up to 85% after 5000 cycles.

Tuning phase and photoluminescent properties of ZrO2:Eu3+ coatings formed by plasma electrolytic oxidation and Judd-Ofelt analysis of composite materials

Eu3+ doped Zirconia coatings were synthesized by the electrochemical plasma electrolytic oxidation method in only 8 min from the pure zirconium substrate. The phase constitution from pure monoclinic to pure tetragonal and exactly in between was achieved by using different concentrations of Na3PO4 and NaAlO2 electrolytes. The complex emission spectra composed of Eu2+, Eu3+, and ZrO2 defect emission greatly depend on the excitation wavelength and phase constitution. Eu3+ photoluminescence properties depend on the phase, which is reflected by the different Stark splitting and different intensities of transitions. Thus, both phase and photoluminescent properties of ZrO2 coatings are fine-tuneable. Judd-Ofelt analysis was performed from the emission and excitation spectra, showing that all 3 intensity parameters depend linearly on the phase constitution, being largest in the pure monoclinic phase. The mixed phase has Judd-Ofelt parameters between those in pure phases. Eu3+ has 2.45 times more preference to get incorporated into the tetragonal than in the monoclinic phase in the mixed phase samples. The general equation for Judd-Ofelt parameters in a compound with mixed constituents and probability of incorporation is introduced, allowing also for a prediction of the spectrum shape based on the Judd-Ofelt parameters of pure-phase compounds. Python software code for estimating the percent of incorporation by multiple linear regression model is also provided.

Economic evaluation of hydrogen production in second and third units of Bushehr nuclear power plant regarding future need of nuclear fission technology

Today, the most important challenge for hydrogen production is the use of suitable energy source for sustainable production. The dual use of nuclear power plants allows them to expand into other markets by eliminating greenhouse gas emissions from processes such as hydrogen production. The significance of this matter especially in countries with ongoing new nuclear power plants is high and shows the future need for nuclear fission technology. In this paper, an economic assessment of hydrogen production in the second and third units of the Bushehr nuclear power plant (BNPP) with the Hydrogen Economy Evaluation Program (HEEP) is carried out and a comparison of CO2 emission in nuclear and non-nuclear methods of hydrogen production is presented. Most nuclear reactors, including Advanced Pressurized WaterReactor (APWR), High Temperature Gas Reactor (HTGR), and Water-Water EnergeticReactor (WWER), can be used as a source of thermal and electrical energy for the process of hydrogen production. In this research, hydrogen production processes based on the Conventional Electrolysis (CE), High Temperature Steam Electrolysis (HTSE), and Sulfur-Iodine (SI) Process using different storage and transportation options are compared to choose the cost-effective method for coupling with the WWER1000 reactor. Hydrogen production, thermal energy, and electricity costs have been calculated and explained in detail. The results showed that the cost-effective option for hydrogen production is using the High Temperature Steam Electrolysis (HTSE) method, Compressed Gas (CG) storage, and pipeline transportation, by 2.88 $/kg. Also, applying this method to produce hydrogen, the nuclear power plant thermal efficiency, and the hydrogen plant efficiency are kept in the best possible conditions by 51.98% and 58.21%, respectively.

Upcycling of spent LiMn2O4 cathode towards sodium-ion battery cathode through molten salt electrolysis approach

Recycling and valorizing spent lithium-ion batteries (LIBs) are requisite to achieve resource sustainability and environment safety. Herein, we reported a molten salt electrolysis method to recycle degraded LiMn2O4, synergistically achieving the selective leaching of lithium (Li) and high-valued reutilization of manganese (Mn). In molten Na2CO3-K2CO3, 94.3 % of Li from LiMn2O4 was released into molten salt by the electrolysis at 1.2 V for 7 h, while in-situ forming Na0.55Mn2O4⋅1.5H2O. During the electrolysis, LiMn2O4 at the cathode was electrochemically decomposed to Li2O and manganese oxide, accompanied by the reaction of resultant Mn oxide with Na2CO3 salt to generate Na0.55Mn2O4⋅1.5H2O. Finally, Li2CO3 in molten salt can be selectively extracted by water leaching. The obtained Na0.55Mn2O4⋅1.5H2O material as a sodium-ion battery (SIB) cathode delivers a discharge specific capacity of 58.9 mAh g−1 at 100 mA g−1, showing good cycle performance with a capacity retention of 93.9 % after 100 cycles. Hence, molten salt electrolysis achieves both extraction of Li and high-value reutilization of Mn, offering an electricity-driven materials separation, recovery, and reutilization with reduced environmental impact.

Combined PEO and Spray Pyrolysis Coatings of Phosphate and ZnO for Enhancing Corrosion Resistance in AZ31 Mg Alloy

Oxide films produced from plasma electrolytic oxidation are porous in structure. While they have some passivating effect in Mg alloys, the pores still lead to corrosion over long periods of exposure. In this study, spray pyrolysis was used to seal the porous oxide layer developed through the plasma electrolytic oxidation method on Mg alloy AZ31. The PEO coating acted as a good base for the application of spray pyrolysis due to its morphology. Three different kinds of coatings were obtained using different precursors: zinc acetate for ZnO, phosphoric acid for phosphate (P), and a mixture of zinc acetate and sodium phosphate for ZnO+P. The corrosion performance of all three coatings was studied by performing electrochemical impedance and polarization tests on the samples. Mass loss over a duration of 1 week was measured in 3% NaCl solution using immersion gravimetry. The coating with only phosphate (P) was found to be most corrosion-resistant with 52 times lower rate of corrosion and 50 times more polarization potential. The chemical composition of the corrosion products was studied using XRD and SEM-EDS analysis. Mass loss in ZnO+P was the highest, at up to 1.4 and 5.1 times higher than ZnO and P, respectively.

An Electrochemical Approach to Recycle and Extraction of Metals from Electronic Waste

Scraped e-waste is a result of increased production and demand for Electrical and Electronic Appliances (EEA). Because the discarded EEA contains heavy metals, it must be carefully disposed of in order to prevent any environmental harm. Researchers and pollution control boards in the relevant nations are taking notice of this rapid increase in e-waste in order to properly dispose of and recycle the garbage. A variety of materials, including gold, silver, copper, iron, etc., are included in e-waste. For research, it is crucial to safely and sustainably remove all of those metals from old electrical and electronic products. Electrochemical, pyrometallurgical, hydrometallurgical, and bioleaching methods for extracting metals from waste scrap have all evolved in the development of environmentally friendly and sustainable technologies. Among all the methods for extracting metals that are accessible, electrochemical extraction is one of the most admired. One of the reported most effective techniques among all of these is electrochemical. (80-95%) of the metal is reported to have been extracted using the previously stated procedure and various electrolytes. Additionally, after processing and chemical leaching of the Waste, various combinations of electrodes are employed to independently recover the metals from E-Waste is presented in the paper. The study presents an electrolysis method for copper extraction. In order to achieve the highest Cu extraction efficiency, a variety of electrode and electrolyte combinations are used in this study work, along with an energy model for the process. adjusting the electrolyte content to examine the Cu extraction rate for improved extraction efficiency. It is possible to extract copper with 99% efficiency using this electrolysis method.

Deposition and Morphology Control of Carbon Film through Electrochemical Reduction of Carbonate Ions in Molten LiCl

Synthesis of a compact, uniform and thick carbon film on nickel substrate were conducted by electrochemical reduction of carbonate ions in LiCl-Li2CO3 molten salt. It was found that the carbon is consistently formed into structure of wire and sphere particle. The uniformity and compactness of the carbon film were found to be dependent on the applied current density, electricity, and the electrolysis method. At lower current densities, the carbon tended to grow locally, resulting in larger-sized wires and particles. At higher current density, a relatively uniform and thin carbon film can be synthesized at the beginning but soon changed to a cluster-like structure. The contradiction between current density and carbonate ions‘ diffusion limit make it is impossible to obtain a compact and uniform film by using constant current electrolysis. By applying pulsed current electrolysis with an average current density of 10 mA cm−2 and a peak current density of 200 mA cm−2, a compact and uniform carbon film with a thickness of approximately 10 μm was successfully prepared.

Chromium Coating of Wollastonite Filled Polyamide 6 and Evaluation of Thermal Cycle Strength

The chromium coating of plastic/polymer materials through electrolysis method has attracted attention for improving material properties. The most common material used to be coated is the Acrylonitrile Butadiene Styrene (ABS), but has disadvantages compared to polyamides (PA), such as low thermal resistance. PA’s high water retention disadvantage can be substituted by using fillers such as clay, etc; so in this study, 40% Wollastonite filled PA has been used for chromium plating to increase the thermal resistance of the PA. The plates used were produced by injection molding method. The research is focused on the effect of time and concentration on coating performance in etching, activation (by palladium) and accelerator processes. SEM and EDX were used to characterize samples for surface morphologies and the microstructures of etching, activation and accelerator in the PA sub-plates. Additionally, cross-cut adhesion test has been applied to analyze the adhesion power of the interfaces. It was found that the thermal resistance of the metal plate on the polymer surface decreased as the time increased, in relation with the increasing wearing time of the metal plate mentioned above. The thermal resistance decreased as the polymer deformed in relation with the increase in etching solution’s concentration. It is also seen that the thermal resistance improved as the activation time increased. The adhesion and the thermal resistance did not improve as the time in accelerator process increased. Furthermore, the cross – cut adhesion tests on the same samples concluded that the results are in agreement with the other thermal resistance results.

Analytical Solutions to Characterize Through-Plane Inhomogeneity of Porous Electrodes Using Electrochemical Impedance Spectroscopy

Characterization of through-plane inhomogeneity in porous media requires knowledge of the distribution of porosity, tortuosity, and double-layer capacitance across the thickness. The thickness-averaged or apparent values of these parameters may not be sufficient to model the transport processes in batteries and fuel cells accurately. Cleverly designed through-plane inhomogeneities can improve the performance of electrochemical systems (e.g., graded-porosity electrodes for batteries or gas diffusion media for fuel cell). In some cases, inhomogeneity can result from manufacturing steps; for example, tortuosity variation due to binder migration in the fast slurry-drying step. In this work, we extend the impedance-based approach to characterize the inhomogeneity of a porous electrode in the through-plane direction. We derive analytical expressions for the impedance response of an electrode having three types of inhomogeneities (step-wise, linear, and inverse-linear variation) in a symmetric cell setup having non-reacting electrode/electrolyte interface (blocking electrode or electrolyte method). We also provide perturbation-theory based approximate solutions and expressions for semi-infinite domain to enable the development of an impedance-based fitting tool for inhomogeneous electrodes. In the end, we provide an impedance-based experimental investigation of gas diffusion media (composite layer) using symmetric cell setup to demonstrate the applicability of the theory and understanding derived in this work.