Hours Of Electrolysis Research Articles

The Role of Cation Exchange Membrane Characteristics in CO2 Electrolysis to CO Using Acid Anolyte

Cation exchange membranes are considered a suitable option for zero-gap CO2 electrolysis due to their potential to avoid carbonation and improve carbon efficiency. However, the use of acidic anolytes remains an issue due to high hydrogen production. This study investigates Nafion® membranes (111, 112, 115, 211, and 212) with different thicknesses produced by extrusion or solution-cast processes in a zero-gap cell with an acidic anolyte containing K2SO4. Faradaic efficiencies for CO production (FECO) are higher with thinner membranes, regardless of the manufacturing process, reaching FECO around 75% at 50 mA cm⁻². Additionally, membranes with similar thicknesses (∼50.8 µm) but produced in different ways displayed flow field carbonation after 3 hours of electrolysis at 30°C and 50 mA cm⁻². Linear sweep voltammetry (LSV) in full and half-cell configurations shows limiting diffusion current (iL) relative to proton transport for all the employed membranes, no matter the thickness. In contrast, the iL for Nafion® 115, the thicker membrane, is suppressed, indicating that proton depletion is fast and the electrode surface alkalinization primarily results from water reduction in this case. A mechanistic analysis was performed to explain the behavior of the limiting currents in the cell with Ar- and CO2-feed, indicating that CO2 reduction aids in the consumption of H+ provided by the membrane, increasing the local pH at less negative potentials. Overall, thinner membranes exhibited higher values of FECO and energy efficiency for CO (EE%CO). However, solution-cast membranes are more prone to provide K+, leading to better performance than those prepared by extrusion.

Electrochemical removal of ethylene glycol monobutyl ether in aviation industry wastewater using a porous Ti4O7/Ti electrode

Titanium alloy chemical milling wastewater contains a significant amount of ethylene glycol monobutyl ether (EGBE), which is toxic and difficult to be degraded by microorganisms, and the emission will lead to severe environmental pollution. To solve this problem, the electrocatalytic oxidation method was employed to remove EGBE in the wastewater, in which a porous Ti4O7/Ti electrode were prepared and employed as the anode, while stainless steel acted as the cathode. The effects of current density, interelectrode distance, and stirring mode on the COD removal rate were also investigated. Results show that the COD of the wastewater significantly decreases from 12410 to 15 mg L−1 after 16 h of electrolysis at 10 mA cm−2 and electrode spacing of 1.0 cm as well as aeration stirring at 100 mL min−1. Moreover, pilot-plant scale testing reveals that the COD decreasing from 11980 to 183 mg L−1 after 24 h of electrolysis. Consequently, the utilization of porous Ti4O7/Ti electrode as anode in the electrocatalytic oxidation method presents significant potential in removal of EGBE in aviation industry wastewater.

Reducing noble metal content in water electrolysis catalysts: A study on high-entropy oxides

This study presents the development of high-entropy oxide (HEO) catalysts based on Iridium-Ruthenium oxides (IrRuOx) for the oxygen evolution reaction (OER) in proton exchange membrane water electrolyzers (PEMWEs). By incorporating 3d transition metals such as Fe, Co, and Ni, we achieved catalysts with enhanced performance and stability. Using density functional theory (DFT) calculations, we predicted that HEOs possess a more favorable electronic structure for catalytic reactions. The synthesized rutile-type HEO catalyst (RuIrFeCoNi)O2, created via a molten salt oxidation method, exhibited a low overpotential of 261 mV and excellent cycling stability, maintaining a stable voltage of 1.73 V at 1 A cm−2 over 100 hours of electrolysis. This innovative approach not only reduces noble metal content but also leverages multimetallic synergistic effects to optimize the catalytic performance and stability, offering a promising avenue for the industrial application of acidic water electrolysis in PEMWEs.

Elimination of phenol by sonoelctrochemical process utilizing graphite, stainless steel, and titanium anodes: optimization by taguchi approach

Phenol is one of the worst-damaging organic pollutants, and it produces a variety of very poisonous organic intermediates, thus it is important to find efficient ways to eliminate it. One of the promising techniques is sonoelectrochemical processing. However, the type of electrodes, removal efficiency, and process cost are the biggest challenges. The main goal of the present study is to investigate the removal of phenol by a sonoelectrochemical process with different anodes, such as graphite, stainless steel, and titanium. The best anode performance was optimized by using the Taguchi approach with an L16 orthogonal array. the degradation of phenol sonoelectrochemically was investigated with three process parameters: current density (CD) (25, 50, 75, and 100 mA/cm2), time (1, 2, 3, 4 h), and phenol concentration (100, and 200 mg/l). Signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were utilized to examine the impact of each factor. The optimal conditions for phenol removal were 100 mA/cm2, 100 mg/l of phenol, and 4 hours of electrolysis. Under optimal operating conditions, the phenol removal efficiency was 80.99%. The CD was the most influential factor on phenol elimination effectiveness, while the phenol concentration had the least impact.

S-doped Yttrium Ruthenate Pyrochlore catalyst for Efficient Electrocatalytic Oxygen Evolution in Acidic Media

The sulfur-doped yttrium ruthenate pyrochlore catalysts was synthesized by simple hydrothermal method and exhibits excellent OER activity and stability under acidic conditions. Remarkably, the Y2Ru2O7S-0.17 catalyst reaches a current density of 10 mA cm−2 with only 237 mV and remains stable during 30 hours of electrolysis. In contrast, the original Y2Ru2O7 and commercial RuO2 require 282 mV and 365 mV, respectively. The introduction of sulfur into the internal lattice, replacing a portion of oxygen ions, creates vacancies that enhance the surface adsorption of oxygen. Furthermore, density functional theory calculations expose that S-doping alters the hybridization between the Ru 4d center and O 2p orbitals, significantly decreasing the energy barrier of the rate-determining step of the OER (O*--OOH*). Consequently, the intrinsic activity of the catalyst is greatly enhanced.

Optimization of Flow-By CO2 Electrolyzers: Impact of Differential Pressure and Gas Diffusion Layer Composition

The electrochemical reduction of CO2 (eCO2R) into valuable chemicals offers a great ecological solution to lower anthropogenic CO2 in the atmosphere, since it can close the carbon cycle by utilizing renewable energy, resulting in a sustainable carbon recycling system. Consequently, it has gathered significant scientific interest over the past decade [1,2]. However, to make significant progress towards making the process industrially feasible, it would be beneficial to replace the typical anodic oxygen evolution reaction at the counter electrode with an economically more interesting one, like alkane dehydrogenation, while at the same time lowering cell potential and increasing energy efficiency. However, this requires the CO2 reduction to operate efficiently at elevated temperatures (up to 100°C) [3]. Unfortunately, little is known on the impact of elevated temperatures on the overall performance of CO2 electrolyzers and its components.In this research, we studied the effect of increasing the temperature on CO2 electrolyzers to ultimately enable selective and stable eCO2R to formic acid not only at room temperature. Heating the system leads to many changes (e.g. decreased electrolyte surface tension, decreased hydrophobicity of the gas diffusion layer (GDL), lower dissolved CO2 content and, increased CO2 diffusion coefficient), all affecting the performance of a conventional CO2 electrolyzer, consequently raising the need for re-evaluating many of its components and their configuration, considering they have been optimized for operation at ambient conditions. Specifically, we focused on the three-phase boundary, where the eCO2R reaction actually takes place. Logically, it is important that this boundary is at the exact location of the catalyst layer (CL), as the catalyst is the active species towards the desired reaction. To this end, GDLs are specifically designed to align this boundary to the right location through variations in hydrophobic additives, thickness, porosity, etc. However, we have found that all these efforts to perfect the GDL's properties can be forfeited if the differential pressure across it were to change as it shifts the three-phase boundary. A shift inwards the GDL will result in a flooded CL, lengthening the diffusion path of the gaseous CO2 in the electrolyte to the active sites of the CL resulting in increased hydrogen evolution. A shift outward the GDL will result in a CL that is not fully used, as such lowering the activity. Since the CL is a thin layer, it can be easily understood that the margin within which the boundary can shift without becoming catastrophic for the overall performance is very small, making it extremely critical to have precise control over its position. Changing the temperature of the system will affect the location of the boundary layer and by optimizing the differential pressure we can shift its location back to its optimal position and increase the performance of the CO2 electrolyzer.We investigated the influence of deliberately altering the differential pressure across a GDE in a flow-by electrolyzer with Bi2O3 nanoparticles for the eCO2R towards formate, at different temperatures. At higher temperatures (i.e. 85°C), flooding was a pronounced problem, which resulted in a rapid decrease of performance, and after 24 hours of electrolysis only a 40% faradaic efficiency towards formate (FEHCOOH) was maintained from the initial 70%. We discovered that by increasing the differential pressure, by elevating the backpressure at the gas side, we could limit flooding of the GDE. By mitigating the flooding, the system was able to maintain a better performance, i.e. FEHCOOH of 65% after 24 hours of electrolysis was maintained, which is a 1.6 factor increase (Figure). The present findings confirm that, without altering any of the more significant electrochemical aspects of the electrolyzer, it is possible to increase performance by solely varying the differential pressure over the GDE, showing the importance of also optimizing the operational conditions.Once the optimal differential pressure of the system was established, it was still necessary to investigate the GDE structure itself. Indeed, the GDE should be designed to appropriately mediate all transport processes necessary to achieve high eCO2R performance and further reduce flooding phenomena, by favourably affecting CO2 transport, local pH and water transport [4]. Therefore, the next step was to investigate and compare other commercially available GDLs. For this research we selected commercially available GDLs that are primarily used in high-temperature proton exchange fuel cells, since their required characteristics (hydrophobicity, thickness and pore structure) are similar to the needs of our system.By re-evaluating and optimizing these (operational) conditions, we are getting closer to making the electrochemical CO2 reduction efficient, also at elevated temperatures.[1] https://doi.org/10.1016/j.petlm.2016.11.003[2] https://doi.org/10.1016/j.joule.2017.09.003[3] https://doi.org/10.1002.celc.201900872[4] https://doi.org/10.1038/s41578-021-00356-2 Figure 1

Electrocoagulation Coupled to Electro-Oxidation for the Electrochemical Treatment of Hemodialysis Wastewater

Hemodialysis is an extracorporeal kidney replacement procedure to remove impurities or waste products from the blood used to treat kidney failure. During this process, large amounts of water are used, which, lacking control, end up in sewage systems, potentially flushing high levels of organic and inorganic contaminants into the receiver’s aqua biota. In recent years, a hybrid electrocoagulation (EC) and electro-oxidation (EO) process in sequential or simultaneous coupling has been used for the treatment of wastewater.This research considered synthetic water from hemodialysis under acid and basic conditions. To better simulate the presence of organic compounds, 10 mg L-1 of amoxicillin (AMX), an antibiotic commonly present in wastewater from clinics and hospitals, was added. Laboratory and pilot tests were performed using coupled EC and EO. They used stainless-steel (SS-304) and aluminum (Al-6061) as sacrificial anodes that were compared in acidic and basic pH during EC. The SS-304 rod anode and a titanium (Ti) mesh cathode were used during EC in acidic conditions at a field strength of 3.0 V, which was applied for 60 min. After EC, the solution obtained was filtered to separate precipitates. The supernatant was then treated with EO using an IrO2-Ta2O5|Ti (70:30) anode and the Ti mesh cathode while applying 10 mA for 120 min. The wear of the SS-304 anode was identified by scanning electron microscopy (SEM) and microanalysis (EDS). Removal of organic compounds, including AMX, was significant. This result was confirmed by decreased concentration found by diode coupled chromatography (UPLC-UV-Vis) detection.In conclusion, combining EC and EO in a sequential arrangement for the treatment of hemodialysis wastewater was carried out. EC was performed using a cylindrical SS-304 bar electrode (f = 0.8 cm) as an anode and a concentric Ti mesh as the counter electrode. A 3.0 V cell potential was maintained over one hour of electrolysis in acidic pH (pH = 5.06, s = 227 mS cm-1). This treatment yielded a removal efficiency of 86 ± 1.25 % of AMX contaminate (pH = 8.21, s = 217.26 mS cm-1, i = 11.36 mA, E = 0.568 kWh m-3). After EC, it was necessary to include a filtration or separation process to remove the Fe(OH)3 and [AMX-cation-AMX] sludge generated (2.3 g). This separation employed a settler. Subsequently, the supernatant was placed in an EO cell to remove residual organic compounds as AMX. It used a similar cell arrangement as in EC but changed the anode to IrO2-Ta2O5|Ti (70:30) (f = 0.5 cm) to perform the EO of the pharmaceutical product. During this step, the team achieved an overall removal efficiency of AMX of 100 % (pH = 8.14, s = 179.83 mS cm-1, E = 500 kWh m-3). EO was performed using a continuous 10 mA cell current for 2 h. EO generated reaction products ADP 1, ADP 2, and ADP 3. Additionally, this process decreased the content of ‘salty’ cations: Na+, K+, Ca2+, and Mg2+, while generating Cl2 gas at the electrode.

Self-supporting CuM LDH (M = Ni, Fe, Co) carbon cloth electrodes for selective electrochemical ammonia oxidation to nitrogen

Electrochemical ammonia oxidation reaction (eAOR) has important applications in ammonia fuel cells and wastewater treatment due to its environmental friendliness and convenient operation. In this study, hydrothermal synthesis was used to create self-supported CuM (M = Ni, Fe, Co) carbon cloth electrodes. After three hours of electrolysis at 1.65 V vs. RHE, a CuCo/CC electrode with the ideal Cu/Co ratio (1:2) achieved the maximum dinitrogen selectivity of 90.0% and Faraday efficiency of 77.4%. The reaction mechanism was investigated using Raman and in-situ IR spectroscopy. Cu serves as NH3 adsorption sites and Co catalyzes the oxidation, and together achieve high efficiency.

P‐Modified Single‐Atom Cu Catalyst Boosting Electrocatalytic Performance of NO3− Reduction to NH3

AbstractElectrochemical conversion of NO3− to NH3 production is of great environmental significance for water pollution treatment and can artificially close the nitrogen cycle. However, direct nine protons and eight electrons transfer lead to low Faraday efficiency (FE) and yield. Herein, the single copper site immobilized on N,P co‐doped carbon substrates (Cu−N4/P) was prepared for efficient NO3−‐to‐NH3 conversion. Benefiting from the electronic redistribution of the Cu site induced by the introduction of the less electronegative element P, the Cu−N4/P catalyst exhibited a high Faraday efficiency of FE (95.89 %) for NH3 product formation at a potential of −0.6 V vs. RHE and 100 % conversion of NO3−−N was achieved after 5 hours of electrolysis. Density functional theory (DFT) explains the effective operation mechanism that P doping can promote the spontaneous hydrogenation of *NO to form *NOH, thus promoting the formation of NH3 from NO3− reduction reaction. The heteroatom doping strategy mentioned proposes a new approach for promoting NO3−‐to‐NH3 conversion at atomic level catalytic sites.

A brush-like Cu2O-CoO core-shell nanoarray: an efficient bifunctional electrocatalyst for overall seawater splitting.

Herein, a brush-like Cu2O-CoO core-shell nanoarray on copper foam (Cu2O-CoO/CF) can achieve efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance in alkaline seawater electrolyte. This Cu2O-CoO/CF shows overpotentials as low as 315 and 295 mV at 100 mA cm-2 for the OER and HER, respectively. Moreover, it could also be operated at 1.82 V with 100 mA cm-2 in a two-electrode electrolyzer and exhibits strong stability for at least 50 hours of electrolysis. The excellent performance and hierarchical structure advantages of Cu2O-CoO/CF provide new ideas for designing efficient seawater splitting electrocatalysts.

Detection of radicals produced during electro-oxidation of atrazine using commercial DSA®-Cl2 in methanol media: Keys to understand the process

This work reports the radicals detected and identified during the degradation of atrazine in methanol medium in the presence and absence of different proportions of water (0%, 5%, and 10%). The determination of these radicals is an important step to understand the electrolysis processes in methanol medium and contribute to clarify the degradation mechanism. Furthermore, the parameters for the successful removal of the contaminant were optimized and the results showed that the application of the technique led to the removal of nearly 99.8% of atrazine after 1 h of electrolysis. The oxidation kinetics was found to be very fast and most of the atrazine molecule in the medium was degraded in the first hour of electrolysis. The results obtained from a thorough analysis conducted with a view to evaluating the effects of different current densities and initial pH values on atrazine degradation showed that the application of higher current densities resulted in lower energy consumption, as this led to faster removal of atrazine. Additionally, the initial pH of the solution was found to favor the formation of different species of active chlorine. The radicals formed during the electro-oxidation process were detected by electron paramagnetic resonance spectroscopy and include hydroxyl, methoxy and hydroxymethyl. The use of methanol for the degradation of pollutants is a highly promising technique and this work shows that the identification of the different radicals formed in the process can be the key to understanding the degradation mechanism.

Selective electrocatalytic hydrogenation of α,β-unsaturated ketone on (111)-oriented Pd and Pt electrodes

In this paper, we study the electrocatalytic reduction of methyl vinyl ketone on Pt(111) and Pd-modified Pt(111) electrodes, as well as some of its expected hydrogenation derivatives and isolated functional moieties. The selectivity and Faraday efficiency have been calculated via sampling the catholyte solution after two hours of electrolysis. Furthermore, the adsorbates involved in the deactivation process on both surfaces were studied by means of potential opening experiments and in situ infrared spectroscopy. The Pd-modified Pt(111) electrode is very active (even mass transport limited) for the selective electrochemical hydrogenation of the C=C to 2-butanone, in the hydrogen underpotential deposition potential window (between 0 and 0.2 VRHE), with limited poisoning. Pt(111) is much less active, and poisons rapidly with adsorbed CO. The poison is formed from the C=C bond, not from the C=O moiety, as evidenced by the same poisoning occurring for ethylene. Further hydrogenation to the saturated alcohol happens at more negative potentials, but with 2-butenol as intermediate, not 2-butanone, as the latter species interacts too weakly with the (111) surface.

Degradation and Mineralization Study of Promecarb by Electro Fenton Process

Organic substances as pesticides, especially aromatic compounds are a major environmental concern. In the present work, solutions of Promecarb or 3-isopropyl-5-methylphenyl-N-methylcarbamate of pH = 3 have been degraded by electro Fenton process, using a volumic electrochemical reactor filled with carbon graphite. Effects of nature of material of cathode, initial concentration of insecticide and applied current on the kinetics of oxidative degradation and mineralization efficiency have been investigated. Kinetic analysis showed that the oxidation of Promecarb by hydroxyl radicals follows a reaction kinetic of pseudo first order. The absolute rate constant for Promecarb oxidation by hydroxyl radicals was determined as 10.88 × 10⁹ L mol^-1 s^-1 by competitive kinetics method and benzoic acid was used as reference compound. Mineralization of this pesticide by hydroxyl radicals consists in its transformation to mineral products. The evolution of the mineralization during Promecarb treatment by electro Fenton process was followed by analysis of Total Organic Carbon TOC. Thus, after 3 hours of electrolysis and at I = 800 mA, more than 50% of the organic carbon present in the solution is mineralized. Several degradation products were formed during its electro Fenton treatment. These intermediates were identified using High Performance Liquid Chromatography HPLC, Ionic Chromatography IC and Liquid Chromatography - Mass Spectrometry LC-MS. Based on identification of aromatic intermediates and carboxylic acids, a plausible Promecarb mineralization pathway is proposed. Also, we realized the measurement of the Biochemical Oxygen Demand BOD₅ of insecticide solution after treatment by electro Fenton process, to evaluate its biodegradability.

Optimum parameters for humic acid removal and power production by Al-air fuel cell electrocoagulation in synthetic wastewater.

Although humic acid (HA) is a complex natural organic matter, it can potentially harm the environment and human health. In this study, aluminum-air fuel cell electrocoagulation (AAFCEC) was used to remove HAs from water while generating electricity. Initial pH, electrolyte concentration, HA concentration electrode distance and external resistance were investigated to determine the power generation and removal efficiency. The results showed that the better performance of power generation has been acquired in the alkaline solution and larger electrolyte concentration and short electrode distance. Further, Al-Ferron complexation timed spectrophotometry was used to determine the Al speciation distribution in the solution under different parameters. The power density of the cell reached 313.47 mW/cm2 for the following conditions: 1 g/L NaCl concentration, 3 cm electrode distance, 20 Ω external resistor, and pH 9. After about an hour of electrolysis, the optimum removal rate of HA was above 99%. The results demonstrated that the AAFCEC is an efficient and eco-friendly water treatment process, and it could be further developed and disseminated in the rural areas and households.

Coupling of cathodic aluminum dissolution and anodic oxidation process for simultaneous removal of phosphate and ammonia in wastewaters

Removal of excessive nutrients (N and P) is one of the most concerned issues for wastewater treatment. This study presents a paired electrolytic system consisting of Al cathode and RuO2/Ti anode for the simultaneous removal of phosphate and ammonia in wastewaters. The comparative study on the dissolving behaviors of Al cathode and Al anode showed that Al cathode could achieve a continuous and stable dissolution of aluminum, thereby forming flocs and small amounts of water soluble aluminum species for decontamination. The electrogenerated OH– in the vicinity of cathode raised the local alkalinity and caused the chemical dissolution of aluminum. According to the experiment of non-electrolytic dissolution of aluminum in alkaline solution, the local pH resulting in the cathodic dissolution of Al was estimated. The paired electrolytic system showed the capability to simultaneously remove ammonia and phosphate in simulated wastewater, and the pH neutralizing effect in association with the formation of Al species could promote the electrochemical oxidation of ammonia. When the paired electrolytic system was applied to the treatment of landfill leachate, 96.9% of ammonia nitrogen, 87.4% of total phosphorous and 89.9% of COD could be eliminated after three hours of electrolysis at 80 mA/cm2. The results shown in study reveal that the dissolution process of Al cathode enables a convenient control on the dissolving-out amounts of aluminum via regulating the applied current density, and the paired electrolytic system can be developed as an energy-efficient electrochemical wastewater treating method.

Unveiling Complete Ethanol Oxidation through a Hybrid Enzymatic and Organic Catalyst Cascade in an Electrochemical Micro-Reactor Device

Biological fuel cells have been extensively reported as a efficient and sustainable device to convert chemical energy to electrical energy [1]. Biofuel cells (BFCs) are alternative energy sources which use enzymes (enzymatic biofuel cell) or microorganisms (microbial fuel cell) as the electrocatalysts instead of the traditional noble metal catalysts. Ethanol is a fuel that can be used in combined enzymatic fuel cell due to its high energy density (8.03 kW h kg -1), low emission, and storage security [2]. The advantage of enzymes is that they exhibit high specificity and turnover rate, however, mimicking the natural metabolism from ethanol through electrometabolic pathways is enormously difficult. To overcome the limitations of using multiple enzymes to achieve the complete ethanol oxidation, a small molecule organic catalyst can be employed. TEMPO (2,2,6,6-tetramethylpiperidin-1-yl) oxyl) is a small organic catalyst that does not present limited substrate specificity such as enzymes face, due to its ability to oxidize oxygen, nitrogen and sulfur-containing functional groups. Thus, hybrid system enables improvement at the rate of electrocatalytic oxidation of several biofuels [2 - 4]. Herein, we described the development of a hybrid catalytic architecture combining an organic oxidation catalyst, 4-amino-TEMPO (TEMPO-NH2), and a recombinant enzyme, oxalate decarboxylase (OxDc) to catalyze complete ethanol electrooxidation. The catalyst system was coupled with a novel small scale electrolysis cell utilizing polycaprolactone (PCL) and carbon composite electrodes for bulk electrolysis. Electrochemical meansurements and product detection by nuclear magnetic resonance (NMR) after 12 hours of electrolysis have shown for the first time that an organic catalyst and decarboxylase enzyme enhances the overall steps in the cascade operating at acidic pH enabling enhanced electrochemical oxidation of ethanol to CO2. To validate the reaction sequence, a novel micro-reactor device enabled low-cost product analysis and allows for high analyte sensitivity. Overall, this work demonstrated that bi-cascade of TEMPO-NH2 and OxDc can be combined in an electrochemical cell to synergistically catalyze the oxidation of substrates that make up the steps of the ethanol oxidation cascade and is promising for a wide array of applications, including biosensors, environmental monitoring, and biofuel cells.

Nanoscale CuTe electrocatalyst immobilized at conductor surface for remarkable hydrogen evolution reaction

Hydrogen generation from electrocatalytic water splitting is of supreme significance for resolving energy crisis and environmental concerns. However, developing earth-abundant, efficient, and durable electrocatalyst for high-performance hydrogen evolution and complete water splitting catalysis is a rare instance. We present here the first demonstration of unique copper tellurides nano-structures (CuTe-NS) based electrocatalyst executing HER with high activity and remarkable stability. CuTe-NS based electrocatalysts grown over conductive NiF via drop-casting approach and employed for HER, while achieving a current decade and a current density of 100 mA/cm2 just at 0.25 V vs. RHE and 0.27 V vs. RHE, which is comparable to the benchmark Pt/C based HER catalyst. The catalyst demonstrates well-balanced kinetic behavior, low Tafel slope of 36 mV/dec, low charge transfer resistance of 1.71 Ω, high roughness factor, and remarkable stability for more than 60 h of electrolysis. Furthermore, post-catalysis characterizations demonstrate no change in catalyst integrity, morphological, and structural attributes even after many hours of electrolysis which show sustainable behavior of catalyst for long term HER activity. Because of electrochemical and structural stabilities after long term electrolysis experiments, accessible method of preparations, and cost-effectiveness, the catalysis is highly encouraging for real-life applications.

Study on the Growth Law of Manganese in Electrolysis Process of MnSO4 Solution Containing Magnesium

At present, there was no good industrial removal method for soluble impurity Mg2+ in electrolytic manganese industrial production, so MgSO4-MnSO4-(NH4)2 SO4 compound salt crystal with minimal solubility was formed by cyclic enrichment in solution. On the one hand, it caused the loss of manganese, ammonium and other main components, on the other hand, a large amount of storage caused environmental pollution. In order to find out the harmful effect of magnesium on the production of manganese in an all-round way, this paper studied the growth and deposition of manganese when the concentration of Mg2+ was 25g/L. The results showed that with the increase of electrolysis time, the grain size increases from 42.11μm for 2h to 185.71 μm for 10h, and the current efficiency gradually decreased from 73.3% for 2h to 67.26% for 10h. After 8 hours of electrolysis, the growth rate of grain size and the decrease rate of current efficiency were improved, and there were a certain relationship between them.

Two-steps synthesis of D-glucaric acid via D-gluconic acid by electrocatalytic oxidation of D-glucose on gold electrode: Influence of operational parameters

Glucose electrooxidation to glucaric acid, a highly valuable platform chemical, has been conducted, for the first time, in two consecutive steps employing a bare gold electrode in a batch reactor. The first step, at low potential, enabled the effective formation of the intermediate, gluconic acid, promoted by the oxidation of the aldehyde group on C1. For this reaction step, except for the reaction time, all the operational parameters had a strong impact on the selectivity. At the optimal conditions of pH 11.3, 5°C and 0.04 M initial glucose, a maximum selectivity of 97.6% was obtained, the highest reported to date for the electrochemical process, with a conversion of 25%. At higher potential, gluconic acid was further converted to glucaric acid by the oxidation of the hydroxymethyl group on C6. For this oxidation step, the variation of the operational parameters (pH, gluconic acid initial concentration, reaction temperature and time) had no conspicuous effect on the selectivity, while the applied potential had a major role: at 1.1 VRHE, a maximum selectivity of 89.5% to glucaric acid was obtained, which is one of the highest values reported in literature so far. In all experiments, irrespective of conditions and reaction time, a maximum concentration of ca 1.2 mM of glucaric acid was achieved, and a drastic decrease of the current density was observed in the first hours of electrolysis. Additional control experiments revealed a poisoning process caused by glucaric acid that, once formed, remains strongly bonded to the catalyst's active sites, thus deactivating it.

Surface-assembled Fe-Oxide colloidal nanoparticles for high performance electrocatalytic water oxidation

Nanoscale electrocatalytic materials having enhanced electroactive sites has been considered trendier and can drive kinetically uphill OER at much lower energy cost with high efficiency. However, very complex synthetic strategies, extensive functionalization processes, and less stability have stimulated quest for economically viable, straightforward and facile preparative methods for designing stable, robust and active nanoscale electrocatalysts engaging geologically abundant materials to ensure their industrial implications. Here we present surface-assembled Fe(OH)x/FeOx type colloidal catalytic thin-films, with or without post annealing, derived from Fe-colloidal NPs in simple carbonate system for efficient water oxidation. Comprehensive electrochemical studies including cyclic voltammetry, chronoamperometry, chronopotentiometry, impedance spectroscopy, Tafel slope analysis, mass activity, electrochemically active surface area measurements are conducted to comparatively evaluate the performance of simple (FeOx/HCO3−@FTO and annealed (FeOx/HCO3−@FTO250, FeOx/HCO3−@FTO500) catalysts for oxygen evolution reaction (OER) under employed conditions. The FeOx/HCO3−@FTO250 annealed at 250 °C initiates water oxidation at much lower overpotential of 1.52 V vs. RHE with remarkable stability during long-term electrochemical experimentations. In addition to enhanced OER activity as evidence by better onset potential (<1.55 V vs. RHE), lower Tafel slope value (36 mV dec1−) and negligible charge transfer resistance, the Fe(OH)x/HCO3−@FTO type catalyst presented excellent electroactive nature during long term controlled potential electrolysis experiments where more and more electroactive sites were getting exposed during continuous hours of electrolysis. The catalysts behave as a potential enduring, inexpensive and competent candidate for catalyzing water oxidation reaction when tested under begin conditions.