Sulfate Electrolyte Research Articles

Electrochemically embedded nickel oxide in a highly porous manganese oxide film with enhanced catalytic kinetics of the urea oxidation reaction

The use of well-dispersed nickel catalysts with atomic-scale sizes is an effective approach for maximizing catalytic activity and selectivity for the urea oxidation reaction (UOR). Herein, a porous ultrathin film of Birnessite-type manganese oxide is anodically deposited on a nickel substrate as a catalyst support. Some of the intercalated sodium ions are replaced by the dissolved nickel ions from the nickel substrate in the anodic process, forming manganese oxide with partially intercalated nickel ions (denoted MnO2). The amount of nickel species can be easily increased by cyclic voltammetry in the nickel sulfate electrolyte (denoted MnO2-Ni), without the relatively time-consuming process of conventional ion exchange. Most of the embedded nickel species are catalytic Ni3+ ions, rendering MnO2-Ni a favorable catalyst to boost the UOR. The cyclic voltammetry results reveal that Ni3+ catalysts, when inserted into the layer-structured manganese oxide, can increase the electroactive surface area for the adsorption of urea and increase the charge-transfer rate constant for the Ni3+/Ni2+ redox couple, leading to an improved catalytic rate constant of the UOR. A highly porous manganese oxide matrix provides many transport pathways for facilitating UOR kinetics. Electrochemical impedance spectroscopy shows that MnO2-Ni has lower direct and indirect UOR impedances than MnO2 and bare Ni electrodes, leading to a greater oxidation current and lower onset potential.

Less is More: Trace Amount of a Cyclic Sulfate Electrolyte Additive Enable Ultra-Stable Graphite Anode for High-Performance Potassium-Ion Batteries.

Graphite can be successfully used as an anode for potassium-ion batteries (PIBs), while its conversion to KC8 leads to huge volume expansion, destruction of solid electrolyte interphase (SEI), and thus poor cycling stability. Incorporating additives into electrolytes is an economical and effective way to construct robust SEI for high-performance PIBs. Herein, we developed a series of sulfur-containing additives for PIB graphite anodes, and the impacts of their molecular structure and contents on the SEI are also systematically investigated. Compared with butylene sulfites and 1,3-propane sultone, the 1,3,2-dioxathiolane 2,2-dioxide (DTD) additive endows the graphite electrode (GE) with a higher reversible capacity, and better cycling stability in both the dilute potassium bis(fluorosulfonyl)imide (KFSI)- and potassium hexafluorophosphate (KPF6)-based carbonate electrolyte, as a result of a thinner and sulfate-enriched SEI. Moreover, the addition of a trace amount (0.2 wt %) DTD to the electrolyte can effectively protect the GE running over 800 cycles at 1 C. Excessive additives in the electrolyte will induce continuous SEI growth and render a rapid capacity fading of the GE. This strategy using the electrolyte additive paves the way for the design of novel PIB electrolytes and thus provides a great opportunity for commercial PIBs.

Термическое разложение дистиллята каменноугольной смолы в присутствии нанопорошка железа

Impact of the nanosized iron powder on the process of thermal degradation of coal tar distillate was determined by the thermogravimetric analysis. Coal tar distillate was obtained by simple distillation up to 350°C of primary coal tar from the Shubarkol deposit. Iron powder was obtained by electrochemical reduction of iron from sulfate electrolytes at simultaneous impact of high-voltage electric discharge on cathodic zone. Scanning electron microscopy showed that iron powder consists of nanosized particles (30-124 nm) forming aggregates. X-ray diffraction analysis revealed the presence of α-Fe and FeO(OH) phases. The average crystallite size determination was made using Scherrer equation and amounted to 31.7 nm. Obtained iron powder was added to the coal tar distillate in amount of 1% of distillate weight and this mixture was subjected to thermal degradation at heating rate 5°C/min in an inert atmosphere. Processing of the data obtained was carried out using the model-fitting Coats-Redfern method. The values of activation energy were calculated from the linear approximation constructed as a result of processing thermoanalytical data. It was found that the addition of iron powder in amount of 1% to the coal tar distillate reduces the activation energy from 153.98 kJ/mol to 84.48 kJ/mol.

Chemical mechanical polishing exploiting metal electrochemical corrosion of single-crystal SiC

A chemical mechanical polishing (CMP) method of single-crystal SiC is proposed based on metal electrochemical corrosion. The oxidation mechanism of SiC by electrochemical corrosion of metals and the mechanism of surface material removal are revealed by corrosion and polishing experiments. The metallic aluminum sheet that is in contact with single-crystal SiC was immersed in sodium sulfate (Na2SO4) electrolyte solution, and the morphological and elemental changes of single-crystal SiC surface were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Then, polishing experiments were conducted on single-crystal SiC using different metal polishing discs and different polishing solutions. The XPS and EDS results show that single-crystal SiC can electrochemically corrode to generate a silica reaction layer. The use of metal polishing discs in CMP significantly improved the material removal rate (MRR) of SiC, with the highest MRR of 1011.43 nm/h for aluminum polishing discs, followed by that for iron polishing discs, and the lowest MRR for copper and alumina ceramic polishing discs. When metal polishing discs were used, the addition of electrolyte solution significantly improved the MRR and reduced the surface roughness of the SiC surface. Polishing with Na2SO4 solution when the polishing disc was aluminum disc, the MRR was higher than that for using deionized water by 105%, and the surface roughness Ra decreased by 37.8% to 2.8 nm. The metal electrochemical corrosion reaction can promote the oxidation of single-crystal SiC and generate a soft SiO2 reaction layer on the SiC surface, thereby improving the polishing efficiency of single-crystal SiC.

Obtaining of copper powder by method of a vortex electrolysis from acid sulphate electrolytes

• A vortex electrolysis unit was designed and assembled. • Finely dispersed copper powders were obtained by method of a vortex electrolysis. • Optimum conditions for obtaining finely dispersed copper powder were established. • The particle size of the powder is 5–10 μm, the current efficiency is 95.5%.

Growth, characterization, and photovoltaic application of copper oxide thin films

• CuO was obtained from the annealing of Cu 2 O electrodeposited on SnO 2 :F electrodes. • Optical properties were modeled in the visible and near-infrared ranges. • Photoelectrochemical measurements confirmed a possible absorber layer application. • CuO samples have presented a strong photocurrent generation. This work presents the fabrication of Cu 2 O thin films using electrodeposition at room temperature. These have been grown using a copper (II) sulfate electrolyte (pH=10) on fluorine-doped tin oxide films. Thermal oxidation at standard atmosphere was applied to obtain CuO samples from Cu 2 O. The characterization of these copper oxide samples has revealed their morphological, compositional, crystalline, vibrational, and optical properties. These results indicate the desired features for photovoltaic conversion applications. Moreover, strong photocathodic current generation in these samples has been found using chronoamperometry. In addition, first-principles calculations based on generalized gradient approximation, in a Perdew-Burke-Ernzerhof parametrization, were performed to determine the structural, electronic, and optical properties of these copper oxides to help in the interpretation of the experimental results.

Mechanistic investigation into flow-through electrochemical oxidation of sulfanilamide for groundwater using a graphite anode

The technical effectiveness/merit of electrochemical oxidation (EO) has been recognized. Nonetheless, its practical application to groundwater remediation has not been fully implemented due to several technical challenges. To overcome the technical incompleteness, this study adopted a graphite anode in the flow-through system and studied the mechanistic roles of a graphite anode. To this end, groundwater contaminated with sulfanilamide was remediated by means of EO, and sulfanilamide oxidation was quantitatively determined in this study. Approximately 60% of sulfanilamide was degraded at the anode zone, and such observation offered that the removal of sulfanilamide was not closely related with current variations (10–100 mA). However, this study delineated that sulfanilamide removal is contingent on the flow speed. For example, the removal of sulfanilamide was lowered from 59 to 25% owing to a short contact time when the flow velocity was increased from 0.14 to 0.55 cm/min. This study also delineated that a shorter anode-cathode distance could offer a favorable chance to enhance the removal of sulfanilamide even under an identical current. A shorter distance could offer a chance to save energy due to the lower voltage operation. This study also offered that chloride (Cl−) and sulfate (SO42−) electrolytes served a crucial role in the generation of active species. In contrast, bicarbonate (HCO3−) and synthetic groundwater electrolytes impeded the oxidation rate because HCO3− scavenged the other active species. In an effort to seek the oxidation mechanisms of a graphite anode, scavenger, cyclic voltammetry test, and electron https://en.wikipedia.org/wiki/Electron_paramagnetic_resonanceparamagnetic resonance (EPR) analysis were done. From a series of the tests, it was inferred that a graphite anode did not directly affect the generation of the active species. Thus, the prevalence of the oxygenated functional groups on an anode surface could be the main mechanism in sulfanilamide removal due to the enhanced electron transfer.

Bismuth-based metal-organic frameworks derived rod-like nanoreactors for neutral aqueous battery-type anode

Bismuth oxide (Bi2O3) has received great attention as the promising battery-type anode due to its high theoretical capacity and wide operating voltage window, yet its slow reaction kinetics and poor cyclability are major obstacles affecting the performance of energy storage devices. Herein, by employing the bismuth-based metal-organic framework (MOF) CAU-17 as both the template and precursor, the Bi-Bi2O3 nanoparticles encapsulated in carbon nanorods (Bi-Bi2O3@CNR) are fabricated through pyrolysis combining deliberate oxidation-state modulation. The Bi-Bi2O3@CNR anode exhibits enhanced electrical conductivity, fast reaction kinetics, high specific capacity, and extended lifespan in sodium sulfate electrolyte. The robust, in situ derived carbon matrix as a rod-like nanoreactor and the introduction of metallic bismuth into the bismuth oxide crystalline structure enable the Bi-Bi2O3@CNR electrode to deliver a package of optimal electrochemical performance, as evidenced by substantial physicochemical characterizations, kinetics analysis and density functional theory calculations. Consequently, the neutral aqueous Na-ion battery-supercapacitor hybrid device based on the Bi-Bi2O3@CNR anode and δ-MnO2 cathode can achieve high energy and power densities simultaneously with an ultra-wide potential window of 2.4 V. This work offers an opportunity to develop high-performance Bi2O3-based electrodes by designing kinetically favorable host structure with high stability and modulating oxidation states of the active component for the neutral aqueous battery-type anode.

In-situ photoelectrocatalytical formation of sulfate radicals on BiPO4 modified carbon paper electrode in sodium sulfate electrolyte for high efficient degradation of pefloxacin

In recent years, advanced oxidation processes (AOP) based on sulfate free radicals (SO4−·) have attracted considerable attention due to the excellent advantages of SO4−· compared with hydroxyl radical (·OH). However, SO4−· generally produced by activating extra persulphates, which causes high cost and risk of secondary pollution. In this work, BiPO4 modified carbon paper electrode (BiPO4/CP) successfully fabricated via simple method can be used as a photocatalyst to effectively activate sulfate originally existed in wastewater to generated sulfate radicals in-situ without adding any extrinsic chemical oxidants. Pefloxacin (PFX) was degraded effectively on BiPO4/CP with the help of applied potential. CP with large surface area and high electrical conductivity as an excellent support for BiPO4 is beneficial to improve the reutilization, electron transfer and photocatalytic performance of BiPO4. Moreover, BiPO4 with large bandgap has sufficient redox capacity to produce not only ·OH, superoxide radical (·O2−), but also SO4−·, which is crucial for photocatalytic pollutant degradation. Detailed characterizations give strong evidences of the successful fabrication of photocatalyst, thermodynamic feasibility of SO4−· in-situ formation, the generation of free radicals, and the possible mechanism. Consequently, under the optimal conditions (pH=5.6, +1.0 V (vs.SCE), [SO42−]=10 mM, 61 μW cm−2 UV light irradiation, 33 mg BiPO4 loaded on CP), the degradation efficiency of PFX (10 mg/L) was 87.8% in 120 min, which was 5.1 ad 8.2 times higher than that in photocatalytic and electrocatalytic system and 3.3 times higher than that without SO42−. Meanwhile, BiPO4/CP maintains high level of degradation efficiency of PFX after 6 cycles under the optimal conditions.

Troubleshooting the Limited Zn2+ Storage Performance of the Ag2V4O11 Cathode in Zinc Sulfate Electrolytes via Favorable Synergism with Reduced Graphene Oxides

Troubleshooting the Limited Zn²⁺ Storage Performance of the Ag₂V₄O₁₁ Cathode in Zinc Sulfate Electrolytes via Favorable Synergism with Reduced Graphene Oxides

Multi-scale self-templating synthesis strategy of lignin-derived hierarchical porous carbons toward high-performance zinc ion hybrid supercapacitors

Chemical activation is a common process for preparing porous carbon electrode materials of supercapacitors. Nevertheless, chemical activation approach has the disadvantages of being chemically caustic, environmentally unfriendly, and expensive. This study constitutes a multi-scale self-template approach for the preparation of lignin-derived hierarchical porous carbons (LHPCs) with high specific surface areas and excellent electrochemical performances. KCl, carbonates, and sulfates, generated in the carbonization process, play the role of multi-scale template agents for the pore-forming process. LHPCs exhibited superb electrochemical performances as electrodes of supercapacitors with alkaline and neutral sulfate electrolytes. In addition, the Zn//LHPCs hybrid supercapacitors (ZIHSCs) achieved an ultra-high energy density of 135 Wh kg−1, which is 20 times higher than symmetric supercapacitors with KOH electrolytes (6.6 Wh kg−1) and 9 times higher than symmetric supercapacitors with Na2SO4 electrolyte (14.8 Wh kg−1). This work proposes a general multi-scale self-template strategy for the synthesis of hierarchical porous carbons from sodium lignosulfonate for supercapacitor applications.

Local electrochemical deposition of copper from sulfate solution

Local electrochemical deposition is a type of electroplating used to plate metal locally or form metal objects using electrochemical principles at a short distance from the working electrode. In this work, deposition of the copper spot was modelled using COMSOL software and experimentally tested in copper sulfate electrolyte using soluble copper anode. The working capillary diameter was 4 mm and the interelectrode distance was 5 mm. The deposited copper of 100 µm height was investigated using the 3D-profilometry technique. The geometry of deposited metal was found to be in good accordance with the COMSOL model. The inclusions of anodic sludge were responsible for the surface inhomogeneity of the deposited copper.

Lanthanum nitrate as aqueous electrolyte additive for favourable zinc metal electrodeposition

Aqueous zinc batteries are appealing devices for cost-effective and environmentally sustainable energy storage. However, the zinc metal deposition at the anode strongly influences the battery cycle life and performance. To circumvent this issue, here we propose the use of lanthanum nitrate (La(NO3)3) as supporting salt for aqueous zinc sulfate (ZnSO4) electrolyte solutions. Via physicochemical and electrochemical characterizations, we demonstrate that this peculiar electrolyte formulation weakens the electric double layer repulsive force, thus, favouring dense metallic zinc deposits and regulating the charge distribution at the zinc metal|electrolyte interface. When tested in Zn||VS2 full coin cell configuration (with cathode mass loading of 16 mg cm−2), the electrolyte solution containing the lanthanum ions enables almost 1000 cycles at 1 A g−1 (after 5 activation cycles at 0.05 A g−1) with a stable discharge capacity of about 90 mAh g−1 and an average cell discharge voltage of ∼0.54 V.

Sustainable production of lignin-derived porous carbons for high-voltage electrochemical capacitors

• CuCl 2 activation mechanism is elucidated. • Lignin-derived porous carbon with high specific surface area. • Lignin-derived porous carbon with high yields up to 49.4%. • High-voltage electrochemical capacitors are fabricated. The high energy storage cost is a crucial factor limiting the wide application of electrochemical capacitors. Herein, we proposed a comprehensive strategy to reduce the cost of electrochemical capacitors with aqueous electrolytes, i.e. , reducing the cost of electrode materials and increasing the energy density of electrochemical capacitors. Low-cost lignin-derived porous carbon electrode materials with high specific surface area and hierarchical porous structure were prepared by CuCl 2 activation. The CuCl 2 activation agent was recycled and thus can be reused. What is more, we proposed that the mechanism of CuCl 2 activation is a solid-phase reaction in which the chloride ions in copper chloride deprive the hydrogen atoms in lignin, resulting in the loss of hydrogen atoms and the formation of pores. High energy density C//C symmetric electrochemical capacitors, Zn//C and Pb//C asymmetric electrochemical capacitors based on lignin-derived porous carbon were fabricated using sulfate electrolytes which endow high working voltage window. This work provides a comprehensive strategy for designing electrochemical capacitors with high energy densities and low cost of energy storage, which is expected to promote the industrial application of electrochemical capacitors with aqueous electrolytes.

БЛЕСКООБРАЗУЮЩЕЕ ДЕЙСТВИЕ ТРИХЛОРЭТИЛАМИДОВ С ТИОАМИДНЫМИ ФУНКЦИЯМИ В ТЕХНОЛОГИИ ЭЛЕКТРОХИМИЧЕСКОГО НИКЕЛИРОВАНИЯ

The effect of trichloroethylamides on the possibility of obtaining shiny coatings in a nickel-plating sulfate electrolyte is investigated. The presence of trichloramide fragments and substituents containing a thiocarbonyl group in the structure of the additive makes it possible to obtain shiny and semi-shiny nickel coatings without the introduction of additional reagents

Regulating the redox reversibility of zinc anode toward stable aqueous zinc batteries

Aqueous zinc batteries are among the most promising large-scale energy storage technologies but their practical application is hindered by the low redox reversibility of Zn anode in aqueous electrolytes. In this work, an indium-coated carbon-zinc composite (ICZ) anode is demonstrated with outstanding cyclic stability in classic aqueous zinc sulfate electrolytes. Compared with Zn and the carbon-zinc composite (CZ) anodes, the ICZ anode reduces the high overpotential required for Zn nucleation, and prevents high-rate HER and its related parasitic reactions, endowing high redox reversibility of the ICZ anode. Consequently, the ICZ anode enhances the cyclic stability of zinc ion batteries and zinc ion capacitors. The practical potential of the ICZ anode is demonstrated by an ICZ//porous carbon pouch cell delivering a high areal capacity of 4.7 mAh cm−2 at 6 mA cm−2. Our work provides an effective redox-kinetics regulation strategy for Zn anodes in aqueous zinc batteries.

The effect of electrocoagulation (EC) on total arsenic, arsenite (As3+) and arsenate (As5+) species removal from model groundwater investigating toxicity and sludge characteristic

This study showed that the model groundwater containing As3+ and As5+ species was successfully treated with electrocoagulation (EC) first time in the literature investigating toxicity reduction, inorganic arsenic species and detailed sludge characterization. The arsenic removal from model groundwater with 1000 µg/l total arsenic containing equal arsenite (As3+) and arsenate (As5+) concentration was examined by the EC treatment optimized with following parameters; current density (5.0, 7.5 and 10.0 mA/cm2) supporting sodium sulfate electrolyte amount (10, 20 and 30 mM Na2SO4) and initial water pH (3, 6 and 9). In EC treatment, the 99.87% arsenic removal was obtained with 10 mA/cm2, 10 mM Na2SO4 at pH 3 after 40 min supplying 1.44 μg/l effluent As concentration lower than the WHO limit for drinking water. Through transformation mechanisms of more toxic As3+ to less toxic and easily settled As5+ according to As speciation analysis, the toxicity of the model groundwater was successfully decreased in parallel with total arsenic, As3+ and As5+ removal during EC. The precipitated Al(OH)3 and Al2O3 coagulants were the main peaks in the FTIR-ATR spectrum as well as As(III)–O vibration observed between 717 and 721 cm−1 peaks and As(V)–O vibration dominated 899 and 972 cm−1 peaks were detected in the produced sludge after the EC. The SEM–EDS morphological analysis was demonstrated that the sludge was consisted of mostly amorphous structure aggregated size range of 200 μm–2 mm, relatively uniform cake including O, Al, As, Na, and S.

Charge storage mechanism in vanadium telluride/carbon nanobelts as electroactive material in an aqueous asymmetric supercapacitor

A novel one-step method for fabricating vanadium telluride nanobelt composites for high-performance supercapacitor applications is reported. The nanobelts are realized by direct tellurization of vanadium oxide in-situ formed via decomposition of ammonium metavanadate in argon atmosphere. Use of melamine as precursor helps in forming graphitic carbon layers during pyrolization on which the nanobelts are grafted. Morphological analysis suggests interconnected nanobelts of ∼23.0 nm width coming out of carbon structure. As pseudocapacitive electrode, vanadium telluride/carbon (C) composite exhibits interesting electrochemical performance within a potential window of 0–1.0 V in 1.0 M sodium sulfate electrolyte along with excellent capacitance retention during 5000 cycles. In-depth analysis suggests that the charge storage mechanism in the composite is governed by both diffusion-controlled and diffusion-independent processes with the former dominating at slower scan rates and later at faster scan rates. The asymmetric supercapacitor assembled using vanadium telluride/C and activated charcoal (AC) as respective positive and negative electrodes exhibited an energy/power combination of 19.3 Wh/kg and 1.8 kW/kg within a potential window of 0–1.8 V in aqueous electrolyte. This strategy to improve capacitance along with potential window in an aqueous electrolyte would facilitate development of high-performance energy storage devices with metal chalcogenides.

Electrochemical Performance of LiMn2O4 Cathodes in Zn-Containing Aqueous Electrolytes

Electrochemical properties of LiMn2O4 cathode were investigated in three types of Zn-containing electrolytes: lithium-zinc sulfate electrolyte (1M ZnSO4/2M Li2SO4), zinc sulfate electrolyte (2MZnSO4) and lithium-zinc-manganese sulfate electrolyte (1MZnSO4/2MLi2SO4/0.1MMnSO4). Cyclic voltammetry measurements demonstrated that LiMn2O4 is electrochemically inactive in pure ZnSO4 electrolyte after initial oxidation. The effect of manganese (II) additive in the zinc-manganese sulfate electrolyte on the electrochemical performance was analyzed. The initial capacity of LiMn2O4 is higher in presence of MnSO4 (140 mAh g−1 in 1 M ZnSO4/2 M Li2SO4/0.1 M MnSO4 and 120 mAh g−1 in 1 M ZnSO4/2MLi2SO4). The capacity increase can be explained by the electrodeposition of MnOx layer on the electrode surface. Structural characterization of postmortem electrodes with use of XRD and EDX analysis confirmed that partially formed in pure ZnSO4 electrolyte Zn-containing phase leads to fast capacity fading which is probably related to blocked electroactive sites.

Preparation and characterization of Cu-GO and Cu-GO-YSZ nanocomposite coating by electrochemical deposition for improved mechanical and anti-corrosion properties

Graphene oxide (GO) and yttria-stabilized zirconia (YSZ) nanoparticle reinforced copper (Cu) matrix nanocomposite coatings were successfully fabricated via direct current electroplating from a copper sulfate electrolyte. Influences of particle concentration (GO/YSZ) in electrolyte, electrodeposition time and applied current density on composition, microstructural and anti-corrosion performance of Cu-GO and Cu-GO-YSZ composite coatings were explored. The corrosion behaviors were evaluated by electrochemical measurement. Results indicated the composite coatings exhibit a uniform and compact surface which was made up of stacked granules, exhibiting morphologies that nanoflake-like structures dispersed on the pyramid-like copper matrix granule clusters network. The crystallite sizes of Cu-GO first increased and then decreased as GO, time and current density increased, while it varied little for Cu-GO-YSZ composite coating. The preferred orientation of Cu matrix composite coating was oriented (220) texture. The content of incorporated GO increased with the introduction of YSZ into the Gu-GO matrix. The Gu-GO coating contains 93.3 wt% Cu and 5.5 GO, and the Gu-GO-YSZ coating contains 91.7 wt% Cu and 7.6 wt% GO. The average roughness Ra of Cu-GO and Cu-GO-YSZ were 240 ± 7 nm and 236 ± 40 nm, respectively. The addition of GO nanosheets could improve the microhardness and decrease the COF of Cu matrix. Both self-lubrication effect and load-bearing capability were improved by introducing GO and YSZ together in the Cu matrix. Deposits obtained at 30 mA cm−2, 30 min, 0.1 g L−1 GO and 10 g L−1 YSZ particles own the optimal corrosion resistance with the maximum Rp. It reveals that corrosion resistance was enhanced by the presence of GO nanosheets in Cu matrix for physical isolation effect of GO and the preferred orientation (220) plane, which benefited the formation of passive film.