Electrolyte Solution Research Articles

Determining the required amount of added solvent (H2O) to obtain a given electrolyte density

Problem. The article proposes a method for determining the required amount of water that must be added to obtain a given density of the electrolyte. Goal. The method of calculating the volume and mass of water necessary for diluting the electrolyte solution to a given density is considered. Methodology. This calculation allows, if necessary, to check the obtained results of measurements of the concentration of the electrolyte and to calculate the given density of the electrolyte taking into account the addition of the solvent (H2O). With periodic dosed replenishment of water consumed from the electrolyte, the electrolysis process occurs at a variable concentration of alkali in the electrolyte. Results. The proposed dependencies and the calculation method developed on their basis make it possible to increase the efficiency of the electrolysis process by reducing energy costs due to ensuring optimal specific conductivity of the electrolyte at a variable concentration of alkali. Originality. The resulting calculation dependence allows both during the development and operation of operating alkaline electrolyzers to calculate the current concentration and the range of changes in the concentration of alkali in the electrolyte. Practical value. The application of the obtained dependence for alkaline electrolyzers with periodic replenishment of feed water and for developed operating electrolyzers allows to analyze the nature of changes in the specific electrical conductivity of the electrolyte, i.e. evaluate the efficiency of the electrolysis process.

In Vitro Effect of Anodization of Titanium Abutments on Color Parameters and Color Difference of Lithium Disilicate All-Ceramic Crowns.

This study assessed the effect of the anodization of titanium abutments on the color parameters and color difference of lithium disilicate (LDS) all-ceramic crowns. In this study, 19 straight abutments were divided into two groups: anodized (n = 9) and non-anodized control (n = 9), with one hybrid zirconia abutment as a reference. Anodization was achieved by applying 63 V energy using seven 9 V flat batteries in series, with an electrolyte solution comprising 1 g trisodium phosphate in 250 mL distilled water for 5 s, resulting in a gold-yellow color. Abutments were then scanned, and full-contour monolithic IPS e.max maxillary central incisor crowns were fabricated with 2 mm thickness and glazed. Reflectance was measured using a spectroradiometer, and color coordinates (L*, a*, b*, h*, and C*) were calculated using CS-10W software. Color differences of the crowns in both groups were quantified using the CIEDE2000 (ΔE00) color difference formula and analyzed by t-test (α = 0.05) compared to the standard sample. The L*, a*, b*, and c* parameters in anodized abutments were significantly higher than those in non-anodized abutments, while the h* parameter in anodized abutments was significantly lower than that in non-anodized abutments (p < 0.001 for all). There was a significant difference in ΔE00 of the two groups (p = 0.043). Anodization of titanium abutments improved the color parameters of LDS all-ceramic crowns and significantly decreased their ΔE compared with non-anodized abutments.

Photo-Crosslinked Polyurethane-Containing Gel Polymer Electrolytes via Free-Radical Polymerization Method.

Using a novel technique, crosslinked gel polymer electrolytes (GPEs) designed for lithium-ion battery applications have been created. To form the photo crosslink via free-radical polymerization, a mixture of polyurethane acrylate (PUA), polyurethane methacrylate (PUMA), vinyl phosphonic acid (VPA), and bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) was exposed to ultraviolet (UV) radiation during the fabrication process. The unique crosslinked configuration of the membrane increased its stability and made it suitable for use with liquid electrolytes. The resulting GPE has a much higher ionic conductivity (1.83 × 10-3 S cm-1) than the commercially available Celgrad2500 separator. A crosslinked structure formed by the hydrophilic properties of the PUA-PUMA blend and the higher phosphate content from BMEP reduced the leakage of the electrolyte solution while at the same time providing a greater capacity for liquid retention, significantly improving the mechanical and thermal stability of the membrane. GPP2 shows electrochemical stability up to 3.78 V. The coin cell that was assembled with a LiFePO4 cathode had remarkable cycling characteristics and generated a high reversible capacity of 149 mA h g-1 at 0.1 C. It also managed to maintain a consistent Coulombic efficiency of almost 100%. Furthermore, 91.5% of the original discharge capacity was maintained. However, the improved ionic conductivity, superior electrochemical performance, and high safety of GPEs hold great promise for the development of flexible energy storage systems in the future.

Dodecagonal GaN Microrods: Chemical Stability of a‐, m‐, and c‐Plane Walls and Their Application to Water‐Splitting

AbstractPhotoelectrolysis of water is a sustainable option for the production of hydrogen fuel. GaN nano‐ or microstructures are considered for water‐splitting due to their general high chemical stability and high surface‐to‐volume ratio enhancing the process effectiveness. In this study GaN structures with dodecagonal microrods are used as a working electrode for the water‐splitting process. Microrods are grown using a plasma‐assisted molecular beam epitaxy process allowing tailoring of microrod height and density. Their unique property is the of presence twelve sidewalls with alternating a‐ and m‐plane orientations. This enables a simultaneous study of the chemical stability of c‐, a‐, and m‐plane walls of GaN. The water‐splitting process is performed using a 1 mol l−1 NaOH electrolyte solution. Non‐zero current measured at zero bias under illumination indicates that the process takes place. A degradation of the GaN structure is observed after a prolonged process time. In short‐term exposures, etching of microrod sidewalls is observed. Roughening of the a‐plane walls studied by transmission electron microscopy indicates that this orientation is etched with a fastest rate. The internal crystalline structure is not influenced by the etching and remains stable as shown by the X‐ray absorption spectroscopy study.

The impact of gelatin on the electrodeposition behavior and microstructure of copper in industrial electrolyte solutions

The impact of gelatin on the electrodeposition behavior and microstructure of copper in industrial electrolyte solutions

Comparison between the dilution of electrolyte concentrate in milk or water for oral rehydration of diarrheal calves

The administration of oral electrolyte solution (OES) is the most used method to correct dehydration and electrolyte and acid-base imbalances in calves with diarrhea. To prepare OES, the electrolyte concentrate (EC) is diluted in water. Alternatively, it can be diluted in milk and the correction of dehydration depends on voluntary water intake. Although dilution in milk is used, its efficacy has not been fully proven. This study compared the effectiveness of two rehydration methods in correcting imbalances in diarrheal calves. Twenty-four neonatal calves with induced osmotic diarrhea were distributed into two treatment groups using a commercial EC: GM with EC diluted in the milk at meals; and GW with EC diluted in water (volumes of 5% BW, at 4 and 12 h). All were fed with milk (volumes of 4% BW, at 0, 8, and 16 h) and had free access to water. Clinical and laboratory variables were monitored over time up to 48 h. The calves presented moderate dehydration, hyponatremia, relative hyperchloremia and moderate strong ion metabolic acidosis. Both rehydration methods were effective in correcting imbalances and reestablishing plasma SID3 at the end of the day of treatment. Plasma volume expansion was faster in GW. Electrolyte-enriched milk is as efficient as OES for treating diarrheal calves.

Transformation of waste thermocol into activated carbon for electrochemical detection of ammonia in an aqueous solution

In this study, waste thermocol sheets are used to synthesize activated carbon (AC) for the electrochemical detection of ammonia in an aqueous solution. The AC is characterized for its morphology, structure, and chemical composition via standard characterization techniques. AC shows promise for detecting ammonia in aqueous solutions due to its high adsorption capacity from large surface area and porosity. The electrochemical approach used to detect ammonia (NH3) in electrolyte solutions uses an AC electrode and is based mostly on the electro-oxidative conversion of ammonia species at the electrode's interface. AC electrodes fabricated on flexible conductive fabric (CF) are used for the electrochemical detection of ammonia at pH 6. The electrochemical sensing of ammonia in aqueous solutions involves its oxidation on the electrode's surface. Cyclic Voltammetry (CV) experiments were conducted over a pH range of 5 to 8, revealing optimal current responses at pH 6. Therefore, phosphate-buffered saline (PBS) at pH 6.0 was employed for all electrochemical analyses. Various concentrations of ammonia (10–100 ppm) were investigated within a voltage window of −0.3 V to 0.3 V, with current signals increasing proportionally with ammonia concentration. The limits of detection (LOD) and quantification (LOQ) were determined to be 28.55 ppm and 86.54 ppm, respectively. An incubation period of 3 min was observed for ammonia concentrations ranging from 0 to 40 ppm. Selectivity evaluations were conducted by assessing interference effects from ethanol (E), methanol (M), toluene (T), and uric acid (UA), revealing ammonia's distinctive peak, indicative of superior selectivity. Notably, the electrode exhibited remarkable stability, retaining approximately 95 % of the original signal over a 5-week duration. The reproducibility of the fabricated electrodes shows significant results. The repeatability was performed at room temperature in a buffer solution of pH 6 and at a 40-ppm concentration of ammonia and has shown almost similar results. Therefore, the fabricated AC sensing electrode has shown prominent stability, reproducibility, and repeatability. These sensing electrodes can be very beneficial for sensing applications.

Electrospun Mn1-xCoxFe2O4 (x=0–0.7) nanofibers for supercapacitors and oxygen evolution reaction

Cobalt manganese ferrite nanofibers (Mn1-xCoxFe2O4; x = 0, 0.3, 0.5, 0.7), were synthesized using sol-gel electrospinning technique. The impact of cobalt incorporation on physical and electrochemical properties of manganese ferrite nanofibers was investigated. The XRD peaks confirmed the formation of a cubic spinel phase and lattice parameter decreased gradually with increasing cobalt concentration. SEM analysis revealed the nanofibers with diameters in the range of 30–60 nm. VSM analysis showed that magnetic parameters such as coercivity, and saturation magnetization were enhanced by cobalt substitution and the sample Mn0.3Co0.7Fe2O4 showed the highest saturation magnetization and coercivity. DRS analysis exhibited that the incorporation of cobalt in the manganese ferrite reduced the band gap energy. The supercapacitive performance of Mn1-xCoxFe2O4 electrodes was investigated using CV, GCD and EIS in 3 M KOH electrolyte solution. The highest specific capacitance (453 F g−1) was obtained with long cycling stability (94.6 % retention after 4000th cycles) for Mn0.7Co0.3Fe2O4. Furthermore, an asymmetric supercapacitor (ASC) was made with reduced graphene oxide (rGO) and Mn0.7Co0.3Fe2O4 as anode and cathode electrodes, respectively. The Mn–CoFe2O4//rGO ASC revealed an impressive energy density of 50.2 Wh kg−1 at a power density of 750 W kg−1. The electrocatalytic oxygen evolution reaction (OER) performance of the Mn0.7Co0.3Fe2O4 and MnFe2O4 catalysts were also investigated in 1 M KOH alkaline electrolyte. Experiments demonstrated that the Mn0.7Co0.3Fe2O4 nanofiber catalyst had a lower overpotential (201 mV) at 10 mA cm−2, a small Tafel slope (106 mV dec−1), a larger ECSA (176 cm2), a greater TOF (7.68 × 10−4 s−1), and better long-term durability (96.3 % for 12 h) than MnFe2O4 for OER. This highlights the potential of the synthesized Mn0.7Co0.3Fe2O4 electrode for supercapacitor and oxygen evolution reaction.

Chronoamperometric flow-cell designed to be unaffected by air bubbles

In this paper, we present a new design for a chronoamperometric flow cell in which air bubbles do not interfere with the control of potential between the working and reference electrodes. The flow-through dual-detection cell consists of two independent parts: an upper compartment containing a quiescent supporting electrolyte solution and a channel that operates under hydrodynamically controlled conditions. In this system, the working and counter electrodes can be placed directly in contact with both compartments, whereas the reference electrode can be assembled to be either isolated or in contact with the flowing stream channel. The design ensures that the potential applied to the working electrode (controlled in the upper compartment) is similar to the potential applied in the flowing channel. The performance of the proposed flow cell in generating accurate results, even in the presence of air bubbles, was evaluated through successive air-analyte-air injections. In both series where the analyte was introduced, suitable reproducibility was achieved. The robustness of the design was definitively proven by performing a series of measurements in analytical applications for the determination of hydrogen peroxide in antiseptic samples, yielding very satisfactory results.

PSV-20 Supplementation of an electrolyte solution improves water intake in receiving beef cattle under commercial feedlot conditions

Abstract During transport to and receiving at feedlots, cattle are exposed to a variety of stressors, including changes in social structure due to separation and mixing of groups, handling, and a lack of access to feed and water for extended periods of time. These stressors often result in loss of body mass and dehydration, which if not adequately addressed upon feedlot arrival, may result in increased morbidity and mortality. The objectives of this experiment were to evaluate changes in body weight (BW) and water intake in cattle supplemented with an electrolyte solution upon feedlot arrival. Shipments of animals were weighed upon arrival at a commercial feedlot operation and moved to a set of holding pens where animals remained for a 3-d receiving period prior to entry into the feedlot. Sets of holding pens (n = 5 sets of 4 pens per treatment) were blocked by arrival date and randomly assigned to receive either a negative control (water) or an electrolyte solution during the receiving period. Daily free-choice fluid intake was monitored per pen, and animals were weighed at the end of the receiving period. Average fluid intake per animal was increased by 46.9 % (10.3 L/d; P = 0.013) in response to the addition of electrolyte. No differences due to treatment were observed in average origin BW, arrival BW, or BW recovery. This suggests that while recovery of BW was not affected, supplementing receiving cattle with an electrolyte solution may be an effective method of improving hydration status prior to feedlot entry. Future work aims to evaluate potential changes in morbidity and mortality during the finishing period following a similar supplementation strategy.

“Enhancing electrochemical performance of Fe@Ir/GQDs electrodes with MoS₂ for advanced energy storage and hydrogen evolution Reaction”

Metal-organic frameworks (MOFs) have unique properties that make them important in energy storage systems. The layered structure, edge locations, wide surface area, and closeness impact of MoS2/GQDs nanostructures enhance their ability for energy storage. We are effectively utilizing the hydrothermal technique to synthesize Fe@Ir-MOF/MoS2/GQDs, a new composite electrode material for supercapattery energy storage devices. Using a three-electrode setup, we are assessing the electrochemical performance of Fe@Ir-MOF, Fe@Ir-MOF/MoS2, and Fe@Ir-MOF/MoS2/GQDs. Fe@Ir-MOF/MoS2/GQDs is showing exceptional electrochemical qualities, demonstrating an excellent specific capacity of 1104C/g in an electrolyte solution containing 1 M KOH. The Ir@Fe-MOF/MoS2/GQDs is exhibiting energy and power density of around 53 W h kg−1 and 2652 W kg−1, respectively. A Coulombic efficiency of 92.23 % and 96.14 % of capacity are being maintained by the Fe@Ir-MOF/MoS2/GQDs//AC material after 5000 cycles of alternative GCD measurements. The results of this work are showing that supercapattery applications can benefit from the new electrode material Fe@Ir-MOF/MoS2/GQDs. The HER is having a lower potential barrier of 32.12 mV dec-1 with a 130 mV overpotential at −10 mA cm−2 due to the Fe@Ir-MOF/MoS2/GQDs composite. This work is providing a way to develop effective bimetallic MOFs nanocomposite materials for use in biomedical and future energy storage systems.

Ionic current rectification of non-Newtonian fluids in pH-regulated conical nanochannels

The ionic current rectification (ICR) phenomenon generated by the geometrically asymmetric properties of conical nanochannels has attracted much attention, but previous studies have mainly focused on Newtonian fluids and fixed surface charge densities. In this study, the ICR characteristics of pH-regulated conical nanochannels with non-Newtonian fluids are investigated by numerical simulations, and the effects of solution pH, power-law index, and electrolyte concentration on the ionic current, rectification ratio, axial potential, ionic conductivity, ionic concentration, surface charge density, and radial velocity at the channel tip are discussed. The rectification effect of shear-thinning fluids is significantly lower than that of Newtonian and shear-thickening fluids at high solution pH and electrolyte concentration. At pH = 8, the surface charge density increases only 8.7 times when the electrolyte concentration is increased from 1 mM from 1000 mM. When the electrolyte concentration is 1 mM, the surface charge density at pH = 9 increases almost 30 times compared to that at pH = 5.

X-ray Induced Cycling of Rare-Earth Elements between Bulk and Interfacial Liquid.

Reversible cycling of rare-earth elements between an aqueous electrolyte solution and its free surface is achieved by X-ray exposure. This exposure alters the competitive equilibrium between lanthanide ions bound to a chelating ligand, diethylenetriamine pentaacetic acid (DTPA), in the bulk solution and to insoluble monolayers of extractant di-hexadecyl phosphoric acid (DHDP) at its surface. Evidence for the exposure-induced temporal variations in the lanthanide surface density is provided by X-ray fluorescence near total reflection measurements. Comparison of results when X-rays are confined to the aqueous surface region to results when X-rays transmit into the bulk solution suggests the importance of aqueous radiolysis in the adsorption cycle. Amine binding sites in DTPA are identified as a likely target of radiolysis products. The molecules DTPA and DHDP are like those used in the separation of lanthanides from ores and in the reprocessing of nuclear fuel. These results suggest that an external source of X-rays can be used to drive rare-earth element separations. More generally, use of X-rays to controllably dose a liquid interface with lanthanides could trigger a range of interfacial processes, including enhanced metal ion extraction, catalysis, and materials synthesis.

Effect of the Atmosphere on the Properties of Aluminum Anodizing

This study aims to quantify the effect of process parameters on the anodizing of Al6061 aluminum. To achieve this, studies on layer thickness, the porosity of the anodized surface, electrochemical techniques, X-ray diffraction, grain size estimation, and statistical analysis were conducted for three different atmospheres (without air, air, and oxygen). Parameter levels were established as follows: temperature (30 °C, 45 °C, and 60 °C), time (20 min, 40 min, and 60 min), electrolyte concentration (0.5 M), voltage (9 V), and current intensity (0.600 A). A 33 experimental design (three factors, three levels) was proposed, and mathematical models were obtained using general factorial design. The experimental design was used to determine the three most important variables in the optimal condition. A total of 27 tests were conducted using sulfuric acid electrolytic solutions, of which 12 samples were selected by the factorial design method, which simultaneously evaluates the effects of factors and their interactions in a single experiment. Measurement of porosity and oxide layer thickness was performed using scanning electron microscopy. The purity of the anodic layer formed was characterized using X-ray diffraction techniques with a vertical goniometer X-ray diffractometer. The electrochemical behavior is presented through potentiodynamic polarization curves for the anodic layer. A general factorial design and an analysis of variance (ANOVA) were conducted to establish the significant factors for layer thickness, grain size, and reaction rate. Finally, the best results and their parameters for each response are presented.

ADDITIONAL PURIFICATION BY ULTRAVIOLET RADIATION OF RED SPD DYE AFTER ELECTROCHEMICAL DESTRUCTION

Surface water pollution by industrial wastewater is one of the serious environmental problems of the Republic of Uzbekistan. A significant source of pollution is the textile industry, whose wastewater contains organic dyes and various related substances. This article presents the results of a study of the photooxidation of the active dye Red SPD after electrochemical degradation in an electrolytic cell with insoluble anodes. Studies have been carried out to determine the efficiency of active chlorine synthesis in the process of electrolysis of chloride solutions, the effect of active chlorine concentration, electrolyte composition, power consumption when using the combined electrochemical/ultraviolet irradiation process, and changes in the spectral characteristics of the dye solution for carrying out the photooxidation process have been studied. The technological parameters of the method of photooxidative post-treatment in treated water after electrochemistry are established, considering the concentration of oxidizing agents. The maximum current output of active chlorine occurs at a treatment time of 10 minutes. The use of NaCl as an electrolyte in comparison with Na2SO4 showed the best result in the purification process. When using NaCl with a concentration of 1.625 g L-1 in the composition of a sulfate-containing electrolyte, it can reduce the concentration of Red SPD to 1.0 mg L-1. Photooxidative degradation can become an alternative for post-treatment of wastewater from textile enterprises. The developed technology confirms the efficiency of using the combined cleaning method.

Extending the understanding of Shannon’s safe stimulation limit for platinum electrodes: biphasic charge-balanced pulse trains in unbuffered saline at pH = 1 to pH = 12

Objective.In neural electrical stimulation, safe stimulation guidelines are essential to deliver efficient treatment while avoiding neural damage and electrode degradation. The widely used Shannon's limit,k, gives conditions on the stimulation parameters to avoid neural damage, however, underlying damage mechanisms are not fully understood. Moreover, the translation from bench testing toin vivoexperiments still presents some challenges, including the increased polarisation observed, which may influence charge-injection mechanisms. In this work, we studied the influence on damage mechanisms of two electrolyte parameters that are differentin vivocompared to usual bench tests: solution pH and electrolyte gelation.Approach.The potential of a platinum macroelectrode was monitored in a three-electrode setup during current-controlled biphasic charge-balanced cathodic-first pulse trains. Maximum anodic and cathodic potential excursions during pulse trains were projected on cyclic voltammograms to infer possible electrochemical reactions.Main results.In unbuffered saline of pH ranging from 1 to 12, the maximum anodic potential was systematically located in the oxide formation region, while the cathodic potential was located the molecular oxygen and oxide reduction region whenkapproached Shannon's damage limit, independent of solution pH. The results support the hypothesis that Shannon's limit corresponds to the beginning of platinum dissolution following repeated cycles of platinum oxidation and reduction, for which the cathodic excursion is a key tipping point. Despite similar potential excursions between solution and gel electrolytes, we found a joint influence of pH and gelation on the cathodic potential alone, while we observed no effect on the anodic potential. We hypothesise that gelation creates a positive feedback loop exacerbating the effects of pH ; however, the extent of that influence needs to be examined further.Significance.This work supports the hypothesis of charge injection mechanisms associated with stimulation-induced damage at platinum electrodes. The validity of a major hypothesis explaining stimulation-induced damage was tested and supported on a range of electrolytes representing potential electrode environments, calling for further characterisation of platinum dissolution during electrical stimulation in various testing conditions.

Fabrication of NiO/TiO2/rGO nanocomposites as a quasi-solid-state asymmetric supercapacitor: Paving the way for PhotoSupercapacitor application

In this present communication, a novel ternary nanocomposite, NiO/TiO2/rGO (NTG), was synthesised via a simple hydrothermal technique for photosupercapacitor application. The XRD pattern confirmed the crystalline nature and phase structure of the as-synthesised material. FE-SEM and HR-TEM analyses demonstrated the embellishment of NiO/TiO2 nanoparticles on the rGO sheets, which facilitates more voids and shorter diffusion paths. The electrochemical investigation of the prepared samples was assessed using 1 M Na2SO4 and Na2CO3 aqueous electrolyte solutions. Among the synthesised samples, NTG-2 carried out under 1 M Na2SO4 electrolyte exhibited a maximum specific capacitance of 1285 Fg-1 at 1 Ag-1, maintaining a capacitance retention of 94 % after 5000 cycles. The NTG-2 electrode was additionally utilised in the construction of an asymmetric supercapacitor that has an impressive specific capacitance of 478 Fg-1 at 1 Ag-1. This displays an intriguing performance in terms of energy and power density of 42.2 Wh Kg−1 at 0.5 kW kg−1. In PSC, the as-fabricated TiO2/N719/I−/I3−/Pt@NTG-2//AC architecture possessed a specific capacitance of 567.5 Fg-1 at 1 Ag-1, with an energy density of 50.4 Wh Kg−1 and a power density of 0.4 kW kg−1. As a result, it has been concluded that the novel NTG-2 device opens new opportunities to develop new architectures for efficient energy storage applications.

Hydrothermally synthesized copper telluride nanoparticles: First approach to flexible solid-state symmetric supercapacitor

Supercapacitors, with their high-power density, rapid charge–discharge rates, and long cycle life, have emerged as promising energy storage devices for numerous applications. Among the various materials explored for supercapacitor electrodes, copper-based chalcogenides have gathered significant attention due to their intriguing electrochemical properties and simple synthesis routes. While there have been thorough investigations in other fields, only a limited number of studies have focused on the specific application of copper telluride nanoparticles as supercapacitors. In this study, we present a novel approach utilizing hydrothermally synthesized copper telluride (Cu2-xTe) nanoparticles as binder-free electrodes on flexible stainless steel (SS) substrates. The Cu2-xTe nanoparticles, with their small particle (38 nm) and highly crystalline structure, enhance charge storage and promotes a pseudocapacitive behavior, resulting in a high specific capacitance [381 F/g (163 mF/cm2) at 2 mV/s] in a 2 M KCl electrolyte solution. Moreover, we studied and explained the distinct contributions of surface-controlled and diffusion-limited processes to the overall charge storage capacity of the electrode. Our pioneering effort includes the fabrication and analysis of flexible, symmetric solid-state supercapacitor devices utilizing Cu2-xTe electrodes with PVA-LiClO4 gel electrolyte. These devices demonstrate an energy density of 11 Wh/kg, a power density of 800 W/kg, and an impressive 85 % retention of cyclic stability after 5000 cycles.

Simulating the Competitive Ion Pairing of Hydrated Electrons with Chaotropic Cations.

Experiments show that the absorption spectrum of the hydrated electron (ehyd-) blue-shifts in electrolyte solutions compared with what is seen in pure water. This shift has been assigned to the ehyd-'s competitive ion-pairing interactions with the salt cation relative to the salt anion based on the ions' positions on the Hofmeister series. Remarkably, little work has been done investigating the ehyd-'s behavior when the salts have chaotropic cations, which should greatly change the ion-pairing interactions given that the ehyd- is a champion chaotrope. In this work, we remedy this by using mixed quantum/classical simulations to analyze the behavior of two different models of the ehyd- in aqueous RbF and RbI electrolyte solutions as a function of salt concentration. We find that the magnitude of the salt-induced spectral blue-shift is determined by a combination of the number of chaotropic Rb+ cations near the ehyd- and the number of salt anions near those cations so that the spectrum of the ehyd- directly reflects its local environment. We also find that the use of a soft-cavity ehyd- model predicts stronger competitive interactions with Rb+ relative to I- than a more traditional hard cavity model, leading to different predicted spectral shifts that should provide a way to distinguish between the two models experimentally. Our simulations predict that at the same concentration, salts with chaotropic cations should produce larger spectral blue-shifts than salts with kosmotropic cations. We also found that at high salt concentrations with chaotropic cations, the predicted blue-shift is greater when the salt anion is kosmotropic instead of chaotropic. Our goal is for this work to inspire experimentalists to make such measurements, which will help provide a spectroscopic means to distinguish between simulations models that predict different hydration structures for the ehyd-.

Quantifying concentration distributions in redox flow batteries with neutron radiography

The continued advancement of electrochemical technologies requires an increasingly detailed understanding of the microscopic processes that control their performance, inspiring the development of new multi-modal diagnostic techniques. Here, we introduce a neutron imaging approach to enable the quantification of spatial and temporal variations in species concentrations within an operating redox flow cell. Specifically, we leverage the high attenuation of redox-active organic materials (high hydrogen content) and supporting electrolytes (boron-containing) in solution and perform subtractive neutron imaging of active species and supporting electrolyte. To resolve the concentration profiles across the electrodes, we employ an in-plane imaging configuration and correlate the concentration profiles to cell performance with polarization experiments under different operating conditions. Finally, we use time-of-flight neutron imaging to deconvolute concentrations of active species and supporting electrolyte during operation. Using this approach, we evaluate the influence of cell polarity, voltage bias and flow rate on the concentration distribution within the flow cell and correlate these with the macroscopic performance, thus obtaining an unprecedented level of insight into reactive mass transport. Ultimately, this diagnostic technique can be applied to a range of (electro)chemical technologies and may accelerate the development of new materials and reactor designs.