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In alkaline water electrolysis, gas bubble coverage of the electrode surface is directly linked with an increase in cell potential. Ultrasonic field presence in water electrolysis has been proven effective in removing gas bubbles from the electrode and enhancing mass transfer and bubble removal. Most studies regarding water electrolysis under sonification focused on low-concentration NaOH electrolyte solutions so there is a lack of information regarding operating conditions similar to commercial solutions. This work focused on an experimental evaluation of the effect of an ultrasonic field with a 40 kHz frequency on water electrolysis using a lab-scale electrolyser with three different KOH solutions varying in concentration (15, 25, 35% (w/w)) at 30, 40, 50, 60 °C. A reduction in cell potential was registered across all test conditions and it was maximum for 15 and 25% KOH solutions at 30 °C with 52 and 34 mV, respectively, and decreased with an increase in temperature. For a 35% KOH solution, the cell potential reduction stayed constant across all temperatures (16–19 mV). This difference was thought to be caused by the ultrasonic frequency and power and therefore required further testing. To further investigate the effect of gas bubble accumulation on the electrode surface, measurements of hydrogen bubbles' critical diameter were taken. It was found that a higher electrolyte concentration results in a lower critical diameter (0.404, 0.356, and 0.293 mm with a 15, 25, and 35% KOH, respectively) assumed to be a consequence of higher viscosity and gas formation rate at higher concentrations. • Effect of ultrasonic field is studied in water alkaline electrolysis. • Three KOH solutions varying in concentration (15, 25, 35% (w/w)) at 30, 40, 50, 60 °C were tested. • A reduction in overpotential was registered across all test conditions. • Overpotential was observed to decrease with increasing temperatures. • Ultrasonic field is effective removing gas bubbles from the electrode and enhancing mass transfer and bubble removal. [ABSTRACT FROM AUTHOR]

This article explores the novel application of a trained artificial neural network (ANN) in the prediction of vanadium redox flow battery behaviour and compares its performance with that of a two-dimensional numerical model. The aim is to evaluate the capability of two ANNs, one for predicting the cell potential and one for the overpotential under various operating conditions. The two-dimensional model, previously validated with experimental data, was used to generate data to train and test the ANNs. The results show that the first ANN precisely predicts the cell voltage under different states of charge and current density conditions in both the charge and discharge modes. The second ANN, which is responsible for the overpotential calculation, can accurately predict the overpotential across the cell domains, with the lowest confidence near high-gradient areas such as the electrode membrane and domain boundaries. Furthermore, the computational time is substantially reduced, making ANNs a suitable option for the fast understanding and optimisation of VRFBs. [ABSTRACT FROM AUTHOR]

Formation of gas hydrates is an important feature of water systems. It occurs undesirably in natural gas pipelines, but also in deep‐sea deposits and unfreezing permafrost. However, the natural occurrence is of particular interest because methane hydrates have one of the highest energy densities of all naturally occurring forms of methane. Therefore, an accurate description of its thermodynamic properties is required. In this work, we demonstrate how the material properties of methane hydrate can be more easily calculated compared to ab initio methods. Furthermore, it is shown how the material properties depend on the cage occupancy by using the comparably fast self‐consistent‐charge density‐functional tight‐binding (SCC‐DFTB) method. The cell potential is calculated and compared to a numerical as well as an ab initio model, and is in good agreement with the literature. [ABSTRACT FROM AUTHOR]

This article explores the novel application of a trained artificial neural network (ANN) in the prediction of vanadium redox flow battery behaviour and compares its performance with that of a two-dimensional numerical model. The aim is to evaluate the capability of two ANNs, one for predicting the cell potential and one for the overpotential under various operating conditions. The two-dimensional model, previously validated with experimental data, was used to generate data to train and test the ANNs. The results show that the first ANN precisely predicts the cell voltage under different states of charge and current density conditions in both the charge and discharge modes. The second ANN, which is responsible for the overpotential calculation, can accurately predict the overpotential across the cell domains, with the lowest confidence near high-gradient areas such as the electrode membrane and domain boundaries. Furthermore, the computational time is substantially reduced, making ANNs a suitable option for the fast understanding and optimisation of VRFBs.

Advanced zero-gap alkaline electrolyzers can be operated at a significantly higher current density than traditional alkaline electrolyzers. We have investigated how their performance is influenced by diaphragm thickness, temperature and pressure. For this a semi-empirical current-voltage model has been developed based on experimental data of a 20 Nm3/h electrolyzer. The model was extrapolated to thinner diaphragm thicknesses and higher temperatures showing that a nominal current density of 1.8 A cm−2 is possible with a 0.1 mm diaphragm at 100 °C. However, these operating parameters also lead to increased gas crossover, which limits the ability to operate at low loads. A gas crossover model has been developed, which shows that crossover is mainly driven by diffusive transport of hydrogen, caused by a high local supersaturation at the diaphragm surface. To enable a low minimum load of 10% the operating pressure should be kept below 8 bara. [Display omitted] • A nominal current density of 1.8 A cm−2 seems achievable for alkaline electrolysis. • To enable a minimum load of 10%, the pressure is preferably kept below 8 bara. • Gas crossover is mainly driven by diffusive hydrogen transport. • Supersaturation at the diaphragm interface plays an important role. [ABSTRACT FROM AUTHOR]

The influence of low‐cost anode materials, aluminum, and graphite on the sediment microbial fuel cell (SMFC) performance is investigated. The cathode in both cells is a high‐conductive pencil electrode. The open‐circuit potentials of the graphite sediment microbial fuel cell (CSMFC) and the aluminum sediment microbial fuel cell (ASMFC) are 600 mV and 1103 mV, respectively. The microbial metabolic activity in polluted marine sediment creates a large potential difference at the marine sediment/seawater interface. The sustainable electrical power from CSMFC and ASMFC are 680 mW.m−2 and 930 mW.m−2 respectively. The high cell potentials of both cells are achieved at ambient temperature. The designed SMFCs could power oceanographic instruments and biosensors in the coastal ocean. The total viable bacterial count (TVBC) and biological parameters of pore water are related to the high cell potential. The higher open‐circuit potential of ASMFC than CSMFC is mainly attributed to the lower charge transfer resistance of aluminum than graphite. This high performance is confirmed by using electrochemical impedance spectroscopy (EIS). The charge transfer resistance (Rct) of aluminum and graphite are 1600 and 2050 Ohm.cm2, respectively. The electrical conductivity of a thin film of aluminum and graphite are 40.1× 104 and 9.99× 103 Siemens/cm, respectively. The electrical resistivity of the ASMFC and CSMFC are 1.506×10−5 and 2.25661×10−5 Ω.m, respectively. These results strongly suggest that ASMFC has a higher electrical power density than CSMFC due to the lower charge transfer resistance, the good electrical conductivity of aluminum, and the lower electrical resistivity of ASMFC. [ABSTRACT FROM AUTHOR]

Similar to an IC (Internal combustion) engine which requires cooling to operate at optimum temperature for better efficiency; electric vehicles do require a similar system. There are various methods used in the current market for thermal management of batteries, of these our paper focuses on phase change materials (PCM). This cooling strategy can store an enormous amount of heat produced inside a battery because of its high latent heat capability. A 3D model of the battery using the multi-scale multi-dimension model (MSMD) for battery simulation and Solidification/melting models were used to showcase the melting of PCM due to the heat generated from a cell. ANSYS fluent was used to carry out the simulations. These computations are carried out at different C-rate to find the time taken for a battery to discharge and to find the impact of C-rate on PCM performance. Besides, temperature data for the cell was recorded before and after PCM was involved to compare the temperature difference between various PCM's. [ABSTRACT FROM AUTHOR]

The cell potential of the cell containing two ion-selective electrodes (ISE), Na-ISE | NaClO4 (m), PEG 4000 (Y), H2O (100-Y) | ClO4-ISE has been measured at temperatures of (288.15, 298.15, and 308.15) K as a function of the weight percentage Y of PEG 4000 in a mixed solvent at a 1 Mpa and the standard state for measured activity coefficients will be a solution of the salt in pure water. Y was varied between (0 and 25) wt.% in five-unit steps and the molality of the electrolyte (m) was between 0.05 mol kg-1 and almost saturation. The values of the standard cell potential were calculated using routine methods of extrapolation together with extended Debye-Hückel and Pitzer equations. The results obtained produced good internal consistency for all the temperatures studied. Once the standard electromotive force was determined, the mean ionic activity coefficients for NaClO4, the Gibbs energy of transfer from the water to the PEG 4000-water mixture, and the primary NaCl hydration number were calculated.

Integrating anodic biomass valorization with carbon dioxide electroreduction (CO 2 RR) can produce value-added chemicals on both the cathode and anode; however, anodic oxidation still suffers from high overpotential. Herein, a photothermal-assisted method was developed to reduce the potential of 5-hydroxymethyl furfural (HMF) electrooxidation. Capitalizing on the copious oxygen vacancies, defective Co 3 O 4 (D-Co 3 O 4 ) exhibited a stronger photothermal effect, delivering a local temperature of 175.47 °C under near infrared light illumination. The photothermal assistance decreased the oxidation potential of HMF from 1.7 V over pristine Co 3 O 4 to 1.37 V over D-Co 3 O 4 to achieve a target current density of 30 mA cm -2 , with 2,5-furandicarboxylic acid as the primary product. Mechanistic analysis disclosed that the photothermal effect did not change the HMF oxidation route but greatly enhanced the adsorption capacity of HMF. Meanwhile, faster electron transfer for direct HMF oxidation and the surface conversion to cobalt (oxy)hydroxide, which contributed to indirect HMF oxidation, was observed. Thus, rapid HMF conversion was realized, as evidenced by in situ surface-enhanced infrared spectroscopy. Upon coupling cathodic CO 2 RR with an atomically dispersed Ni-N/C catalyst, the Faradaic efficiencies of CO (cathode) and 2,5-furandicarboxylic acid (FDCA, anode) exceeded 90.0 % under a low cell potential of 1.77 V., (© 2024 Wiley-VCH GmbH.)

Astrocytes represent a diverse and morphologically complex group of glial cells critical for shaping and maintaining nervous system homeostasis, as well as responding to injuries. Understanding the origins of astroglial heterogeneity, originated from a limited number of progenitors, has been the focus of many studies. Most of these investigations have centered on protoplasmic and pial astrocytes, while the clonal relationship of fibrous astrocytes or juxtavascular astrocytes has remained relatively unexplored. In this study, we sought to elucidate the morphological diversity and clonal distribution of astrocytes across adult cortical layers, with particular emphasis on their ontogenetic origins. Using the StarTrack lineage tracing tool, we explored the characteristics of adult astroglial clones derived from single and specific progenitors at various embryonic stages. Our results revealed a heterogeneous spatial distribution of astroglial clones, characterized by variations in location, clonal size, and rostro-caudal dispersion. While a considerable proportion of clones were confined within specific cortical layers, others displayed sibling cells crossing layer boundaries. Notably, we observed a correlation between clone location and developmental stage at earlier embryonic stages, although this relationship diminished in later stages. Fibrous astrocyte clones were exclusively confined to the corpus callosum. In contrast, protoplasmic or juxtavascular clones were located in either the upper or lower cortical layers, with certain clones displayed sibling cells distributed across both regions. Our findings underscore the developmental origins and spatial distribution of astroglial clones within cortical layers, providing new insights into the interplay between their morphology, clonal sizes, and progenitor heterogeneity., (© 2024 The Authors. GLIA published by Wiley Periodicals LLC.)

The present study reports a simple, inexpensive, and direct method for the preparation of nanocomposite (NC) material (Ni/Co-NC) as advanced catalysts for hydrogen production (HP). The Ni/Co-NC was prepared using solvothermal method (STM) followed by thermal annealing, characterized and tested for HP in 0.6 M H 2 SO 4. The as-synthesized Ni/Co-NC contains a high density of active edge sites, exhibits high electro-catalytic HP activity under small cathodic onset potential (V ON-P) of −0.03 V, and a small Tafel slope of approximately 29 mV/decade, which exceeds the activity of previously studied Pt-free catalysis. Annealing temperature significantly affects the Ni/Co-NC activity toward HP by forming active nanoparticles with an optimum identified at 250 °C. The HP process is controlled via Volmer-Tafel charge-transfer mechanism over the electrode interface. The presented method can be used as a new strategy for manufacturing advanced electro-catalysts for the production of hydrogen from different resources. • A methodology for designing electro-catalysis for energy production is presented. • Ni–Co electro-catalyst was developed for electro-chemical production of hydrogen. • Significant hydrogen production was achieved under very low potential. • Electro-catalyst configuration improved electrochemical property and reduce internal resistance. [ABSTRACT FROM AUTHOR]

Similar to an IC (Internal combustion) engine which requires cooling to operate at optimum temperature for better efficiency; electric vehicles do require a similar system. There are various methods used in the current market for thermal management of batteries, of these our paper focuses on phase change materials (PCM). This cooling strategy can store an enormous amount of heat produced inside a battery because of its high latent heat capability. A 3D model of the battery using the multi-scale multi-dimension model (MSMD) for battery simulation and Solidification/melting models were used to showcase the melting of PCM due to the heat generated from a cell. ANSYS fluent was used to carry out the simulations. These computations are carried out at different C-rate to find the time taken for a battery to discharge and to find the impact of C-rate on PCM performance. Besides, temperature data for the cell was recorded before and after PCM was involved to compare the temperature difference between various PCM's.

The effect of laxose concentration as Lactobacillus bulgaricus bacterial substrate on the cell potential produced in Microbial Fuel Cell System has been done. This study aims to determine the effect of lactose concentration as bacterial substrate, to generate electricity, maximum electric potential and determine the potential value of standard lactose (E ° Lactose.) Based on Nernst equation. The MFC system of two compartments and bridges of salt as a linkage is used in this study. Anode contains lactose with variation of concentration 3 - 7% and bacteria. The cathode contains a 1M KMO4. The electrodes used are graphite. MFC operational time is 14 days. The results showed that the lactose concentration had an effect on the cell potential produced in the MFC system. Maximum cell potential yielded at 4% lactose concentration, that is 710 mV then based on Nerst equation theory obtained E ° Lactose value in MFC system of + 0,236 V.

A method for operating membrane capacitive deionization (MCDI) systems without electrode reactions at a high cell potential was studied. The charge supplied to the cell was controlled to suppress Faradaic reactions. The maximum allowable charge (MAC) that can be supplied to a carbon electrode without electrode reactions was measured to be 58 C/g. Adsorption experiments were conducted while supplying a charge of 55 C/g (95% of the MAC value) in constant-current (CC) and constant-voltage (CV) mode. The cell potential increased to 1.42 V in CC (1.43–4.29 mA/cm2) mode, but the concentration and pH of the effluent were kept constant. In addition, the effluent pH was stable in CV (1.25–2.0 V) mode. The salt adsorption capacities and charge efficiencies were approximately 15.5 mg/g and 92%, respectively, regardless of the current densities and cell potentials applied to the cell. With increasing cell potential, the concentration polarization in the feed stream was intensified, resulting in an increase in cell resistance. It was thought that electrode reactions did not occur at a high cell potential because of the high voltage drop due to the cell resistance. The higher the cell potential (or current density) is, the faster the desalination rate in MCDI operation. It is expected that this operation method applying the MAC concept will contribute to the stable operation of MCDI systems and an improvement in desalination performance. Image 1 • A stable operation method for MCDI systems at high cell potentials was proposed. • Faradaic reactions were suppressed by controlling the charge supplied to the cell. • The MCDI desalination performance was stable regardless of cell potential. • The voltage drop due to cell resistance increased with increasing cell potential. [ABSTRACT FROM AUTHOR]

Intense laser powers used in confocal Raman micro-spectroscopy can photoablate thermally sensitive samples. This has precluded study of the “dark” catalytic layers of hydrogen air fuel cells that consist of carbon supported Pt catalysts embedded in a polymer electrolyte. We now describe how photoablation is mitigated, with retention of z sectioning capability, by lifting the focal point above a transversely homogenous sample surface. This results in a circular conical illumination volume below the focal point. The geometric probability of photons generated in this volume, having pathways to the detector pinhole, is at least two orders of magnitude lower than those emerging from a focal point. However, adequate signal to noise can still be attained by sequestering the laser focal point in an isotropic medium that has no interfering Raman bands. This enables Raman photons from the circular conical illumination volume to dominate the spectra. A finite element model elucidates how incorporation of the isotropic medium for focal point sequestration recovers an order of magnitude in sensitivity. The above methodology provided spectroscopic evidence of the transition of a Nafion exchange site from a protonated sulfonic acid group with no local symmetry, to a dissociated sulfonate exchange site with C 3 v symmetry at the onset of the oxygen reduction reaction in a fully operating fuel cell. [ABSTRACT FROM AUTHOR]

A microkinetic model (MKM), independent from the assumptions of surface coverage or rate determining steps, was developed to understand reactivity trends of several metal and bimetallic catalysts for application as a Solid Oxide Fuel Cell (SOFC) anode at operating conditions ranging from the low (673 K) to high (1273 K) temperatures. A 1:1 composition of H 2 : CO was used as the fuel, which may be obtained from internal or external reforming of a variety of hydrocarbon fuels fed to the SOFC anode. The reactivity of the catalysts was plotted as a volcano plot against two descriptors; the carbon and oxygen binding energies of all the surface intermediates, reactants and products species. While water production rates gave a direct indication of catalyst activity for the oxidation reaction, CO 2 production rates were indirectly interpreted as its ability to oxidize surface adsorbed carbon to provide long-term stable operations. Following the interpolation principle, the volcano plot of the monometallic (Ag, Au, Cu, Pd, Pt, Ni, Co, Rh, Ru, and Re) catalysts dictated opportunities for alloying. A series of bimetallic catalysts containing Ni and other metals were screened for the same oxidation reaction. The results were significant in interpreting previously reported experimental trends on the reactivity of monometallic and bimetallic catalysts as well as in predicting novel compositions of bimetallic catalysts for achieving high catalyst activity and desired stability for a SOFC anode. Additionally, the effect of an applied electrode potential was studied on the activity of transition metal catalysts at SOFC conditions using volcano diagram. The MKM was constructed at an applied potential of U = 1.5 V with respect to a standard oxygen electrode (SOE) and analyzed at T = 873 K and T = 1073 K. Significant decrease in the H 2 oxidation rates were observed, while CO oxidation rates remained unaffected at the applied potential. [ABSTRACT FROM AUTHOR]

The purpose of this work is to develop a one-dimensional mathematical model for predicting the cell performance of a direct formic acid fuel cell and compare this with experimental results. The predicted model can be applied to direct formic acid fuel cells operated with different formic acid concentrations, temperatures, and with various electrolytes. Tafel kinetics at the electrodes, thermodynamic equations for formic acid solutions, and the mass-transport parameters of the reactants are used to predict the effective diffusion coefficients of the reactants (oxygen and formic acid) in the porous gas diffusion layers and the associated limiting current densities to ensure the accuracy of the model. This model allows us to estimate fuel cell polarization curves for a wide range of operating conditions. Furthermore, the model is validated with experimental results from operating at 1-5 M of formic acid feed at 30-80 °C, and with Nafion-117 and silane-crosslinked sulfonated poly(styrene-ethylene/butylene-styrene) (sSEBS) membrane electrolytes reinforced in porous polytetrafluoroethylene (PTFE). The cell potential and power densities of experimental outcomes in direct formic acid fuel cells can be adequately predicted using the developed model. [ABSTRACT FROM AUTHOR]

CdSe thin films were prepared by chemical bath and doped in situ with Er 3+ ions. Three impurity levels were prepared by changing the relative volume of the salt solution containing Er 3+ ions in the CdSe growing solution. Changes in the grain size (∼5.5–3.5 nm) and band gap energy (∼1.80–2.25 eV) were observed in the undoped and doped CdSe films, respectively. Photoluminescence studies displayed room temperature emission exhibiting NIR-to visible upconversion. The transition bands 4 I 13/2 → 4 I 15/2 , 2 I 9/2 → 4 I 15/2 and 2 F 9/2 → 4 F 15/2 in the ∼700–850 nm region were investigated. Upconversion emissions were observed from the CdSeEr sample under light excitation (325 nm). The upconversion emission intensity ratio of these transitions is attributed to the variation of the local structure around Er 3+ ions. These results confirm that visible upconversion emissions of Er 3+ in the CdSeEr nanocrystals are mainly produced via two-photon excited-state absorption and energy transfer upconversion processes. [ABSTRACT FROM AUTHOR]

Mineral carbonation is considered to be a promising method for sequestering atmospheric CO2. This paper studied the technical feasibility of mineral carbonation of waste phosphogypsum assessed by investigating the details of the electrochemical reaction in an electrolytic cell. In a series of experiments, phosphogypsum was shown to exhibit high carbonation reactivity at conditions of room temperature and atmospheric pressure. Results show that preparation of a catholyte solution with an optimal alkalinity of pH 11 will enable production of large quantities of calcium carbonate of purity greater than 90 % at a carbonation rate of 95 %. In comparison with the traditional electrolysis process, membrane electrolysis can significantly reduce the necessary cell voltage required for the reaction to take place, while avoiding the production of chlorine gas. Injection of CO2 in the cathode chamber of the electrochemical cell decreases the pH of the catholyte, thereby depolarizing the cathode and reducing the energy consumption of the entire electrolytic process. This renders the method to be economically feasible. [ABSTRACT FROM AUTHOR]