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The present work is focused on the manufacturing of a special self‐developed tribocorrosion setup with a controlled incubated environment. The comparative studies between wrought Co27Cr6Mo and Ti6Al7Nb alloys are performed with the respective tribometer in Ringer's solution at 37 °C. It is found that the CoCrMo alloy demonstrated a noble open circuit potential not only in non‐wear condition but also under wear conditions, in comparison to Ti6Al7Nb. The mass loss rate examined at open circuit potential and at a constant potential of 0.2 V versus Ag|AgCl|3.5 m KCl also suggests a similar superiority of the CoCrMo alloy. [ABSTRACT FROM AUTHOR]

The effect of SnCl2 dopant concentration on the properties of Sn-doped polyaniline (PANI) as a hole transport layer (HTL) for perovskite solar cells (PSC) was investigated. PANI films were synthesized by potentiostatic electropolymerization at 1 V vs. Ag/AgCl in sulfuric acid containing 0.1 M of aniline. The study analyzed various processes, including anodic charge transfer, diffusion, crosslinking, and coordination of SnCl2. Results showed that SnCl2 doping decreased the branching of PANI chains and enhanced the thermal properties of PANI. The Raman spectrum confirmed crosslinking behavior due to the incorporation of Sn. Thermogravimetric analysis, derivative thermogravimetry, and differential scanning calorimetry supported SnCl2 coordination to the PANI backbone. Optical measurements revealed a decrease in transmittance and reflectance and a substantial decrease in the band gap as the concentration of SnCl2 increased. Mechanism of PANI growth and different early stage reactions are thoroughly discussed. [ABSTRACT FROM AUTHOR]

Electrochromic (EC) films are widely used in smart windows, automobile mirrors, and low-power displays due to their capability of reversibly changing color under an external potential. Transition metal oxides, due to their ability to switch between multiple oxidation states, are primarily used as EC films. They require low operating power and provide high coloration efficiency in EC applications. However, their thin-film fabrication through a low-cost and scalable process is still challenging. Here, nickel oxide (NiO) EC films have been synthesized by room-temperature electrochemical oxidation of Ni thin films. The Ni films were grown by electroless deposition and annealed at three different temperatures of 100°C, 200°C, and 300°C. The morphological, optoelectronic, and electrochemical properties of the films have been comparatively analyzed to obtain an optimized EC film. The NiO film annealed at 100°C exhibited superior properties with coloration and bleaching times of 1.8 s and 2.9 s, respectively, and a coloration efficiency of 20 cm2/C. This annealed film is further used to fabricate a EC device with NiO and tungsten oxide (WO3) as the electrode layers and a phosphoric acid-based gel as the electrolyte. The low-temperature deposition process used here can also be extended to flexible substrates. [ABSTRACT FROM AUTHOR]

Lithium insertion reactions occur via two main processes: nucleation growth in the initial stage and three-dimensional diffusion in the subsequent stage. This study aims to understand the effect of particle size on these processes, which are crucial for optimizing battery performance. The lithium insertion kinetics of MgMn2O4 particles of varying sizes is analyzed by chronoamperometry. The results show that smaller particles exhibit faster lithium insertion kinetics than larger particles. The experimental data is fitted to a solid-state reaction model that accurately describes the observed current profiles. The fitting analysis reveals that the rate constants of nucleation growth (kA) and three-dimensional diffusion (kD) are influenced by the particle size. Specifically, kA and kD increase exponentially as the particle size decreases. This relationship indicates that smaller particles have larger surface areas and shorter diffusion distances, which facilitate faster lithium insertion. In addition, the overvoltage dependence of kA remains constant across different particle sizes, indicating a consistent reaction mechanism. Overall, these findings emphasize the importance of particle size in optimizing lithium insertion kinetics in battery materials. A smaller particle size can significantly improve the reaction rates, but trade-offs, such as reduced electrode density and increased side reactions due to a larger surface area, must be considered. Thus, understanding the particle size dependence of lithium insertion kinetics is essential for designing high-performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

To prepare Mg–Al-Nd alloys electrochemically, the electrochemical co-reduction mechanism of Mg(II), Al(III), and Nd(III) was probed in the LiCl-NaCl-MgCl2-AlF3 melts on a molybdenum electrode by means of various electrochemical measurement techniques, i.e., cyclic voltammetry, square wave voltammetry, chronopotentiometry, and open circuit chronopotentiometry. It was found that Nd could deposit on pre-deposited Al metal and form Nd-Al intermetallics in the LiCl-NaCl-NdCl3-MgCl2-AlF3 system, and the electrochemical signal related to the formation of ternary intermetallics was not detected. The co-reduction of Mg(II), Al(III), and Nd(III) was carried out on molybdenum electrode by galvanostatic electrolysis to prepare Mg–Al-Nd alloy, and samples were characterized by X-ray diffraction, scanning electron microscopy (SEM) with energy-dispersive spectrometry (EDS), and inductively coupled plasma-atomic emission spectrometry (ICP-AES). The results indicate that the alloy products were comprised of Al2Nd intermetallic, Mg and Al phases, and the Mg–Al compound was not observed in the alloys. [ABSTRACT FROM AUTHOR]

The sensitivity of lead dioxide coating properties to the deposition conditions and electrolyte composition has allowed the preparation of coatings with different properties for different applications. In this study, the effects of electrolyte additives on the electrodeposition process were investigated using electrochemical measurements such as cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The results showed that the presence of fluoride ions significantly reduces the possibility of TiO2 formation. The addition of copper ions not only prevents lead loss at the cathode but also leads to the formation of copper oxide on the surface at the initial stages, which hinders nucleation of PbO2. The presence of sodium dodecyl sulfate (SDS) also interferes with the nucleation process as it occupies active nucleation sites. The a-PbO2 interlayer prevents copper oxidation and solves the problem of lead dioxide nucleation. Finally, it was found that the simultaneous use of all additives together with the a-PbO2 interlayer has a positive effect on the coating process. [ABSTRACT FROM AUTHOR]

Current diagnostic and prognostic tests for prostate cancer require specialised laboratories and have low specificity for prostate cancer detection. As such, recent advancements in electrochemical devices for point of care (PoC) prostate cancer detection have seen significant interest. Liquid-biopsy detection of relevant circulating and exosomal nucleic acid markers presents the potential for minimally invasive testing. In combination, electrochemical devices and circulating DNA and RNA detection present an innovative approach for novel prostate cancer diagnostics, potentially directly within the clinic. Recent research in electrochemical impedance spectroscopy, voltammetry, chronoamperometry and potentiometric sensing using field-effect transistors will be discussed. Evaluation of the PoC relevance of these techniques and their fulfilment of the WHO's REASSURED criteria for medical diagnostics is described. Further areas for exploration within electrochemical PoC testing and progression to clinical implementation for prostate cancer are assessed. [ABSTRACT FROM AUTHOR]

There are no documented electroanalytical methods for quantifying the anti-inflammatory drug bumadizone (BUM) in pharmaceutical or biological matrices. So, a new voltammetric method was developed to determine BUM at nano concentrations in pharmaceutical forms, in the presence of its alkaline degradant, and in biological fluids. Five electrodes were tested, including three nano-reduced graphene oxide (nRGO) electrodes (5%, 15%, and 20%), a carbon paste electrode (CPE), and a 10% nRGO-modified CPE. The 10% nRGO-modified electrode showed the best performance, offering high selectivity and low detection limits, with good linearity in the concentration range of 0.9 × 102 to 15 × 102 ng mL−1. Differential pulse voltammetry successfully applied this electrode for BUM determination in various samples, achieving excellent recovery without preliminary separation. The method was validated according to ICH guidelines and compared favorably to the reference method. Its environmental impact was assessed using AGREE and Eco-scale metrics in addition to the RGB algorithm, showing superior greenness and whiteness profiles due to safer solvents and lower energy consumption, along with high practical effectiveness using the BAGI metric. [ABSTRACT FROM AUTHOR]

Molecular electrocatalysis has emerged as a crucial branch of molecular electrochemistry, finding applications across various fields such as energy generation, electroanalysis, and electrosynthesis. In recent years, the study of these processes within confined spatial domains, has been increasingly frequent. However, a significant gap exists in the theoretical understanding of the interplay between different kinetics (redox and chemical) and mass transport under these conditions, and how their combined effects influence the electrochemical response. As a first step to address the aforementioned gap, this manuscript presents a theoretical expression for the current‐potential‐time response of a catalytic reaction occurring under finite diffusive conditions. The results indicate that, when the chemical kinetics is not fast, there are significant differences in electrochemical responses due to mass transport influences. Thus, in the case of bounded finite diffusion, a loss of efficiency in the process is observed, resulting in lower currents compared to those corresponding to semi‐infinite diffusive conditions. The validity of well‐known methods, such as the analysis of the current plateau or the foot of the wave under stationary conditions, is discussed. Experimental validation of these results is also provided through the study of the oxidation of Solketal mediated by the oxidation of TEMPO radical. [ABSTRACT FROM AUTHOR]

The hydrogen evolution reaction in alkaline water electrolysis is facilitated through the electrodeposition of trimetallic catalyst on nickel foam using the chronoamperometry technique. Specifically, the trimetallic catalyst CoWRu@NF is deposited onto a nickel foam substrate. The catalytic performance of this trimetallic catalytic electrode for the Hydrogen Evolution Reaction (HER) is then assessed in a 1.0 M potassium hydroxide (KOH) solution. This specially designed trimetallic catalytic electrode system efficiently provides the more active sites through the Co component. Subsequently, it facilitates the reduction of protons (H+) to generate hydrogen gas using the Ru component. Tungsten acts as a co‐catalyst in the system for water dissociation promotor by removing hydroxide formed after water dissociation and preventing the deactivation of Ruthenium by certain reaction intermediates. The CoWRu@NF trimetallic catalyst demonstrates excellent activity, showcasing a low overpotential (−8 mV) to achieve a current density of (−10 mA/cm2. Additionally, it exhibits low Tafel slope values (101.2 mV dec−1), credited to the presence of cobalt and tungsten alongside Ruthenium in the catalytic system. This configuration is specifically designed to enhance the kinetics of the hydrogen‐evolving reaction. [ABSTRACT FROM AUTHOR]

Herein we report the use of electrochemical faradaic spectroscopy in biosensors, with application on a commercially used first‐generation glucose biosensor manufactured by Zimmer and Peacock. The mechanism for the glucose sensor was explained and approximated as an EC' mechanism, where E is for electron transfer step, whereas C' signifies catalytical chemical step. Experimental chronoamperograms in electrochemical faradaic spectroscopy are compared to chronoamperometry, where it was found that the sum component in electrochemical faradaic spectroscopy gives higher response, resulting in better sensitivity of the sensor. Theoretical simulations give an insight of the response in electrochemical faradaic spectroscopy for an EC' mechanism and its dependence on different parameters (dimensionless electrode kinetic parameter, mid potential, dimensionless chemical kinetic parameter). For some specific set of parameters (large electrode and catalytic reaction kinetics), theoretical chronoamperograms in electrochemical faradaic spectroscopy can become similar to the experimental. The property of the sum component to have higher response in EC' mechanism for specific parameters is not limited only for electrochemical faradaic spectroscopy. Exemplified with square‐wave voltammetry, it is shown that other pulse techniques for an EC' mechanism can also result with higher sum component. Hence, for better sensitivity in quantitative analysis in EC' mechanism, one should quantify the sum component. [ABSTRACT FROM AUTHOR]

The present work describes the colour removal of Rhodamine B (Rh B), a cationic dye by photo-electrocatalysis and sono-photo-electrocatalysis on MgFe2O4 as an anode. The spinel MgFe2O4 synthesized by sol–gel route was characterized by physical and electrochemical methods, a preamble of Rh B oxidation. The XRD pattern shows the formation of the single phase, which crystallizes in a face-centred cubic lattice (space group, Fd − 3 m), with spherical crystallites (0.42 nm). The Zeta-sizer analysis gives an average grain size of 0.46 µm and a zeta potential of − 30 mV. The SEM analysis revealed the porosity of the oxide and the Mg-O and Fe–O bonds were confirmed by the FT-IR analysis. The direct optical gap (2.16 eV) assigned to d − d internal transition comes from the crystal field splitting of Fe3+ octahedrally coordinated. The low electron mobility is assigned to a narrow conduction band of Fe3+—3d parentage with activation energy (0.12 eV) in conformity with a conduction mechanism by small lattice polaron hopping. The intensity potential J(E) profile in Na2SO4 (10−2 M) exhibits a small hysteresis similar to a chemical diode. The semi-logarithmic plot (logJ − E) indicates the chemical stability of MgFe2O4 in the working solution (Na2SO4). Curiously and unlike most spinels, the capacitance plot exhibits n-type conduction confirmed by chrono-amperometry, plotted at the free potential (+ 0.5 V) with a flat band potential (Efb) of 0.29 V, due to Fe3+ insertion. As an application, Rh B (20 mg L−1) was successfully oxidized by photo-electrocatalysis on MgFe2O4 with an abatement of 75% under solar irradiation and a direct current of 150 mA which has a bactericidal effect. An enhancement up to 97% has been reached by sono-photo-electrocatalysis at a frequency of 60 kHz; almost complete discoloration occurred within 90 min in the "US-Electric Current-Sunlight-MgFe2O4". The Rh B elimination follows a pseudo-first-order kinetic with a rate constant of 3.9 × 10−2 mn−1 (t1/2 = 18 min), and a reaction mechanism is suggested. [ABSTRACT FROM AUTHOR]

An electrochemical sensor was developed for the detection of hydrogen peroxide (H2O2), utilizing the synergistic effects of graphene (Gr) and MOF-on-MOF nanozymes (FeCu-NZs). Initially, Fe-MOF with peroxide-like activity is synthesized using a solvothermal method. Subsequently, the organic ligand on its surface binds Cu2+, enhancing the enzyme-like activity further. The resulting FeCu-NZs exhibit a distinctive electrochemical signal in response to H2O2. Moreover, integrating FeCu-NZs with Gr significantly amplifies the electrochemical signal and effectively reduces the sensor's detection limit. The developed sensor exhibited linear ranges of 0.1–3800 μM, with a limit of detection (LOD) of 0.06 μM. Additionally, FeCu-NZs catalyze H2O2 to generate abundant •OH radicals, and colorimetric detection of H2O2 is facilitated using the color rendering principle of 3,3',5,5'-tetramethylbenzidine (TMB). Notably, this detection method was applied to determine H2O2 concentrations in real samples, achieving a recovery exceeding 95.7%. In summary, this research provides a practical platform for the construction of traditional nanozymes and the integration of electrochemical systems, which have broad applications in food analysis, environmental monitoring, and medical diagnosis. [ABSTRACT FROM AUTHOR]

The sensitivity of lead dioxide coating properties to the deposition conditions and electrolyte composition has allowed the preparation of coatings with different properties for different applications. In this study, the effects of electrolyte additives on the electrodeposition process were investigated using electrochemical measurements such as cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The results showed that the presence of fluoride ions significantly reduce the possibility of TiO2 formation. The addition of copper ions not only prevents lead loss at the cathode, but also leads to the formation of copper oxide on the surface at initial stages, which hinders nucleation of PbO2. The presence of sodium dodecyl sulfate (SDS) also interferes with the nucleation process as it occupies active nucleation sites. The α-PbO2 interlayer prevents copper oxidation and solves the problem of lead dioxide nucleation. Finally, it was found that the simultaneous use of all additives together with the α-PbO2 interlayer has a positive effect on the coating process.

Abstract There are no documented electroanalytical methods for quantifying the anti-inflammatory drug bumadizone (BUM) in pharmaceutical or biological matrices. So, a new voltammetric method was developed to determine BUM at nano concentrations in pharmaceutical forms, in the presence of its alkaline degradant, and in biological fluids. Five electrodes were tested, including three nano-reduced graphene oxide (nRGO) electrodes (5%, 15%, and 20%), a carbon paste electrode (CPE), and a 10% nRGO-modified CPE. The 10% nRGO-modified electrode showed the best performance, offering high selectivity and low detection limits, with good linearity in the concentration range of 0.9 × 102 to 15 × 102 ng mL−1. Differential pulse voltammetry successfully applied this electrode for BUM determination in various samples, achieving excellent recovery without preliminary separation. The method was validated according to ICH guidelines and compared favorably to the reference method. Its environmental impact was assessed using AGREE and Eco-scale metrics in addition to the RGB algorithm, showing superior greenness and whiteness profiles due to safer solvents and lower energy consumption, along with high practical effectiveness using the BAGI metric.

Solid oxide fuel cells (SOFCs) have gained great attention as a stationary power generation application due to their high efficiency, fuel flexibility and environmental friendliness. The devices and power age could be revolutionized with the commercialization of these technologies. The SOFC-based stationary power generator is one step closer to commercialization however, it is delayed due to the inherent bottleneck of insufficient long-term durability. The cathode current collecting layer (CCCL) is crucial in stack applications to minimize the contact loss between cell and metallic interconnects. Herein, we report an easy-to-fabricate and highly robust CCCL to boost electrochemical performance and long-term durability of flat tubular (FT) short stack. The tailored structure of the CCCL was employed in the fabrication of the FT short-stack. The G/Ag porous structure exhibited increased porosity of 61.2 %, thereby enhancing the mass transport and improving the overall performance and long-term durability. The four-cell FT stack was manufactured without an interconnect and open air-gas channel. Subsequently, the FT short-stack is tested for performance and long-term durability for elapsed 5000 h at a chronopotentiometry test. The porous layer of graphite/Ag on the cathode layer maintained structural integrity without defects and mechanical failure. Consequently, the stack voltage remains stable throughout operation owing to improved structural stability and uniform temperature distribution across four FT cell stack. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigates the impact of the uranium electrodeposition process on a boron-doped diamond electrode (BDD) surface at varying potentials as a means of environmental uranium remediation. The chronoamperometry technique was employed for the electrodeposition process, applying potentials ranging from − 0.60 to − 2.00 V vs. the reversible hydrogen electrode (RHE). A 2-mM uranyl acetate dihydrate (UO2(C2H3O2)2·2H2O) solution in 0.1-M KClO4 served as a model uranyl ion (UO22+) source. Analysis using scanning electron microscopy, energy-dispersive X-ray fluorescence spectroscopy, and atomic force microscopy (AFM) confirmed the presence of uranium and the formation of a thin layer on the electrode surface. Roughness measurements obtained through AFM analysis at different applied potentials vs. RHE were compared before and after uranium electrodeposition at BDD electrodes. Additionally, the identification of various uranium oxides resulting from the electrodeposition procedures was conducted using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. These analyses revealed the presence of UO2, UO3, and U3O8 on the BDD electrode surface due to the electrochemical deposition process, with a notable proportion of U3O8 observed. Ultimately, the optimal potential for efficient U6+ remediation from aqueous media and the formation of a homogenous thin layer conducive to nuclear technology development was determined to be − 1.75 V vs. RHE. [ABSTRACT FROM AUTHOR]

To study the nucleation and growth mechanism of Ni/SiC composite coatings, electrodeposition was conducted in the Ni bath containing SiC particles with different sizes. Compared to the Ni coating electrodeposited from the bare Ni bath, the Ni/SiC composite coatings exhibited similar grain size but rougher surface morphology due to the incorporation of SiC particles. By means of chronoamperometry (CA) and linear sweep voltammetry (LSV) techniques, it was found that the introduction of SiC particles did not change the nucleation mode of Ni: the Scharifker-Hills three-dimensional instantaneous nucleation mode. However, the nucleation sites on the cathode were reduced due to the inert surface and low conductivity of SiC particles. At a step potential of −0.94 V, Ni presented the maximum nucleation density (N0) of 3.09 × 107 cm−2, which was reduced by one order of magnitude for the Ni/SiC. Furthermore, SiC particles in the bath would extend the diffusion path of Ni2+ ions, resulting in the decrease in diffusion coefficient from 1.04 × 10−7 cm2 s−1 (Ni) to 9.91 × 10−9 cm2 s−1 (Ni/50 nm SiC), 1.83 × 10−8 cm2 s−1 (Ni/500 nm SiC) and 2.29 × 10−8 cm2 s−1 (Ni/5 μm SiC), suggesting the “Blocking effect”. COMSOL simulation further confirmed the “Blocking effect”. The “Blocking effect” would lead to excessive interface gaps around 5 μm SiC particles due to the uneven electrodeposition of Ni. To address the issue, we proposed that adding non-ionic surfactants into the bath to lower the electrochemical reaction rate of Ni2+ ions and accordingly gained composite coatings with fine continuity.

Featured Application: Measurement of glycerol content for wine safety and quality. This paper describes the design and development of a novel electrochemical biosensor for measuring glycerol in wine. Our initial detailed studies were aimed at deducing the optimum conditions for biosensor operation by conducting hydrodynamic voltammetric and amperometric studies. The resulting voltammograms revealed a maximum electrocatalytic current at 0.0 V vs. Ag/AgCl, which we used for all further studies. We also examined the effect of pH (8–10) on the amperometric responses of different glycerol concentrations over a range of 0.04 to 0.20 mM. Based on our findings, we propose that pH 9 would be suitable as the supporting electrolyte for further studies with the amperometric biosensor. The biosensor was constructed by immobilising 10 units of GLDH and 660 μg NAD+ onto the MB-SPCE surface using glutaraldehyde (GLA) as a cross-linking agent. Calibration studies were performed with glycerol over the 1.0–7.5 mM concentration range. Chronoamperometry was the electrochemical technique chosen for this purpose as it is convenient and can be performed with only 100 μL of sample directly deposited onto the biosensor's surface. In the current study, we observed linear calibration plots with the above standard solutions using current measurements at a selection of sampling times along the chronoamperograms (30–340 s). We have evaluated the glycerol biosensor by carrying out an analysis of commercially available red wine. Overall, these findings will form a platform for the development of novel rapid technology for point-of-test evaluation of glycerol in the production and quality control of wine. [ABSTRACT FROM AUTHOR]

This study introduces an innovative method for producing environmentally friendly hydrogen using glucose-assisted electrolysis in an alkaline Ni-based membrane-less electrochemical cell. Three sets of experiments were performed: i) cyclic voltammetry with photographic visualization of bubbles at the anode on a standard three-electrode electrochemical cell; ii) chronoamperometry experiments with in-situ O 2 measurements with an optical sensor on a gas-tight electrochemical cell and iii) gas-flow measurements in a membrane-less electrolyser. Results demonstrate that at glucose concentrations exceeding 100 mM, the Oxygen Evolution Reaction (OER) in a 1.0 M NaOH electrolyte can be entirely replaced by glucose oxidation on the Ni-based anode. Furthermore, experiments with the membrane-less electrolyser also serve as a proof-of-concept for the feasibility of removing the membrane in alkaline organic-assisted electrolysis processes. This breakthrough simplifies electrolyser design, reduces costs, and allows to use biomass-derived glucose as a renewable feedstock, advancing in the H 2 production technology. [Display omitted] • Under presence of glucose, no O 2 is produced in the OER region (1.7 V vs. RHE). • Under certain conditions, OER is completely replaced by the glucose oxidation. • Hydrogen is the unique gas produced during glucose-assisted electrolysis. • A membrane-less electrolyser can be used for glucose-assisted electrolysis. • A novel concept for simplifying electrolyser configuration is presented. [ABSTRACT FROM AUTHOR]

Thin films of polythiophene/graphene oxide (PTh/GO) were prepared using chronoamperometry. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (FESEM), UV-Vis spectroscopy, and photoluminescence spectroscopy (PL) were used for characterization purposes. PTh and PTh/GO thin films were achieved through chronoamperometry at a constant anodic potential of +1.9 V vs. Ag/AgCl. The PTh/GO thin films exhibited visible light absorption. The thicknesses of the thin films were approximately 2.42 μm. [ABSTRACT FROM AUTHOR]

This work presents studies to study the nucleation and growth mechanism of electrochemical NiMo films suitable for the decomposition reaction of water as an electrocatalyst, in which the value of the potential established from polarization measurements was maintained constant. Optimal conditions for the electrochemical synthesis of the Ni-Mo alloy on the surface of platinum and nickel electrodes were established using voltammetric studies examining the influence of many electrolysis parameters on the process of co-deposition of nickel with molybdenum. The chronoamperometric method provides more detailed information about the electrodeposition process by studying the nucleation and growth mechanism of electrochemical films in which the potential value determined from polarization measurements was kept constant. The curves were taken at various potential values -0.1, -0.2, -0.3, -0.4, -0.5, -0.6, -0.7, -0.8 and -0.9 V at room temperature. The study of these curves can be carried out by comparing the experimental calculated data with the equations of the Scharifker-Hills model. It was found that in the early stage, at potentials of -0.1 and -0.2 V, the experimental data fit into the curve of the progressive nucleation model, according to which Ni-Mo nucleation occurs on many active areas of the substrate surface, but at other potentials (from -0.3 to -0.9 V) deposition deviates towards instantaneous nucleation and growth. [ABSTRACT FROM AUTHOR]

The express-method proposed recently for experimental determination of diffusion coefficients of electroactive ions inside a membrane and their distribution coefficients at the membrane/solution boundary (Russ. J. Electrochem., 2022, 58, 1103) is based on the comparison of the measured non-stationary current for the electrode/membrane/electrolyte solution system upon the applying of a potential step with the theoretical expressions for the current–time dependence. Application of this method for the study of bromide-anion transport across the membrane was performed in the previous work under the condition of the membrane permselectivity where the amplitude of the electric field inside the membrane was suppressed owing to a high concentration of non-electroactive counterions. Then, the coion (bromide anion) transport occurred by the diffusional mechanism, for which the solution was available in an analytical form. The present study considers for the first time a non-stationary electrodiffusional transmembrane transport of two singly charged ions (e.g., background cation М+ as the counterion and electroactive anion X– as the coion) having identical diffusion coefficients where the current passage induced a transient electric field in this space, resulting in a deviation from predictions for the diffusional mechanism. It is found that within the short time interval after the applying of the potential step from the membrane equilibrium state to the limiting current regime (where the thickness of the non-stationary diffusion layer is significantly smaller than that of the membrane) the non-stationary distributions of the ion concentrations and of the electric field strength as a function of two variables (the spatial and temporal ones, x and t) can be expressed via a function of one variable, Z(z), where z = x/(4Dt)1/2. The form of the expression, depending on the ratio of the surface concentration of component X to the fixed charge density inside the membrane (Xm/Cf) has been found by numerical integration. The limiting current varies with time according to the Cottrell formula (I ~ t–1/2); the dependence of the dimensionless current amplitude, i, on the Xm/Cf ratio is found by numerical calculation; an approximate analytical formula has also been proposed. In particular, the passing current is shown to be close to the diffusion-limited one for a low coion concentration at the membrane/electrolyte solution boundary as compared with the concentration of immobile charged groups inside the membrane (Xm/Cf 1), whereas the migration contribution to the ionic fluxes doubles the limiting current when the opposite condition (Xm/Cf 1) is fulfilled. [ABSTRACT FROM AUTHOR]

Four polyoxomolybdated compounds based on Tetp (Tetp = 4-[4-(2-Thiophen-2-yl-ethyl)-4H-[1, 2, 4]triazole-3-yl]-pyridine), namely [Zn(Tetp)2(H2O)2][(β-Mo8O26)0.5] (Zn-Mo8), [Co(Tetp)2(H2O)2][(β-Mo8O26)0.5] (Co-Mo8), [Cu4(Tetp)6(H2O)2]{H3[K(H2O)3](θ-Mo8O26)(Mo12O40)}·8H2O (Cu-Mo20) and [Cu3(Tetp)3][PMo12O40]·H2O (Cu-PMo12) are synthesized by hydrothermal methods and are used as electrode materials for supercapacitors(SCs) and electrochemical sensors. Inserting polyoxometalates (POMs) with redox active sites into transition metal compounds (TMCs) can improve the internal ion/electron transfer rate, thus effectively enhancing the electrochemical performance. Compared with the parent POMs, four compounds exhibit excellent electrochemical properties. In particular, Cu-PMo12 shows an excellent specific capacitance (812.3 F g−1 at 1 A g−1) and stability (94.42%), as well as a wide detection range (0.05 to 1250 µM) and a low detection limit (0.057 µM) for NO2- sensing. [ABSTRACT FROM AUTHOR]

A composite is a material in which more than one metal salt or polymer can be mixed to enhance the processed product's physical and chemical properties. Due to their high band gap and enhanced excitation energy, composites can be used in numerous areas, such as solar cells, fuel cells, catalysts, and energy storage. Over a large area of applications in different fields, few studies have examined the ability of composites to sense the efficiency of riboflavin/vitamin B2. The present work explores the utilisation of trimetallic-based nanocomposite nanoparticles (TMNCsNPs) as a sensing material, which is synthesised and characterised in detail. The TMNCsNPs were used to understand the exposure of riboflavin to glassy carbon electrodes (GCE). Several electrochemical parameters were selected for the electrochemical study of the processed sensor. Initially, a long-range concentration of riboflavin (0.976–125 μM in PBS) was selected to check the efficiency of the produced sensor (TMNCsNPs/GCE). Low-to high-potential windows (0.5–15 mV/s) were chosen to measure the effect on TMNCsNPs/GCE in PBS. The chronoamperometry (CA) responses were analysed at different time intervals (0–900 s). The cyclic response (CR) was analysed for TMNCsNPs/GCE sensor for up to one month. The interference of metal was examined, and real sample analysis was also conducted and discussed with possible mechanism. [Display omitted] [ABSTRACT FROM AUTHOR]

Despite many recent efforts, the field of organic electrosyn‐thesis faces important challenges due to the intricate nature of heterogeneous redox processes, the wide parameter space to be explored and the lack of standardized methods. To overcome these limitations, we developed a cost‐effective high‐throughput electrochemical (HTE) reactor capable of running 24 individually controlled parallel reactions. This system allows the rapid testing of electrochemical parameters on a given reaction, assessing not only yield but also reproducibility. Using the hypervalent iodine‐mediated dearomatization of phloretic acid as a demonstration of HTE capabilities, we ran more than 200 electrosyntheses in different experimental conditions and demonstrate the effect of parameters such as total charge transferred, current, electrode materials, electrolyte formulation and concentration, mediator formulation and concentration and electrochemical technique of oxidation. Notably, this report demonstrates that while catalytic amounts of iodine mediator can be used successfully, the reproducibility may be affected, which calls for a cautious approach when developing similar transformations. Using cyclic voltammetry, density functional theory, chronopotentiometry, and Raman spectroscopy, we shed light on the causes of this issue. [ABSTRACT FROM AUTHOR]

The anodic behavior of Ni48Fe47Cu5 and Ni42Fe38Cu20 alloys in NaF-KF-AlF3-Al2O3 electrolyte was studied using electrochemical methods, such as chronopotentiometry, chronoamperometry, and linear sweep voltammetry at 770°C. The cryolite ratio and potassium ratio were 1.3 and 0.7, respectively. The steady-state polarization curves were obtained before and after galvanostatic polarization for 2 h. The current densities in the passivation region were lower for both anodes after polarization than before, indicating the formation of a protective passive layer during polarization. When anodes were subjected to potentiostatic polarization at 2.2 V (vs. reference), a passive film was readily formed. Linear sweep voltammograms were obtained on Ni48Fe47Cu5 and Ni42Fe38Cu20 alloys, and the polarization resistances were 5.227 Ω cm−2 and 5.968 Ω cm−2, respectively. During the galvanostatic electrolysis, the anodic potential (vs. reference) constantly varied with time for the Ni48Fe47Cu5 anode. In contrast, the anodic potential of Ni42Fe38Cu20 remained almost constant throughout the electrolysis. The thickness of the oxide layer formed on the anodes Ni48Fe47Cu5 and Ni42Fe38Cu20 after 2 h of electrolysis were around 90 μm and 30 μm, respectively. [ABSTRACT FROM AUTHOR]

Redox‐active materials that exhibit both electrochromism and electrofluorochromism have great potential as multifunctional elements in optoelectronics. Here, in situ spectroelectrochemistry is presented on NU‐1000, a zirconium pyrenetetrabenzoate metal–organic framework. A thin film of NU‐1000 exhibits reversible color changes between light yellow and dark blue when subjected to an alternating electrochemical potential. In situ fluorescence excitation‐emission spectral mapping elucidates a dominant blue emission of highly fluorescent electrochromic NU‐1000 that is being quenched via an oxidation reaction. Density‐functional theory calculations reveal the forbidden optical transition between the singly occupied molecular orbital (SOMO) and the lowest unoccupied molecular orbital (LUMO) in the oxidized linker as the cause of the quenching. Double potential step chronoamperometry measures response times as fast as a dozen seconds and excellent switching stability over 500 cycles without noticeable attenuation of the color contrast. These findings provide valuable insight into the electrochromism and electrofluorochromism in metal–organic frameworks, offering exciting opportunities for developing advanced multifunctional porous materials with potential applications in optoelectronics and sensing. [ABSTRACT FROM AUTHOR]

Methods for detecting contaminants in drinking water are crucial for protecting public health. Despite manganese (Mn) being an essential mineral for humans, Mn in high concentrations is suspected of being associated with negative cognitive and neurological effects on humans, especially on children. Current methods of detection, though reliable, are limited in the application to real-time easy-to-use, field or bench-top monitoring applications for testing drinking water. Herein, chronoamperometry (CA) is explored to quantitatively analyze manganese samples for drinking water applications. CA proved to be effective at measuring the concentration of Mn2+ in water samples with excellent recovery rates (97.8%) and reproducibility between electrodes. With 1-min deposition using bare gold electrodes, CA was able to obtain a detection limit of 34.3 µM. Furthermore, with a 5-min deposition using bare gold electrodes, CA was able to obtain a detection limit of 4.64 µM. This new CA method also offers a simplified cleaning method that will allow electrodes to be used continuously for differing samples or replicate tests. The cleaning procedure permits the reuse of electrodes, while simultaneously eliminating the need for special surface modifications on the electrodes. Ultimately, this cleaning procedure offers a faster and more efficient procedure than previous methods such as polishing. The CA method also demonstrated minimal interference effects when tested with varieties of water hardness, ionic strength, common electroactive species (Cu2+, Fe2+, Fe3+, and Cl−), and organic matters in aqueous environments. This CA method is easy to use, requires portable equipment, uses reagents that are easily accessible, and does not require extensive sample preparation. [ABSTRACT FROM AUTHOR]

This study integrates hollow microneedle arrays (HMNA) with a novel jellyfish-shaped electrochemical sensor for the detection of key biomarkers, including uric acid (UA), glucose, and pH, in artificial interstitial fluid. The jellyfish-shaped sensor displayed linear responses in detecting UA and glucose via differential pulse voltammetry (DPV) and chronoamperometry, respectively. Notably, the open circuit potential (OCP) of the system showed a linear variation with pH changes, validating its pH-sensing capability. The sensor system demonstrates exceptional electrochemical responsiveness within the physiological concentration ranges of these biomarkers in simulated epidermis sensing applications. The detection linear ranges of UA, glucose, and pH were 0~0.8 mM, 0~7 mM, and 4.0~8.0, respectively. These findings highlight the potential of the HMNA-integrated jellyfish-shaped sensors in real-world epidermal applications for comprehensive disease diagnosis and health monitoring. [ABSTRACT FROM AUTHOR]

The current study focused on the design of an extremely sensitive electrochemical sensor of ascorbic acid based on a mixture of NiAl2O4-NiO nanoparticles that, produced in a single step using the sol–gel method, on an ITO electrode. This new sensing platform is useful for the detection of ascorbic acid with a wide range of concentrations extending from the attomolar to the molar. SEM micrographs show the porous structure of the NiAl2O4-NiO sample, with a high specific surface area, which is beneficial for the catalytic performance of the nanocomposite. An XRD diffractogram confirmed the existence of two phases, NiAl2O4 and NiO, both corresponding to the face-centred cubic crystal structure. The performances of the modified electrode, as a biomolecule, in the detection of ascorbic acid was evaluated electrochemically by cyclic voltammetry and chronoamperometry. The sensor exhibited a sensitive electrocatalytic response at a working potential of E = +0.3 V vs. Ag/Ag Cl, reaching a steady-state current within 30 s after each addition of ascorbic acid solution with a wide dynamic range of concentrations extending from attolevels (10−18 M) to molar (10 mM) and limits of detection and quantification of 1.2 × 10−18 M and 3.96 × 10−18 M, respectively. This detection device was tested for the quantification of ascorbic acid in a 500 mg vitamin C commercialized tablet that was not pre-treated. [ABSTRACT FROM AUTHOR]

The approach for the determination of antioxidants of various hydrophilicity using the complex of the iron(III) with bipyridine as a model oxidizing agent and chronoamperometric recording of the analytical signal is proposed. The choice of the oxidant is determined by its solubility in aqueous, organic and aqueous-organic media. The conditions for recording chronoamperograms are selected: the medium is the acetonitrile-acetate buffer solution (pH 3.6) (9 : 1), the electrolyte is the LiClO4, the potential is E = 1.25 V, the current registration time is 80 s. Antioxidants soluble in organic and aqueous-organic media are studied: α-tocopherol, quercetin, catechin, and caffeic acid. The analytical ranges are (0.5−4) × 10–4 M. The antioxidant capacity (AOC) of ethanol extracts from medicinal plant materials is determined. A high correlation is observed between the AOC values obtained by the chronoamperometric and the spectrophotometric approaches, but only for samples whose intrinsic colors do not contribute to the absorbance of the Fe(II)-bipyridine complex. The application of the proposed approach and the potentiometric method using the K3[Fe(CN)6]/K4[Fe(CN)6] system showed that the values obtained by the potentiometric approach are significantly lower for most of the studied infusions. Thus, it is advisable to analyze multicomponent objects, containing substances of different hydrophilicity, using approaches with oxidizing agents of different solubilities, such as the Fe(III)-bipyridine complex. [ABSTRACT FROM AUTHOR]

Simple and sensitive determination of total antioxidant capacity (TAC) in food samples is highly desirable. In this work, an electrochemical platform was established based on a silica nanochannel film (SNF)-modified electrode, facilitating fast and highly sensitive analysis of TAC in colored food samples. SNF was grown on low-cost and readily available tin indium oxide (ITO) electrode. Fe3+-phenanthroline complex-Fe(III)(phen)3 was applied as the probe, and underwent chemical reduction to form Fe2+-phenanthroline complex-Fe(II)(phen)3 in the presence of antioxidants. Utilizing an oxidative voltage of +1 V, chronoamperometry was employed to measure the current generated by the electrochemical oxidation of Fe(II)(phen)3, allowing for the assessment of antioxidants. As the negatively charged SNF displayed remarkable enrichment towards positively charged Fe(II)(phen)3, the sensitivity of detection can be significantly improved. When Trolox was employed as the standard antioxidant, the electrochemical sensor demonstrated a linear detection range from 0.01 μM to 1 μM and from 1 μM to 1000 μM, with a limit of detection (LOD) of 3.9 nM. The detection performance is better that that of the conventional colorimetric method with a linear de range from 1 μM to 40 μM. Owing to the anti-interfering ability of nanochannels, direct determination of TAC in colored samples including coffee, tea, and edible oils was realized. [ABSTRACT FROM AUTHOR]

Silver(I) oxide is considered as one of the promising materials for photoelectrochemical technologies because it has an optimal band gap, relatively low cost, and a wide variety of production methods. However, its characteristics such as quantum efficiency, morphology, and crystal structure parameters require optimization, which can be achieved by applying the most suitable method for the obtaining of the material. One of the fairly simple methods is the anodic oxidation of silver or its alloys in alkaline media, which allows obtaining oxide phases with a controlled composition and predictable properties by varying the concentration of the alloy components and electrolysis mode. The purpose of this work is to reveal the features of anodic formation and to determine the photoelectrochemical characteristics of silver(I) oxide on silver–palladium alloys in deaerated 0.1 M KOH solution. The regularities of the anodic formation of Ag(I) oxide on alloys of the Ag–Pd-system with the palladium atomic fraction from 0.05 to 0.20 in deaerated 0.1 M KOH solution were studied by non-stationary electrochemical methods of cyclic voltammetry, chronoamperometry with synchronous recording of photocurrent, and photopotential measurements. The phase composition of the alloys (alpha phase) was determined from the results of X-ray diffractometry. Chemical composition was determined by energy dispersive microanalysis. Photoelectrochemical parameters were calculated from the results of the photocurrent and photopotential measurements. It was established that the Ag(I) oxide anodically formed on silver–palladium alloys is characterized by n-type conductivity and the predominance of donor defects. On the alloys with a relatively low palladium concentration (5 and 10 at %), Ag(I) oxide with a higher concentration of defects is formed, while on alloys with a relatively high palladium concentration (15 and 20 at %), with a lower concentration of defects than on pure silver. [ABSTRACT FROM AUTHOR]

Herein, a simple electrochemical process was proposed for the electrochemical modification of a graphite rod electrode (GrE) with a zinc hydroxide thin film. Two sequential steps were enough for the modification of the graphite rod using chronoamperometry technique. In the first step, the metallic zinc film was electrochemically deposited on GrE surface at pH 4.5, by reducing Zn2+ on GrE at − 1.78 V vs. saturated calomel electrode (SCE) for only 210 s forming GrE@ZnNPs. In the second step, the electrode previously coated with a metallic zinc film was oxidized in buffer solution at pH 7, at 0.1 V vs. SCE for 360 s to form GrE@Zn(OH)2NPs. X-ray diffraction, optical microscope and interferometric microscope were used to confirm and identify the obtaining of the desired layer (Zn and Zn(OH)2 nanoparticles (NPs) thin layer). Then, several electrochemical techniques were used before and after the modification in order to study the electrochemical properties of the bare and modified electrodes. These analyses are based on the comparison of open-circuit potentials, polarization resistances of fast electrochemical systems (Rp), potentiodynamic polarizations (Tafel curves) and electrochemical impedances. [ABSTRACT FROM AUTHOR]

The Hamma groundwater provides water to Constantine, a city in eastern Algeria. The high concentration of calcium ions (136 mg/L) and hydrogen carbonate (442 mg/L) accounts for the strong scaling power of the water. This study is the first attempt to mix green inhibitors randomly to determine which is the most effective. The use of three new mixtures gallic acid+quercetin, quercetin+alginate, and gallic acid+alginate) to decrease or to prevent calcium carbonate formation is the main topic of this research. Due to their low environmental impact, these mixtures have proven to be effective green scale inhibitors. The inhibition efficiency occurs at extremely low concentrations: gallic acid+quercetin (6mg/L), quercetin+alginate (60mg/L), and gallic acid+alginate (3mg/L). The inhibition effects of these mixtures are evaluated using electrochemical techniques (chronoamperometry and impedancemetry). The results showed that the most efficient scaling inhibitor is gallic acid+alginate since it produced positive results at a lower dosage (3mg/L) than the other mixtures. [ABSTRACT FROM AUTHOR]

Simple and reliable electrochemical sensors are highly demanded in medicine and pharmacy for the fast determination of metabolites and biomarkers of diseases. In this work, a flow-through biosensor system was developed on the base of a screen-printed carbon electrode modified with pillar[3]arene[2]quinone and ferrocene implemented in carbon black. The modification was performed in a single step and resulted in the formation of a stable layer with good operation characteristics. Uricase was immobilized on the inner walls of a replaceable reactor by carbodiimide binding. A flow-through cell was manufactured by 3D printing from poly(lactic acid). The flow-through system was first optimized on the hydrogen peroxide assay and then used for the determination of 1 nM–0.1 mM uric acid (limit of detection 0.3 nM, 20 measurements per hour). Implementation of ferrocene resulted in a synergetic increase in the cathodic current of H2O2 reduction measured by flow switching in chronoamperometric mode. The developed system was tested on the determination of uric acid in artificial urine and Ringer–Locke solution and showed a recovery rate of 96–112%. In addition, the possibility of determination of H2O2 in commercial disinfectants was shown. Easy assembly, fast and reliable signal and low consumption of the reagents make the system developed attractive for routine clinical analysis of metabolites. [ABSTRACT FROM AUTHOR]

AbstractInflammatory bowel disease (IBD) is a serious global health problem, mainly manifested as chronic progressive gastrointestinal inflammation, which damages the gastrointestinal mucosa and affects the life of human beings. This disease is difficult to eradicate, prone to recurrent attacks, has a potential cancer risk and includes Crohn’s disease (CD) and ulcerative colitis (UC). Unfortunately, the available drugs serve to induce remission but may result in adverse reactions and drug dependence. However, in the case of inflammation-related diseases, it is possible to assess and measure the severity of the disease and the impact of treatment by monitoring the levels of hydrogen peroxide (H2O2). Moreover, in-situ detection is of great significance as it represents the inflammatory site. In this study, a carbon fiber microelectrode modified by platinum nanoparticles was prepared and used to monitor H2O2 in intestine of an UC Drosophila model established by dextran sodium sulfate. The results show that the electrochemical biosensor provides sensitive, real-time determination of H2O2 in vivo, which provides a new methodological basis for studying the occurrence and development of UC and drug screening. [ABSTRACT FROM AUTHOR]

In the present work, the Mo 2 C electrocatalyst has been synthesized using waste plastic as carbon source. The use of plastic bottle has been chosen to reduce the cost of electrocatalyst as well to address the environmental issues caused due to these wastes. The pure phase sample was synthesized at 800 °C by carburizing MoO 3 in an autoclave. The synthesized sample shows high activity towards HER with a lower Tafel slope of 85.7 mVdec−1. One of the exceptional features of the developed electrocatalyst is the long-term stability up to 7 days as determined by chronopotentiometry results. The improved activity and stability have been attributed to the presence of graphene like structures encapsulating the Mo 2 C particles. The presence of carbon also shows higher storage ability with an electrochemical double layer capacitance (EDLC, C dl) of 91.0 μF. The synthesized sample shows an efficient and stable electrocatalyst towards HER. • Mo 2 C electrocatalyst has been synthesized using waste plastic as carbon source. • Mo 2 C pure phase was obtained by carburizing MoO 3 at 800 °C in an autoclave. • The sample showed a lower Tafel slope of 85.7 mVdec−1 towards HER. • The prepared electrocatalyst demonstrated long-term stability up to 7 days. • Higher storage ability (C dl = 91 μF s) was observed in the prepared sample. [ABSTRACT FROM AUTHOR]

In the current study, silver nanoparticles doped polymethylmethacrylate (Ag/PMMA) nanocomposite was created not using any enzyme, checked for glucose detection. Firstly, chemical reduction method was employed to make the silver nanoparticles and secondly, the silver nanoparticles were mixed with PMMA via solution casting and sonication method to obtain the binary nanocomposite of Ag/PMMA. The morphology imaging and physical properties of Ag/PMMA nanocomposite were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and Fourier transform infrared spectroscopy (FTIR). In order to build an electrochemical sensor, a glassy carbon (GC) electrode was altered with Ag/PMMA, and our findings showed that the custom-made electrode displayed electrocatalytic performance for the detection of glucose (C6H12O6) in 0.1 M solution of phosphate buffer (PBS, pH = 7.0). Voltammetric and amperometric sensors for the electrochemical detection of glucose were created based on these altered electrodes. The range of the voltammetric sensor was linear (from 0.1 to 1 mM) and high sensitivity of 41 µA mM−1 cm−2. [ABSTRACT FROM AUTHOR]

Iron oxides (hematite, Fe2O3, and magnetite, Fe3O4), previously used as electron mediators in the galvanic system with zero-valent aluminum (ZVAl), have been shown to recover Au upon cementation in Au–Cu ammoniacal thiosulfate media selectively, and this warrants further investigation. This research is focused on investigating the role of the semiconductive properties of metal oxides by performing a cementation experiment by mixing 0.15 g of electron mediators (Fe3O4, Fe2O3, TiO2 (anatase and rutile)) and 0.15 g of zero-valent aluminum powder as an electron donor in various electrochemical experiments. The results revealed that upon the cementation experiment, synthetic Fe2O3 and Fe3O4 were consistently able to selectively recover Au at around 90% and Cu at around 20%. Compared to activated carbon (AC), TiO2, in anatase and rutile forms, obtained selective recovery of gold, but the recovery was utterly insignificant compared to that of iron oxides, obtaining an average of 93% Au and 63% Cu recovery. The electrochemical and surface analysis supports the results obtained upon the cementation process, where TiO2, upon cyclic voltammetry (CV), obtained two reduction peaks centered at −1.0 V and −0.5 V assigned to reducing Au and Cu ions, respectively. Furthermore, various electrochemical impedance spectroscopic analyses revealed that the flat band potential obtained in the Mott–Schottky plot is around −1.0 V and −0.2 V for iron oxides and titanium oxides, respectively, suggesting that the electrons travel from semiconductor interface to electrolyte interface, and electrons are accessible only to Au ions in the electrolyte interface (reduction band edge around −1.0 V). The determination of this selective cementation mechanism is one of a kind. It has been proposed that the semiconductive properties of Fe2O3, Fe3O4, and, by configuring their relative energy band diagram, the travel of electrons from the iron oxide–electrolyte interface facilitate the selective cementation towards Au(S2O3)23+ ions in gold–copper ammoniacal thiosulfate solutions. [ABSTRACT FROM AUTHOR]

Microfluidics explores the fluid behavior at micron scale and is therefore suited to applications that need precise manipulation of fluids at small length or volume scales. In a span of over two decades, microfluidics has become an essential tool for modern genome sequencing platforms, single-cell analysis and common diagnostic tests. Despite many successful applications, the field has various challenges: Fabrication processes are yet to transition to commercial materials, microfluidic systems are reliant on skilled operators, and supporting equipment. Technological innovations in automation are needed to enable easy to use, completely on-chip microfluidic systems. Sensors are a critical component of any automated system. Fluid and flow properties such as flow rate, pressure, temperature, viscosity are critical to applications in drug development, and material/chemical synthesis. The flow rate (μL/min or nL/min) predictions based on external (off-chip) flow measurements can lead to erroneous calculations. The present work explores a technique based on chronoamperometry to measure flow rates inside a microchannel. Chronoamperometry based redox cycling of aqueous NaCl was performed by using interdigitated electrodes (IDE). The sensor measures current transients (which are modulated by the flow rate of the solution) effected by redox reactions on surface of the electrodes. The sensor demonstrated a sensitivity of 0.016 (μL/min)−1 change in charge transfer per unit change in flow rate and 3σ resolution of 9.3 μL/min. The calibration curve is linear in the range 0 – 200 μL/min, with a limit of detection (LoD) of 5 μL/min, making it suitable for various microfluidics applications.

Depression is a common mental illness. However, its current treatments, like selective serotonin reuptake inhibitors (SSRIs) and micro-dosing ketamine, are extremely variable between patients and not well understood. Three neurotransmitters: serotonin, histamine, and glutamate, have been proposed to be key mediators of depression. This review focuses on analytical methods to quantify these neurotransmitters to better understand neurological mechanisms of depression and how they are altered during treatment. To quantitatively measure serotonin and histamine, electrochemical techniques such as chronoamperometry and fast-scan cyclic voltammetry (FSCV) have been improved to study how specific molecular targets, like transporters and receptors, change with antidepressants and inflammation. Specifically, these studies show that different SSRIs have unique effects on serotonin reuptake and release. Histamine is normally elevated during stress, and a new inflammation hypothesis of depression links histamine and cytokine release. Electrochemical measurements revealed that stress increases histamine, decreases serotonin, and leads to changes in cytokines, like interleukin-6. Biosensors can also measure non-electroactive neurotransmitters, including glutamate and cytokines. In particular, new genetic sensors have shown how glutamate changes with chronic stress, as well as with ketamine treatment. These techniques have been used to characterize how ketamine changes glutamate and serotonin, and to understand how it is different from SSRIs. This review briefly outlines how these electrochemical techniques work, but primarily highlights how they have been used to understand the mechanisms of depression. Future studies should explore multiplexing techniques and personalized medicine using biomarkers in order to investigate multi-analyte changes to antidepressants. [ABSTRACT FROM AUTHOR]

This study explores the stability of electrodeposited copper catalysts utilized in electrochemical CO2 reduction (ECR) across various amine media. The focus is on understanding the influence of different amine types, corrosion ramifications, and the efficacy of pulse ECR methodologies. Employing a suite of electrochemical techniques including potentiodynamic polarization, linear resistance polarization, cyclic voltammetry, and chronopotentiometry, the investigation reveals useful insights. The findings show that among the tested amines, CO2-rich monoethanolamine (MEA) exhibits the highest corrosion rate. However, in most cases, the rates remain within tolerable limits for ECR operations. Primary amines, notably monoethanolamine (MEA), show enhanced compatibility with ECR processes, attributable to their resistance against carbonate salt precipitation and sustained stability over extended durations. Conversely, tertiary amines such as methyldiethanolamine (MDEA) present challenges due to the formation of carbonate salts during ECR, impeding their effective utilization. This study highlights the effectiveness of pulse ECR strategies in stabilizing ECR. A noticeable shift in cathodic potential and reduced deposit formation on the catalyst surface through periodic oxidation underscores the efficacy of such strategies. These findings offer insights for optimizing ECR in amine media, thereby providing promising pathways for advancements in CO2 emission reduction technologies. [ABSTRACT FROM AUTHOR]