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[Display omitted] • Two bare electrodes are used for non-faradaic electrochemical impedance spectroscopy (EIS) data and machine learning. • Automated electro-mechanical fluidic system is built to prepare 148 solutions of LiCl, NaCl, and KCl and measure EIS data. • A data-augmentation model is proposed for non-faradaic voltage sweep EIS datafor deep neural network (DNN) training. • Ion types and their concentrations are detected successfully with machine learning. • Trained DNN models was successful with 4.51 mM average deviation from the 200 mM total solution concentration. Detecting ion types and their concentrations in multi-ion aqueous solutions poses a complex challenge with significant implications for sensing applications. This paper introduces an automated fluidic system using two bare electrodes to measure electrochemical impedance spectroscopy (EIS) data and evaluates deep neural network (DNN) for ion type and concentration detection. Additionally, a data-augmentation model is proposed for non-faradaic voltage sweep EIS data, intended for neural network training. To validate the effectiveness of our approach, prepared solutions featuring varying concentrations of LiCl, NaCl, and KCl are experimented. Impedance (Z) vs DC bias voltage (V) data, i.e., ZV-EIS are measured from −400 mV to + 400 mV at 9 different frequencies up to ∼ 200 kHz, for 148 automatically prepared solutions, having total salt concentrations up to 200 mM. DNN models are trained with augmented samples and successfully identified individual ions in test set solutions and their concentrations with 4.51 mM average deviation. The study delves into the nuanced impacts of factors such as sampling voltage window, and measurement frequency on the performance of the machine learning models, 8 mV and 20 Hz giving the most significant results. [ABSTRACT FROM AUTHOR]

Sequence of redox processes in LiCl-KCl eutectic at graphite electrode was studied in temperature range 698-798 K using cyclic voltammetry and electrochemical impedance spectroscopy. There were two reduction steps observed when potential was scanned from −0.25 to −1.50 V (vs. ▪); a single-step two-electron transfer process due to reduction of carbon to ▪ followed by reduction of ▪. Electrolysis at −1.20 V at 773 K led to formation of ▪ on graphite surface. Complex impedance data were modelled using equivalent circuits and it was established that ▪ film formed around graphite electrode restricting both diffusion of ▪ in melt and metallic ▪ into graphite framework. These results are relevant in terms of their consequences in molten salt electrorefining of metal fuels. • Redox behaviour of LiCl-KCl eutectic melt at graphite electrode investigated at 698-798 K. • Sequence of reduction involved two steps in potential range −0.20 to −1.50 V (vs. Ag+|Ag). • Reduction steps involved formation of C 2 2 − and intercalation of Li in graphite. • Formation of Li 2 C 2 confirmed by potentiostatic polarization at graphite and XRD. • Complex impedance data by EIS fitted to equivalent circuit models. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pt-Ag/AC bimetallic catalyst synthesis via a gradual reduction method. • The synergistic effect was revealed between Pt and Ag for EOR. • Pt-Ag/AC has good cyclic stability: activity retention of 65.2% till 1000 cycles. • The anti-poisoning property of Pt-Ag/AC is impressive with j f /j b ratio of 3.5. • A detailed kinetic study is provided for EOR on Pt/AC (2 wt%) and Pt-Ag/AC catalysts. Due to the scarcity of fossil fuels and their severe environmental consequences, the development of high-efficiency energy conversion devices such as fuel cells (FCs) has gained considerable attention. The specific energy conversion efficiency of FC is highly influenced by the activity of the electrocatalysts. Platinum (Pt) is widely used as an electrocatalyst due to its high activity and stability, but high cost and depletion of resources hinder its commercialization. One of the workable strategies for the practical application of Pt is to reduce its content by alloying with non-precious metals and simultaneously maintain its electrochemical performance. In this context, we developed a low Pt-loaded Pt-Ag/AC alloy electrocatalyst. The electrocatalytic activity and kinetics of the as-synthesized catalyst were evaluated by cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS) using the three-electrode electrochemical workstation at room temperature. The electrocatalytic investigations reveal that the resultant AC-supported Pt-Ag with Pt: Ag = 1.8:2.3 at% has higher activity i.e., 32.7 mA cm−2 as compared to that of Pt/AC (20.8 mA cm−2) in an alkaline electrolyte and makes it an efficient electrocatalyst for the electro-oxidation of ethanol. The electron donation from Ag to Pt during the alloying process helps in weakening the interaction with CO and other intermediate species, thereby lowering their binding and poisoning effect on the surface, which may partly be responsible for the improved catalytic performance of Pt-Ag/AC. The activated carbon (AC) support also favors charge transport by reducing ohmic resistance. The cyclic stability studies also reveal that Pt-Ag/AC performs significantly better than Pt/AC with a current retention of 65.2 % and 48.3 % till 1000 cycles, respectively. Therefore, alloying Pt with earth-abundant Ag under rational composition provides optimized surface and electronic properties that result in improved ethanol electro-oxidation activity while reducing the utilization of precious noble metals. [ABSTRACT FROM AUTHOR]

• A sensitive and selective bromate sensor. • Impedance and voltammetric detection of bromate in food samples via CoPcMWCNTs-GCE. • CoPcMWCNTs-GCE - a promising electrochemical bromate sensor for food safety assessment. Bromate in food and water has been linked to cancer risks for lifetime exposures, and the present techniques for its detection have significant limitations that necessitate the development of new and more efficient approaches. The study describes the synthesis and characterization of CoPcMWCNTs nanocomposites before modifying a glassy carbon electrode for bromate detection. The nanocomposite CoPcMWCNTs was prepared from cobalt nanoparticles, phthalocyanine, and functionalized MWCNTs via ultrasonication. The successful synthesis of the nanomaterials was confirmed via XRD, UV–visible spectroscopy, SEM, and TEM. The CV and EIS studies in 5 mM [Fe(CN) 6 ]4−/[Fe(CN) 6 ]3− prepared in 0.1 M PBS (pH 7) revealed that the GCE-CoPcMWCNTs exhibited higher current response and faster electron transfer than the other electrodes. The electrochemical reduction of bromate was achieved in a solution containing 0.1 M H 2 SO 4 at a pH of 1 using the techniques of electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV). Using the SWV technique, an LoD of 1.31 μM was obtained with a sensitivity of 497.59 μA μM−1 over a linear dynamic range (LDR) of 6–20 μM. In contrast, utilizing the EIS technique yielded a lower limit of detection (LoD) of 0.32 μM, accompanied by a sensitivity of 72.42 μM kΩ−1, over a linear dynamic range (LDR) of 1–8 μM. The developed sensor exhibited good selectivity, high stability (93.5 %), and good reproducibility (% RSD; 3.9 %). The proposed sensor successfully detected bromate in bread samples, exhibiting a reasonable recovery rate. Thus, demonstrating the practical application of the sensor to detect bromate in real samples (bread). [ABSTRACT FROM AUTHOR]

[Display omitted] • The electric double layers in MgCl 2 solution and molten salt hydrates were compared. • Electrochemical windows in MgCl 2 solution and molten salt were analyzed by CV tests. • KCl can change the structure of [Mg(H 2 O) 6 ]2+ in molten salt hydrate and increase H+. • Reactions on the electrode surface were analyzed by EIS and DRT at a high frequency. The electric double layer on Pt cathode surface in the process of cathodic polarization was analyzed with cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Raman spectroscopy, and Scanning electron microscope (SEM) in magnesium chloride (MgCl 2) solution and MgCl 2 molten salt hydrate (MSH). The effects of KCl on the structure of MgCl 2 molten salt hydrate and electrode reaction were discussed. EIS data were fitted to propose the equivalent electric circuits to simulate the structure of electric double layers on Pt electrodes. Distribution of relaxation times (DRT) analysis was estimated to identify each process for MgCl 2 solution and MgCl 2 molten salt hydrate on the Pt cathode. The results show that the solution transforms into MSHs as the water content in the solution decreases. The solution and molten salt exhibit different double-layer properties. The movement of hydrated ions has greater resistance in MSHs which leads to the reduction of electrode reaction rate. The DRT and EIS results demonstrate that H+ and hydrated Mg2+ are simultaneously adsorbed on the Pt surface to form a double electric layer in MgCl 2 solution or MSHs. In the MgCl 2 MSHs, H+, H 2 O, and compact hydrated Mg2+ on the Pt electrode surface form a double layer. KCl plays an important role in changing the structure of MgCl 2 molten salt hydrate, increasing the active H 2 O, and offering H+ adsorbed on the Pt surface. [ABSTRACT FROM AUTHOR]

• Influence of the solution resistance for the porous electrode in the presence of dc concentration and ac potential gradients but in the absence of dc potential gradient is presented. • Presence of the solution resistance causes formation of the high-frequency straight line at 45° followed by two semicircles. • This high-frequency feature increases with the increase of the solution resistivity and the electrode porosity. • For moderate porosities the obtained impedances can be well fitted to the classical de Levie's equation although the parameters obtained differ, especially for the low-frequency semicircle. In a recent paper, we have presented behavior of the porous electrodes in the presence of electroactive species and the absence of the dc and ac potential gradients. This paper presents a model without dc potential gradient but including ac potential drop due to the solution resistance in pores. In this case, a high-frequency straight line at 45° characteristic of porous electrodes appears at high frequencies on the complex plane plots followed by two semicircles. This high-frequency line increases with the increase of the electrode porosity, i.e. Thiele modulus, and solution resistivity. Fitting these impedances to the classical de Levie's model does not reproduce well the parameters of the second semicircle although the overall fit is good for moderate porosities. [ABSTRACT FROM AUTHOR]

• A TDM using a preset ECM was examined for EIS of an LIB in the low frequency range. • The employed preset ECM consists of many series-connected RC parallel elements. • Small and long duration CC charge or discharge is suitable for the applied signal. • The TDM can perform EIS while excluding the apparent impedances from OCV change. • Two diffusion impedances were identified and their characteristics were made clear. A time domain measurement technique using a preset equivalent circuit model consisting of many series-connected resistor and capacitor parallel elements was examined as a measurement method of the electrochemical impedance spectrum of a lithium-ion battery excluding the apparent impedances from open circuit voltage change in the low frequency range. At first, a comprehensive experimental study was carried out to determine the standard condition of the applied signal suitable for this technique. It was established that an impedance spectrum from several tens of microhertz to several tens of millihertz can be accurately measured by selecting a proper, small rate and long duration constant current charge or discharge as the applied signal. Next, impedance spectra excluding the apparent impedances from open circuit voltage change were measured under various conditions using this technique, and basic characteristics of the impedances of the solid state diffusion processes of lithium that exist in the corresponding low frequency range were investigated. It was revealed that the impedance spectrum excluding the apparent impedances from open circuit voltage change in the low frequency range, from several tens of microhertz to several tens of millihertz, can be reasonably separated into two finite length Warburg impedances that can be clearly characterized by difference in their diffusion time constant values and in the state of charge dependence of their diffusion resistances. An Arrhenius type temperature dependence was confirmed for both of their diffusion resistances. [ABSTRACT FROM AUTHOR]

[Display omitted] • The stability domain of Be(OH) 2 was detremined by thermodynamic calculations and pH measurements. • The degree of passivation of Be(OH) 2 was evaluated by open circuit potential measurements and electrochemical impedance spectroscopy as a function of the pH solution. • Be is protected against the corrosion from neutral to basic pH. The corrosion is the lowest around pH 12. Beryllium wastes produced by nuclear industry could be managed by encapsulation in cements. The main risk is the aqueous corrosion, which leads to the hydrogen production and cracks causing a loss of radioactivity confinement. However, the corrosion can be limited by the formation of the hydroxide solid phase Be(OH) 2(s). A study on the influence of the pH on the reactivity of beryllium was carried out in aqueous solution. The solubility diagram was drawn and showed that the hydroxide solid phase is stable until very high basic pH of 14. The pH variation of solution at different initial pH was measured after immersion of metallic beryllium. The results are in good agreement with the calculated solubility diagram. The open circuit potential (OPC) and the electrochemical impedance spectra (EIS) were recorded at a beryllium electrode from pH 2 to 15. The simulation of the EIS by using an electric equivalent circuit allowed to evaluate the Be reactivity by measuring the charge transfer resistance as a function of the pH. The experimental results confirm that the corrosion of beryllium is limited at neutral to basic pH and this low reactivity was attributed to the formation of the hydroxide solid phase Be(OH) 2. The OCP and EIS measurements put also in evidence that the corrosion of beryllium is the lowest in solution having pH around 12. In this pH range, the Be metal would be protected against the corrosion both by the formation of the hydroxide solid Be(OH) 2 and by the adsorption of hydroxide ions (OH−) at the metal surface. [ABSTRACT FROM AUTHOR]

[Display omitted] • A synergetic effect between ultrasonic cavitation and the electrochemically induced discoloration of a dye contaminated solution was observed. • EIS experiments showed that the synergetic effect takes place in the electrode-solution interphase. • Cavitation induces a strong oxidative environment and a decrease of the interphasial electron transfer resistance. • Cavitation on a polarized interphase may be characterized by a strong ionic insertion of iron cations in the barrier zone of the CF electrodes. • Efficient discoloration was observed in oxygen-free cavitation assisted electrochemical tests. In this work, we report the results of a study to detect and quantify the discoloration of a model dye by an electro-Fenton process, in the presence and in the absence of ultrasound induced cavitation. As expected, a substantial increase in the color removal rate of the solution was observed, reflecting a strong synergetic interaction between the electrochemically induced discoloration kinetics and the ultrasound promoted cavitation. Control experiments to assess the dye degradation kinetics due to pure cavitation, also revealed that the synergetic effect under study takes place at the electrode-solution interphase. In order to gain understanding on the nature of the synergy observed, an electrochemical impedance spectroscopy (EIS) study was carried out. The fitted results of the experimental data suggest that, while the effects of ultrasonic cavitation are significant at the carbon cathode|electrolyte interphase, even in the absence of dissolved O 2 gas, the effect is comparatively negligible in the bulk of the solution as well as in the electrolyte located inside the pores of the carbon electrode. EIS results also suggest that the synergy observed during the cavitation assisted electrochemical generation of OH radicals in the absence of dissolved O 2 , points to the future development of novel wastewater treatment processes that, using air saturated solutions, will overcome the low solubility of O 2 that frequently limits traditional electro-Fenton approaches. [ABSTRACT FROM AUTHOR]

• The performance of a LIB under extreme operating conditions was investigated. • The LIBs is tested under vibration and high temperature conditions. • The ICA-based and impedance-based HIs for degradation feature were introduced. • The impedance-based HI is proposed to diagnose degradation and identify fault. • The optimal HI based on degradation mode is proved by comparing ICA-based HIs. Research is underway on ex-situ and in-situ methods for diagnosing the degradation of performance in lithium-ion batteries (LIBs) under various environmental conditions. Incremental capacity analysis (ICA) and electrochemical impedance spectroscopy (EIS) are a non-destructive in-situ method for determining battery health during operation. An electric vehicle (EV) operates for a long time under various environment and load conditions, so it is required to additionally investigate the battery degradation under extreme operating conditions. ICA-based and impedance-based health indicator (HI) are generally known to be capable of diagnosing a battery degradation mode (DM). Most of the EIS and ICA literatures are conducted at operating conditions, so it is questionable whether DM can be classified under extreme condition such as mechanical and high temperature conditions. This paper extracts impedance-based and ICA-based HI for diagnosing the soundness of lithium-ion batteries and proposes the optimal HI that can classify DM under extreme operating conditions. The degradation procedure was performed under extreme operating conditions, such as 60 °C temperature and vibration. The validity of the HIs was verified by comparing ICA-based and impedance-based HIs through environmental tests. [ABSTRACT FROM AUTHOR]

• Asymmetric and symmetric cobalt phthalocyanines (Pcs) coupled with S/N graphene quantum dots (SNGQDs) • The Pc -SNGQDs are attached to an aptamer for the detection of the human epidermal growth factor 2 (HER2). • The asymmetric Pc gave a lower limit of detection (0.0027 ng/mL) and sensitivity of 72,253 Ωng−1mL. • The efficiency of the designed sensors was tested using detection HER2 in human serum. Surface functionalization in biosensor design remains the major contributor to biosensor efficiency and selectivity. In electrochemical biosensor design, the surface is usually functionalized to achieve immobilization of the biorecognition element as well as electron transfer mediation for signal amplification. An asymmetric cobalt tris-(acetylphenoxy)-mono-phenoxyacrylic acid phthalocyanine (CoMPhAaPc) and a symmetric cobalt tetra-acetylphenoxy phthalocyanine were used for immobilization of HB5 aptamer and signal amplification towards the electrochemical detection of the human epidermal growth factor 2 (HER2). The efficiency of the two phthalocyanines is compared in relation to the substituents and symmetry. The two phthalocyanines were further coupled with sulphur nitrogen graphene quantum dots (SNGQDs) via π-π interactions, for enhanced activity and performance towards HER2 detection. The efficiency of the designed sensors was tested using the detection of HER2 in human serum. The best performance was observed for the SNGQDs(π)CoMPhAaPc/HB5 (amide) with limit of detection value of 0.0027 ng/mL and sensitivity of 72,253 Ωng−1mL. Considering these results, the aptasensors demonstrate great potential for improved monitoring of human epidermal growth factor receptor 2 levels for the management of breast cancer. [ABSTRACT FROM AUTHOR]

Complex collection efficiency in channel electrodes was revisited using numerical methods. This method has practical application when one wants to measure collection efficiency in systems where a side reaction unresponsive to the ac perturbation dominates the response. For complex collection efficiency to be applied experimentally, deviations from the purely diffusion limited reactions should be investigated. Three cases were modeled in this work: ideal case; EC reaction (coupling with a homogeneous chemical reaction); and linear kinetics at the detection electrode. From the modeling, an experimental framework and interpretation method was established that allows for the identification of the type of non-ideality and possible quantification of kinetic parameters. The ideal case was demonstrated experimentally using a microfluidic cell produced in-house. Unlabelled Image • Complex collection efficiency was revisited using numerical modeling. • Three cases; ideal case, homogeneous reaction, and heterogeneous reaction. • The cases can be distinguished by their response to change in flow rate. [ABSTRACT FROM AUTHOR]

Abstract Sulfonated polymeric surfactants integrated polypyrrole composites have been prepared and exploited as electrode material for supercapacitor application where sulfonated poly (ether ether ketone) SPEEK and poly (styrene sulfonate) PSS have been used as surfactant as well as dopant in polypyrrole (PPy). These composites are conveniently prepared via in-situ chemical oxidation polymerization of pyrrole using FeCl 3 as oxidant at varying weight ratio of SPEEK/PSS and investigated through Fourier transforms infrared spectroscopy, Thermal gravimetric analysis/Derivative thermal gravimetric, Field emission scanning electron microscopy, and electrochemical performance. Field emission scanning electron micrographs divulge granular morphology of composite with spongy and baggy structure. Electrochemical performance of all the composites has been investigated through cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS) measurements. Results reveal that electrochemical properties of composites significantly depend upon different feeding ratio of SPEEK or PSS due to the availability of sulfonating groups. After comparative study, high specific capacitance 330 F/g of SP4 (PPy:SPEEK (w/w) 60:40) at scan rate of 2 mV/s, that also correlates well with the GCD findings. High energy density obtained as 23.8 Wh/kg of SP4 composite at power density of 1000 W/kg demonstrates as new promising electrode material for supercapacitors. Graphical abstract Schematic illustration of preparation of PPy and its composites. Unlabelled Image Highlights • Exclusive features like good charge storage capacity and easy transport of electrons as well, made the composites quite efficient. • Composite SP4 has 330 F/g specific capacitance while PSS2 and PPy have 262 F/g and 142 F/g respectively. • High energy density obtained as 23.8Wh/Kg of SP4 composite at power density of 1000W/kg. [ABSTRACT FROM AUTHOR]

Abstract In this study, a non-enzymatic glucose sensor (NEGs) based on the electrochemical deposition of nickel nanoparticles on screen-printed electrodes modified with gold nanoparticles, Ni(OH) 2 /AuNp/SPE, is obtained. SEM and XPS measurements, and electrochemical performance reveal synergist effects of gold nanoparticles in the behavior of the catalyst when both Ni(OH) 2 /SPE and Ni(OH) 2 /AuNp/SPE systems were compared. SEM images show a homogeneous distribution of nickel spherical nanoparticles (~85 nm of diameter) in Ni(OH) 2 /AuNp/SPE. XPS spectra indicate the presence of nickel(II), probably as nickel hydroxide catalyst at the surface. The electrochemical response of Ni(OH) 2 /AuNp/SPE toward glucose oxidation and the selectivity of the proposed NEG in the presence of ascorbic acid and dopamine were evaluated by Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). In the single-frequency impedance measurements, the imaginary impedance values (Z Im) showed the best linear response with glucose concentration in the range of 0.10 to 2 mM, at 0.1 Hz and + 0.400 V vs Ag/AgCl. The calibration curve for 1/Z Im as a function of glucose concentration in artificial saliva samples was obtained with a slope of 0.073 KΩ−1 mM−1, R2 = 0.995, and limit of detection of 0.04 mM of glucose. Finally, impedimetric Ni(OH) 2 /AuNp/SPE was proposed for the quantification of glucose in non-blood samples. Graphical abstract Unlabelled Image Highlights • Ni(OH) 2 /AuNp/SPE impedimetric sensor is developed. • Gold nanoparticles favor the formation of a stable active catalytic species. • Glucose impedimetric detection in artificial saliva samples is achieved. • Correlation between Z Im and glucose concentration at 0.1 Hz is obtained (R2 = 0.995). [ABSTRACT FROM AUTHOR]

A novel electrochemical cytosensor was developed for detection of human osteosarcoma 143B cells based on graphene-three dimensional nanostructure gold nanocomposites (G-3D Au) using facile and rapid one-step electrochemical co-reduction technique. Characterizations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the gold nanoparticles in the scale of about 5–80 nm were deposited on the graphene sheets - showing pinecone-like 3D gold nanostructures. The proposed cytosensor, due to the increasing surface area and enhanced electron transfer rate by the nanocomposite, provided a highly stable and efficient matrix for the convenient conjugation of target CXCR4 antibody and the following incubation of cells. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) showed that the developed cytosensor was able to detect 143B cells ranging from 5.0 × 10 3 to 5 × 10 6  cells mL −1 with a lower detection limit of 1292 cells mL −1 . This electrochemical cytosensor showed a fast response, high sensitivity and selectivity, which could be used in various applications such as cancer diagnosis, drug screening and cell adhesion studies. [ABSTRACT FROM AUTHOR]

A new oligo(ethylene glycol)-thioacetyl substituted theophylline (THEO) has been synthesized and used to form self-assembled monolayers (SAMs) on different gold substrates. The THEO-SAMs formed are compact and passivate the gold surface in an important extension. The thioacetyl group can be deprotected to release the mercapto-derivative that gives place to Au-S bond either in the absence or in the presence of base. Evidences that the THEO molecules bind to gold as thiolates are given by the behavior of the reductive desorption process of the SAM as a function of solution pH. However, some of the molecules can suffer breakage in the C-S position releasing thioacetic acid and the fragment oligo(ethylene glycol)-theophylline that can't bind to gold. The thioacetic acid generated at the gold surface can be catalytically decomposed to acetyl and atomic sulfur. The later can be bound to gold as it has been demonstrated by electrochemical as well as by XPS techniques. The resulting THEO-SAM has been structurally characterized by IRRAS. Comparison of the IRRAS with the spectrum of the bulk molecules allows us to conclude about some degree of organization of the THEO chains upon SAM formation. The results of this study can be translated to a gold nanomaterial conjugate to be assayed in studies of theophylline derivatives drug delivery in living systems. [ABSTRACT FROM AUTHOR]

Hydrogen absorption/diffusion into Pd 80 Rh 20 alloy (50 μm foil) was studied using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy in 0.1 M H 2 SO 4 at 25 °C in the absence and presence of crystal violet. The double layer capacitance, charge transfer resistance, diffusion coefficient and mass transfer coefficient of hydrogen were determined. The mechanism of hydrogen absorption was discussed. Hydrogen adsorption inhibits the kinetics of hydrogen absorption and, in the presence of crystal violet, it proceeds much faster. At more positive potentials crystal violet is probably desorbed and the kinetics of absorption in the absence and in the presence of crystal violet proceeds with similar rate. [ABSTRACT FROM AUTHOR]

The ability to tune the permeability of cell membranes might have significant implications in targeted drug delivery applications. In this work we employ electrochemical methods as well as nanolithography realized in the environment of in-situ atomic force microscopy (AFM) to demonstrate that bioactive compound apigenin is capable of altering the permeability of a model phospholipid dipalmitoylphosphatidylcholine bilayer supported by a gold surface. The electron transfer rate through the bilayer was investigated employing [Fe(CN) 6 ] 4− /[Fe(CN) 6 ] 3− redox couple as an electroactive probe. The value of the standard heterogeneous rate constant obtained in the absence of apigenin ( k 0  = 6.60∙10 −5  cm·s −1 ) indicates that the electron transfer through the bilayer is rather sluggish confirming its compactness. The addition of apigenin to the system leads to a considerable increase of the electron transfer rate to k 0  = 5.74∙10 −3  cm·s −1 being virtually identical to the value obtained at the bare electrode/electrolyte interface ( k 0  = 2.24∙10 −3  cm·s −1 ). This suggests that apigenin induces a significant rearrangement of the supported lipid bilayer increasing thus its permeability. The AFM nanolithography performed in-situ in the presence of apigenin confirmed that the supported lipid bilayer reorganizes itself to a monolayer of molecules laying parallel to the electrode surface. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of polycrystalline gold electrode (PAuE) modified by self-assembled monolayers (SAMs) of thiolated calix[4]arene (C4A) and undecanethiol (C11) was investigated by voltammetric methods and electrochemical impedance spectroscopy. Coverage of the thiol SAMs and their stability was tested. The C11 layer is very stable; the desorption peak was recorded only in basic solutions of pH 12 and higher (at −1.30 V vs. Ag|AgCl (3 mol L −1 KCl)). The position of the C4A desorption peak is more pH dependent and it was recorded at −1.08 V at pH 13. Molecular coverage for C4A and C11 SAMs modified PAuE is 364 ± 52.9 μC cm −2 and 137 ± 20.0 μC cm −2 respectively. The properties of the PAuE modified by C11 and/or C4A were investigated using the model compounds hydroquinone, ferrocene and potassium ferrocyanide. It is assumed that the oxidation of the hydroquinone cannot be realized inside the C4A cavity because the hydroquinone molecule is too big to enter the cavity. Similar behavior was observed using potassium ferrocyanide. In contrast, cyclic voltammograms of ferrocene oxidation were only negligibly affected by the electrode modification. Moreover, capacitance measurements proved accumulation of ferrocenium ions at the C4A modified electrode. [ABSTRACT FROM AUTHOR]

• Orange peels Biomass-derived biochar carbon (OPAC) is an electrode material for energy. • Phosphomolybdic acid was embedded in OPAC to form a stable electrode material of OPAC-PMA, which exhibited 17.55 W kg−1 specific energy. • The OPAC-PMA electrode showed higher cycle stability. • The electrode can light up a red LED bulb for more than a minute. In high-performance, clean, safe, and cost-effective ways, supercapacitors are among the most promising ways to store and release nonfossil energy. In recent years, renewable biomass-derived activated carbon has been explored as a potential option for electrode material. It restricts their specific capacitance despite being environment-friendly and possessing intrinsic mechanical strength. In order to overcome this limitation and preserve all other properties, we are infusing polyoxometalate into the activated carbon; this increases specific capacitance with its fast reversible redox behaviour and preserves the carbon's characteristics. Beside suffusing phosphomolybdic acid (PMA) into biomass waste material, such as orange peel-derived activated carbon (OPAC), a new hybrid material (OPAC-PMA) was developed. The nanohybrid design was revealed by structural and morphological research, which showed high interfacial contact, allowing polyanions to redox rapidly. The novel hybrid electrode material (OPAC-PMA) has a capacitance value of 66% higher than the bare OPAC electrode. A further study showed that OPAC-PMA composite showed 88.23% cycle stability in 0.5 M H 2 SO 4 electrolyte at 6 A g−1 for 4000 cycles. [ABSTRACT FROM AUTHOR]

• A novel chalcone derivative DMPO was synthesized. • DMPO effectively inhibit corrosion of AZ91 Mg alloy in 3.5% NaCl Solution. • Langmuir adsorptive isotherm was observed. • DMPO was a mixed-type corrosion inhibitor that primarily functioned as a cathodic inhibitor. • Maximum inhibition efficiency of 93.7 % was achieved. Magnesium is the lightest structural metallic element, and exhibited an important developmental potential due to the growing need for lightweight electronics and transportation (aerospace, automobile, etc.). A novel chalcone derivative 4-(3-(4-(4-((4-(4-(3-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1 H -pyrazol-4-yl)acryloyl)-5-methyl-1 H -1,2,3-triazol-1-yl)phenyl)sulfonyl)phenyl)-5-methyl-1 H 1,2,3-triazol-1-yl)-3-oxoprop-1-en-1-yl)-1,5-dimethyl-2-phenyl-1,2-dihydro-3 H -pyrazol-3-one (DMPO) was synthesized. The chemical structure of the newly synthesized DMPO was inferred from its spectral data (H1-NMR, C13-NMR, and FT-IR). Its structure was also affirmed by field emission scanning electron microscopy-energy dispersive X-ray (SEM-EDX), and thermal stability was studied by thermal gravimetric analysis (TGA-DTA). Then, its potency as a remarkable corrosion inhibition for AZ91 magnesium alloys in NaCl (3.5 wt%) solution was studied. Hydrogen evolution, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) investigations were utilized to assess the impact of the newly synthesized chalcone derivative DMPO on the electrochemical performance of AZ91 Mg alloy in NaCl solution (3.5 wt%). SEM-EDX was used to evaluate the surface and elemental analysis of an AZ91 Mg alloy immersed in NaCl solution (3.5 wt%) with and without DMPO inhibitor. The obtained electrochemical evaluation revealed that DMPO functions as a high-performance, environmentally friendly AZ91 Mg alloy inhibitor in NaCl (3.5%) recording inhibition efficiency 93.7% at 100 ppm. Potentiodynamic polarization experiments revealed that the corrosion was inhibited due to the adsorption of inhibited molecules which follows the Langmuir adsorptive process. The findings also affirmed the development of protective film on Mg alloy surface. In electrochemical tests, it was discovered that DMPO molecules were mixed-type corrosion inhibitors. [ABSTRACT FROM AUTHOR]

Lactophoricin-I (LPcin-I), an antimicrobial cationic peptide with 23 amino acid residues isolated from bovine milk, and LPcin-II, which lacks six N-terminal amino acids with respect to LPcin-I, were investigated at a mercury-supported tethered bilayer lipid membrane (tBLM) consisting of a 2,3,di- O -phytanyl- sn -glycerol-1-tetraethylene-glycol- d , l -α lipoic acid ester thiolipid (DPTL) with a dioleoylphosphatidylcholine (DOPC) or dioleoylphosphatidylserine (DOPS) monolayer on top. The two LPcins were incorporated via scans of electrochemical impedance spectra (EISs) regularly distributed from − 0.30 to − 1.00 V and vice versa. During the pristine negative-going EIS scan the distal lipid monolayer is disrupted via a carpet mechanism, as revealed by an EIS exhibiting inductive behavior, whereas it heals during the positive-going scan. LPcin-I forms ion channels yielding voltage-gated cyclic voltammograms (CVs) at pH 3 and 5.4 in DPTL/DOPC tBLMs, but only at pH 3 in DPTL/DOPS tBLMs; no ion channels are formed at pH 6.8. LPcin-II does not form ion channels in DPTL/DOPC tBLMs at the three pH values investigated; however, in DPTL/DOPS tBLMs it forms ion channels at pH 5.4 and 6.8. This overall behavior is explained by dual electrostatic interactions between the zwitterionic polar heads of DOPC or DOPS and neighboring pairs of oppositely charged residues in the peptide chain. [ABSTRACT FROM AUTHOR]

Non-enzymatic glucose monitoring for biomedical applications asks for long-term stable and selective sensors at neutral pH. A hierarchical platinum micro-/nanostructured electrode along with a novel measurement scheme leads to increased sensitivity, selectivity and stability compared to state-of-the-art. The hierarchical electrode coating was applied by a scalable two-step process, which combined electrochemical deposition and colloidal synthesis to obtain a hierarchical structure with high surface roughness. This three-dimensional structure consists of a cauliflower-like platinum deposition, which is coated by a platinum nanowire network. Amperometric glucose measurements showed a 10,000-fold increase in sensitivity (473 μA cm −2  mM −1 ) compared to unmodified electrodes and linear behavior in the physiological range. The obtained sensitivities are among the highest values reported for non-enzymatic glucose sensors in neutral pH media. The hierarchical morphology provides a selectivity mechanism depending on the reaction kinetics, improving the selectivity for glucose in the presence of the interferent ascorbic acid 2000-fold. Selectivity was further enhanced by low-frequency electrochemical impedance spectroscopy (EIS). Chronoamperometric protocols were developed to achieve long-term stability and overcome the loss of sensitivity due to electrode poisoning. Using chronoamperometric protocols for both the amperometry and the EIS measurements improved stability significantly. The presented results make hierarchical platinum micro-/nanostructured electrodes a promising candidate for continuous glucose monitoring. [ABSTRACT FROM AUTHOR]

A comprehensive experimental investigation of the influence of the chain length on the electric field induced proton transfer at α,ω-mercaptoalkanecarboxylic acids self-assembled monolayers (SAMs) is conducted by means of voltammetric and electrochemical impedance spectroscopic measurements. The chain length has a significant impact on the total protonation/deprotonation charge and on the kinetics of the phenomenon. The results are discussed in light of existing theoretical models describing this electric field driven protonation/deprotonation process. Characteristic proton transfer frequencies were independently determined by impedance spectroscopy and by scan rate dependent voltammetric analyses. The two types of measurements are in mutual agreement and show that the protonation/deprotonation slows down as the chain length increases. [ABSTRACT FROM AUTHOR]

Glyme-based electrolytes with various lithium bis(trifluoromethane) sulfonamide (LiTFSI) salt concentrations have been investigated for their use in Li‑oxygen battery applications. Charge/discharge cycling with a cycle capacity of 500 mAh·g −1 showed an improvement as high as 300% for electrolytes containing higher LiTFSI concentrations. Electrochemical impedance spectroscopy (EIS) studies of Li-O 2 full cells and Raman spectroscopy studies on the discharged cathodes revealed that the superior cyclability at higher LiTFSI contents was due to a decrease in the rate of growth of glyme degradation products (lithium carbonate species). Raman spectroscopy analyses of the electrolytes also suggested that the increase in LiTFSI concentration afforded the formation of cationic and anionic complexes that helped mitigate the tetraglyme degradation. [ABSTRACT FROM AUTHOR]

The classical way to modify a gold electrode surface for immunosensor development is through self-assembly of functionalised thiols for subsequent attachment of antibodies. Here is described a new pathway for surface modification using a diazonium salt-based immunosensor for detection of methotrexate (MTX) with electrochemical immittance spectroscopy (EIS). The diazonium salt, 4-carboxybenzenediazonium tetrafluoroborate was synthesized using a diazotization reaction and characterized by IR and cyclic voltammetry (CV). The Au electrode was electrografted with diazonium and used for anti-MTX antibody immobilization. The EIS detection of MTX was studied with and without application of redox probe; Fe(CN) 6 3 −/4 − . MTX could not be detected using Fe(CN) 6 3 −/4 − as redox probe, whereas EIS measurements without redox probe and analysis of the data with singular decomposition (SVD) gave good results. A multivariate calibration model showed good linear behavior on a logarithmic scale with a detection limit for MTX of 7 × 10 − 12 mol L − 1 . [ABSTRACT FROM AUTHOR]

Nisin, the most prominent lantibiotic used as a food preservative, due to its high potency against certain Gram-positive bacteria, was investigated in mercury-supported lipid monolayers and bilayers, with the distal monolayer consisting of a dioleoylphosphatidylcholine (DOPC) or dioleoylphosphatidylserine (DOPS) monolayer. The voltage-gated behavior of the cyclic voltammogram (CV) of nisin at DPTL/DOPC tBLM in a pH 5.4 unbuffered solution of 0.1 M KCl is converted into an ohmic behavior upon addition of the glucopeptide CSF114(Glc), under favorable experimental conditions. This indicates that nisin targets Gram-positive bacteria mainly at the NHAc-substituted α - d -glucose ring, which is present both in the peptidoglycan polymer forming their cell walls and in CSF114(Glc). While the β - d -glucose and β - d -galactose rings of the glycosphingolipid GM1 are ineffective, addition of α - d -glucose, which interacts attractively with the GM1 sugar chain, has a moderate but significant enhancing effect on the nisin CV. This suggests a synergic effect of α - d -glucose and NHAc substitution in creating a target for nisin attack. Conversely, CSF114(Glc) has no appreciable effect on the DOPS distal monolayer at both pH values 5.4 and 6.8 and does not induce ohmic behavior. More precisely, at pH 6.8 the DOPS polar heads are negatively charged and recruit the positively charged nisin molecules, preventing their penetration into the hydrocarbon tail region. This penetration becomes possible at pH 5.4, where the DOPS distal monolayer is neutral, allowing the formation of an ion channel that yields a voltage-gated CV. [ABSTRACT FROM AUTHOR]

Here in, a high sensitive electrochemical aptasensor for the determination of tetracycline has been developed using of MWCNTs and electropolymerized poly (L-glutamic acid) as a suitable platform for immobilization of anti-TET aptamer. Electropolymerization of biocompatible polymer was performed by cyclic voltammetry (CV) and constant potential-based techniques. Due to the unique properties of impedance technique (electrochemical impedance spectroscopy (EIS)) and modification of electrode surface by constant potential electropolymerizarion, a wide linear range (1.0 × 10 − 16 –1.0 × 10 − 6 M) and low detection limit (3.7 × 10 − 17 ) for TET detection was observed. The stepwise modification process of the aptasensor fabrication was characterized by CV, EIS and scanning electron microscopy (SEM). The optimization of the loading amount of MWCNTs, detection time of TET, aptamer immobilization time, anti-TET aptamer concentration was performed in detail. Under the optimum conditions, the EIS and DPV data were used to establish a calibration curve. The developed aptasensor were successfully applied for determination of tetracycline in drug and honey samples. [ABSTRACT FROM AUTHOR]

Pure cardiolipin deposit onto electrodes is optimized and shown to yield an efficient supported lipid film for promoting cytochrome- c immobilization and electroactivity. Cyclic voltammetry and electrochemical impedance spectroscopy measurements in an aqueous electrolyte with potassium ferri- and ferrocyanide as a redox probe evidence that an optimized pure cardiolipin film is reached for a 7 μg cm − 2 deposit onto glassy carbon electrode. At this optimized surface concentration the pure cardiolipin deposit yields the most compact and less permeable supported lipid film on electrode surface. The thickness and the organization of the pure cardiolipin films were analyzed by atomic force microscopy (AFM) measurements. AFM imaging in aqueous buffer shows that the lipid deposit onto the surface forms a thick deposit of approximately 30 ± 10 nm of height with 4 nm average roughness and includes defects. Cytochrome- c electroactivity was studied with the redox protein either in solution or immobilized onto the modified electrode. First, the optimized amount of pure cardiolipin was deposited onto glassy carbon electrodes to study the stable and electrochemically quasi-reversible redox system of cytochrome- c in solution. Then, the potential cycling of a pure cardiolipin-modified glassy carbon electrode in a cytochrome- c solution led to the immobilization of the protein in its native state keeping intact its electrochemical properties, and with a surface coverage of 8 pmol cm − 2 corresponding to 50% of a monolayer. [ABSTRACT FROM AUTHOR]

Due to recent advancements in electrochemical devices such as batteries, fuel cells, and supercapacitors, novel electrochemical processes for industrial plant scale including water treatment and desalination are being actively investigated. Slurry electrodes for flow-electrode capacitive deionization (FCDI) are representative process technology with continuous and easy scale-up characteristics. These characteristics are feasible as slurry electrodes can be flowed in microchannels, instead of stacking conventional electrodes fixed on plates. However, the electrochemical properties of slurry electrodes for electrochemical process engineering have not been clearly identified, compared to those of conventional fixed electrodes. In the present study, we investigated the electrochemical properties of capacitive slurry electrodes with changes in carbon content and electrolyte salt concentration using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and deionization/regeneration cycle tests with newly fabricated button-type cells. The CV patterns were rectangular, symmetrical, and reversible at a scan rate of 2 mV/s, indicating electrical double-layer capacitive behavior. The results of the EIS and cycle tests demonstrated that increasing the carbon content and electrolyte salt concentration in slurry electrodes improved the cell efficiency due to the higher capacitance and lower total resistance. [ABSTRACT FROM AUTHOR]

A label-free impedimetric glycosensor has been developed for the direct detection of cholera toxin (CT). The glycosensor has been fabricated by forming the self-assembled monolayers of β-galactose derivatives containing poly-ethyleneglycol (PEG) spacer on gold electrode surfaces. The selective binding of CT to the β-galactose receptors on the fabricated glycosensor has been directly monitored by electrochemical impedance spectroscopy in the presence of 5.0 mM K 3 Fe(CN) 6 /K 4 Fe(CN) 6 (1:1, v/v) redox couple. gmonolayers on gold electrode surface has been determined to be ca. 2.53 × 10 10 M − 1 , indicating that the present glycosensor can selectively capture the target CT from sample solutions. Therefore, the present monosaccharide β-galactose derivative can be used as a receptor for CT as an alternative to CT-specific antibodies or pentasaccharide ganglioside GM 1 , most widely used in conventional CT assays. The present glycosensor can detect CT in the concentration range from 1.18 × 10 − 12 M to 1.18 × 10 − 9 M ( r 2 = 0.963) with a limit of detection (S/N = 3) down to 7.83 × 10 − 13 M, which is much lower than those obtained with other detection methods. Since the present glycosensor-based CT assay does not require complex and time-consuming signal amplification steps generally employed in sandwich-type immunoassays, it enables the simple and rapid detection of CT. [ABSTRACT FROM AUTHOR]

Carbon-black is heat-treated with nitrogen-containing precursor (ammonia or melamine) to yield N-doped carbon. The nitrogen content in the sample depends on the type of the precursor and the heat-treatment temperature and it is estimated using CHN analysis. The electrochemical impedance spectroscopy (EIS) patterns of the samples recorded in argon-saturated 0.1 M KOH show a high-frequency equivalent distributed resistance (EDR) and a low-frequency capacitive straight line, tilted slightly away from the y-axis. The EDR and the tilt of the capacitive straight line decrease with increase in nitrogen-content in the N-doped carbon samples. Further, EIS of oxygen reduction reaction (ORR) is recorded with carbon and N-doped carbon in oxygen-saturated 0.1 M KOH. The EIS patterns of ORR suggest that the high-frequency EDR feature is not negligible, unlike that with carbon-supported and unsupported Pt catalysts in both acidic and alkaline media. Therefore, nitrogen content and EDR have important implications in deciding the electrocatalytic activity and the features of the EIS patterns of carbon-based metal-free catalysts. Because of the change in EDR and the capacitance with nitrogen-content, the EIS patterns of ORR with N-doped carbon are complex to analyze. [ABSTRACT FROM AUTHOR]

A simple and inexpensive electrochemical methodology was used to develop a new method to inspect the biochemical action of Bleomycin (BLM). Furthermore, the effect of some metal ions such as Fe(II), Fe(III), Cu(I), Cu(II), Zn(II), Mn(II) and Co(II) on the operation of BLM was investigated. To prove the role of ionic metals some chelators and reducers were used too. In this study, a pretreated pencil graphite electrode (PGE) modified with gold nanoparticles (AuNPs) and a synthesized zinc(II)-Schiff base complex (ZnSB) decorated with ds-DNA was used to identify DNA damage induced by BLM in the presence of metal ions. The change in the charge transfer resistance (R ct ) using EIS method as well as appearance of 8-Oxo guanine (8-OxoG) peak in DPV method after immersion of the DNA biosensor in BLM solution were used as indicators of DNA damage. Our results showed that the BLM alone cannot destroy DNA and in the other words the BLM has not any interaction with ds-DNA but BLM in the presence of some metal ions can destroy the ds-DNA. By comparing the performance of metal ions and investigation of their effect on action of BLM, the mechanism of DNA damage induced by BLM was presented. [ABSTRACT FROM AUTHOR]

As a new performance, nanostructured nickel oxide (Nano-NiO) thin film was considered at the optimized instrumental deposition conditions on the F-doped SnO 2 conducting glass (FTO) by reactive radio frequency (RF) magnetron sputtering system. The attained uniform Nano-NiO thin film was successfully exploited to immobilize glucose oxidase enzyme (GOx) for impedimetric glucose quantification. Step by step film monitoring using field emission-scanning electron microscopy (FE-SEM) before and after enzyme immobilization established nanostructured NiO thin film with great isoelectric point (IEP ~ 10.7) was a suitable biosensing media for enzymes with low IEP (4.5). Observing of biosensor fabrication was accomplished using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The impedimetric results for invented FTO/Nano-NiO/GOx biosensor exhibited good sensitivity 4.45 kΩ/mM for glucose detection within 0.20–4.0 mM range, good electrocatalytic activity, and low detection limit as 24 μM via appropriate enzyme activity and stability. The suggested disposable biosensor demonstrated a potential application for real sample analysis with unknown interferences. [ABSTRACT FROM AUTHOR]

Composites of cobalt oxide with activated carbon (AC) and multi wall carbon nano tubes (MWCNTs) were synthesised using hydrothermal method. X-ray diffraction and scanning electron microscopy (SEM) has revealed the Co 3 O 4 nano phase well embedded over the AC and MWCNTs matrices. Materials were further characterised using FTIR measurements. Cyclic voltammetry and charge discharge experiments were carried out in 1 M KOH solution. Both the materials have shown superior electrochemical properties and good long time cycle ability. The Co 3 O 4 with MWCNTs composite (Co 3 O 4 /MWCNTs) has shown better electrochemical characteristics compared to the composite of Co 3 O 4 with AC (Co 3 O 4 /AC) due to the symmetric entanglement of the materials all over the MWCNT surface. The discharge specific capacitance of Co 3 O 4 /AC and Co 3 O 4 /MWCNTs composites was obtained as 620 and 788 Fg − 1 respectively. The electrochemical performance of the materials was modelled using electrochemical impedance modelling and the results revealed the presence of unsaturated surface charge over the composite electrode surface. [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy technique was applied to study bilayer membranes formed with egg yolk phosphatidylcholine containing as an additional component one of two carotenoid pigments: canthaxanthin or β -carotene. The results show that both carotenoids present in the lipid membranes at relatively low concentration modify significantly electrical capacitance and electrical resistance of the membranes. Domain structures appear as a result of interactions between components within analyzed bilayers. The equilibrium of domain formation can explain the deviation from the additivity rule. This equilibrium was described by mathematical equations as well as verified experimentally. Moreover, the surface area of domains was calculated and their stoichiometry was proposed. [ABSTRACT FROM AUTHOR]

We present results from the anodization of single crystal Al(100) and Al(111) surfaces and the aluminum alloy AA 6063 studied in situ by X-ray reflectivity and electrochemical impedance spectroscopy. We observe that the anodic oxide layer grows linearly with the anodization potential and that the thicknesses are similar for all samples. However, the thicknesses obtained from X-ray reflectivity are higher than that obtained from electrochemical impedance spectroscopy. We attribute the higher thicknesses to an outer porous oxide layer, which is not detected by electrochemical impedance spectroscopy. Both, electrochemical impedance spectroscopy and X-ray reflectivity suggests that a more heterogeneous and rough oxide is formed on AA 6063 due to the influence of the alloying elements and intermetallic particles during the growth. [ABSTRACT FROM AUTHOR]

Primary Na/MnO 2 cells are expected to gain importance for replacement of primary Li/MnO 2 cells in future akin to the Na-ion cells as alternative for Li-ion cells. Amorphous MnO 2 is prepared by a drop-wise addition of KMnO 4 solution to MnSO 4 solution, and coin cells of Na/MnO 2 are fabricated in a non-aqueous electrolyte of Na salt. The electrochemical impedance spectroscopy (EIS) data provides a high resistance of Na metal due to the surface passive film. On subjecting the cell for discharge, the surface film causes a delay response of the cell voltage and the closed circuit voltage reaches the normal discharge level following dielectric breakdown of the film. The EIS data measured at different stages of cell discharge are subjected to non-linear least square fitting with the aid of an appropriate equivalent circuit. The impedance parameters are examined to throw light on state-of-charge of Na/MnO 2 primary cells. [ABSTRACT FROM AUTHOR]

[Display omitted] • Corrosion resistance increases with increasing tempering temperature. • SSP transforms the coarse grained structure into a nanostructured one. • SSP decreases corrosion resistance despite inducing the formation of nanograins. • Dislocations strongly influence corrosion resistance. • Pitting corrosion has been observed at the Mn inclusion in the SSP series. In this study, the effect of tempering temperature on the corrosion behavior of a low carbon steel (F1272) was analyzed by means of electrochemical tests: linear polarization resistance, potentyodinamic polarization and electrochemical impedance spectroscopy (EIS) in freely aerated 3.5% NaCl solution, at room temperature. The results show that corrosion resistance of the steel increases with elevating tempering temperature from 200 to 500 °C and finally, to 680 °C. Additionally, a severe shot peening (SSP) treatment was applied in the sample with the best corrosion behavior (TT680), in order to modify the grain structure. Results evidence that corrosion resistance of the TT680 sample decreases after the applied SSP treatment (10A and 5000% coverage). Corrosion behavior is discussed through the different microstructural singularities induced both the heat treatments and the SSP. [ABSTRACT FROM AUTHOR]

• Smaller 50 nm Si nanoparticles (NPs) provide highest surface area resulting in lowest charge transfer resistance responsible for highest SEI layer resistance which is attributed to high Li+ reacting with electrolyte. • Bigger size 150 nm Si-NPs possess low surface area and provides high charge transfer resistance with low SEI layer resistance. • The mixture of the 50 and 150 nm NPs in (w/w/ = 1:1) exhibit optimum surface area that shows compromise between the solid electrolyte interface (SEI) resistance and charge transfer resistance provides highest capacity. Silicon is an attractive anode material in Li-ion batteries due to its high specific capacity, but the stability of silicon limits its industrial-scale application. To avoid this, the particle size reduction below 150 nm (critical radius) showed improved reactivity and cycle life but still below the benchmark for industrial-scale application. In this work, we applied the impedance analysis to understand the physicochemical processes occurring at the anode (Si electrode)/electrolyte interface. For this, we fabricated three samples of Si anode with 50 nm, 150 nm, and a mixture of 50 and 150 nm particles in equal ratios. The small particle size sample showed low charge transfer resistance, showing the highest activity towards lithiation and delithiation reaction, but high SEI formation hampers the overall capacity of the device. On the other hand, the 150 nm sample showed the low SEI formation but high charge transfer resistance due to low surface area. Finally, the mixed sample showed the compromise between the charge transfer reaction and SEI formation showing the lowest polarisation resistance after 50 cycles. Thus, the mixed sample having the advantage of intermediate surface area and intermediate SEI formation gives the highest capacity. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI)/graphene nanoplatelet (GNP)/multi-walled carbon nanotube (MWCNT) composite films deposited on fluorine-doped tin oxide (FTO) substrates were successfully fabricated through electrochemical method without pre-treatment of GNP and MWCNT to provide a lower cost counter electrode (CE) for dye-sensitized solar cells (DSSCs). By varying the contents of GNP and MWCNT in the PANI composite CE, the short-circuit current density of DSSC was found to linearly relate to the reduction current density of I − /I3 − redox couples measured by cyclic voltammetry. The open-circuit voltage ( V OC ) is also highly dependent on the reduction potential of redox couples. Besides, the charge transfer resistance at the electrolyte/CE interface measured by electrochemical impedance spectroscopy has an approximately linear relationship with the sheet resistance of PANI composite CE. Notably, the DSSC with the CE fabricated by the weight ratio of PANI/GNP/MWCNT at 1:0.003:0.0045 yielded the highest power conversion efficiency of 7.67 ± 0.05%, which is comparable with the conventional Pt cell (7.62 ± 0.07%). [ABSTRACT FROM AUTHOR]

Here, a novel biomolecular-repellent electrochemical biosensor platform is fabricated with a hydrophilic material-independent poly-dopamine, Fe3 +-mediated tannic acid (TA) deposition and the branched structure of four-armed polyethylene glycol (PEG). Dopamine (DA) and TA acted as initiator anchor for surface functionalization, and PEG was then grafted on TA/pDA-coating surface via layer-by-layer (LBL) technique. The whole process of building DNA biosensor platform is optimized and characterized with scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), contact angle measurements (CA). PEG/TA/pDA platform demonstrates excellent characteristics in terms of electrode stability and tendency to resistance to biomacromolecules adsorption. Subsequently, the gold nanoparticles with thiol-modified oligonucleotides were deposited on PEG/TA/pDA platform as enhancer to realize the reliable detection of BACA1 in PBS solution or 10% (V/V) human blood serum. Experimental results shows that charge-transfer resistance (Rct) versus target concentration is constituted from a good linear correlation from 0.1 fM to 10 pM and is associated with a limit of detection as low as 0.05 fM (S/N = 3). Advantageously, this potentially cheap and reusable assay suggests the feasible potential for diagnostic applications in clinical analysis of breast cancer. [ABSTRACT FROM AUTHOR]

The electrocapillarity and zero-frequency differential capacitance, C d , have been studied using pendant drop method, at the Hg interface of an ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide, [C 2 mim + ][TFSA − ], and have been compared with those of [C 2 mim + ]BF 4 − , an IL with the common cation and a different anion, to focus on the anion dependence of zero-frequency C d . The Hg interface of [C 2 mim + ][TFSA − ], the IL of the larger anion in the present study, exhibits greater zero-frequency C d than that of [C 2 mim + ]BF 4 − , the IL of the smaller anion. This behavior contradicts a simple expectation in which larger ion leads to smaller C d . This apparent contradiction is explained by proximity of the charged moiety of TFSA − to the electrode surface compared with that of BF 4 − . The potential dependence of zero-frequency C d for the two ILs both exhibits one-hump camel shape around the potential of zero charge ( E pzc ), which has been predicted to be specific behavior of the electrical double layer of ILs by theory and simulation. The humps are located at potentials more negative than E pzc . From a mean-field lattice-gas theory for the EDL in ILs, this negative shift can be interpreted that the charged moiety for C 2 mim + is more easily condensed in the EDL than those for BF 4 − and TFSA − . [ABSTRACT FROM AUTHOR]

Present investigation describes the photoelectrochemical studies of electrosynthesized CdSe and indium doped CdSe (In:CdSe) thin films deposited on stainless steel (SS) substrates. The photoelectrochemical (PEC) studies of both films are carried out with CdSe and In:CdSe(SS)/1 M Polysulfide/C cell. It is observed that indium doping in CdSe enhances the fill factor from 0.56 to 0.63 and photo-conversion efficiency from 0.80% to 2.01%. In order to study the consequence of doping, undoped and indium doped CdSe thin films are further characterized by capacitance-voltage, electrochemical impedance spectroscopy (EIS), spectral response, transient response, speed of response characterization techniques. By using capacitance-voltage measurement, various physical parameters are estimated and accordingly energy band diagrams have been constructed. [ABSTRACT FROM AUTHOR]

Electrochemical impedance spectroscopy (EIS) is a highly useful approach for the label free measurement of DNA hybridisation at functionalised electrode surfaces. Since label free detection relies upon a change in the electrochemical signal arising directly from the presence of target oligonucleotide or DNA/RNA sequences it is necessary to improve understanding of the conditions which produce a stable baseline value, promote optimal hybridisation of complementary sequences and can reduce non-specific binding effects. This study investigates both artificial DNA oligonucleotide sequences and clinical samples of MRSA genomic DNA, initially demonstrating that the use of tris(2-carboxyethyl)phosphine (TCEP) during probe layer formation improves both the initial baseline signal reproducibility and also the magnitude of the response upon hybridisation with a complementary target. Having demonstrated enhanced performance from TCEP modified electrodes, the assay is then used to detect clinical samples of MRSA. It is shown that improved performance is achieved both in terms of signal magnitude and discrimination against negative controls. Finally, formamide is added to the EIS measurement buffer and it is demonstrated that EIS measurement is possible in the presence of high formamide concentrations and that non-specific binding is also reduced under such conditions. The importance of these findings lies in the design of future electrochemical assays for nucleic acid biomarkers which are capable of functioning under ambient conditions but still have discriminatory power. A diagnostic device which does not have to operate at elevated temperatures will lead to increased simplicity and substantial battery and time savings which will further the widespread realisation of portable clinical diagnostic devices. [ABSTRACT FROM AUTHOR]

Hydrogen evolution reaction (HER) was studied over a rough rotating disk palladium electrode in 0.1 M sulfuric acid using steady-state polarization current measurements and electrochemical impedance spectroscopy (EIS). Among all the applied potentials, up to − 0.074 V, two semicircles were found on the complex plane plots, which were attributed to the HER. Surface roughness factor, R f = 23, was determined from the double-layer capacitance. The Tafel slope was − 0.097 V dec − 1 and the value of the intrinsic exchange current density was 0.22 mA cm − 2 . The double layer capacitance, charge transfer resistance, adsorption resistance, and pseudocapacitance as functions of potential were also determined from the EIS results. The HER proceeds through the Volmer-Heyrovsky mechanism. [ABSTRACT FROM AUTHOR]

Porous copper was electrodeposited using hydrogen bubble dynamic template. Various electrolytes having CuSO 4 and H 2 SO 4 in fixed molar ratio approximately equal to 0.3 and at temperature 18 °C were utilized for potentiostatic electrodeposition at various cathodic potentials. After electrodeposition, electrochemical impedance spectroscopy studies were conducted in 2.5 M NaCl solution at room temperature for determining electrochemically active true surface area. The surface morphologies of the deposits were analyzed using scanning electron microscope. Electrolyte with composition 0.12 M CuSO 4 and 0.4 M H 2 SO 4 resulted in maximum electrochemically active true surface area due to more open structure with thick dendrite branches which was correlated to high hydrogen evolution rate. [ABSTRACT FROM AUTHOR]

A simple, highly sensitive, and cost-effective electrochemical method for the detection of Zn 2 + is constructed employing unmodified gold nanoparticles (AuNPs) and a specific binding peptide. AuNPs are firstly modified on a glassy carbon electrode, which show excellent electrical conductivity and provide a large superficial area for subsequent attachment of peptide with cysteine residues. Acidic amino acids residues of the peptide contribute to large electron transfer resistance, which is recorded by electrochemical impedance spectroscopy. Nevertheless, in the presence of Zn 2 + , the recognition sequence of the peptide (CCPGC) binds to Zn 2 + with a high affinity and is therefore not able to be modified on the electrode. By analyzing the decrease in electron transfer resistance, Zn 2 + level could be determined. The sensitivity of the proposed method is comparable to atomic absorption spectrometry and higher than most fluorescent, colorimetric and electrochemical sensors for Zn 2 + assay. Moreover, negligible interference is observed when detecting other ions. Therefore, the developed method has great potential environmental monitoring and clinical applications. [ABSTRACT FROM AUTHOR]

The objective of this research was to evaluate interactions of hydrogen and hydroxide ions with bilayer membranes formed from phosphatidylcholine and lysophosphatidylcholine. Theoretical deliberations were successfully verified by experimental research studies that were conducted using electrochemical impedance spectroscopy and chronopotentiometry methods. Electrical capacitance and electrical resistance measurements were made on the membranes in various pH electrolyte solutions. The theoretical calculations were based on previously derived two theoretical models. In both models the contributions of the individual lipid molecule forms to the membrane electrical parameters were assumed to be additive. [ABSTRACT FROM AUTHOR]

Nickel oxide (NiO) has been considered widely as an electrochemical capacitor or supercapacitor electrode material. NiO thin films are successfully deposited at various substrate temperatures. Influence of substrate temperature on various physical and electrochemical properties has been studied. X-ray diffraction analysis confirms cubic phase of polycrystalline nickel oxide. SEM images show porous surface having inhomogeneous randomly shaped heaps. Optical band gap energy is found to be in the range of 3.04–3.28 eV. Electrical resistivity confirms the semiconducting behavior of NiO with room temperature activation energies 0.30–0.38 eV. Electrochemical characterization is carried out by testing the NiO electrodes for cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. Specific capacitance of 405 Fg − 1 at the scan rate of 5 mV s − 1 is observed. Galvanostatic charge-discharge study confirmed the pseudocapacitive nature. Furthermore, the specific capacitance of the NiO can still keep a good retention of 92.10% after 1000 cycles at 1 Ag − 1 , demonstrating the outstanding long-term electrochemical stability. This work offers useful reference for supercapacitor applications in the future. [ABSTRACT FROM AUTHOR]