Electrochem, Volume 3, Issue 4 (December 2022) – 17 articles

Hydrogen production using an Anion exchange membrane (AEM) electrolyzer allows the use of non-platinum group metal catalysts for oxygen evolution reaction (OER). Nickel and Cobalt-based oxides are active in an alkaline environment for OER and are relatively inexpensive compared to IrO₂ catalysts used in Polymer electrolyte membrane (PEM) electrolysis. Mixed metal oxide catalysts NiFeO_x and NiFeCoO_x catalysts were synthesized by the coprecipitation method using NaOH. X-ray diffraction results showed mainly NiO diffraction peaks for the NiFeO_x catalyst due to the low concentration of Fe, for the NiFeCoO_x catalyst, NiCo₂O₄ diffraction peaks were observed. NiFeCoO_x catalysts showed a higher Anion exchange membrane water electrolysis (AEMWE) performance compared to NiFeO_x and commercial NiO, the highest current density at 2 V was 802 mA cm⁻² at 70 °C using 1 M KOH as an electrolyte. The effect of electrolyte concentration was studied by using 0.01 M, 0.1 M and 1 M KOH concentrations in an electrolysis operation. Electrochemical Impedance spectroscopy was performed along with the equivalent circuit fitting to calculate ohmic and activation resistances, the results showed a decrease in ohmic and activation resistances with the increase in electrolyte concentration. Commercially available AEM (Fumasep FAA-3-50 and Sustainion dioxide membrane X-37-50 grade T) were tested at similar conditions and their performance was compared. EIS results showed that X-37-50 offered lower ohmic resistance than the FAA-3-50 membrane. Full article

The residual ions of the acid cleaning processes induce the further corrosion of the metals, and this could be minimized using green inhibitors. Alkaloids extracted from plant parts could be cost effective and efficient inhibitors. In this work, alkaloids from Solanum xanthocarpum stem were successfully extracted, and they were characterized by qualitative chemical tests and spectroscopic measurements. As-extracted alkaloids were employed as green corrosion inhibitors for mild steel. The effectiveness of the inhibitor was determined by the weight loss and electrochemical measurement methods. From the weight loss measurement, the maximum inhibition efficiency of 93.14% was achieved. The temperature effect study revealed that the inhibitor can work up to a temperature of 58 °C. This could be one of the highest working temperatures among the reported green inhibitors. The electrochemical measurement reveals that the alkaloids could inhibit effectively up to 98.14% of the corrosion and serve as a mixed-type green inhibitor. A study on the kinetic parameters reflects that the inhibitor forms a potential barrier for the protection of a mild steel surface against corrosion. The values obtained from the thermodynamic parameters study reflect that the process is a spontaneous endothermic process. Based on the findings, it is revealed that the alkaloids extracted from S. xanthocarpum can serve as an excellent, eco-friendly and a promising green inhibitor against mild steel corrosion. Full article

The present work consisted of the development of an electrode based on carbon paste modified with magnetic molecularly imprinted polymer (CPE-MagMIP) for 17-β-estradiol (E2) detection. The incorporation of magnetic material (MagMIP) improved sensor performance, an increase of over 317%. The proposed method resulted in a linear response range from 0.5 to 14.0 μM, and the detection limit (LOD) and quantification limit (LOQ) were equal to 0.13 and 0.44 μM, respectively. Under optimized conditions, the developed sensor obtained satisfactory parameters in E2 determination in water samples, demonstrating selectivity, accuracy, and precision, making it a promising method for monitoring E2 in environmental samples. Full article

The electric double layer (EDL) is the most important region for electrochemical and heterogeneous catalysis. Because of it, its modeling and investigation are something that can be found in the literature for a long time. However, nowadays, it is still a hot topic of investigation, mainly because of the improvement in simulation and experimental techniques. The present review aims to present the classical models for the EDL, as well as presenting how this region affects electrochemical data in everyday experimentation, how to obtain and interpret information about EDL, and, finally, how to obtain some molecular point of view insights on it. Full article

Lithium-ion batteries (LiBs) are used as the main power source in electric vehicles (EVs). Despite their high energy density and commercial availability, LiBs chronically suffer from non-uniform cell ageing, leading to early capacity fade in the battery packs. In this paper, a non-invasive, online characterisation method based on deep learning models is proposed for cell-level SoH estimation. For an accurate measurement of the state of health (SoH), we need to characterize electrochemical capacity fade scenarios carefully. Then, with the help of real-time monitoring, the control systems can reduce the LiB’s degradation. The proposed method, which is based on convolutional neural networks (CNN), characterises the changes in current density distributions originating from the positive electrodes in different SoH states. For training and classification by the deep learning model, current density images (CDIs) were experimentally acquired in different ageing conditions. The results confirm the efficiency of the proposed approach in online SoH estimation and the prediction of the capacity fade scenarios. Full article

Due to its prevalence in nature and its particular properties, silicon is one of the most popular materials in various industries. Currently, metallurgical silicon is obtained by carbothermal reduction of quartz, which is then subjected to hydrochlorination and multiple chlorination in order to obtain solar silicon. This mini-review provides a brief analysis of alternative methods for obtaining silicon by electrolysis of molten salts. The review covers factors determining the choice of composition of molten salts, typical silicon precipitates obtained by electrolysis of molten salts, assessment of the possibility of using electrolytic silicon in microelectronics, representative test results for the use of electrolytic silicon in the composition of lithium-ion current sources, and representative test results for the use of electrolytic silicon for solar energy conversion. This paper concludes by noting the tasks that need to be solved for the practical implementation of methods for the electrolytic production of silicon, for the development of new devices and materials for energy distribution and microelectronic application. Full article

In this study, an electrochemical sensor for the monitoring of Hg (II) at trace levels by using differential pulse anodic stripping voltammetry has been reported. Basically the electrochemical sensor is a Phanerochaete chrysosporium-based carbon paste electrode. Here, Phanerochaete chrysosporium has played a new vital role in electrochemical detection of heavy metal apart from its known contribution in their removal. Optimal voltammetric response was observed at −0.7 V deposition potential l, 5% biomass concentration ratio (w/w), and neutral pH conditions with 12 min as the accumulation time. Selectivity was evaluated in the presence of different interfering cations. Linear range was observed for 5–50 µgL⁻¹ of metal concentration with a detection limit of 4.4 µgL⁻¹. The equivalence of new and reference analytical methods was statistically assessed in mercury samples collected from chlor-alkali industrial effluent by correlation of results (Pearson’s product-moment correlation), weighted Deming regression analysis, paired comparison test, relative standard deviation (RSD), median relative error (MRE), root mean square error (RMSE), and predicted residual sum of square (PRESS). This work presented a simple, efficient, and promising analytical tool in trace level detection of Hg (II), as compared to previously reported carbon paste electrodes based on biological material. Full article

Platinum dissolution in PEM fuel cells is an increasingly important indicator for the state-of-health and lifetime prediction of fuel cells in real applications. For this reason, portable online analysis tools are needed that can detect and quantify platinum with high sensitivity, selectivity, and accuracy in the product water of fuel cells. We validated the hanging mercury drop electrode (HMDE) and non-toxic bismuth film electrodes for the voltammetric determination of platinum for this purpose. Bismuth films were prepared by reductive deposition on both a glassy carbon solid state electrode and on a screen-printed electrode (film on-chip electrode). Both bismuth film electrodes could be successfully validated for the determination of platinum by adsorptive stripping voltammetry. An LOD of 7.9 μg/L and an LOQ of 29.1 μg/L were determined for the bismuth film solid state electrode, values of 22.5 μg/L for the LOD and of 79.0 μg/L for the LOQ were obtained for the bismuth film on-chip electrode. These numbers are still much higher than the results measured with the HMDE (LOD: 0.76 ng/L; LOQ: 2.8 ng/L) and are not sufficient to detect platinum in the product water of a fuel cell run in different load tests. The amount of dissolved platinum produced by a 100 W fuel cell stack upon dynamic and continuous high load cycling, respectively, was in the range of 2.9–4.1 ng/L, which could only be detected by the HMDE. Full article

Using natural plant extracts on metallic substances is the most frequently studied green corrosion inhibition approach in corrosion science. In this work, Coriaria nepalensis Stem Alkaloid (CNSA) has been successfully extracted and characterized by qualitative chemical (Mayer’s and Dragendroff’s) test and spectroscopic (UV and FTIR) measurement. CNSA has been employed as a green inhibitor for Mild Steel (MS) corrosion subjected to 1 M H₂SO₄ solution. The corrosion inhibition efficacy has been assessed by weight loss and polarization measurement methods. The effect of inhibitor concentration, immersion period, and temperature on the inhibition efficiency for the MS immersed in both acid and inhibitor solutions of different concentrations have been investigated. The maximum inhibition effect observed for CNSA is 96.4% for MS immersed in 1000 ppm inhibitor solution for 6 h at 18 °C by the weight loss measurement method. Similarly, the polarization measurement method observed a 97.03% inhibition efficiency for MS immersed for 3 h. The adsorption of inhibitor molecules on the MS surface aligns with the Langmuir model. The free energy of adsorption obtained is −28.75 kJ/mol indicating physical adsorption dominance over chemical adsorption. These findings suggested that CNSA has greater potential as an efficient green inhibitor. Full article

The theoretical model for a packed porous catalytic particle of the slab, cylindrical, and spherical geometries shape in fixed-bed electrochemical reactors is discussed. These particles have internal mass concentration and temperature gradients in endothermic or exothermic reactions. The model is based on a nonlinear reaction–diffusion equation containing a nonlinear term with an exponential relationship between intrinsic reaction rate and temperature. The porous catalyst particle’s concentration is obtained by solving the nonlinear equation using Akbari-Ganji’s method. A simple and closed-form analytical expression of the effectiveness factor for slab, cylindrical, and spherical geometries was also reported for all values of Thiele modulus, activation energy, and heat reaction. The accordance with results of a reliable numerical method shows the good accuracy that their approximate solution yields. Full article

Electrochemical energy storage technology has the characteristics of convenient use, fast response, and flexible configuration. At present, the energy storage technology used in smart electric vehicles is mainly electrochemical energy storage technology. In particular, the promotion of electrochemical energy storage technology in the field of smart electric vehicles is an effective way to achieve the goal of carbon neutrality. One of the most critical issues limiting the development and popularity of intelligent electric vehicles is the performance and range of power batteries; vehicle path planning is very important to the performance of power batteries and the driving range. Improved path planning algorithms can obviously shorten the path length and reduce the time of searching and planning a path under the condition of the same starting point and end point, that is, to increase the range of the power battery. On the premise of the comprehensive analysis of the intelligent electric vehicle’s grasp of environmental information, trajectory planning methods are divided into local trajectory planning and global trajectory planning methods. The main content of the trajectory planning method is given, the key technologies involved in the research are discussed, and its advantages and disadvantages are analyzed. Finally, the main development trends of intelligent electric vehicle trajectory planning technology in the future are proposed. Full article

In situ corrosion inhibition in acid cleaning processes by using green inhibitors is at the forefront of corrosion chemistry. Plant extracts, especially alkaloids, are known to be good corrosion inhibitors against mild steel corrosion. In this research, alkaloids extracted from Acacia catechu have been used as green corrosion inhibitors for mild steel corrosion in a 1 M H₂SO₄ solution. Qualitative chemical tests and FTIR measurements have been performed to confirm the alkaloids in the extract. The inhibition efficiency of the extract has been studied by using weight-loss and potentiodynamic polarization methods. A weight-loss measurement has been adopted for the study of inhibitor’s concentration effect, with a variation employed to measure the inhibition efficiency for time and temperature. The weight-loss measurement revealed a maximum efficiency of 93.96% after 3 h at 28 °C for a 1000 ppm alkaloid solution. The 1000 ppm inhibitor is effective up to a temperature of 48 °C, with 84.39% efficiency. The electrochemical measurement results revealed that the alkaloids act as a mixed type of inhibitor. Inhibition efficiencies of 98.91% and 98.54% in the 1000 ppm inhibitor concentration solution for the as-immersed and immersed conditions, respectively, have been achieved. The adsorption isotherm has indicated the physical adsorption of alkaloids. Further, the spontaneous and endothermic adsorption processes have been indicated by the thermodynamic parameters. The results show that alkaloids extracted from the bark of Acacia catechu can be a promising green inhibitors for mild steel corrosion. Full article

Digital medicine based on the integration of all medical data from a particular patient has become a reality today, thanks to information technology. Traditional medical examinations can be supplemented by assessment results of the oxidative-anti-oxidative (OAO) status of the body. Electrochemical sensors are able to not only determine the integral indicators of the OAO system of the body but also to depict details of the processes occurring in the system. The main obstacle to the widespread use of electrochemical sensors in medical diagnostics is the extremely small amount of received information in comparison to the tens of thousands of known human diseases. The problem can be eliminated only by rethinking the purpose of electrochemical measurement within the framework of thermodynamics of information processes and information theory. In the information paradigm of electrochemical analysis of biological fluids, a sample is considered an electrochemical message created by a sensor. The purpose of electrochemical measurement is to obtain information in a volume sufficient to identify the sample composition within the range of possible concentrations of its components. The fundamentals of the thermodynamics of information processes are considered and conclusions that are of practical importance for the development of electrochemical sensors and analyzers are derived. It is shown that the potentiostatic control of the sensor is physically impacted by the electromechanical instability of the electrical double layer, which is the main source of sensor signal noise. Estimates of a minimum amount of analytical signal information required for the identification of a sample of known composition, such as a biological fluid, are provided. Examples of highly informative analytical signals for flowing and stationary samples are presented. Problems related to the visualization of such signals are noted. Full article

Reliability of proton exchange membrane fuel cells (PEMFCs) is a major issue for large industrialization and commercialization. Indeed, performance can be degraded due to abnormal operating conditions, namely, faults, which lead either to a transient decay of the fuel cell performance or to permanent damage that cannot be recovered. The literature shows that long-time exposure to faults leads to fuel cell degradation. Therefore, it is necessary to use tools that can not only diagnose these faulty conditions, but also modify the fuel cell operations to recover a healthy operating point. For that purpose, one approach is the Active Fault Tolerant Control (AFTC) strategy which is composed of three functions. First, a diagnosis part allows fault detection and identification. Then a decision part, which is an algorithm aiming at finding a new operating point that mitigates the occurring fault. Finally, a control part applies the mitigation strategy established by the decision algorithm. The present work focuses on the decision part. and aims to bring a new contribution to PEMFCs reliability improvement and address water management issues, namely, the cell flooding and membrane drying out with the developed AFTC tool. The strategy is tested and validated on a single PEMFC cell and results are presented, analyzed, and discussed. Full article

Naturally occurring phytonutrients/phyto-components are likely to have therapeutic values. These phyto-derived naturally occurring components, such as polyphenols, phenolics, flavonoids and phenolic acids have a hydrocarbon background with a polyphenolic ring, an ester bond with a polyphenolic ring, etc. Their structures play a critical role in determining the chemical and physical attributes that define their activity/functions and roles. Owing to their chemical structure, most of them are electroactive. Thus, these phytochemicals can be used in the preparation of electrochemical sensors. Gaining an understanding of functional genotypical units using electrochemistry is a unique study. The feasibility of incorporating an array of biosensors into a fully-automated micro-electrochemical system is further explored. This review is intended to provide in-depth knowledge of biosensors’ applications based on/for Plantae kingdom and varieties. The discussion focuses primarily on the fields associated with the fully-automated micro-electrochemical system and appropriate methods for its advancement. The intended approach is to provide a selective outlook including the setbacks/shortcomings and usefulness of opting for the concerned technique. Full article

Hydrogen is considered to be the fuel of the future and with the advancement of fuel cell technology, there is a renewed interest in hydrogen production by the electrolysis of water. Among low-temperature water electrolysis options, polymer electrolyte membrane (PEM) electrolyzer is the preferred choice due to its compact size, intermittent use, and connectivity with renewable energy. In addition, it is possible to generate compressed hydrogen directly in the PEM electrolyzer, thereby reducing the additional pressurization cost for hydrogen storage. The development of electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is a major focus of electrolysis research. Other components, such as PEMs, gas diffusion layers (GDL), and bipolar plates (BPs) have also received significant attention to enhance the overall efficiency of PEM electrolyzers. Improvements in each component or process of the PEM electrolyzer have a significant impact on increasing the energy efficiency of the electrolyzer. This work discusses various synthesis techniques to improve the dispersion of OER electrocatalyst and reducing catalyst loading for the PEM electrolyzer. Various techniques are discussed for the development of electrocatalysts, including nanostructured, core shell, and electrodeposition to deposit catalysts on GDL. The design and methodology of new and improved GDL are discussed along with the fabrication of gas diffusion electrodes and passivation techniques to reduce the oxidation of GDL. The passivation technique of BPs using Au and Pt is summarized for its effect on electrolysis efficiency. Finally, the optimization of various operating conditions for PEM electrolyzer are reviewed to improve the efficiency of the electrolyzer. Full article

Lab-on-a-chip has recently become an alternative for in situ monitoring for its portability and simple integration with an electrochemical immunoassay. Here, we present an electrochemical cell-on-a-chip configured in a three-electrode system to detect benzo(a)pyrene (BaP) in water. 11-Mercaptoundecanoic acid (MUA), a self-assembled monolayer (SAM), was used to modify a gold chip surface to reduce the randomness of antibody binding. A carboxylic acid group was activated with -ethyl-3-(3-dimethylaminopropyl) (EDC) in combination with N-hyrodsuccinimide (NHS) before antibody immobilisation. The mechanism of the electrochemical reactions on a gold surface and SAM formation were investigated by cyclic voltammetry and contact angle measurements. The data revealed a lower contact angle in the modified chip and a scan rate of 50 mV/s. Through the addition of modification layers and thiol end groups to the SAM, our design allowed the chip surface to became more insulated. All were tested by amperometric detection using the developed Q-sense system. This novel technique detected multiple samples, and completed the analysis reasonably quickly. While the integrated system proved successful in a lab setting, the aim of the research is to use this system for in situ analysis, which can be brought into a water environment to carry out tests with existing processes. In this way, any issues that may arise from an environmental setting can be rectified in an efficient manner. Full article