Electrochem, Volume 5, Issue 2 (June 2024) – 8 articles

The influence of the component composition of coal batches and the final temperature of the coking process on the resistivity of coke was studied. Taking into account that the resistivity and reactivity are influenced by some common factors, such as the temperature level and coke readiness, which indicates the orderliness of its structure, the relationship between these indicators was established. The electrical resistivity can be considered a cumulative characteristic of coke properties, as evidenced by the mathematical dependencies of the change electrical resistance on the ash content, sulfur content, volatile yield, and petrographic composition. Analysis of the dependencies and their statistical evaluation indicate that the studied relationships are characterized by high values of correlation (0.6–0.84). The proposed regression equations can be recommended for optimizing the component composition and quality of production batches, given their significant impact on the resistivity of coke. This is especially relevant when coke is used in electrothermal processes, since the productivity and the electrical and thermal efficiency of the furnace depends on the resistivity of the coke in electrochemical processes in which carbon materials are used as anodes and lining elements and in the production of capacitor technology. As the resistivity test requires much less time to perform than the reactivity test, it can be considered as an alternative approach to the reactivity testing currently performed for quality control purposes. Full article

Electrochemical biosensors are valued for their sensitivity and selectivity in detecting biological molecules. Having the advantage of generating signals that can be directly or indirectly proportional to the concentration of the target analyte, these biosensors can achieve specificity by utilizing a specific biorecognition surface designed to recognize the target molecule. Electrochemical biosensors have garnered substantial attention, as they can be used to fabricate compact, cost-effective devices, making them promising candidates for point-of-care testing (POCT) devices. This study introduces a label-free electrochemical biosensor employing a gold screen-printed electrode (SPE) to detect lysophosphatidic acid (LPA), a potential early ovarian cancer biomarker. We employed the gelsolin–actin system, previously introduced by our group, in combination with fluorescence spectrometry, as a biorecognition element to detect LPA. By immobilizing a gelsolin–actin complex on an SPE, we were able to quantify changes in current intensity using cyclic voltammetry and differential pulse voltammetry, which was directly proportional to the LPA concentration in the solution. Our results demonstrate the high sensitivity of the developed biosensor for detecting LPA in goat serum, with a limit of detection (LOD) and a limit of quantification (LOQ) of 0.9 µM and 2.76 µM, respectively, highlighting its potential as a promising tool for early-stage diagnosis of ovarian cancer. Full article

In the present study, LiFePO₄/CNF self-standing cathodes for LIBs are synthesized by electrospinning. A lower active material amount (12.3 and 34.5 wt%) is used, compared to the conventional tape-casted cathodes (70–85 wt%). The characterization techniques (XRPD, SEM, TEM, EDS, Raman spectroscopy, and thermogravimetry) confirm that the olivine-type structure of LiFePO₄ is maintained in the binder-free electrodes, and the active material is homogeneously dispersed into and within the carbon nanofibers. The electrochemical investigation demonstrates that higher Li⁺ diffusion coefficients (1.36 × 10⁻¹¹ cm²/s) and improved reversibility are reached for free-standing electrodes, compared to the LiFePO₄ tape-casted cathode (80 wt% of active material) appositely prepared for comparison. The 34.5 wt% LiFePO₄ self-standing cathode displays a lower capacity fading, good reversibility and stability, enhanced capacity values at C-rates higher than 5C, and a good lifespan when cycled 1000 cycles at 1C and further cycled up to 20C, compared to the tape-casted counterpart. Notably, the improved electrochemical performances are obtained by only the 34.5 wt% of active material. The results evidence the relevant role of the CNF matrix suitable to host LiFePO₄, to promote electrolyte permeation and contact with the active material, and to increase the electronic conductivity. Full article

This study reports on the use of supercritical CO₂ (scCO₂) for the metallization of ultrahigh-molecular-weight polyethylene (UHMW-PE) filaments, which are used as functional components in weavable devices. UHMW-PE is well known for its chemical and impact resistance, making it suitable for use in bulletproof clothing and shields. However, its chemical resistance poses a challenge for metallization. By utilizing scCO₂ as the solvent in the catalyzation process, a uniform and defect-free layer of Ni-P is successfully deposited on the UHMW-PE filaments. The deposition rate of Ni-P is enhanced at higher temperatures during the scCO₂ catalyzation. Importantly, the durability of the Ni-P-metalized UHMW-PE filaments is improved when the scCO₂ catalyzation is carried out at 120 °C, as evidenced by minimal changes in electrical resistivity after a rolling test. Full article

Food quality assessment is becoming a global priority due to population growth and the rise of ionic pollutants derived from anthropogenic sources. However, the current methods used to quantify toxic ions are expensive and their operation is complex. Consequently, there is a need for affordable and accessible methods for the accurate determination of ion concentrations in food. Electrochemical sensors based on potentiometry represent a promising approach in this field, with the potential to overcome limitations of the currently available systems. This review summarizes the current advances in the electrochemical quantification of heavy metals and toxic anions in the food industry using potentiometric sensors. The healthcare impact of common heavy metal contaminants (Cd²⁺, Hg²⁺, Pb²⁺, As³⁺) and anions (ClO₄⁻, F⁻, HPO₄⁻, SO₄²⁻, NO₃⁻, NO₂⁻) is discussed, alongside current regulations, and gold standard methods for analysis. Sensor performances are compared to current benchmarks in terms of selectivity and the limit of detection. Given the complexity of food samples, the percentage recovery values (%) and the methodologies employed for ion extraction are also described. Finally, a summary of the challenges and future directions of the field is provided. An overview of technologies that can overcome the limitations of current electrochemical sensors is shown, including new extraction methods for ions in food. Full article

The ability of a diagnosis tool to observe an abnormal state of a system remains a major issue for health monitoring. For that purpose, several diagnosis tools have been proposed in the literature. Most of them are developed for specific system characterization, and the genericity of the approaches is not considered. Indeed, most approaches proposed in the literature are based on an expert offline consideration that makes it hard to apply the strategy to other systems. It is therefore important to develop a diagnostic tool that takes as little as possible expert knowledge to reduce the dependency between the tool and the system. This paper, therefore, focuses on the application of a generic diagnosis tool on an open cathode fuel cell. The goal is to feed the diagnosis algorithm with a voltage measurement and let it proceed to a self-clustering of the signal components. Each cluster’s interpretation remains to be established by the expert point of view that is then involved downstream of the diagnosis tool. Full article

Electrochemistry is a hotspot in today’s research arena. Many different domains have been extended for their role towards the Internet of Things, digital health, personalized nutrition, and/or wellness using electrochemistry. These advances have led to a substantial increase in the power and popularity of electroanalysis and its expansion into new phases and environments. The recent COVID-19 pandemic, which turned our lives upside down, has helped us to understand the need for miniaturized electrochemical diagnostic platforms. It also accelerated the role of mobile and wearable, implantable sensors as telehealth systems. The major principle behind these platforms is the role of electrochemical immunoassays, which help in overshadowing the classical gold standard methods (reverse transcriptase polymerase chain reaction) in terms of accuracy, time, manpower, and, most importantly, economics. Many research groups have endeavoured to use electrochemical and bio-electrochemical tools to overcome the limitations of classical assays (in terms of accuracy, accessibility, portability, and response time). This review mainly focuses on the electrochemical technologies used for immunosensing platforms, their fabrication requirements, mechanistic objectives, electrochemical techniques involved, and their subsequent output signal amplifications using a tagged and non-tagged system. The combination of various techniques (optical spectroscopy, Raman scattering, column chromatography, HPLC, and X-ray diffraction) has enabled the construction of high-performance electrodes. Later in the review, these combinations and their utilization will be explained in terms of their mechanistic platform along with chemical bonding and their role in signal output in the later part of article. Furthermore, the market study in terms of real prototypes will be elaborately discussed. Full article

A silicon nanoparticle–graphite nanosheet composite was prepared via a facile ball milling process for use as the anode for high-rate lithium-ion batteries. The size effect of Si nanoparticles on the structure and on the lithium-ion battery performance of the composite is evaluated. SEM and TEM analyses show a structural alteration of the composites from Si nanoparticle-surrounded graphite nanosheets to Si nanoparticle-embedded graphite nanosheets by decreasing the size of Si nanoparticles from 250 nm to 40 nm. The composites with finer Si nanoparticles provide an effective nanostructure containing encapsulated Si and free space. This structure facilitates the indirect exposure of Si to electrolyte and Si expansion during cycling, which leads to a stable solid–electrolyte interphase and elevated conductivity. An enhanced rate capability was obtained for the 40 nm Si nanoparticle–graphite nanosheet composite, delivering a specific capacity of 276 mAh g⁻¹ at a current density of 1 C after 1000 cycles and a rate capacity of 205 mAh g⁻¹ at 8 C. Full article