Electrochemical Impedance Spectroscopy Research Articles

Synthesis of a new quaternary ammonium salt for efficient inhibition of mild steel corrosion in 15 % HCl: Experimental and theoretical studies

The corrosion phenomenon and its economic impacts can hardly be ignored in any application. This study synthesized a quaternary ammonium salt (3) containing hydrophobic dodecyl and electron-rich diallylbenzyl amine moieties to be used in 15 % HCl as a corrosion inhibitor of mild steel. Several techniques, such as 1H and 13C NMR, IR, TGA, and elemental analysis, have been used to characterize inhibitor 3. Popular corrosion measurement techniques, namely weight loss, potentiodynamic polarization techniques, and electrochemical impedance spectroscopy, have been used to determine the efficiency of inhibitor 3. At 303 K and a moderately low concentration of 50 ppm, the quaternary ammonium salt-based inhibitor demonstrated a maximum efficiency of ≈95.0 %. At elevated temperatures of 313, 323, and 333 K, the inhibition efficacy values were recorded as 91.3, 82.8, and 75.0 %, respectively. Adsorption isotherm study revealed that the adsorption of inhibitor 3 followed Langmuir adsorption isotherm. The value of ΔGads° was found to be – 40.19 kJ mol−1, indicating that inhibitor 3 became adsorbed via a mixed physi-chemisorption mechanism. A very high adsorption constant (Kads) of 1.53 × 105 L mol−1 suggested strong adsorption of inhibitor 3. The difference in activation energy (Ea) value of 42.4 kJ mol−1 between the control and the inhibited solution indicated an efficient adsorption of inhibitor 3. The ability of inhibitor 3 to retard both anodic and cathodic half-cell reactions was proved via open circuit potential and Tafel curves studies. Detailed discussions on the change in corrosion current densities (icorr), polarization (Rp) and charge transfer (Rct) resistances have been offered to discuss the inhibition efficiency. Water contact angle measurement showed a drastic increase in mild steel surface hydrophobicity following inhibitor 3 adsorption. SEM-EDX and XPS studies confirmed the definitive presence of inhibitor 3 on the mild steel surface. Density functional theory (DFT) studies revealed the frontier molecular orbitals with which the metal surface interacts. A detailed corrosion inhibition mechanism has been offered in the context of adsorption isotherm and DFT studies.

Defect engineering on metal-organic frameworks for enhanced photocatalytic reduction of Cr(VI)

Cr(VI) stands as a profoundly toxic chemical and photocatalysis technology has shown promising potential in photocatalytic reduction of Cr(VI) to Cr(III), where the reduced Cr(III) is less toxic and can be further precipitated in a wide pH range. Metal-organic frameworks (MOFs), as emerging class of porous coordination polymers, is expected to be ideal platform for photocatalysis. In this study, defect engineering on MOFs was applied to promote photoreduction of Cr(VI). The obtained oxygen vacancy-containing MIL-125-NH2 samples showed modified electron structure, adjusted surface and porous properties, and enriched active sites. Among these oxygen vacancy-containing MIL-125-NH2 samples, the 300-M (MIL-125-NH2 heated at 300 °C for 2 h under N2 atmosphere) displayed the most remarkable performance in terms of photocatalytic Cr(VI) reduction. The pronounced efficacy of 300-M is evident from the achieved removal rate of Cr (VI), reaching an impressive 98 % in just 20 mins (19.6 mgCr(VI) g−1cata min−1), in stark contrast to MIL-125-NH2, which exhibited a modest removal rate of 53 %. Remarkably, the k-value for 300-M is 5.1 times that of MIL-125-NH2, further underscoring the superior efficiency of 300-M. The photoreduction mechanism of 300-M was further substantiated through a battery of advanced characterization techniques including transient photocurrent, electrochemical impedance spectroscopy, fluorescence spectroscopy, the Mott-Schottky analysis, and electron spin resonance. Those results disclosed that oxygen vacancies and mesopores introduced via controlled heat treatment play a pivotal role in facilitating the photoreduction of Cr(VI) within the MIL-125-NH2 structure. More advanced characterizations for the structures of photocatalysts and the photocatalytic mechanisms including charge transfer path need further studied. The systematic exploration of temperature-dependent effects on material properties opens avenues for future research in designing efficient and versatile MOF-based photocatalysts for environmental remediation applications.

Understanding the heat generation mechanisms and the interplay between joule heat and entropy effects as a function of state of charge in lithium-ion batteries

The thermal performance of lithium-ion battery cells is critical for ensuring their safe and reliable operation across various applications. In this study, we employed an isothermal calorimetry method to investigate the heat generation of commercial 18650 lithium-ion battery fresh cells during charge and discharge at different current rates, ranging from 0.05C to 0.5C, and across various temperatures: 20 °C, 30 °C, 40 °C, and 50 °C. Our findings revealed a direct correlation between heat generation and current rates, indicating that higher current rates lead to increased heat generation within the cells. Conversely, we observed that heat generation remained relatively stable as the temperature rose, suggesting that temperature changes within this range may not significantly impact the heat generation of fresh cells during typical operations. Furthermore, our study explored irreversible heat generation, which depends on the applied current and overpotential, using the galvanostatic intermittent titration technique at 0.05C–0.5C and 30 °C. Additionally, electrochemical impedance spectroscopy was performed on the same cells during charge and discharge at 20 °C, 30 °C, and 40 °C to analyze cell impedance. Our results indicated a consistent dependence of impedance on the state of charge and depth of discharge, with a significant increase in impedance observed at the end of the discharge process.

Exploring novel nanostructural architecture of doubly doped ceria (Ce0.85Sr0.075Sm0.075O2-δ) and barium cerate (BaCeO3) as electrolytes for low-temperature solid oxide fuel cells

This study presents the development of a composite electrolyte for use in low-temperature (300–500 °C) Solid oxide Fuel Cells, focusing on a novel nanostructural design. The electrolyte comprises co-doped ceria (Ce0.85Sr0.075Sm0.075O2-δ, DCO) and barium cerate (BaCeO3, BCO), integrated into a unique nanostructural architecture. Initially, the constituent phases of the composite DCO and BCO are synthesized using a soft-chemical route separately, followed by their integration through liquid mixing technique in various compositions (90:10, 80:20, 70:30, 60:40, 50:50) of DCO:BCO in weight ratio. The composite structure is confirmed by X-ray diffraction, and refined the structural data by Rietveld refinement indicating a structural agreement with cubic and fluorite phases of DCO and BCO, respectively. Scanning Electron microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX) reveal a uniform distribution of two phases with fine size distribution below 50 nm. Transmission Electron microscopy (TEM) images illustrate the core-shell-like integration of the two phases. High-resolution TEM images indicate that the core consists of the DCO phase, while the shell is composed of the BCO phase. The microstructure of sintered pellets exhibits gas-tight densification, with grains dominated by the DCO phase and BCO phase dispersed along grain boundaries. The ionic conductivity of composite systems is extracted from Electrochemical impedance spectroscopy (EIS) studies, showing that DCO-BCO-40 exhibits the highest conductivity 1.132 × 10−3 Scm−1 @400 °C, which is higher than pristine DCO (0.34 × 10−4 Scm−1 @400 °C). Single cells fabricated using DCO-BCO-40 electrolytes deliver a power output of 280 mW cm−2 whereas pristine DCO showed 279 mW @500 °C. This study exhibits the potential of the core-shell-like nanostructural architecture of electrolytes in advancing Low-temperature solid oxide Fuel cell (LT-SOFC) technology and facilitating the transition toward sustainable energy systems.

Is the oxygen plasma cleaning technique indicated for any electrochemical purpose?: The case of FTO electrodes

Fluorine-doped tin oxide (FTO) is among the most used transparent conductive oxides (TCOs) in phototovoltaic devices such as photoelectrochemical and solar cells. Preparation of films on these TCOs can be achieved by several deposition techniques including electrodeposition. Among the several cleaning and activation procedures before a thin film deposition there is the oxygen plasma treatment, which has been successfully applied on several kind of substrate materials. Surprisingly, the use of this step on TCOs previously to the electrodeposition of a film is not a usual practice. Here we present a detailed study on the consequences of oxygen plasma process over FTO electrodes that are subsequently employed in several electrochemical reactions of practical importance. Open circuit potential (OCP) measurements from oxygen plasma treated FTO have proven the resorption of ions and/or solvent molecules in aqueous electrolyte following a pseudo-second order kinetic. Electrochemical reactions were quite sensible to the oxygen plasma treatment, even under mild conditions. In all cases FTO become deactivated for such electrochemical processes independently of the plasma set up employed except for metal electrodeposition. Partial recovering of the electrochemical response of FTO in the ferri/ferro system after annealing at 450 °C explains why oxygen plasma process is worthy only for other deposition techniques such as spray pyrolysis where similar temperatures are employed. Electrochemical Impedance Spectroscopy (EIS) analysis revealed a decrease of the majority carrier density (ND). This is mainly attributed to the oxyanion implantation on oxygen vacancies sites during the plasma process thus explaining the loss of activation of FTO. Energy level diagrams reveal the decrease of degeneracy of FTO towards an n-type semiconducting SnO2 film which is also supported by ultraviolet photoelectron spectroscopy (UPS). A band gap energy dependence with the plasma conditions allowed to check the filling of oxygen vacancies on the FTO surface without discard the loss of fluorine. Anodic polarization in acid media proved the impossibility of oxygen vacancies restitution, being the dominating process the partial etching of FTO.

Selective laser melting of Ti6Al4V alloy: Effects of graphene-TiO2 nanotubes composites corrosion and biocompatibility

This study investigates the effects of graphene amount on TiO2 nanotubes (TNT) synthesized on Ti6Al4V alloy via selective laser melting (SLM) to optimize corrosion resistance and biocompatibility. XRD analysis indicated the presence of anatase and rutile phases in TNTs, and the peak shifts indicated that graphene was successfully incorporated into the TNT structure. SEM images revealed that increasing the amount of graphene resulted in smaller nanotube diameters, increased contact angles, and imparted hydrophobic properties. Corrosion tests including Tafel polarization and electrochemical impedance spectroscopy (EIS) showed that graphene, especially C4-TNTs, exhibited superior corrosion resistance with high Ecorr and Rt values. Biocompatibility tests with human dermal fibroblast cells (HDFa) demonstrated cell viability with the incorporation of graphene into TNTs. The findings suggest that the optimum amount of graphene can significantly improve the corrosion resistance and biocompatibility of TiO2 nanotubes on Ti6Al4V alloy, making them more suitable for biomedical implants.

Creative synthesis of pH-dependent nanoporous pectic acid grafted with acrylamide and acrylic acid copolymer as an ultrasensitive and selective riboflavin electrochemical sensor in real samples

In current research, an innovative pectic acid was grafted with poly (acrylamide-co-acrylic acid) [PA-g-poly (AAm-co-AA)] nanoporous membrane using a free radical-mediated grafting copolymerization process. The optimized parameters for the grafting copolymerization reaction such as initiator concentration, monomer concentrations, polymerization reaction time, and temperature were studied. Additionally, the solid content, graft percentage, and conversion were calculated. The unique polymeric membrane was characterized using Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetry (TG), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) supported by energy dispersive X-ray spectroscopy (EDX). The formulated novel PA-g-poly (AAm-co-AA) had a nanoporous structure with a diameter of 113 nm. pH-dependent swelling and biodegradation measurements were also studied. The electrochemical characterizations of PA-g-poly (AAm-co-AA) were conducted through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Furthermore, the screen-printed electrode (SPE) was modified with pure PA and the new generation of its grafted polymeric nanoparticles to detect and quantify the concentration of riboflavin (RF) in real samples using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The modified electrode showed two linear concentration ranges from 0.01 - 2 nM and 2 – 90 nM with low detection limits (LODs) of 0.004 and 0.97 nM, respectively, demonstrating high sensitivity. Besides, the fabricated sensor exhibited more selectivity, simplicity, great reproducibility, repeatability, and good stability. Finally, the PA-g-poly (AAm-co-AA)-modified SPE based sensor was effectively used in real sample analysis of egg yolk, milk, and vitamin B2 drugs with good recovery rates.

Site Disorder Drives Cyanide Dynamics and Fast Ion Transport in Li6PS5CN.

Halide argyrodite solid-state electrolytes of the general formula Li6PS5 X exhibit complex static and dynamic disorder that plays a crucial role in ion transport processes. Here, we unravel the rich interplay between site disorder and dynamics in the plastic crystal argyrodite Li6PS5CN and the impact on ion diffusion processes through a suite of experimental and computational methodologies, including temperature-dependent synchrotron powder X-ray diffraction, AC electrochemical impedance spectroscopy, 7Li solid-state NMR, and machine learning-assisted molecular dynamics simulations. Sulfide and (pseudo)halide site disorder between the two anion sublattices unilaterally improves long-range lithium diffusion irrespective of the (pseudo)halide identity, which demonstrates the importance of site disorder in dictating bulk ionic conductivity in the argyrodite family. Furthermore, we find that anion site disorder modulates the presence and time scales of cyanide rotational dynamics. Ordered configurations of anions enable fast, quasi-free rotations of cyanides that occur on time scales of 1011 Hz at T = 300 K. In contrast, we find that cyanide dynamics are slow or frozen in Li6PS5CN when site disorder between the cyanide and sulfide sublattices is present at T = 300 K. We rationalize the observed differences in cyanide dynamics in the context of elastic dipole interactions between neighboring cyanide anions and local strain induced by the configurations of site disorder that may impact the energetic landscape for cyanide rotational dynamics. Through this study, we find that anion disorder plays a decisive role in dictating the extent and time scales of both lithium ion and cyanide dynamics in Li6PS5CN.

Electrochemical impedance spectroscopy unmasks high-risk atherosclerotic features in human coronary artery disease.

Coronary plaque rupture remains the prominent mechanism of myocardial infarction. Accurate identification of rupture-prone plaque may improve clinical management. This study assessed the discriminatory performance of electrochemical impedance spectroscopy (EIS) in human cardiac explants to detect high-risk atherosclerotic features that portend rupture risk. In this single-center, prospective study, n = 26 cardiac explants were collected for EIS interrogation of the three major coronary arteries. Vessels in which advancement of the EIS catheter without iatrogenic plaque disruption was rendered impossible were not assessed. N = 61 vessels underwent EIS measurement and histological analyses. Plaques were dichotomized according to previously established high rupture-risk parameter thresholds. Diagnostic performance was determined via receiver operating characteristic areas-under-the-curve (AUC). Necrotic cores were identified in n = 19 vessels (median area 1.53 mm2) with a median fibrous cap thickness of 62 μm. Impedance was significantly greater in plaques with necrotic core area ≥1.75 mm2 versus <1.75 mm2 (19.8 ± 4.4 kΩ vs. 7.2 ± 1.0 kΩ, p = .019), fibrous cap thickness ≤65 μm versus >65 μm (19.1 ± 3.5 kΩ vs. 6.5 ± 0.9 kΩ, p = .004), and ≥20 macrophages per 0.3 mm-diameter high-power field (HPF) versus <20 macrophages per HPF (19.8 ± 4.1 kΩ vs. 10.2 ± 0.9 kΩ, p = .002). Impedance identified necrotic core area ≥1.75 mm2, fibrous cap thickness ≤65 μm, and ≥20 macrophages per HPF with AUCs of 0.889 (95% CI: 0.716-1.000) (p = .013), 0.852 (0.646-1.000) (p = .025), and 0.835 (0.577-1.000) (p = .028), respectively. Further, phase delay discriminated severe stenosis (≥70%) with an AUC of 0.767 (0.573-0.962) (p = .035). EIS discriminates high-risk atherosclerotic features that portend plaque rupture in human coronary artery disease and may serve as a complementary modality for angiography-guided atherosclerosis evaluation.

Optimization of the polyaniline solid contact in potentiometric sensors for detection of paralytic shellfish toxins in mussels

The present study optimized the properties of the electropolymerized polyaniline (PANI) solid inner contact for a potentiometric chemical sensor by varying the thickness of the polymer layer. A potentiometric sensor for detecting one of the paralytic shellfish toxins, decarbamoyl saxitoxin (dcSTX), in mussel extracts was selected as a case study. The plasticized PVC membrane composition, developed in previous work for the detection of this toxin, was used. The structure and electrical properties of PANI layers of different thicknesses were studied using scanning electron microscopy and electrochemical impedance spectroscopy. The effect of PANI solid contact thickness on the characteristics of the potentiometric sensor, including sensitivity, detection limit, and selectivity to dcSTX in buffer solutions and mussel extracts, was evaluated. The formation of a water layer at the inner solid contact and PVC membrane interface was investigated using electrochemical impedance spectroscopy and a water test. PANI layer thickness 1.1 µm was found to be optimal for solid inner contact for potentiometric sensor with PVC membrane providing highest sensitivity and selectivity.

Impact of biocatalytic behavior of Shewanella sp. through electron transfer processes on effective treatment of beer brewing wastewater in a microbial fuel cell and power generation

AbstractThis study examines the performance of a microbial fuel cell (MFC) utilizing Shewanella bacteria through electrochemical impedance spectroscopy (EIS). Exo‐electrogen bacteria are key agents in an MFC. Shewanella sp. as a common exo‐electrogen bacteria can transfer electrons from the cell surface through different electron transfer mechanisms. In this work, EIS was used to probe the effects of biofilms of Shewanella sp. and the solution of 10% V/V Shewanella on the MFC performance. This research investigates the effects of both microbial biofilms and Shewanella bacterial solutions on MFC efficacy. Findings revealed that biofilm formation on the anode surface significantly reduces anode charge transfer resistance, thereby enhancing power generation. Notably, a 10% Shewanella solution resulted in a 25% higher power density compared to the biofilm. Furthermore, the MFC demonstrated up to 80% chemical oxygen demand removal efficiency in treating brewery wastewater. The study underscores the viability of Shewanella bacterial solutions as an efficient alternative to biofilms, emphasizing their role in improving MFC performance and wastewater treatment efficiency.

Enhanced oxygen evolution and power density of Co/Zn@NC@MWCNTs for the application of zinc-air batteries

Rechargeable zinc-air batteries (ZABs) are viewed as a promising solution for electric vehicles due to their potential to provide a clean, cost-effective, and sustainable energy storage system for the next generation. Nevertheless, sluggish kinetics of the oxygen evolution reaction (OER), the oxygen reduction reaction (ORR) at the air electrode, and low power density are significant challenges that hinder the practical application of ZABs. The key to resolving the development of ZABs is developing an affordable, efficient, and stable catalyst with bifunctional catalytic. In this study, we present a series of bifunctional catalysts composed of Co/Zn nanoparticles uniformly embedded in nitrogen-doped carbon (NC) and multi-walled carbon nanotubes (MWCNTs) denoted as Co/Zn@NC@MWCNTs. The incorporation of MWCNTs using a facile and non-toxic method significantly decreased the overpotential of the OER from 570 to 430 mV at 10 mA cm−2 and the peak power density from 226 to 263 mW cm−2. Besides, the electrochemical surface area measurements and electrochemical impedance spectroscopy indicate that the three-dimensional (3D) network structure of MWCNTs facilitates mass transport for ORR and reduces electron transfer resistance during OER, leading to a small potential gap of 0.86 V between OER and ORR, high electron transfer number (3.92–3.98) of the ORR, and lowest Tafel slope (47.8 mV dec−1) of the OER in aqueous ZABs. In addition, in-situ Raman spectroscopy revealed a notable decrease in the ID/IG ratio for the optimally configured Co/Zn@NC@MWCNTs (75:25), indicating a reduction in defect density and improved structural ordering during the electrochemical process, which directly contributes to enhanced ORR activity. Hence, this study provides an excellent strategy for constructing a bifunctional catalyst material with a 3D MWCNTs conductive network for the development of advanced ZAB systems for sustainable energy applications.

The anticorrosion behavior and mechanism of Ti3C2 nanosheets for titania pigmented epoxy coatings

Utilization of Ti3C2 nanosheets for enhancing anticorrosion of epoxy resin coatings has been reported. But the epoxy coatings in real world are mainly pigmented coatings. Unfortunately, the anticorrosion behavior of Ti3C2 nanosheets for the pigmented epoxy coatings is rarely concerned. In this work, both 0.5 wt% unmodified Ti3C2 nanosheets (U-Ti3C2) or 0.5 wt% (3-glycidyloxypropyl)trimethoxysilane-modified Ti3C2 nanosheets (G-Ti3C2) were introduced into solvent-based titania pigmented epoxy coatings. Corrosion resistance of coatings was evaluated by electrochemical impedance spectroscopy and salt spray tests. A titania concentration effect was interestingly exhibited for the anticorrosion behavior Ti3C2-containing pigmented coatings. Enhanced anticorrosion was only demonstrated when TiO2 content was not above 10 wt% for U-Ti3C2 or 5 wt% for G-Ti3C2. Moreover, the pigmented coatings with U-Ti3C2 have better corrosion resistance than those with G-Ti3C2, being contrary to the phenomenon observed in pure epoxy resin coatings. The different anticorrosion behavior of Ti3C2 nanosheets for epoxy coatings with various TiO2 contents was mainly attributed to the different dispersion states of TiO2 pigments, that is, improved dispersion at low TiO2 content and deteriorated dispersion at high TiO2 content, after addition of Ti3C2 nanosheets.

Development and experimental investigation of a new direct urea fuel cell

This study concerns the development and experimental investigation of Direct Urea-Hydrogen Peroxide Fuel Cells (DUHPFC), with a particular emphasis on electrode preparation using nickel zinc iron oxide coated on stainless steel foil via the electrochemical deposition method, and the performance evaluation of single cells under varying operational conditions is also performed. This electrochemical deposition helps achieve a uniform and stable anode coating, which exhibits the high catalytic activity and stability, resulted in significantly enhanced urea oxidation reaction. The research further identifies an optimal performance for a single cell at 25 °C with 9 M KOH and 0.5 M urea, achieving a peak power density of 46.38 mW/cm2. The single cell demonstrates an open circuit voltage (OCV) of 0.72 V. Both energy and exergy efficiencies are further investigated for the cell performance and found to be 58% and 24%, respectively, at 5 M KOH. The electrochemical impedance spectroscopy (EIS) results reveal a significant reduction in impedance, from 30-Ωcm2 at 25 °C to 15-Ωcm2 at 65 °C, indicating an enhanced ionic conductivity and a reduced resistance. The present study results suggest that optimizing the electrode composition and operational parameters significantly improves the DUHPFC's performance, offering valuable insights for future fuel cell development.

Development of ultrasensitive genosensor targeting pathogenic Leptospira DNA detection in artificial urine

In the last decades, to access the stages of leptospirosis pathogenicity, site of infection, progression, monitor disease, and after-treatment were required especially non-invasive techniques. This becomes one of the significant goals for researchers. In this study, we developed a highly sensitive DNA-based electrochemical sensor to detect pathogenic leptospires in urine samples using a gold screen-printed electrode. The gold working electrode was electrodeposited with diazonium salt (CMA) with external carboxylic acid from the surface, and the specific Loa22 single-stranded DNA (ssDNA) probe to Leptospira interrogans was immobilized through a carbodiimide chemical reaction. The modified working electrode was characterized by contact angle measurement, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). After that, targeted DNA testing showed the EIS change in the range of 5 ag mL-1 - 16 fg mL-1 with a correlation R2 of 0.9638. The high sensitivity electrochemical sensor indicated a lower limit of detection to the attomolar level specifically 5 ag mL-1. Additionally, the developed genosensor exhibited high specificity without crossing other bacteria present in urine such as Escherichia coli, Staphylococcus aureus, and S. typhi as well as non-pathogenic leptospires L. biflexa serovar Patoc. Leptospires DNA was analyzed in both buffer solution and diluted artificial urine and detection in diluted artificial urine 1:1,000 was possible despite salt interferences. This study provides a highly sensitive lower detection platform for leptospirosis, offering potential for further development as a portable and point-of-care testing tool.

Impact of plasma treatment of Au electrodes on response of EIS biosensors used in aquaculture pathogen detection

This study examines the effect of plasma treatment on gold electrodes used in construction of biosensors. Plasma treatment aims to improve the adhesion of bioreceptor layers, enhancing sensor performance. Gold substrates were exposed to plasma for different durations, and their reactivity was analyzed using electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Results show that plasma treatment significantly enhances the hydrophilicity of gold surfaces, leading to better formation of bioreceptor layer. Optimal treatment duration was found to be around 60 s, beyond which improvements in impedance values diminished. Plasma-treated electrodes displayed superior bioreceptor adhesion without altering surface topography. In conclusion, plasma treatment improves biosensor performance by enhancing bioreceptor layer adhesion. Integrating this process into biosensor production can lead to more efficient and reliable pathogen detection in aquaculture, promoting healthier aquatic environments and sustainable food production.

Corrosion inhibition effect of several amino acids on an Al-Zn-Mg-Cu alloy: Electrochemical study, DFT and MD simulation

The corrosion inhibition performance of three amino acids, namely L-Phenylalanine (Phe), L-Methionine (Met) and L-Histidine (His) on 7150 Al alloy in 0.1 M HCl + 1 M NaCl solution was investigated by using electrochemical impedance spectroscopy (EIS), cyclic polarization, DFT and MD simulations. Electrochemical results indicate that all the studied amino acid inhibitors are cathodic type, and the inhibition efficiency follows the following order under all studied temperatures (25, 35 and 45 ℃): His > Met > Phe. A strong correlation between corrosion inhibition efficiency and DFT parameters is not evident, but the adsorption sites (N and O of NH2-COOH-, S atom of Met and two N atoms in the imidazolyl ring of His) can be determined by Fukui indices and Mulliken charges of the local atoms. In addition, MD simulations indicate that corrosion inhibition efficiency increases with the decreasing of adsorption energy.

Assessment of the inhibition performance of ZIF-8 on corrosion Mitigation of API 5L X65 steel in 3.5 wt% NaCl: Experimental and theoretical insight

The synthesis and application of ZIF-8 as an effective corrosion inhibitor for the corrosion of API 5L X65 steel in 3.5 wt% NaCl have been studied. The synthesized ZIF-8 was characterized using some surface probe approaches, which include field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR TEM), and X-ray photoelectron spectroscopy (XPS), respectively. The results showed that ZIF-8 exhibited regular hexagonal and orthorhombic-shaped nanoparticles. An approximately 62% yield was achieved. Electrochemical studies such as open circuit potential (OCP), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) were performed. The polarization results show that ZIF-8 is a mixed-type inhibitor, revealing a strong impact on both the anodic and cathodic polarization current values. The EIS studies reveal an increase in the charge transfer resistance upon the introduction of ZIF-8. The existence of a strong protective film adsorbed on X65 steel was recognized via XPS and FT-IR analysis. The highest inhibition efficiency value of 98.1% was recorded at a concentration of 0.120 wt% ZIF-8. Quantum chemical computations in the framework of DFT and molecular dynamic simulation were used to determine the reaction sites on the inhibitor, and as such, in-depth insight into the reaction mechanism was revealed.

Boosting the Production of Hydrogen from an Overall Urea Splitting Reaction Using a Tri-Functional Scandium-Cobalt Electrocatalyst.

The creation of highly efficient and economical electrocatalysts is essential to the massive electrolysis of water to produce clean energy. The ability to use urea reaction of oxidation (UOR) in place of the oxygen/hydrogen evolution process (OER/HER) during water splitting is a significant step toward the production of high-purity hydrogen with less energy usage. Empirical evidence suggests that the UOR process consists of two stages. First, the metal sites undergo an electrochemical pre-oxidation reaction, and then the urea molecules on the high-valence metal sites are chemically oxidized. Here, the use of scandium-doped CoTe supported on carbon nanotubes called Sc@CoTe/CNT is reported and CoTe/CNT as a composite to efficiently promote hydrogen generation from highly durable and active electrocatalysts for the OER/UOR/HER in urea and alkali solutions. Electrochemical impedance spectroscopy indicates that the UOR facilitates charge transfer across the interface. Furthermore, the Sc@CoTe/CNT nanocatalyst has high performance in KOH and KOH-containing urea solutions as demonstrated by the HER, OER, and UOR (215mV, 1.59, and 1.31V, respectively, at 10mA cm-2 in 1m KOH) and CoTe/CNT shows 195 mV, 1.61 and 1.3V, respectively. Consequently, the total urea splitting system achieves 1.29V, whereas the overall water splitting device obtaines 1.49V of Sc@CoTe/CNT and CoTe/CNT shows 1.54, 1.48 V, respectively. This work presents a viable method of combining HER with UOR for maximally effective hydrogen production.

Production of rGO based hybrid composite buckypaper cathodes by using copper oxide polysulfide adsorbent for Li-S batteries

Lithium-sulfur batteries are particularly noteworthy for applications requiring large capacity and long battery life. Transition metal oxides have emerged as polar host materials for lithium polysulfides to further modulate the bonding energy with polysulfides and increase the coupling density of the electrodes. Polar metal oxides naturally adsorb polysulfides on their hydrophilic surfaces. In this study, the polysulfide adsorbing ability of CuO against the shuttle effect is utilized. For this purpose, copper(II) oxide (CuO) is used as polysulfide adsorbent and CuO - reduced Graphene Oxide / Sulphur (CuO-rGO/S) hybrid composite buckypaper electrodes are produced as cathodes in Li-S batteries without using binders. In this work, optical, morphological and structural analyzes of composite films were carried out by Fourier transformed infrared spectroscopy (FT-IR), Raman spectroscopy, field emission gun scanning electron microscopy (FEG-SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) analysis, respectively. After the CR2032 button cell was assembled using the produced cathode materials, cyclic voltammetry (CV), charge-discharge performance tests, rate capability and electrochemical impedance spectroscopy (EIS) analyzes were performed to investigate the Li-S battery capacities. With the CuO-rGO/S hybrid composite cathode containing 2 % CuO, a discharge capacity of 1205 mAh g−1 was obtained in the first cycle. At the end of the 1000 cycles, the discharge capacity of the cathode was achieved as high as 696 mAh g−1. As a result, the battery capacity of rGO/S-based composite electrodes has been improved by taking advantage of CuO added to the cathode structure to adsorb polysulfides.