Rct Value Research Articles

In-depth investigation of corrosion inhibition mechanism: Computational, electrochemical, and theoretical studies of vanillin meldrum’s acid on mild steel surface in 1 M HCl

Vanillin Meldrum’s acid (VanMA) was successfully synthesized and thoroughly examined using techniques like elemental analysis, FTIR, NMR, UV–Vis spectroscopies, and single crystal X-ray diffraction. It crystallizes in a triclinic crystal system under the P-1 space group. A quantitative analysis of the intermolecular interactions in the crystal structures was performed using Hirshfeld surface analysis, which reveals that H···H contacts are the most significant contributing 43.2 % and the O···H/H···O contacts contributing 36.2 % of the total Hirshfeld surfaces. VanMA proved effective as a corrosion inhibitor in 1 M HCl, demonstrating a 62.19 % inhibition efficiency at an optimal concentration of 0.1 mM. It creates a protective layer on mild steel surfaces, adhering to the Freundlich adsorption isotherm (R2 = 0.9983) and displaying a physical adsorption mechanism (−12.72 kJ/mol). The corrosion inhibition efficacy of VanMA (0.1 mM) decreases in 1 M HCl as the temperature increases from 303 to 383 K. A shift towards physisorption is indicated by the increase in activation energy (Ea) from 12.37 to 16.42 kJ/mol. VanMA’s adsorption efficacy reduces at higher temperatures, increasing surface exposure and corrosion rates, but increasing activation enthalpy (ΔH° = 31.32 kJ/mol) and ΔS° = −113.63 J mol−1 K−1). The diameter of the semicircle rose as the concentration of VanMA increased, indicating that VanMA adsorption is responsible for the mild steel surface’s greater resistance to corrosion with increasing Rct values from 224 to 641 Ω cm2 and decreasing capacitance double layer (Cdl) values from 4.480 × 10−5 to 1.560 × 10−5 μFcm2, confirming VanMA’s efficacy as a corrosion inhibitor at 65.05 %. The SEM-EDX and AFM images show the smoother mild steel surface at 0.1 mM VanMA. VanMA was verified as a mixed-type inhibitor by showing shifts of less than 85 mV with respect to the blank PDP. The inhibition efficiency (IE%) increased up to 77.89 % while the icorr values decreased to 1.1850 × 10−5 A/cm2 as the VanMA concentration rose. In XPS, the presence of VanMA was identified by the presence of FeO (713.60 eV) and CO (287.93 eV), which signifies the adsorption of VanMA onto mild steel by the O atom and the negatively charged O ion via a mixed adsorption. DFT and Mulliken population analysis deduced that the VanMA interacted with the mild steel through mixed adsorption. VanMA adsorbs almost parallel to the Fe (1 1 0) surface, forming a barrier that protects from corrosion, according to the MD modeling. While the significant negative adsorption energy (−309.490 kcal/mol) verifies the stability and spontaneity of the adsorption process.

Synthesis and surface engineering of carbon-modified cobalt ferrite for advanced supercapacitor electrode materials

The precise design and surface modification of electrode materials are crucial challenges for advancing the supercapacitor technology. In this study, we report a straightforward two-step process for the synthesis of a cobalt ferrite (CoFe2O4)/carbon hetero nanostructure. The CoFe2O4 nanoparticles were first synthesized using a simple chemical oxidation method, followed by carbon modification using glucose. The modified samples were calcined at 400 and 600 °C for 4 h in N2 atmosphere to optimize the structural and electrochemical properties.. The increase in the grain size of carbon modified cobalt ferrite magnetic nanoparticles (MNPs) was observed from 22 to 28 nm with post annealing temperature. The presence of carbon was confirmed by the FTIR spectroscopy, FESEM and TEM analyses. The carbon decoration on the cobalt ferrite partially showed a core–shell like morphology. The saturation magnetization of bare cobalt ferrite was observed to be 76 emu/g and the same was decreased by the surface modification with carbon. A high specific capacitance of 323 F/g was observed for the carbon-modified cobalt ferrite MNPs annealed at 600 °C. The electrochemical impedance spectroscopy (EIS) analysis demonstrated that the charge-transfer resistance (Rct) decreased significantly in the carbon-modified CoFe2O4 MNPs, particularly for the sample annealed at 600 °C, with an Rct value of 17 Ω. The carbon layer effectively enhanced conductivity and reduced the electrode/electrolyte interface, led to the improved electrochemical performance, as reflected in the enhanced specific capacitance. An improved capacitance retention of 84 % was achieved in the case of carbon-modified cobalt ferrite MNPs based electrode even after 4000 cycles. The study suggested that the prepared carbon-modified cobalt ferrite MNPs stand in the limelight as a better candidate electrode material for the electrochemical applications.

Sol–Gel Fabrication of Sm‐Doped MnTiO3 Perovskite Electrode for Enhanced Oxygen Evaluation Reaction

ABSTRACTExcessive usage of fossil fuels has led to significant depletion, creating an energy crisis and environmental concerns. This has prompted the creation of sustainable energy conversion systems. This study explores sol–gel incorporation of Sm‐doped MnTiO3 nanostructure, which exhibits OER activity. Different analytical techniques were used to assess the material's morphology, structure, and textural properties. BET analysis confirmed increased surface area (34 m2 g−1) of Sm‐doped MnTiO3 nanostructure, which enhanced OER performance. The electrochemical results showed that the fabricated doped nanostructure had a lower overpotential of 201 mV, resulting in a current density of roughly 10 mA cm−2 and a Tafel slope of 40 mV dec−1. In EIS analysis, a low Rct value of Sm‐doped MnTiO3 (0.20 Ω) compared with pure MnTiO3 (0.23 Ω) indicates highly efficient charge transfer and a faster faradaic reaction. Chronoamperometry and cyclic stability analyses of Sm‐doped MnTiO3 nanostructure demonstrate stability over 35 h. The fabricated nanostructure has remarkable electrochemical characteristics, making it a promising material for future applications in electrical and other areas.

3D printer fabrication of boron doped Cu-MWCNT/PLA electrodes: Investigation of its efficiency in electrocatalytic hydrogen production

In this study, three-dimensional (3D) electrodes based on MWCNT-Cu/PLA with high electrocatalytic efficiency, large surface area and different amounts of nano‑boron doped MWCNT-Cu/PLA were fabricated using Fused Granular Fabrication (FGF) method with a 3D printer. When FE-SEM images are examined, MWCNT fibers and copper particles are seen more clearly on the surface due to the formation of more dense conductive networks between the conductive carbon fibers trapped in the PLA structure due to the increasing amount of boron. When XRD results are examined, it is observed that the characteristic peaks belonging to the face-centered cubic structure of Cu are dominant and the crystal size increases as MWCNT addition and boron doping increase. When Raman spectra were analyzed to investigate the internal structural changes of MWCNTs, three characteristic bands corresponding to the D band (defect), G band (graphite band) and G' band (D overtone) of MWCNTs were determined and it was observed that the ID/IG ratio decreased with increasing boron doping compared to MWCNT-Cu/PLA electrode. The B1s spectrum of the 3D 0.8B@MWCNT-Cu/PLA electrode confirmed the presence of boron with the peak corresponding to B@C bonds at 191.2 eV. The obtained 3D electrocatalysts were used as cathodes in an electrolysis cell in aqueous solution containing 1 M KOH and their catalytic efficiency in hydrogen evolution reaction (HER) was tested. In order to increase the activity of the 3D electrodes, unlike the literature, they were activated by electrochemical activation process without using organic solvent and HER measurements of the activated electrodes were performed. Before activation, the charge transfer resistance (Rct) value of the Cu/PLA electrode, which was 6219.00 Ω cm−2, decreased to 681.90 Ω cm−2 after 5 % MWCNT doping. It is seen that with boron doping, a greater decrease in Rct value is realized, reaching values of 66.50–74.56 Ω cm−2. The cathodic Tafel slopes show that the Volmer reaction is the rate-determining step for HER and the rate-determining step is the electrochemical adsorption of hydrogen on the metal surface. In addition, energy efficiency tests of the 3D electrodes in HER were also performed and electrochemically active surface areas were determined. Thus, this study has taken an important step toward using 3D electrocatalysts, which are produced with more cost and more flexible designs, unlike previous production techniques, for hydrogen energy production.

New Brønsted–Lowry acid Co(II) complexes: Synthesis, characterization, and investigation of electrochemical application for sensing of salbutamol

In recent years, the employment of transition metal complexes for working electrode surface modification for sensor fabrication has become an area of research direction. Based on this, in this study, three Co(II) complexes: Co(phen)Cl2 (CoC12H8N2Cl2) (C1), and Brønsted–Lowry acids Co(phen)(HTA)Cl (CoC16H13N2O6Cl)(C2), and Co(phen)(HTA)2 (CoC20H18N2O12)(C3) were synthesized and characterized using various techniques such as UV–Vis, FT-IR, ICP OES, TGA, DTA, pXRD as well as electrolytic conductivity, and acid-base property analysis. C and C3 were found polycrystalline whose size falls within the nano range of 50 and 51 nm, respectively. The synthesis was intended to get materials for voltammetrically modifying glassy carbon electrodes for the determination of salbutamol. Salbutamolis a short-acting β2adrenergic receptor agonist that is applied for opening the medium and large airways in the lungs and eventually treats asthma among other problems. The electrochemical application of the synthesized materials was studied by fabricating through electropolymerization of C1, C2, and C3 on glassy carbon electrodes. The poly(C1)/GCE, poly(C2)/GCE, and poly(C3)/GCE) revealed effective surface area is 0.174 cm2, 0.183 cm2, and 0.281 cm2, respectively, and electrochemical catalysis of the materials increased with the number of the tartrate. The Rct values are 5686, 242, 216, and 185 Ω cm2, while the Cdl values are 9.93 × 10−8, 5.35 × 10−6, 1.25 × 10−5, and 2.72 × 10−5, for bare GCE, poly(C1)/GCE, poly(C2)/GCE and poly(C3)/GCE, respectively. Similarly, the rate of charge transfer (k°) increased significantly on the modified electrode compared to the bare GCE. Salbutamol demonstrated a single well-shaped irreversible oxidative peak at the modified electrodes in the ascending order of poly(C1)/GCE, poly(C2)/GCE, and poly(C3)/GCE when compared to a bare GCE.

Fluorinated reduced graphene oxide nanosheets for symmetric supercapacitor device performance

This study explores the potential of using spent lithium-ion battery anodes (graphite) for fabricating symmetric energy devices through a simple regeneration process. Specifically, the use of fluorine-doped reduced graphene oxide (RGO) nanosheets derived from waste batteries as the basis for a symmetric supercapacitor (SC) device is investigated. To enhance the electrochemical energy storage capabilities, a facile hydrothermal technique is employed to synthesize fluorinated graphene. Fluorination of the graphene sheets is successfully realized, as confirmed by the presence of boron with a 2.94 at.% fluorine-doped level, according to the Energy dispersive spectroscopy (EDS) spectrum analysis. Electrochemical analysis of the F-RGO electrode performance consistent with electric double-layer capacitance. Moreover, with a three-electrode system, the F-RGO electrode achieves a maximum specific capacitance of 207F/g under a current density of 1 A/g. A two-electrode symmetric device employing F-RGO exhibits a specific capacitance of 54F/g at 1 A/g. Furthermore, electrochemical impedance measurements demonstrate low charge transfer resistance (Rct) values, specifically 8.63 Ω for F-RGO, signifying improved electrochemical performance. Thus, fluorine atomic doping in RGO nanosheets contributes to the improvements of the specific capacitance and overall superior electrochemical performance of F-RGO, and F-RGO is a highly electrochemical active material for high-performance energy storage electrodes for SCs.

One-pot synthesis of 2D-Ni-MOF from waste PET plastic in aqueous medium for selective electrooxidation of glycerol, ethanol, and methanol

This study investigates the electrochemical performance and selectivity of a nickel-based metal-organic framework (Ni-MOF) catalyst synthesized from waste PET plastic using a one-pot approach in aqueous media. The Ni-MOF electrode was evaluated for glycerol electrooxidation reaction (GEOR), ethanol electrooxidation reaction (EEOR), and methanol electrooxidation reaction (MEOR). Linear sweep voltammetry (LSV) revealed current densities of 30mA/cm² at 0.5639V for GEOR, 50.07mA/cm² at 0.35V for EEOR, and 45.73mA/cm² at 0.39V for MEOR, indicating superior catalytic activity. Nyquist plots showed lower charge transfer resistance (Rct) values of 11.0 Ω for GEOR, 2.79 Ω for EEOR, and 2.69 Ω for MEOR, confirming efficient electron transfer. Bode impedance plots demonstrated lower impedance for alcohol electrooxidation compared to oxygen evolution reaction (OER). Chronoamperometry (CA) tests indicated excellent stability with 75.72% glycerol conversion for GEOR and selectivities of 94% for glyceric acid, 65.59% for acetic acid in EEOR, and 70.54% for formic acid in MEOR. These results highlight the potential of Ni-MOF derived from recycled PET plastic for sustainable and efficient electrooxidation of C1-C3 alcohols.

Step-by-Step Tuning of Tribological and Anticorrosion Performance of Zinc Phosphate Conversion Coatings through Effective Integration of Spherical P-Doped MoS2 Nanoparticles.

Surface coatings with enhanced mechanical stability, improved tribological performance, and superior anticorrosion performance find immense application in various industrial sectors. Herein, we report the development of multifunctional composite zinc phosphate coatings by the effective integration of a structurally and morphologically tuned P-doped MoS2 nanoparticle additive (3P-MoS2) into the zinc phosphate matrix to offer attractive characteristics suitable for industrial applications. The integration of spherical nanoparticles as additive leads to the formation of homogeneous and compact coatings with a densely packed crystalline microstructure having enhanced microhardness, distinctive leaf-like morphology, and comparatively smooth topographical features. The attractive lubricity of the additive (3P-MoS2), coupled with its spherical morphology, facilitates a transition from sliding to rolling friction and contributes significantly toward the performance enhancement of the tuned composition of the composite zinc phosphate coating (0.3-PMS). Thus, the tuned 0.3-PMS coating delivers the lowest specific wear rate (1.334 × 10-5 mm3/Nm) and coefficient of friction (0.114) that significantly outperform bare-zinc phosphate coating. Further, the electrochemical corrosion study results indicate the improvement in corrosion resistance behavior of the composite zinc phosphate coatings with reduced corrosion current density (icorr) and charge transfer resistance (Rct) values, as compared to the bare-zinc phosphate coating. The effect of passivation in conjunction with the barrier protection characteristics of the composite coatings induced by the optimal composition of the integrated additive nanoparticles (3P-MoS2) can efficiently prevent the infiltration of corrosive ions and thereby significantly reduce the rate of corrosion.

Ni–Cu Bimetallic Oxides with Tailored Morphology for High‐Performance Alkaline Water Oxidation

AbstractWater oxidation, a crucial step in electrochemical water splitting, is often hindered by its complex kinetics. In our pursuit of designing efficient electrocatalysts, we have found that morphological modifications during synthesis are powerful tools. By manipulating various parameters, such as reaction time and temperature, we have tuned the morphology of the catalysts, leading to a significant enhancement in the oxygen evolution reaction (OER) rate. Our thorough research involves using a simple hydrothermal method for synthesizing bimetallic Ni–Cu oxides, resulting in the emergence of different morphologies by varying reaction times from 4 to 24 h. The OER performance in an alkaline medium, using a 1 M KOH solution, has been meticulously investigated, and our results have unveiled the highest activity for Ni–Cu fabricated with a growth time of 24 h. Ni–Cu oxide 24 exhibits a remarkably low onset potential for OER at 222 mV with a Tafel slope of 373 mV/dec. The catalyst boasts the lowest Rct value of 2.788 ohm, ensuring faster charge transfer rates and stability up to 1000 cyclic voltammetry (CV) cycles, thereby supporting its electrochemical applications for water splitting.

Voltammetric determination of uric acid using a miniaturized platform based on screen-printed electrodes modified with platinum nanoparticles

Disposable and sensitive screen-printed carbon electrodes (SPCE) modified with multi-walled carbon nanotubes (MWCNT) and platinum nanoparticles (PtNPs) were constructed to analyse uric acid (UA) in biological samples using a miniaturized smartphone potentiostat system. Combining the nanomaterials with Nafion® yielded a stable dispersion that could be successfully used as an electroactive layer. Transmission electron microscopy (TEM) and energy dispersive scanning (EDS) were used to characterize the morphology of PtNPs. These revealed approximately spherical shapes with emission lines characteristics of platinum. Furthermore, PtNPs/MWCNT/SPCE film was characterized by scanning electron microscopy (SEM), which demonstrated the tubular characteristic of MWCNT distributed and covered by carbon black (CB) spheres present in the screen-printed ink. An enhanced current response was observed for UA voltammetric analysis, especially due to the synergism effect of PtNPs and MWCNT, which reduced the Rct value. The values of Dapp (1.6 × 10−6 cm−2 s−1) and kcat (2.76 × 103 mol−1 L/s) were determined for UA using the proposed sensor. The sensor displayed linear response for UA in the range from 5.0 × 10−6 mol/L to 6.9 × 10−4 mol/L, with a detection limit of 4.9 × 10−7 mol/L. Along with detectability, excellent performances were verified in terms of repeatability, anti-interference features, and analysis of UA in the biological samples.

Spinel-type calcium manganese oxide adorned on g-CN composite: A highly proficient electrocatalyst for oxygen evolution reaction (OER)

A comprehensive study was performed on water electrolysis to address environmental challenges and energy issues. Eco-friendly and renewable energy systems are required to produce cost-effective electro-catalysts with long-term durability and higher electrocatalytic efficiency to enhance OER. Spinel oxide has recently been used as a promising substitute for transition metal catalysts. They can function as very effective electrocatalysts in water oxidation processes. In current study, the CaMn2O4/g-CN composite was prepared using the hydrothermal technique in 1.0 M KOH in primary media. Distinctive physical and electrochemical analyses evaluated the prepared material's morphology, structure and electrocatalytic components. The composite material showed enhanced electrocatalytic efficacy for OER having a reduced overpotential (η) of 220 mV than pure CaMn2O4 278 mV and possesses a minimal Tafel value (35 mV/dec) contrasted with pristine CaMn2O4 (57 mV/dec). In case of overpotential, the composite material revealed good performance than its pure material while the Tafel slope of CaMn2O4/g-CN exhibited lower value than its individual material (CaMn2O4). Additionally, cyclic stability and chronoamperometric studies measured the electrodes' durability over 30 h. Electrochemical impedance spectroscopy (EIS) investigations indicated that charge transformation at an electrode-electrolyte surface might be feasible with minimal Rct value (0.19 Ω) and it showed excellent improved performance (63 %) better than its pure material, leading it to boost OER properties, attributed to its remarkable electrical conductivity, greater surface area and outstanding stability. These outstanding electrochemical features of the CaMn2O4/g-CN differentiate as an attractive choice for future OER utilization.

Millettia aboensis leaves extract as eco-friendly corrosion inhibitor for mild steel in acidizing solution: From experimental to molecular level prediction

The development of environmentally friendly corrosion inhibitors is becoming more popular since conventional inhibitors are poisonous and non-biodegradable. The anti-corrosive effectiveness of Millettia aboensis leaves extract (MALE) has been assessed in this study using several methods, such as electrochemical measurements, X-ray Photoelectron spectroscopy and scanning electron microscopy on mild steel in acidic solution. Gas chromatography-mass spectrometry (GC-MS) analysis was combined with qualitative and quantitative phytochemical analysis to identify the phytochemicals linked to the activity of the Millettia aboensis extracts and identified key phytoconstituents such as Hexanedioic acid, Phenol derivatives, Octadecanoic acid, and Linolenic acid, which play significant roles in the extract's inhibitory performance. The results showed that the inhibition efficiency (IE%) improved to 88.6 % with the addition of inhibitor concentration from 0.1 g/L to 3.0 g/L and that the corrosion rate drastically reduced from 56.91 mpy to 16.09 mpy. Furthermore, at a greater concentration (3.0 g/L), the Rct values rose from 61.42 Ω cm2 to 176.3 Ω cm2 thus, indicating that the inhibitor molecules were forming a protective film over the metallic surface. Scanning Electron Microscopy (SEM) provided visual evidence of surface morphology, revealing a smoother surface in the presence of the inhibitor, indicative of the protective film formed by the adsorption of organic molecules onto the steel surface. Theoretical calculations using the ωB97XD functional and def2svp basis set further supported the experimental findings, showing that the protonated form of C21H36O4 exhibited the highest interaction energy, correlating with its superior inhibition efficiency on the metal surface.

Effect of graphene on microstructure, strain hardening and corrosion behaviour of dual phase Mg-Li matrix processed through liquid metallurgy route

The significance of this study lies in the potential enhancement of magnesium (Mg)-based materials through the addition of graphene, aiming to improve their mechanical properties and corrosion resistance. This research investigates the development of graphene-Mg composites, employing a liquid metallurgy route to fabricate a dual-phase structured Mg-8Li composite. Mg-Li dual-phase composites are of interest due to their lightweight nature and promising mechanical properties, making them suitable for applications in aerospace, automotive, and structural engineering. Graphene was incorporated into the Mg matrix at varying percentages (0.2, 0.4 and 0.6 wt.%), and the resulting materials were subjected to microstructural, mechanical, and corrosion analyses. Microstructural characterization results reveals that the increase in graphene content results in decrement in grain size of α-Mg and β-Li up to ∼33 and ∼11.5% respectively. Likewise, additions of graphene improvise tensile and yield strength of base matrix up to ∼47 and ∼44% respectively. Strain hardening exponent (n) values of base material decrease from 0.21 to 0.17 with respect to graphene addition which confirms the effect of graphene that acts as effective barrier to slip that decreases the deformation. Corrosion analysis revealed a decrease in corrosion rate and increased pitting resistance with the addition of graphene, indicating improved corrosion resistance. Electrochemical impedance spectroscopy results depict that the composite with 0.4 wt.% graphene exhibits larger semi conducting loop with higher charge transfer resistance ( Rct) value of 128 Ω cm2.

Designing a MXene-based heterostructure nanocomposite with extensive interfacing as ions exchange and controllable release inhibitors for intelligent coating

In this work, the surface of I–Ti3C2Tx MXene was modified by (MgAl-)LDH via coprecipitation followed by the introduction of BTA, forming the novel I–Ti3C2Tx@LDH/BTA (ITLB) heterostructure nanocomposites. ITLB acted as a pH-responsive nanocontainer to release benzotriazole (BTA) and adsorbed/captured Cl− ions by ion exchange. ITLB could be systematically arranged within an epoxy matrix, enhancing interface interaction and improving mechanical properties. The ITLB/EP coating exhibited excellent corrosion protection and self-healing performance. The impedance value of the intact ITLB/EP coating was 1011 Ω cm2, which was three orders of magnitude higher than that of EP, and presented the highest Rc and Rct values compared to other coatings throughout the immersion period. When defects in the ITLB/EP coating, ITLB underwent a rapid pH-response to localized corrosion to release BTA, forming a dense protective [BTA-Fe-BTA]n complex with Fe2+ and effectively preventing further corrosion. Thus, ITLB exhibited dual functionality as a nanocomposite corrosion inhibitor, providing both pH-response behavior and intelligent protection. This newly created 2D/2D heterostructure nanocomposite will provide the theoretical basis and technical support for the development of intelligent coatings.

Advancing the assessment of ICCP efficiency for steel reinforcement: A novel electrochemical investigation

Impressed current cathodic protection (ICCP) is an electrochemical technique employed to mitigate corrosion. The evaluation of its effectiveness has traditionally relied on qualitative criteria such as protection potential and potential decay. This study proposes a novel electrochemical setup to enable measurements during current-controlled ICCP treatment. The experimental outcomes demonstrate that the proposed approach, in conjunction with protection potential analysis, allows for the quantitative determination of the optimal ICCP current density. As the protection current density increased, the fitted charge transfer resistance (Rct) initially showed an upward trend, followed by a gradual decline. To accurately interpret the results, it is crucial to discern whether the Rct values correspond to oxidation reactions (referred to as corrosion reactions in this context) or reduction reactions. Furthermore, it was observed that the optimal current density was closely associated with the severity of initial corrosion, in line with previous findings. This consistency serves to further validate the efficacy of the proposed method.

Ta-ions doping impact on structural modifications and bandgap tuning of NiCo2O4 hexagonal nanosheets for high rated pseudocapacitor electrodes

Getting higher activity, lower cost and especially better stability at the same time is still one of the biggest problems in the supercapacitors research. Morphology tailoring and crystal imperfections induce d due to doping based defects in ternary transition metal oxides at the nano-scale level is crucial for enhancing the performance of supercapacitors. This research investigates of the utilization of Ta-doped NiCo2O4 (Ta-NCO) hexagonal nano-sheets for supercapacitor electrodes. The structural and morphological study of pristine and Ta-doped samples has been determined using XRD, SEM, TEM and HRTEM. The enhanced inherent conductivity and diffusion at the interface are also confirmed using electrochemical measurements study. The NCO-5 material exhibits a notable enhancement in capacitance and cycling retention. The NCO-5 electrode demonstrates a high specific capacitance (Cs) of 2445.7 F/g at 1 A/g. The pseudocapacitive behavior by power law (b = 0.67) and an increase in capacitive contribution with the scan rate reaching a value of 47.2 % at 100 mV/s by Dunn method exhibits it suitability of pseudocapacitors. The low Rct value signifies it improved capacitive performance as deduced from EIS measurements. Crucially, it maintains around 95.3 % of its capacitance after undergoing 10,000 GCD cycles. The high specific capacitance, remarkable capacitive characteristics and high stability of NCO-5 make it an excellent contestant for supercapacitor applications. The fabricated asymmetric supercapacitor (NCO-5//AC) shows exceptional energy density (ED) of 96.35 Wh/kg with power density (PD) of 825.03 W/kg.

Assessment of Warionia saharea Essential Oil as a Green Corrosion Inhibitor for Mild Steel in HCl: Experimental and Computational Studies

The objective of this research work is the study of the inhibitory effect of Warionia saharea essential oil (WSEO) on the corrosion of mild steel (MS) in molar HCl solution, employing both experimental and theoretical methods. This inhibitory effect (IE) has been evaluated by using a combination of weight loss measurements (LW) and various electrochemical methods, such as open circuit potential (OCP), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) experiments. The LW results indicated that IE increased with inhibitor concentration, reaching 83.34% at 3.00 g/L. The PDP analysis suggested that WSEO functions as a mixed inhibitor, while in the EIS results the Rct values increased with inhibitor concentration to reach 165.8 Ω cm2 at 2.00 g/L, suggesting a defensive film formation by WSEO molecules over the metallic surface. The thermodynamic study demonstrated that the WSEO molecules adsorption on the MS surface followed a Langmuir isotherm, involving mixed physical and chemical (physicochemical) adsorption on the MS surface. Theoretical methods, including density functional theory (DFT) and molecular dynamics (MD) simulations, were employed to elucidate the inhibition mechanisms of the three main components of WSEO. The quantum chemical analysis, using density functional theory (DFT) and molecular dynamics (MD) simulations, showed a low ΔEgap value of 6.30 eV and a low adsorption energy (Eads) value on an Fe (110) substrate of −258 Kcal/mol for (E)-Nerolidol, indicating the significant contribution of this molecule to the overall corrosion inhibition effect of WSEO. The scanning electron microscope (SEM) analysis verified the presence of a protective film formed by the inhibitor on the MS surface. This study highlights the potential of WSEO as a sustainable and green corrosion inhibitor in acidic environments.

Uncovering accurate values of the polarization resistance in molten fluorides using electrochemical impedance spectroscopy

High-temperature operation and the presence of oxidizing impurities in molten chloride and fluoride salts pose significant corrosion risks to structural alloys in molten salt nuclear reactors. Electrochemical impedance spectroscopy (EIS) offers an operando, real-time method to study the instantaneous corrosion behavior of these materials non-destructively. However, signal noises may originate from sources extraneous to the electrochemical systems that limit the ability to perform quality impedance measurements in low-frequency regime where polarization resistance (Rp) dominates. Using the exposure of pure Cr in molten LiF-NaF-KF containing 1 wt% EuF3 at 600 °C as a model corrosion system, the extent of Non-Uniform Current and Potential (NUCP) distribution during an AC perturbation associate with the disk electrodes is evaluated in terms of two dimensionless correction factors kfRct(=Rct/Reff) and kfCdl(=Cdl/Ceff). Results show that a small area Cr disk electrode increases the transition frequency that marks the dominance of Rp to a conventional terminational frequency above 10−2 Hz, enabling a reliable charge-transfer resistance (Rct) value to be determined via circle fitting of an electrical equivalent circuit model (ECM) model. Experimental results were supported by EIS simulations considering commonly used ECM models that factor in the NUCP effect of disk geometries.

Enhanced electrochemical performances of ternary polypyrrole/MXene/Gum arabic composites as supercapacitors electrode materials

The development of supercapacitor electrodes for high energy storage applications requires the use of ternary composites made of PPy, Mxene, Gum Arabic (PPy/Mxene/GA) these materials are special because they have new characteristics like cyclic stability, and high specific capacitance. The pure PPy, PPy/Mxene and PPy/Mxene/Gum Arabic show the shifting and appearance of new peaks in UV-Visible spectra, which are further supported by the Fourier transform infrared spectroscopy (FT-IR). The appearance of new peaks in X-ray diffraction (XRD) of PPy confirms presence of Mxene and Gum Arabic, which is in agreement with the energy dispersive X-ray (EDX) analysis. The electrochemical techniques such as Cyclic Voltammetry (CV), Galvanostatic Charge Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS) show that the (PPy/Mxene/GA) ternary composite maintains 94 % of the specific capacitance retention after 2000 cycles and; reaches a maximum specific capacitance of 657.64 F/g at 1 A/g. As compared to Pure PPy and PPy/Mxene composite the PPy/Mxene/GA composite show small intrinsic resistance Rs and charge transfer Rct values 0.11Ω and 6.15Ω respectively. The outstanding electrochemical properties of PPy/Mxene/GA composite are ascribed to the blending of three different type compounds PPy, Mxene and GA and theirs mutual beneficial effects. These findings show that ternary composite material holds great promise for use in these condition involving portable electronic storage devices.

Simultaneous Electrodeposition of Gold Nanoparticles and Electropolymerization of L-Cysteine through Paper-Based Microfluidic Sensor

Introduction Using catalytic active modifiers and additives e.g. to improve electron or ion transport in electrochemical sensors usually offers significant benefits by improving sensitivity and selectivity. An elegant way to introduce both is electrodeposition and electropolymerization. Examples are known, where through these methods enhanced catalytic activity, stability, reproducibility, and active surface area could be achieved [1,2]. Paper-based microfluidic electrochemical sensors (μCS) have gained significant attention due to their simplicity, portability, cost-effectiveness, and potential for point-of-care applications. Although electrodeposition of AuNPs and electropolymerization of (L-cysteine) have been widely studied in static voltammetry using glassy carbon electrodes or screen-printed carbon-based electrodes (SPCE), their application by the microfluidic systems has been limited, and based on our knowledge, no report has been done on electrodeposition and electropolymerization through a μCS.In this work, we show the electrodeposition of AuNPs and electropolymerization of (L-cysteine) onto the electrodes of paper-based microfluidic electrochemical sensor, while using the microfluidic channel also for transport of the electrodeposition solution. Experimental The alignment of the component for the μCS device is sketched in Scheme 1. After providing the HAuCl4 and L-cysteine solution through the sponge the electrochemical fabrication and detection are carried out through cyclic voltammetry (CV). AuNPs were electrodeposited and L-cysteine were electropolymerized simultaneously through the μCS by handling a potential window of −1.5 to +2.2 V at a scan rate of 100 mV/s for 10 cycles in a solution of 0.1 M PBS at pH = 5.5 consists of 1.0 mM HAuCl4 and 1.0 mM L-cysteine. Scanning electron microscope (SEM), CV, and electrochemical impedance spectroscopy (EIS) were employed to certify that the AuNPs and poly (L-cysteine) were attached successfully to the working electrode surface. Results and discussion CVs of the platforms were recorded in the redox probe solution consisting of 5.0 mM of [Fe(CN)6]3−/4−. By modifying the platforms by simultaneous electrodeposition of AuNPs and electropolymerization of (L-cysteine) not only did peak currents increase dramatically but also ΔEp were decreased to 17 mV and 13 mV for SPCE/S (ED & EP) and μCS/S (ED & EP), respectively. This decrement behavior indicating the presence of AuNPs, and poly (L-cysteine) enhances the reversible nature of the electrochemical reaction.By comparing the Nyquist plots related to the bare SPCE and μCS it is clear that the Rct value for μCS (46 Ω) is much lower than SPCE (690 Ω) It may be attributed to the 3D and sandwich-like structure of μCS devices. SPCE/S (ED & EP) and μCS/S (ED & EP) present very smaller semicircles with Rct values of 225 Ω and 13 Ω, respectively. This remarkable increase in the current and substantial decrease in resistance of the modified platforms at first confirms which AuNPs and poly (L-cysteine) were successfully achieved onto the WE surface. Interestingly, the simultaneous deposition of AuNPs and poly (L-cysteine) by using μCS shows the lowest Rct and could be a highly interesting sensing electrode.To ensure the performance of both simultaneous electrodeoposition of AuNPs and electropolymerization of (L-cysteine) and μCS in the enhancement of the surface area, accordingly, the calculated A of the SPCE/S (ED & EP) and μCS/S (ED & EP) were estimated to be 0.09 cm2 and 1.14 cm2, respectively. In comparison with the A value of the bare SPCE (0.06 cm2) and μCS, (0.31 cm2) these increases are 1.5 times for the SPCE and 3.6 times for the μCS. Conclusion The μCS/S (ED & EP) offers several core advantages over SPCE/S (ED & EP) in terms of cost, simplicity, and sensitivity. These unique advantages are due to the combined microfluidic configuration, 3D electrode layout, and a unique electrochemical modifier. According to the SEM results, the images corroborated that the simultaneous synthesis of nanocomposite on the working electrode surface is carried out successfully. This strategy can assist as the proper way to boost the surface area of the sensor. We believe our findings would have significant implications in developing other portable, fast, and cost-effective electrochemical detection platforms, such as clinical diagnosis and security inspection. References Mei, Xue, et al. "A novel electrochemical sensor based on gold nanobipyramids and poly-l-cysteine for the sensitive determination of trilobatin." Analyst 148.10 (2023): 2335-2342.Ghanbari, Mohammad Hossein, et al. "Simultaneous electrochemical detection of uric acid and xanthine based on electrodeposited B, N co-doped reduced graphene oxide, gold nanoparticles and electropolymerized poly (L-cysteine) gradually modified electrode platform." Microchemical Journal 175 (2022): 107213.Bard, Allen J., Larry R. Faulkner, and Henry S. White. Electrochemical methods: fundamentals and applications. John Wiley & Sons, 2022. Figure 1