Electrochemical Investigation Research Articles

Mesomorphic cyanobiphenyl appended thiols as anti-corrosive materials: Electrochemical and theoretical investigations

Mesomorphic cyanobiphenyl appended thiols as anti-corrosive materials: Electrochemical and theoretical investigations

Electrochemical investigations of Mn-doped ZnO/rGO nanoparticles electrode material for supercapacitor application and its enhanced antimicrobial activity

Electrochemical investigations of Mn-doped ZnO/rGO nanoparticles electrode material for supercapacitor application and its enhanced antimicrobial activity

A sustainable approach for the corrosion control of mild steel using Cocous nucifera gum: An electrochemical investigation

The study of corrosion inhibition on mild steel (MS) in an acid medium (1 M HCl) solution was performed using a crude extract of Cocousnucifera gum (CNG). Cocousnucifera develops gum exudates on its palm, the exudate process occurs mainly after some physical or microbiological injuries and is formed on the fruit of the palm. The gum was utilized to study the corrosion inhibition of MS by electrochemical and surface studies. The characterization of the crude gum was done by Fourier transform infrared spectroscopy (FT-IR) which revealed the presence of several active components (aromatic and oxygen-containing functional groups) in its structure. The electrochemical studies resulted in the maximum inhibition efficiency value of 75.64 % at the highest inhibitor concentration of 4000 ppm at 308 K. It was inferred that both the anodic dissolution of the metal and cathodic hydrogen evolution were effectively decreased in the presence of Cocous nucifera gum extract, revealing that inhibitor is of mixed type. From the adsorption studies, it was found that the best fit with R2 ∼ 0.9 followed Langmuir adsorption isotherm indicating the monolayer adsorption of the inhibitor on the metal surface. Gibb’s free energy of adsorption values was found <−20 kJ/mol, a characteristic of predominant physical adsorption. To support the electrochemical data SEM (scanning electron microscopy), AFM (Atomic force microscopy), and X-ray diffraction analysis were performed and these are in good agreement.

Insights over the in-situ grown copper sulfide/NiFe-LDH composites for alkaline and urea water electrolysis

Harnessing hydrogen fuel through electrocatalytic water splitting offers an eco-friendly alternative to the traditional fossil fuels. The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are the two half-cell reactions, that make up the electrocatalytic water splitting. Replacing the sluggish OER in the electrocatalytic water splitting with less energy demanding urea oxidation reaction (UOR) might benefit overall water splitting with reduced cell voltages. On the other hand, developing electrodes based on non-precious metals is essential for cost-effective and efficient water splitting. Herein, composites comprising non-precious nickel iron layered double hydroxide (NiFe-LDH) and copper (II) sulfide (CuS) are grown over the nickel foam and subjected to electrochemical measurements for alkaline water electrolysis (AWE) and urea water electrolysis (UWE). Structural and morphological investigations reveal that the 10 wt% CuS composited NiFe-LDH (NFCS10) is supposed to have effective catalytic features for water electrolysis. The electrochemical investigations in the three-electrode system with silver/silver chloride (Ag/AgCl, reference electrode) and platinum (Pt, counter electrode) revealed that the NFCS10 requires only a minimal overpotential (Ƞ50) of 235 mV for UOR and 400 mV for OER respectively. For bifunctional performance, NFCS10 requires an overall cell potential (OCP) of 1.65 V and 1.50 V to reach 10 mA/cm2 current density in AWE and UWE, respectively. X-ray photoelectron spectroscopy identifies the enrichment of oxygen vacancies in NiFe-LDH:CuS heterostructure, which could influence the charge transport and stability of the proposed electrode. This study emphasizes the interfacial interactions between the LDH and metallic sulfide, as well as their impact on the electrocatalytic activity in alkaline and urea water splitting.

Enhanced ionic conductivity and electrochemical performance of environmental friendly guar gum-based bio polymer gel electrolytes doped with Al2O3 nanofibers for Li-ion batteries.

Recently, biopolymers made from natural resources are gaining popularity as polymer electrolytes (PEs) in electrochemical devices. In the present work, a series of guar gum (GG)-based biopolymer gel electrolytes (BGEs) filled with different amounts of Al2O3 nanofibers are synthesized and tested. The BGEs containing 7.5 wt% Al2O3 nanofibers show the maximum room temperature ionic conductivity of 2.37 × 10-3 S/cm at an uptake ratio of 120 %. Given the high conductivity, this uptake ratio is low, demonstrating that Al2O3 nanofibers affect GG's ion transport characteristics. XRD reveals that the Al2O3 in GG can create conducive environment for ion conduction. FTIR and XPS analyses demonstrate that nanofibers have the ability to generate supplementary routes for ion conduction in GG. Electrochemical investigations show that BGEs with 7.5 wt% nanofibers have a broad electrochemical potential range of 4.6 V. BGEs are stable at metallic electrodes and have a cationic transference number of 0.59. The initial discharge capacity at 0.5C has been measured to be 127 mAh g-1 for Li|BGE|LiFePO4 cell in the first cycle and 116 mAh g-1 with coulombic efficiency of over 94 % after 100 cycles. Nanofiber-dispersed BGEs have high thermal and mechanical stabilities, according to TGA, DSC, and UTM tests.

Electrocatalytic performance on methanol oxidation reaction of highly stabilized Pt–Pd–Co ternary alloys by organometallic approach in alkaline medium

CoPtPd/C ternary alloys were prepared in situ as catalysts in different compositions by tuning the architecture and composition of cobalt in the reduction and displacement of ligands method to improve the efficiency of renewable energy, specifically in the methanol oxidation reaction (MOR) in alkaline medium. Chemical analyses shown that the theoretical and experimental compositions were well matched to obtain Pt70Pd10Co20/C, Pd70Pt10Co20/C, Co70Pt20Pd10/C and Co70Pt10Pd20/C ternary alloys, indicating that the method allowed precise control of components loading. Electrochemical investigations confirmed that the proposed method promoted a better synergistic effect between the components when Co is added in large amounts (70 wt%) regardless of the noble metal ratio, accelerating the oxidation of the adsorbed CO to CO2, inhibiting the poisoning during MOR. The Co70Pd20Pt10/C electrode materials displayed the highest electroactivity on MOR. This method is a promising alternative to reduce the amount of noble metal in catalysts used in direct alcohol fuel cells.

Electrochemical study and modeling of an innovative pyrazole carboxamide derivative as an inhibitor for carbon steel corrosion in acidic environment.

The impact of N,1-dibenzyl-5-methyl-1H-pyrazol-3-carboxamide (BPC) on the carbon steel (CS) corrosion in hydrochloric acid (1M) was studied in this work, considering concentration and temperature effects. Electrochemical investigation indicated that BPC functions as a mixed-type inhibitor. For an optimal BPC concentration of 125ppm, the inhibition efficiency of 91.55% was obtained at 298K. According to adsorption isotherm of Langmuir, the BPC adheres to the CS with standard adsorption free energy (ΔG°ads) of - 26.76kJmol-1. Furthermore, the calculation of dissolution activation parameters revealed an increase in energy (Ea) from 46.48 to 94.97kJmol-1, an elevation in the enthalpy (∆Ha) from 43.89 to 92.37kJmol-1, and a rise in the entropy (∆Sa) from - 91.17 to 51.43Jmol-1K-1 in the presence of 125ppm of BPC. The experimental results were confirmed by quantum chemistry calculations based on density functional theory (DFT) and molecular simulations using the Monte Carlo method. These theoretical approaches also allowed for a comparison of the inhibitory performances of BPC with its protonated form, BPCH, the latter being found more effective. Moreover, the study of the radial distribution function g(r) predicted that the nature of the bond formed with the steel surface is of a chemical type.

A Complex Oxide Containing Inherent Peroxide Ions for Catalyzing Oxygen Evolution Reactions in Acid.

Proton exchange membrane water electrolyzers powered by sustainable energy represent a cutting-edge technology for renewable hydrogen generation, while slow anodic oxygen evolution reaction (OER) kinetics still remains a formidable obstacle that necessitates basic comprehension for facilitating electrocatalysts' design. Here, we report a low-iridium complex oxide La1.2Sr2.7IrO7.33 with a unique hexagonal structure consisting of isolated Ir(V)O6 octahedra and true peroxide O22- groups as a highly active and stable OER electrocatalyst under acidic conditions. Remarkably, La1.2Sr2.7IrO7.33, containing 59 wt % less iridium relative to the benchmark IrO2, shows about an order of magnitude higher mass activity, 6-folds higher intrinsic activity than the latter, and also surpasses the state-of-the-art Ir-based oxides ever reported. Combined electrochemical, spectroscopic, and density functional theory investigations reveal that La1.2Sr2.7IrO7.33 follows the peroxide-ion participation mechanism under the OER condition, where the inherent peroxide ions with accessible nonbonded oxygen states are responsible for the high OER activity. This discovery offers an innovative strategy for designing advanced catalysts for various catalytic applications.

Effect of Synthesis Conditions on the Structure and Electrochemical Properties of Vertically Aligned Graphene/Carbon Nanofiber Hybrids

In recent years, significant efforts have been dedicated to understanding the growth mechanisms behind the synthesis of vertically aligned nanocarbon structures using plasma-enhanced chemical vapor deposition (PECVD). This study explores how varying synthesis conditions—specifically hydrocarbon flow rate, hydrocarbon type, and plasma power—affect the microstructure, properties, and electrochemical performance of nitrogen-doped vertically aligned graphene (NVG) and nitrogen-doped vertically aligned carbon nanofibers (NVCNFs) hybrids. It was observed that adjustments in these synthesis parameters led to noticeable changes in the microstructure, with particularly significant alterations when changing the hydrocarbon precursor from acetylene to methane. The electrochemical investigation revealed that the sample synthesized at higher plasma power exhibited enhanced electron transfer kinetics, likely due to the higher density of open edges and nitrogen doping level. This study contributes to better understanding the PECVD process for fabricating nanocarbon materials, particularly for sensor applications.

Sensitive electrochemical sensing of carbosulfan in food products on laser reduced graphene oxide sensor decorated with silver nanoparticles

A simple, low-cost, eco-friendly, highly sensitive and selective electrochemical sensor based on laser reduced graphene oxide (LrGO) decorated with silver nanoparticles (LrGO/AgNPs) on a recycled green polyethylene terephthalate (PET) substrate was fabricated for the detection of carbosulfan in food products. An inexpensive disposable PET substrate was used to fabricate the flexible sensor using eco-friendly laser printing. Electrochemical investigations and surface characterization of sensor surfaces were performed with cyclic voltammetry (CV), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). Under the optimum conditions, the LrGO/AgNPs sensor showed a well-developed CV peak current with a good linear dynamic range (LDR) from 0.01 to 10 mg·kg−1 for the determination of carbosulfan with a limit of detection (LOD) of 0.005 mg·kg−1. The LrGO/AgNPs sensor was successfully applied for CV determination of carbosulfan in food products (apples, oranges and basmati rice) with a promising recovery from 90 % to 105 % and relative standard deviations (RSD) lower than 5 %. The novel sensor showed remarkable sensitivity, selectivity, reproducibility, and long-term stability. Therefore, this study showed that the fabricated electrochemical LrGO/AgNPs sensor is an excellent tool for the determination of carbosulfan in food products.

Electrochemical and quantum chemical investigation on the adsorption behavior of a schiff base and its metal complex for corrosion protection of mild steel in 15 wt% HCl solution

This work evaluates the effectiveness of Schiff base derivatives, namely, 2,2'-((1E,1′E)-((2,2-dimethylpropane-1,3-diyl)bis(azaneylylidene))bis(methaneylylidene))diphenol (DAMD) and (2-((E)-((3-(((E)-2-hydroxybenzylidene)amino)-2,2dimethylpropyl)imino)methyl)phenoxy) zinc (HDMZ), as corrosion inhibitors for mild steel in a 15 % HCl solution. By employing a blend of experimental assessments and theoretical computations, such as electrochemical tests, morphological observations, and theoretical simulations, the study achieved an impressive up to 94.6 % inhibition efficiency. Notably, HDMZ exhibited significant protective properties. The results of PDP showed that both inhibitors act as mixed-type corrosion inhibitors. SEM surface analysis of the uninhibited and inhibited samples revealed the formation of a protective layer of inhibitor molecules on the mild steel surface to mitigate its corrosion. The Langmuir adsorption model verified the occurrence of dual adsorption, while theoretical simulations offered insights into the underlying interaction mechanisms. The identification of Schiff-based inhibitors reveals a pronounced synergistic effect in corrosion inhibition, marking a significant advancement in understanding corrosion control mechanisms. This study illuminates the process of forming covalent bonds between inhibitor molecules and iron atoms, presenting a hopeful path towards the advancement of corrosion inhibitors tailored for industrial use. The parallel adsorption configuration and mutual interactions form a stable structure, reinforcing the organic-metal bonds and enhancing both chemical and physical adhesion to the steel surface. These findings indicate that the synergistic effect of molecular interactions and polar-rich regions offers a promising strategy for designing functional hybrid materials.

Boosting the Microbial Electrosynthesis of Formate by Shewanella oneidensis MR-1 with an Ionic Liquid Cosolvent.

Microbial electrosynthesis (MES) is a rapidly growing technology at the forefront of sustainable chemistry, leveraging the ability of microorganisms to catalyze electrochemical reactions to synthesize valuable compounds from renewable energy sources. The reduction of CO2 is a major target application for MES, but research in this area has been stifled, especially with the use of direct electron transfer (DET)-based microbial systems. The major fundamental hurdle that needs to be overcome is the low efficiency of CO2 reduction largely attributed to minimal microbial access to CO2 owing to its low solubility in the electrolyte. With their tunable physical properties, ionic liquids present a potential solution to this challenge and have previously shown promise in facilitating efficient CO2 electroreduction by increasing the CO2 solubility. However, the use of ionic liquids in MES remains unexplored. In this study, we investigated the role of 1-ethyl-3-methylimidazolium acetate ([EMIM][Ac]) using Shewanella oneidensis MR-1 as a model DET strain. Electrochemical investigations demonstrated the ability of S. oneidensis MR-1 biocathodes to directly convert CO2 to formate with a faradaic efficiency of 34.5 ± 26.1%. The addition of [EMIM][Ac] to the system significantly increased cathodic current density and enhanced the faradaic efficiency to 94.5 ± 4.3% while concurrently amplifying the product yield from 34 ± 23 μM to 366 ± 34 μM. These findings demonstrate that ionic liquids can serve as efficient, biocompatible cosolvents for microbial electrochemical reduction of CO2 to value-added products, holding promise for more robust applications of MES.

Development of heterostructured ZnCo2O4@Ni-MOF electrode for the asymmetric supercapacitor and electrocatalytic oxygen evolution reaction applications

The stable structure and material combination design significantly improve the performance of electrochemical energy storage and water splitting. In the present study, we developed a ZCO@Ni-MOF core-shell structure over a nickel foam electrode, which is synthesized through a two-step hydrothermal treatment. The developed material is comprehensively analyzed to confirm structural, chemical, electronic, surface, and morphological characteristics using X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscope (SEM), and transmission electron microscope (TEM). Electrochemical investigations using a three-electrode system revealed that ZCO@Ni-MOF demonstrated an impressive specific capacitance of 1800 F g−1 at a current density of 2 A g−1 in a 1 M KOH electrolyte. The electrochemical findings are consistent across various electrochemical techniques. Furthermore, in-depth studies regarding p-n junction formation, interlayer spacing, and reaction kinetics studies are briefly analyzed with Mott-Schottky, Ex-situ XRD, and operando impedance studies. Moreover, an asymmetric supercapacitor (ASC) is assembled with ZCO@Ni-MOF as the positive electrode and activated carbon as the negative electrode in a Swagelok cell. This configuration demonstrated an energy density of 13.6 Wh kg−1 at a power density of 225 W kg−1. The ASC exhibited performance by retaining 91 % of its initial capacity even after 1500 cycles. For practical demonstration, two ASCs are fabricated and assembled in series to light up an LED, and the light-up duration is analyzed. For the oxygen evolution reaction (OER) study, the ZCO@Ni-MOF-based electrode exhibited activity with a lower overpotential of 340 mV (50 mA cm−2) in an alkaline environment and was responsible for stability for about 10 h. This combination reiterates the promising material aspects in energy storage and conversion devices, instilling hope for its potential applications.

An open source electrochemical channel flow cell setup for kinetics studies. Application to investigations on oxygen electrocatalysis

Herein, an electrochemical channel flow cell setup that allows for conducting electrochemical investigations up to 80°C and pressurized gases up to 3 bar is presented in details, including technical drawings and list of parts, in an attempt to facilitate the adoption of such setup by the community for electrochemical/electrocatalytic kinetic studies. The oxygen reduction reaction (ORR) on a commercial Pt/C catalyst, chosen as a model reaction, was investigated to demonstrate the reliability of the experimental setup, including the hydrodynamic properties, to provide hands on practical guidelines to carry out experiments, and, on the other hand, to illustrate the capabilities of this electrochemical setup for an assessment of basic quantities. Among the various quantities that have be determined experimentally for the ORR, a monotonic decay of the activation enthalpy and bell-shaped variation of the entropy of activation were resolved as the overpotential for the ORR increases. These fundamental thermodynamic/kinetic data are briefly discussed within the frame of the established reaction mechanism and can serve as a feed for the benchmarking of the outputs from theoretical/computational models. Furthermore, a remarkable agreement was obtained between the change in the activation free Gibbs energy determined for the ORR with the flow cell setup and the kinetic region of fuel cell polarization curve obtained with the same Pt/C catalyst embedded in the cathode of an a hydrogen proton exchange membrane fuel cell. This enables potentially a bridge of the environmental gap existing between model experiments conducted at active material level in contact with liquid electrolyte and experiments with porous gas diffusion electrode embedding the same active material that are employed in practical device.

Multifunctional benzoselenadiazole-capped organic molecule-based nanohybrid for efficient asymmetric supercapacitor and oxygen evolution reaction

Nanostructured hybrid materials have attracted significant interest in the field of energy storage and conversion. To investigate the effect of all nanohybrids on electrochemical properties, we have synthesized organic-inorganic nanohybrids through in situ galvanostatic electrodeposition using a monometallic and bimetallic composition of nickel, cobalt salts and an organic molecule. The electrochemical studies reveal that BSeFY/NCDH (20:20) (BSe = benzo[2,1,3]selenadiazole, F = L-phenylalanine and Y = L-tyrosine; NCDH = nickel‑cobalt double hydroxide) hybrid electrode performs more efficiently than 40:0, 0:40, 10:30, 30:10 and nickel‑cobalt double hydroxide-20:20 (NCDH-20:20) electrodes. The specific capacitance of the 20:20 hybrid electrode is measured to be 1338.46 F/g at 2 A/g current density. The AC/NF negative electrode was made using activated carbon, carbon black and polyvinylidene fluoride (PVDF) in a ratio of 80:15:5. The fabricated asymmetric device reveals the energy density of 35.48 Wh/kg at a power density 751.36 W/kg. Furthermore, the device exhibits a capacitance retention of 91.24 % after 5000 cycles at 7 A/g current density. This fabricated device has the ability to illuminate a red LED and operate a small fan. Furthermore, the designed and fabricated hybrid materials are highly efficient for the oxygen evolution reaction (OER). Among the fabricated materials, the 20:20 hybrid electrode is highly active and achieves a lower overpotential of 240 mV with a low Tafel slope of 62 mV/dec at a current density of 10 mA/cm2. Furthermore, the BSeFY/NCDH (20,20) hybrid is highly robust and shows negligible activity loss after 55 h of chronopotentiometry measurement at 10 mA/cm2 current density. Furthermore, multistep chronopotentiometry was performed in the current density range of 4 to 40 mA/cm2 and the results exhibit that the potential rapidly levels off in the next 400 s due to the robust electrochemical stability, rapid mass and electron transportation ability of 20:20 nanohybrid. Therefore, the electrochemical investigations demonstrate that the bimetallic organic-inorganic nanohybrid is highly active in supercapacitor and OER due to its abundant electrochemical active sites, high conductivity, enhanced Faradaic redox properties, multiple valence transitions and the easy synergistic effect between metal ions and organic moiety.

Electrochemical Investigation of the Oxidation of Phenolic Compounds Using Hypervalent Iodine Oxidants.

The chemical oxidation of simple phenolic compounds by the hypervalent iodine reagent [hydroxy(tosyloxy)iodo]benzene (HTIB) was investigated using electrochemical and spectroscopic methods. HTIB oxidized phenol and benzenediol isomers hydroquinone (HQ), catechol, and resorcinol to form various quinone structures. HQ and catechol, two compounds that show reversible electrochemical behavior, exhibited simple oxidative chemistry to their respective quinone structures that could be electrochemically reduced at a glassy carbon electrode. An HTIB:compound ratio of 2:1 resulted in the complete chemical oxidation of these model compounds. However, phenol and resorcinol, two compounds that are known to readily foul electrode surfaces upon their electrochemical oxidation, required a 6:1 HTIB:compound ratio to achieve complete chemical oxidation. The oxidation of resorcinol resulted in a compound that could not be electrochemically reduced; however, the oxidation of phenol from HTIB resulted in an electrochemical redox couple that suggested the preferential formation of benzoquinone, with the possibility of some o-quinone also being produced. This work serves as a proof-of-concept method for the possible indirect electrochemical detection of phenolic compounds.

Electrochemical investigations of decorated graphite felt electrodes with Nafion/TiO2 nanoparticles for vanadium redox flow battery: Improving electro-catalytic characteristics

The present study aimed to investigate the effect of Nafion/TiO2 nanoparticles as an electrocatalyst on the electrochemical behavior of graphite felt (GF) electrodes in a vanadium redox flow battery. Various electrochemical tests, including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV), were conducted to assess the performance of these electrodes at different concentrations of nanoparticles (2–4 g l-1). Additionally, X-ray diffraction, Fourier transform infrared spectroscopy, and field emission scanning electron microscopy were employed to analyze the chemical composition, bonding, and morphology of the decorated electrodes, respectively. The CV results revealed several effects of TiO2 nanoparticles on the GF electrode, such as increased peak intensity and shifted peak sites. As the concentration of nanoparticles increased, the peak intensity rose by up to 44%. Moreover, the potentials of the decorated electrodes shifted towards the favorable side compared to the GF electrode, with changes ranging from 18 to 84%. Overall, the optimal concentration of TiO2 nanoparticles (3 g l-1) exhibited excellent electrode performance, characterized by the highest calculated diffusion coefficient, greater reversibility, enhanced electron transfer kinetics, improved stability, lower over-potential, and the lowest activation energy for redox reactions. EIS results demonstrated a significant decrease in polarization resistance (67.2–70.8%) for the decorated electrodes. Furthermore, LSV measurements indicated that the utilization of nano-electrocatalysts effectively inhibited hydrogen evolution at negative potentials.

Eco-friendly high microporosity low temperature plasma exposed activated carbon from coconut shell for nano hybrid supercapacitors

Abstract This study looked at the structural, chemical, and electrochemical properties of coconut shell activated carbon (CSAC) before and after plasma treatment. Structural analysis using x-ray diffraction (XRD) demonstrated that plasma treatment improves graphitic structure by plans at (002) and (101) for higher angles. Chemical investigation utilizing Fourier-transform infrared spectroscopy (FTIR) revealed an increase in hydroxyl groups and carboxylic content following plasma treatment, which enhances electrochemical performance. Raman spectroscopy revealed a drop in the ID/IG ratio from 1.00 to 0.90, indicating enhanced graphitic order. Scanning electron microscopy (FESEM) showed that plasma treatment improves surface shape, while elemental analysis assessed the high carbon content (76.56% by weight). Contact angle measurements showed a decrease from 114° to 65°, showing improved hydrophilicity after treatment. Electrochemical investigation shows that the plasma-treated CSAC had a maximum specific capacitance of 1612 F g−1, compared to 729 F g−1 for the untreated CSAC, and a total capacitance of plasma treated1685 F/g are untreated 1400 F g−1. A Type II+III pattern on the isotherms implied capillary condensation in mesopores. The plasma treatment indicated improved porosity and potential adsorption capacity by increasing the specific surface area and decreasing the average pore width. The cyclic stability tests indicated that the plasma-treated CSAC retained 94% capacitance and 98% coulombic efficiency after 3000 cycles, which is superior to the untreated CSAC’s 92% capacitance retention and 95% coulombic efficiency. This reveals that plasma-treated CSAC has significantly improved performance and stability, making it an excellent alternative for high-performance and cost-effective energy storage applications.

Effects of plasma surface modification of Mg-2Y-2Zn-1Mn for biomedical applications

Magnesium (Mg) alloys have emerged as promising materials for biodegradable implants in orthopedic, oral, and cardiovascular applications. Despite their potential, high corrosion rate, and release of diatomic hydrogen in the surrounding environment remain the unmet challenges. In this research, oxygen plasma ion immersion implantation (O-PIII) was investigated in an attempt to modify the degradation rate of Mg-2Y-2Zn-1Mn alloy. In particular, the effects of pulse duration (tpd) and pressure (p) on the degradation rate were investigated. For all the investigated conditions, plasma treatment enriched the surface chemical composition with O, forming a Mg- and Y- rich oxide layer. Mg and Y elements were mainly concentrated at grain boundaries. The concurrent phenomena of sputtering and energetic implantation led to crystalline Y2O3 formation. Electrochemical investigations confirm that the degradation rate of samples decreased significantly, from ∼0.23 mm/y for untreated to ∼0.07 mm/y for O-PIII conditions. These findings demonstrate the effectiveness of O-PIII in changing surface properties and controlling corrosion rate of Mg alloys.

Complexation of Trivalent Lanthanides with Hexaalkyl Nitrilotriacetamides into Methylimidazolium-Based Ionic Liquids: Spectroscopic, Electrochemical, Calorimetric, and Theoretical Insights.

Exothermic, spontaneous inner-sphere complexation of trivalent lanthanides with N,N,N',N',N″,N″-hexaalkyl-substituted nitrilotriacetamides (HRNTAs) into 1-hexyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide (C6mim NTf2) is reported with a predominant presence of ML and ML2 complexes having complexation constants, β1Eu 3.10 ± 0.02 ,β1Nd 2.67 ± 0.03 and β2Eu 5.22 ± 0.04, β2Nd 4.95 ± 0.02, respectively, for the n-butyl-substituted HRNTA (HBNTA); while those for the n-hexyl derivative (HHNTA) are β1Eu 4.27 ± 0.03, β1Nd 3.71 ± 0.03 and β2Eu 7.70 ± 0.03, β2Nd 7.18 ± 0.04, respectively. HHNTA shows better complexing ability; whereas the stronger complexation of the Nd3+ over Eu3+ is attributed to the lanthanide contraction. Furthermore, the nature of the ionic liquid also influences the extent of complexation with the trend: C4mim NTf2 > C6mim NTf2 > C8mim NTf2, which follows the order of their dielectric constants. Judd-Ofelt parameters were calculated from photoluminescence data to get an idea about the symmetry of the Eu3+ complexes. Electrochemical investigations give diffusion coefficient values of 1.17 × 10-7 and 8.26 × 10-8 cm2/s for the Eu3+ complexes of HBNTA and HHNTA, respectively. Changes in the spectral characteristics and peak positions are evidenced in the FTIR spectra on the complexation of Eu3+ with the HRNTA ligands in C6mim NTf2. Structure optimization for the complexes was performed by DFT computations.