Electrochemical Impedance Spectroscopy Analysis Research Articles

Optimization of Intercalated 2D BiOCl Sheets into Bi2WO6 Flowers for Photocatalytic NH3 Production and Antibiotic Pollutant Degradation.

Photocatalytic N2 fixation is a complex reaction, thereby prompting researchers to design and analyze highly efficient materials. Herein, one-pot hydrothermal Bi2WO6-BiOCl (BW-BiOCl) heterojunctions were synthesized by varying the molar ratio of tungsten: chlorine precursor. Major morphological transformations in BiOCl were observed wherein it turned from thick sheets ∼230 nm in pure BiOCl to ∼30 nm in BW-BiOCl. This was accompanied by extensive growth of {001} facets verified from X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) analyses. A p-n heterojunction was formed between Bi2WO6 and BiOCl evidenced via photoluminescence (PL), time-resolved photoluminescence (TRPL), photocurrent response, and electrochemical impedance spectroscopy (EIS) analyses. The formation of heterojunction between Bi2WO6 and BiOCl led to the reduction of the work function in the BW-BiOCl 0.25 hybrid confirmed via ultraviolet photoelectron spectroscopy (UPS) analysis. BW-BiOCl 0.25 could produce ammonia up to 345.1 μmol·L-1·h-1 owing to the formation of a robust heterojunction with an S-scheme carrier transport mechanism. Recycle tests resulted in no loss in N2 reduction activities with post-catalytic analysis, showcasing the high stability of the synthesized heterojunction. Novel performance was owed to its excellent chemisorption of N2 gas on the heterojunction surface verified by N2-temperature programmed desorption (TPD). BW-BiOCl 0.25 also displayed a superior rate constant of 3.03 × 10-2 min-1 for 90 min CIP degradation time, higher than pristine BiOCl and Bi2WO6. Post-photocatalytic Fourier transform infrared (FTIR) spectroscopy of BW-BiOCl 0.25 revealed the presence of C-H stretching peaks in the range of 2850-2960 cm-1 due to adsorbed CIP and methanol species in CIP degradation and N2 fixation, respectively. This also confirmed the enhanced adsorption of reacting species onto the heterojunction surface.

Electrochemical investigation of the corrosion susceptibility of hybrid reinforced Al6063 with SiC and PKSA in 1.0 M sulfuric acid environment

AbstractThe recycling of agro‐waste as complementary reinforcements has received significant recognition in the development of aluminium matrix composites. Hence, this study examines the corrosion behavior of Al6063 reinforced with hybrid SiC/PKSA (palm kernel shell ash) particles. Through various ratios of SiC and PKSA particles in Al6063 alloy, composites were fabricated by double stir casting. Samples were cut and metallographically prepared for 1 M H2SO4 solution corrosion experiments. Gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopic analyses were employed. The composites corroded initially at relatively high rates, gradually declining during long immersion times in the acidic solution. The intersection of reinforcements at the general surfaces of the composites where flawed oxide skins predominate acted as active sites for corrosion initiation. From potentiodynamic polarization studies, the corrosion currents increased with time for all specimens, with A9 being 1075.65 μA/cm2 at 72 h as against 857.99 μA/cm2 at 24 h of measurement. The corrosion potentials for all the specimens hovered around −654.00 to −647.22 mV. Bode plots revealed similar electrochemical reactions over all the substrates' surfaces. The relative corrosion resistance by the specimen depends on the oxide films' nature as the cathodic interfacial reinforcements dropped off into the acidic environment.

Self-Standing Pd-Based Nanostructures for Electrocatalytic CO Oxidation: Do Nanocatalyst Shape and Electrolyte pH Matter?

Tailoring the shape of Pd nanocrystals is one of the main ways to enhance catalytic activity; however, the effect of shapes and electrolyte pH on carbon monoxide oxidation (COOxid) is not highlighted enough. This article presents the controlled fabrication of Pd nanocrystals in different morphologies, including Pd nanosponge via the ice-cooling reduction of the Pd precursor using NaBH4 solution and Pd nanocube via ascorbic acid reduction at 25 °C. Both Pd nanosponge and Pd nanocube are self-standing and have a high surface area, uniform distribution, and clean surface. The electrocatalytic CO oxidation activity and durability of the Pd nanocube were significantly superior to those of Pd nanosponge and commercial Pd/C in only acidic (H2SO4) medium and the best among the three media, due to the multiple adsorption active sites, uniform distribution, and high surface area of the nanocube structure. However, Pd nanosponge had enhanced COOxid activity and stability in both alkaline (KOH) and neutral (NaHCO3) electrolytes than Pd nanocube and Pd/C, attributable to its low Pd-Pd interatomic distance and cleaner surface. The self-standing Pd nanosponge and Pd nanocube were more active than Pd/C in all electrolytes. Mainly, the COOxid current density of Pd nanocube in H2SO4 (5.92 mA/cm2) was nearly 3.6 times that in KOH (1.63 mA/cm2) and 10.3 times that in NaHCO3 (0.578 mA/cm2), owing to the greater charge mobility and better electrolyte-electrode interaction, as evidenced by electrochemical impedance spectroscopy (EIS) analysis. Notably, this study confirmed that acidic electrolytes and Pd nanocube are highly preferred for promoting COOxid and may open new avenues for precluding CO poisoning in alcohol-based fuel cells.

Robust Proton Conduction against Mechanical Stress in Flexible Free‐Standing Membrane Composed of Two‐Dimensional Coordination Polymer

AbstractIntroduction of mechanical flexibility into proton‐conducting coordination polymers (CPs) is in high demand for future protonic applications such as fuel cells and hydrogen sensors. Although such mechanical properties have been primarily investigated in one‐dimensional (1D) CPs, in this study, we successfully fabricated highly flexible free‐standing CP membranes with a high surface‐to‐volume ratio, which is beneficial for enhanced performance in the aforementioned applications. We fabricated a layered CP, Cu2(NiTCPP) (H4(H2TCPP); 5,10,15,20‐tetrakis(4‐carboxyphenyl) porphyrin), in which a two‐dimensional (2D) square grid sheet composed of tetradentate nickel porphyrins and paddlewheel‐type copper dimers was connected to each other by weak van der Waals forces. The mechanical flexibility was evaluated by bending and tensile tests. The flexural and Young's moduli of the membrane were significantly higher than those of conventional Nafion membranes. Electrochemical impedance spectroscopy analysis revealed that the in‐plane proton conductivity of the membrane was maintained even under applied bending stress. Because the X‐ray diffraction analysis indicates that the proton‐conducting pathway through the hydrogen bonding network remains intact during the bending operation, our present study provides a promising strategy for the fabrication of new and advanced 2D CPs without using substrates or additional polymers for protonic devices.

Robust Proton Conduction against Mechanical Stress in Flexible Free-Standing Membrane Composed of Two-Dimensional Coordination Polymer.

Introduction of mechanical flexibility into proton-conducting coordination polymers (CPs) is in high demand for future protonic applications such as fuel cells and hydrogen sensors. Although such mechanical properties have been primarily investigated in one-dimensional (1D) CPs, in this study, we successfully fabricated highly flexible free-standing CP membranes with a high surface-to-volume ratio, which is beneficial for enhanced performance in the aforementioned applications. We fabricated a layered CP, Cu2 (NiTCPP) (H4 (H2 TCPP); 5,10,15,20-tetrakis(4-carboxyphenyl) porphyrin), in which a two-dimensional (2D) square grid sheet composed of tetradentate nickel porphyrins and paddlewheel-type copper dimers was connected to each other by weak van der Waals forces. The mechanical flexibility was evaluated by bending and tensile tests. The flexural and Young's moduli of the membrane were significantly higher than those of conventional Nafion membranes. Electrochemical impedance spectroscopy analysis revealed that the in-plane proton conductivity of the membrane was maintained even under applied bending stress. Because the X-ray diffraction analysis indicates that the proton-conducting pathway through the hydrogen bonding network remains intact during the bending operation, our present study provides a promising strategy for the fabrication of new and advanced 2D CPs without using substrates or additional polymers for protonic devices.

Desalination performance of shale gas produced water by flow-electrode capacitive deionisation process

The cost-effective desalination of shale-gas produced water (PW) has long been an industrial research hotspot. Flow-electrode capacitive deionisation (FCDI), a recently developed electrochemical desalination technology, may be a novel option for PW disposal because of its attractive advantages. However, reports on the desalination test of actual high-salinity industrial wastewater by FCDI are lacking. In this study, a laboratory-scale FCDI device with an online monitoring system was used to desalinate shale-gas PW. FCDI achieved relatively stable desalination efficiency for pretreated PW with a salinity of 2.65 % and reached an energy-normalised salt removal of 0.479 mg/J. The flow electrode chemically activated by KOH increased the FCDI average desalination rate by 98.5 % for the pretreated saline PW. Electrochemical impedance spectroscopy analysis revealed that the majority of fouling accumulated on the anion-exchange membrane (AEM) side. Residual pollutants were adsorbed by the flow electrode in the AEM chamber, which destroyed the optimal ion-transport path and electric double-layer structure. Results showed that FCDI was more suitable for PW’s reverse-osmosis (RO) permeate desalination to form an RO–FCDI hybrid. This study provided a practical experimental case on the electrochemical desalination of saline PW by FCDI.

The advanced polymer composite coated fabrics as an anode electrode and photocatalytic glucose micro fuel cell design

At present, poly N-isopropyl acrylamide (PNIPAM) polymer composites containing titanium dioxide (TiO2) and carbon-TiO2 (C-TiO2) were designed for photocatalytic glucose electrooxidation by coating the textile fabric surface such as wool blended fabrics called Sign Cocana (SC), Valencia (VC), Dante (DT), and Broadway (BW). C-TiO2 was obtained from TiO2 in a furnace under hexane gas with a certain temperature and time. Polymer synthesis was realized by a polymerization method. The surface analyses of these polymer composite fabric electrodes were characterized by scanning electron microscopy-energy dispersive X-Ray (SEM-EDX) and mapping analysis. In addition, tear and breaking strengths were examined. Photocatalytic activity of the polymer composite electrodes was examined by cyclic voltammetry (CV). The C-TiO2-graft(g)-PNIPAM/SC electrode exhibited the best photocatalytic activity under UV illumination with a specific activity of 2.80 mA/cm2 both in the dark and compared to other fabric electrodes. In addition, it was observed that it exhibited the best stability and resistance by chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) analyses. It could be a promising anode electrode for photocatalytic fuel cells and wearable electronics.

Bionanocomposites containing SnO2 with improved chemical resistance and hydrophobic behaviours for applications in food packaging industry

The influence of poly(asparagine-co-phenylalanine) (P(Asn-co-Phe)/SnO2) on the protection performance of epoxy coating was investigated. The electrochemical impedance spectroscopy (EIS) analysis indicates the better protection against coating degradation of epoxy (EP)−P(Asn-co-Phe)/SnO2 nanocomposite on tinplate compared to that of pure epoxy coatings. The coating resistance (Rcoat) of the EP−P(Asn-co-Phe)/SnO2 nanocomposite is found to be 3854.70 kΩ·cm2. The Rcoat of EP−P(Asn-co-Phe)/SnO2 nanocomposite coating is found to be over 38 times greater than that of the EP coating. Scanning electrochemical microscopy (SECM) analysis shows less current distribution for the EP−P(Asn-co-Phe)/SnO2. The analyses of degradation products by XRD and SEM/EDX confirm the influence of functionalized SnO2 particles on the protecting ability of epoxy coating. The hydrophobic nature of the EP−P(Asn- co-Phe)/SnO2 nanocomposite coating (θ=133°) is confirmed by water contact angle measurement. The resultant nanocomposite coatings display enhanced mechanical properties. The results show that the EP−P(Asn-co-Phe)/SnO2 nanocomposite in wells increased the antibacterial activity as compared with pure EP. Therefore, it is concluded that the newly synthesized EP−P(Asn-co-Phe)/SnO2 nanocomposite provides an outstanding barrier and mechanical properties due to the addition of P(Asn-co-Phe)/SnO2 nanoparticles to the epoxy matrix, which obstructs the degradation of materials and assists in prolonging the life of the coated steel.

An impedance-based chemiresistor for the real-time, simultaneous detection of gut microbiota-generated short-chain fatty acids

Short-chain fatty acids (SCFAs) are key molecules, produced by gut bacteria in the intestine, that are absorbed into the bloodstream and strongly influence human health. SCFA disruption and imbalances have been linked to many diseases; however, SCFAs are seldom used diagnostically as their detection requires extensive sample preparation and expensive equipment. In this work, an electrochemical sensor was developed to enable real-time (requiring less than 2 min per measurement), quantitative measurement of SCFAs from complex samples in liquid phase without the need for extraction, evaporation, or destruction. An impedance-based sensor for in vitro detection of acetic acid, propionic acid, and butyric acid (accounting for more than 85% of SCFAs in the intestine) was fabricated by the deposition of ZnO and polyvinyl alcohol (PVA) on the surface of a microfabricated interdigitated gold electrode. The sensor was first exposed to a broad, physiologically relevant range of concentrations of SCFAs in isolation (0.5–20 mg/ml in electroanalytical cell), and, unlike previously published SCFA sensors that could detect only in gas form with the aid of evaporation, it was able to detect them directly in the liquid phase at room temperature. Subsequently, Electrochemical Impedance Spectroscopy (EIS) analysis was utilized in a complex medium, accompanied by Fe(CN)63−/4−. This was applied to a mixture of SCFAs, prepared in varying ratios and concentrations spanning from 0.5 to 10 mg/ml. The analysis successfully demonstrated the sensor's capacity to accurately measure SCFAs in a mixture of experimental relevance. The recorded faradaic responses were then used to train a fit-to-data model to screen human bacterial isolates and detect which species secrete SCFAs in vitro. This research paves the way for swift, non-destructive assessment of SCFA levels in complex biological samples. The end product is a miniaturized sensor that is highly stable and sensitive, making it ideal for real-time monitoring applications.

Designing of manganese-based oxides and oxyhydroxides as positive electrode materials and activated carbon from Phyllanthus emblica as negative electrode material for battery type supercapacitor

Effective energy storage and prompt energy discharge using better catalysts is the cornerstone for clean energy-based applications. Manganese based materials is an abundant, environmentally friendly and low-cost catalyst for supercapacitor applications. In this work, three manganese based systems (β-MnO2, γ-MnOOH and Mn3O4) were synthesised by hydrotermal method. The ability of manganese to interchage it oxidation state through electron transfer reactions made manganese based systems become one of the prominent cathode material for supercapaciter applications. The supercapacitor studies were carried out using Cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) analysis. In this work Mn3O4 showed better charge transfer resistence and specific capacity (597 C/g) compared to β-MnO2 and γ-MnOOH. The high surface area (1189.14 m2/g) activated carbon prepared in-house from Phyllanthus emblica was used as negative electrode and Mn3O4 as positive electrode in device fabrication. The cycling stability study of the fabricated device reveals 92% capacity retention after 5000 cycles at 100 mV/s. The Power density value of 800 W/kg and the energy density of 4 W/kg was achieved at a current density 1 A/g.

Investigating the Inhibitory Properties of Cupressus sempervirens Extract against Copper Corrosion in 0.5 M H2SO4: Combining Quantum (Density Functional Theory Calculation-Monte Carlo Simulation) and Electrochemical-Surface Studies.

The study investigates the potential of Cupressus sempervirens (EO) as a sustainable and eco-friendly inhibitor of copper corrosion in a 0.5 M sulfuric acid medium. The electrochemical impedance spectroscopy analysis shows that the effectiveness of corrosion inhibition rises with increasing inhibitor concentrations, reaching 94% with the application of 2 g/L of EO, and potentiodynamic polarization (PDP) studies reveal that EO functions as a mixed-type corrosion inhibitor. In addition, the Langmuir adsorption isotherm is an effective descriptor of its adsorption. Scanning electron microscopy/energy-dispersive X-ray spectroscopy, atomic force microscopy surface examination, and contact angle measurement indicate that EO may form a barrier layer on the metal surface. Density functional theory calculations, Monte Carlo simulation models, and the radial distribution function were also used to provide a more detailed understanding of the corrosion protection mechanism. Overall, the findings suggest that Cupressus sempervirens (EO) has the potential to serve as an effective and sustainable corrosion inhibitor for copper in a sulfuric acid medium, contributing to the development of green corrosion inhibitors for environmentally friendly industrial processes.

Smart Temperature-Gating and Ion Conductivity Control of Grafted Anodic Aluminum Oxide Membranes.

Over the past few decades, stimuli-responsive materials have been widely applied to porous surfaces. Permeability and conductivity control of ions confined in nanochannels modified with stimuli-responsive materials, however, have been less investigated. In this work, the permeability and conductivity control of ions confined in nanochannels of anodic aluminum oxide (AAO) templates modified with thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) brushes are demonstrated. By surface-initiated atom transfer radical polymerization (SI-ATRP), PNIPAM brushes are successfully grafted onto the hexagonally packed cylindrical nanopores of AAO templates. The surface hydrophilicities of the membranes can be reversibly altered because of the lower critical solution temperature (LCST) behavior of the PNIPAM polymer brushes. From electrochemical impedance spectroscopy (EIS) analysis, the temperature-gating behaviors of the AAO-g-PNIPAM membranes exhibit larger impedance changes than those of the pure AAO membranes at higher temperatures because of the aggregation of the grafted PNIPAM chains. The reversible surface properties caused by the extended and collapsed states of the polymer chains are also demonstrated by dye release tests. The smart thermo-gated and ion-controlled nanoporous membranes are suitable for future smart membrane applications.

Synergistic effect of Polydopamine incorporated Copper electrocatalyst by dopamine oxidation for efficient hydrogen production

Tuning the metal-support interaction in electrocatalysts has been proposed as a viable method for manipulating the electronic structure and catalytic activity. In this work, inspired by natural hydrogenase enzyme, electrocatalysts with a hybrid metal-matrix complex using polydopamine (PDA) as a supporting matrix were synthesized for efficient green hydrogen production. Among the various Metal-PDA electrocatalysts, Cu-PDA shows outstanding catalytic activity (low overpotential (ƞ) of 104 mV at 10 mA cm−2 and small Tafel slope of 60.67 mV dec-1) with high stability at neutral pH. Also, the electrochemical impedance spectroscopy analysis verified the fast charge transfer properties of Cu-PDA (2.8 Ω cm2) than PDA (26 Ω cm2), indicating a faster proton-coupled electron transfer process in Cu-PDA electrocatalyst. Therefore, emerging nature inspired organic ligand-transition metal ion complexes can be extensively encouraged as a prospective HER electrocatalyst under neutral conditions.

Spectroscopic analysis of plant trace element incorporated silver nanoparticles synthesis from Datura metel l.

Here in we report, silver nanoparticles (Ag NPs) prepared from leaf extract of Datura metel L. via green synthesis method. Datura metel L. is an herbal medicinal plant of solanaceae family. The as - prepared Ag NPs characterized employing UV-Vis spectrometer, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX) techniques. The appearance of Surface Plasmon Resonance (SPR) peak at 415 nm suggested that creation of Ag NPs in UV-Vis spectrum. XRD pattern showed face centered cubic crystal structure of Ag NPs with organometallic complex phase. Peaks in FTIR spectrum reveal the existence of biomolecules. SEM image illustrate their clastic rock morphology and EDAX profile authenticate the company of Ag and plant trace element. The Cyclic voltammetry (CV), Choronopotentiometry, and Electrochemical impedance spectroscopy (EIS) analysis were performed as prepared Ag electrode. The specific capacitance of 267.59 F/g at 0.5 A/g and cyclic retention of 83.7% after charge-discharge 5000 cycles are obtained. Hence this material could be utilized as Supercapacitor energy storage devices.

Capacitive polymer sensors: Factors influencing performance and design principles

Capacitive polymer sensors present a promising approach for machine olfaction arrays capable of detecting and classifying various analytes. In this study, a comprehensive analysis of factors influencing capacitive vapor sensors is performed. An in-depth analysis of performance of sensing polymers with a wide range of solubility interactions and dielectric constants is performed providing a foundation for sensor design principles. Unique frequency-dependent signal-to-noise behavior was observed for each polymer-analyte pair due to variations in polarization mechanisms, which was in turn used to tune the array for a better sensitivity. Film thickness and background humidity on array sensitivity was also explored. Design principles based on this study are used to optimize sensor arrays for the classification and quantification of analytes exhibiting distinct solubility interactions (alcohol, ketone, ester, and two hydrocarbons). Electrochemical impedance spectroscopy analysis provides valuable insight into the different physical processes and polarization mechanisms for each sensing polymer. The design principles explored have broad implications for other dielectric-based sensing systems, including integrated circuit-based arrays such as field-effect transistors.

Facile and environmentally friendly synthesis of highly efficient two-dimensional hematene nanosheets for photocatalytic applications

Exfoliation of bulk hematite (α-Fe2O3), as an environmentally friendly, nontoxicity, and low-cost semiconductor oxide, exhibited greater photocatalytic activity under visible light irradiation. Herein, we described two preparation methods of novel two-dimensional non-van der Waals hematene (2D-Hm) nanosheets including ultrasound-assisted liquid-phase exfoliation (US-Hm) and chemical-assisted liquid-phase exfoliation (CH-Hm). The photocatalytic activity of 2D-Hm nanosheets was evaluated for the decomposition of Tetracycline (TC). Various advanced analyses were used to investigate the physical and chemical properties of the exfoliated samples. SEM and TEM analyses confirmed the layered structures of 2D-Hm. The crystalline structure of 2D-Hm samples was confirmed successfully by XRD analyses. After exfoliation of bulk hematite, the surface area increased remarkably from 5.73 m2/g to 24.16, and 15.26 m2/g using US-Hm, and CH-Hm exfoliation methods, respectively. The photoelectrochemical photocurrent and electrochemical impedance spectroscopy (EIS) analysis indicate that 2D-Hm samples have higher charge-transfer efficiency than bulk hematite. Additionally, the formation of hydroxyl (•OH) radicals was approved using the o-phenylenediamine (OPD) and photoluminescence (PL) analysis. The leaching iron concentration in the aqueous phase was measured within five consecutive examinations. To recognize the intermediates formed during the degradation process, gas chromatography-mass spectrometry (GC–MS) was employed.

Electrode potential, inflammatory solution chemistry and temperature alter Ti-6Al-4V oxide film properties

Post implantation, a thin TiO2 film protects Ti-6Al-4V in vivo. Mechanically and chemically destructive conditions may disrupt this oxide film and promote corrosion at the device interface. While tribocorrosion has been explored in vitro, pre-clinical tests fail to fully reproduce the damage documented on retrievals. A gap persists in our fundamental knowledge of the oxide film and its response to adverse electrochemical events. In this study, we first characterized the TiO2 oxide film structure after inducing β phase selective dissolution. Next, we used electrochemical impedance spectroscopy and Mott-Schottky analysis to investigate the oxide film on freshly prepared surfaces following negative potential excursions. We systematically increased electrode potential from -1 V vs. Ag/AgCl in 0.1 V steps to +0.5 V. Various H2O2 concentrations (0.1 M to 0.001 M) in phosphate buffered saline and temperatures ranging from 24 °C to 55 °C were investigated. Atomic force microscopy showed morphological changes to oxide domes over the α phase following β phase selective dissolution. Below the Ti-6Al-4V open circuit potential (ca. -0.3 V), we identified systematic variations in polarization resistance (Rp) and capacitance (C) with potential, solution chemistry, and temperature. The combined effect of cathodic activation and H2O2 solution concentration synergistically and systematically decreased Rp by orders of magnitude (p = 0.000). Increased solution temperatures decreased Rp (p = 0.000). At high concentrations of ROS (0.1 M), we documented changes in constant phase element capacitance, from n-type to p-type. Finally, we developed empirical equations to predict Rp for a given concentration, temperature, and potential. In totality, these experiments help to further elucidate the complex interactions at the oxide-biology interface in vivo and provide guidance for in vitro testing methods development.

Combined electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy analysis of the passive films formed on 5083 aluminium alloy

A combined electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) approach showed that the corrosion behaviour of 5083 Al alloy was controlled by Mg dissolution at the Mg-rich intermetallic coarse particles (IMCs) that were defects of the passive film. It was thus shown that microstructures with high amount of Mg-rich IMCs were less resistant to corrosion. EIS experimental data were well superimposed with fitted ones calculated using a model proposed in the literature for pure magnesium. The model allowed to plot the resistivity profiles of the passive films, which highlighted their double-layer structure evidenced by XPS.

Gemcitabine drug intercalation with ds-DNA at surface of ds-DNA/Pt–ZnO/SWCNTs/GCE biosensor: A DNA-biosensor for gemcitabine monitoring confirmed by molecular docking study

Herein, a facile and highly sensitive electroanalytical tool for monitoring and quantifying the antineoplastic drug gemcitabine in real sample was provided. In this regard, a novel DNA-biosensor based on Pt-doped ZnO decorated single walled carbon nanotubes (Pt–ZnO/SWCNTs) hybrid nanomaterial modification of glassy carbon electrode (GCE) was fabricated. Ds-DNA (Calf Thymus), as a biological recognition element, was decorated onto nanomaterial-modified GCE via layer-by-layer fabrication strategy to attain ultimate biosensor ds-DNA/Pt–ZnO/SWCNTs/GCE. The characterizations confirmed the successful fabrication of hybrid nanomaterial, as well as the modification of electrode surface by fabricated nanomaterial. The electrochemical impedance spectroscopy (EIS) analysis revealed that the nanomaterial modification of GCE surface enhanced the electrical conductivity thanks to the synergistic effects of Pt–ZnO and SWCNTs structures, thereby boosted the electrocatalytic activity of the resultant biosensor. The electrochemical characterization results showed that the suggested biosensor is capable of detecting gemcitabine in a wide concentration range of 0.01–30.0 μM, with a detection limit of 5.0 nM. The intercalation binding mode of Gemcitabine inside guanine and cytosine rich region of DNA receptor was approved by molecular docking study. The results of the experimental data were well congruent with the molecular docking analysis, which showed that the binding mode of gemcitabine drug with ds-DNA was intercalation.

Comparison of the capacitance of MnCo2O4 supercapacitor electrode synthesized with different morphologies

In this research, manganese cobaltite (MCO) nanoparticles with different morphologies were synthesized by a simple hydrothermal method with excellent electrochemical properties. To investigate the physical features of prepared samples, XRD analysis was used to study the crystalline structure. The SEM and TEM proved that the morphology of synthesized materials formed as flake and nanoplane structures. The electrode of samples was prepared using the hydrothermal method and the electrochemical properties of samples were investigated by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), electrochemical impedance spectroscopy (EIS) and cyclic stability analysis. Results showed that the flake structures of nanoparticles revealed the highest capacitance of 1971.98[Formula: see text][Formula: see text] at 0.5[Formula: see text]Ag[Formula: see text] as well as longer stability compared to the others with the nanoplane structure. The high cyclic stability of 91.47% after 5000 cycles introduces this electrode as a durable and promising electrode for use in energy storage devices.