Electrochemical Impedance Spectroscopy Research Articles

Effect of Tungsten Doping on the Properties of Titanium Dioxide Dye-Sensitized Solar Cells

Tungsten-doped TiO2 thin films were prepared by sol–gel method on fluorine-doped tin oxide-coated substrates as working electrodes of dye-sensitized solar cells. The influences of different W doping (0, 2, 4, 6, and 8 at%) on the microstructure, optical, and photovoltaic properties of the W-TiO2 thin-film DSSCs were studied by the measurement of X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) analysis, and electrochemical impedance spectroscopy (EIS). An optimal DSSCs performance was observed with a 6 at% W-doped TiO2 thin film, resulting in a Voc of 0.68 V, a Jsc of 20.2 mA/cm2, an FF of 68.6%, and an efficiency (η) of 9.42%. The efficiency of DSSCs with 6 at% W-doped TiO2 photoanode improved by 75%. This is because the 6 at% W-doped TiO2 thin film increases the specific surface area and electron transfer rate.

Corrosion behaviors of La doped in-situ synthesized nano TiB2/6061 composites

The microstructure and corrosion behaviors of the in-situ synthesized nano TiB2/6061 composites with La doping were investigated by scanning electron microscope, potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5 wt% NaCl solution. The results indicated that La can make a significant improvement of corrosion resistance for TiB2/6061 composites. The corrosion potential of La-TiB2/6061 composites has increased by 11.31% compared with the composites without La. With La doping, the dispersive distribution of TiB2 particles suppressed the extending of corroded pits, the refined grains promoted the formation of oxide film in passive environment.

A novel molecularly imprinted electrochemical sensor based on MnO-Fe3O4@C was designed with DFT theoretical study for the detection of thiamphenicol in food

In this study, a new molecularly imprinted electrochemical sensor is presented for thiamphenicol (TAP) based on MnO-Fe3O4@C and a molecularly imprinted polymer (MIP). In the synthesis process of MIP, the density functional theory (DFT) was applied to simulated the interaction between different functional monomers and template molecules, and screen the optimal functional monomers and the ratio of optimal template molecules to functional monomers, which guided the electrochemical in-situ polymerization of MIP. The composite materials were evaluated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and the electrochemical performance of molecular imprinted electrode was evaluated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under the optimal conditions, there is a strong linear correlation between the current response and TAP concentration in the 0.01–1 μM (R2=0.9988) and 1–40 μM (R2=0.9954) range. The lowest detection limit (S/N = 3) was 0.007 μM. Besides, the sensor has good reproducibility, stability and anti-interference ability, and has successfully detected analytes in milk and egg samples, which provides application prospects for constructing selective detection of TAP in food samples.

Performance and mechanism of triethanolamine-triisopropanolamine corrosion inhibitor to deterioration of reinforced concrete under the coupling effect of freeze-thaw cycles and chloride attack

The purpose of this study is to propose an efficient and economical organic triethanolamine-triisopropanolamine corrosion inhibitor (OTTCI) to reduce the corrosion of steel in reinforced concrete. The influence of OTTCI on corrosion of steel in reinforced concrete under the coupling effect of freeze-thaw cycles and chloride attack (FTCs-CA) were characterized by electrochemical impedance spectroscopy (EIS), dynamic electrode potential (PDP), mechanical properties (mass loss rate (M), compressive strength (fn) and relative dynamic elastic modulus value (Pi)), capillary water absorption (CWA), bubble spacing coefficient (BSC) and scanning electron microscope (SEM). The inhibition mechanism of OTTCI was also analyzed and summarized. The results displayed that the dosage of OTTCI delayed the degradation of reinforced concrete under FTCs-CA. After 150 cycles, the M value of specimens with 1.0 % OTTCI reduced by 66.31 % compared to that of specimens without OTTCI, the Pi value increased by 51.9 %, and the polarization resistance and corrosion inhibition efficiency reached 2744.19 Ω cm2 and 92.88 %, respectively. In addition, OTTCI significantly reduced the CWA value and porosity. After 150 cycles, the CWA and porosity with 1.0 % OTTCI decreased by 60.1 % and 54.54 % respectively. The capillary water absorption coefficient increased linearly with the increase of FTCs-CA. SEM tests illustrated that OTTCI inhibited the development of internal cracks and macropores in concrete and promoted the formation of hydrated calcium silicate gels and calcite. The application of this study not only provides a new method to alleviate the deterioration of reinforced concrete, but also offers theoretical and technical support for further investigate on the deterioration characteristics of reinforced concrete in harsh environments.

Synthesis of Rod‐Like Sb2Se3@MWCNT as Conductive‐Additive Free Anode for Sodium‐Ion Batteries

AbstractAntimony selenide (Sb2Se3) is a promising electrode material for sodium‐ion batteries (SIBs) due to its high theoretical capacity. However, volume expansion during sodiation/desodiation and the low conductivity of Sb2Se3 reduce the electrochemical performance. Herein, we synthesized Sb2Se3 nanorods (NRs) and combined them with multi‐walled carbon nanotubes (MWCNTs) using one‐step composite process to address these issues. MWCNTs can accommodate volume expansion and provide high conductivity. The fabricated Sb2Se3 NRs@MWCNT electrode exhibits improved cycle performance and cyclic stability without additional conductive carbons. The Sb2Se3 NRs@MWCNT electrode showed an enhanced specific capacity of 440 mAhg−1 at a current density of 0.1 Ag−1, compared to 220 mAhg−1 for the Sb2Se3 NRs electrode. Additionally, it exhibited good stability at high current density. The in‐situ electrochemical impedance spectroscopy (EIS) and Galvanostatic intermittent titration technique (GITT) were used to estimate the electrochemical properties and kinetics of Sb2Se3 NRs@MWCNT. These results showed that Sb2Se3 NRs@MWCNT have the potential as a conductive‐free anode material in SIBs.

Synergistic Effect of NiAl-Layered Double Hydroxide and Cu-MOF for the Enhanced Photocatalytic Degradation of Methyl Orange and Antibacterial Properties

This study synthesized NiAl-layered double hydroxide (LDH)/Cu-MOF photocatalyst using a simple impregnation method involving NiAl-LDH and Cu-MOF. The successful synthesis was confirmed through Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), zeta potential measurements, thermogravimetric analysis (TGA), ultraviolet diffuse reflectance spectroscopy (UV-DRS), N2 adsorption at −196 °C, and electrochemical impedance spectroscopy (EIS). Photocatalysts based on NiAl-LDH, Cu-MOF, and NiAl-LDH/Cu-MOF were used to remove methyl orange (MO) dye from contaminated water. The impact of various factors, including pH, dye concentration, and photocatalyst amount, on MO degradation efficiency was assessed. FTIR analysis was conducted both before and after dye degradation. The optimal degradation conditions were a photocatalyst dose of 25 mg and a pH of 3. Kinetic studies indicated that the degradation of MO dye onto NiAl-LDH/Cu-MOF followed a pseudo-first-order and an L–H or Langmuir–Hinshelwood model. The value of R2 = 0.94 confirms the validity of pseudo-first-order and Langmuir–Hinshelwood (L–H) kinetic models for the photocatalytic degradation of MO dye. This study highlights the importance of developing novel photocatalysts with improved degradation efficiency to protect the water environment. Antibacterial activity was also performed with antibacterial sensibility testing by disk diffusion to determine minimal inhibitory and bactericidal concentrations. In short, NiAl-LDH/Cu-MOF can be helpful for various biomedical and industrial applications.

The effect of glass sealing stabilization on LSM–YSZ cathode poisoning and oxygen reduction reaction processes in solid oxide fuel cell

AbstractThe perovskite structure and electrochemical activity of (La0.80Sr0.20)0.95MnO3−x–(Y2O3)0.08(ZrO2)0.92 (LSM–YSZ) composite cathode can be significantly affected by volatile boron species originated from sealing glass–ceramics. Herein, we investigate the impact of doping the varying Er2O3 content (ranging from 0 to 4%) into an aluminoborosilicate glass to mitigate boron volatilization, its interaction with the LSM–YSZ cathode and consequent effects on its electrochemical performance. The results reveal that the volatility of boron species can be significantly suppressed by introducing Er oxide into the glass network by enhancing the conversion of [BO3] to [BO4] units, thereby increasing the binding energy of boron and strengthening of the glass structure. Moreover, the electrocatalytic performance for the O2 reduction reaction on the LSM–YSZ/8YSZ/LSM–YSZ symmetric cells is studied under open‐circuit conditions in the presence and absence of glass sealants. The analyses utilizing electrochemical impedance spectroscopy (EIS) and distribution of the relaxation times (DRT) analysis indicate that the electrocatalytic performance of LSM–YSZ cathodes can be enhanced in the presence of glass with 4% Er2O3 (GE4). This enhancement in the electrocatalytic activity of the LSM–YSZ electrode for the oxygen reduction reaction (ORR) is attributed to formation of the thin layer on the electrode surface, leading to a notable reduction in the polarization resistance (Rp) from 0.81 Ω cm2 in the glass absence to 0.45 Ω cm2 in the presence of GE4. However, DRT analysis demonstrates that the prolonged exposure of the cathode to GE4 causes a deterioration in cell performance primarily due to the blocking the cathode active sites, which impedes dominant cathode processes of oxygen dissociative adsorption/desorption and charge transfer and consequently reducing kinetics of the ORR.

Na+ conductivity of (100−x)Na3PS4−xCa3N2 glass and glass−ceramics

AbstractThe ionic conductivity of Na3PS4 can be improved via the aliovalent substitution of P and S as well as multivalence cation substitution of Na. Although the enhanced ionic conductivities of tetragonal and cubic Na3PS4 have been theoretically and experimentally studied, the dynamics of sodium ions in these systems have been rarely reported. In this study, (100−x)Na3PS4−xCa3N2 (0 ≤ x ≤ 10) glass samples were synthesizing using high‐energy planetary ball‐milling method. These samples were subjected to heat treatment at 280°C for 1 h in an argon atmosphere to obtain glass–ceramic samples. The structures of these samples were characterized via Raman spectroscopy and X‐ray diffraction analysis. The lattice parameter and cell volume of the glass–ceramic samples strongly depended on the x value in (100−x)Na3PS4−xCa3N2 (0 ≤ x ≤ 10). Their ionic conductivities were determined via alternating current electrochemical impedance spectroscopy (EIS). 92Na3PS4−8Ca3N2 glass–ceramics exhibited an ionic conductivity of 8.14 × 10−4 Scm−1 at 25°C. Charge carrier concentration and hopping rate were extracted from the EIS data to determine the ionic conductivities of the samples. The activation energies of DC conductivity and mobile ion formation and migration were also derived from the EIS data to analyze the effect of Ca3N2 doping on the ionic conductivity of the synthesized samples.

Interfacial capacitance in lithium disilicate glass: Experimental factors and charge carrier density

AbstractThe formation of an electric double‐layer (EDL) is an important phenomenon for many research areas, including energy storage technology. Although EDL is well‐known in electrochemistry, most of the studies involve the characterization of liquid electrolyte/electrode interfaces, and only a limited number of studies in solid‐solid contacts, such as solid electrolyte/electrode interface are available. This paper employed electrochemical impedance spectroscopy (EIS) to systematically investigate the influence of experimental factors in the interfacial capacitance arising from the electrode polarization in a lithium disilicate glass/gold electrode interface. It analyzed the influence of a.c. input voltage amplitude, samples' roughness (mechanical and chemomechanical polishing) and thickness, range of applied frequency and temperature, and the number of impedance cycles. In short, it was found that an input voltage range of 15–60 mV is indicated to minimize potential electrochemical processes during electrode polarization, where the data is reproducible from the second measurement cycle onward. Smoother surfaces closely approximated ideal electrode spike behavior, with surface treatment exhibiting influence on interfacial capacitance values. Moreover, as expected, we observed an increase in relative permittivity values with increasing thickness, accompanied by decreased capacitance values. Finally, by employing optimal experimental conditions and analyzing the inflection frequency () of the versus log() curve, we determined that the ratio between effective charge carriers () and the total number of charge carriers () falls within the range of 5–12% between 130°C and 280°C.

Bioreceptors’ immobilization by hydrogen bonding interactions and differential pulse voltammetry for completely label-free electrochemical biosensors

Label-free electrochemical biosensors show great potential for the development of point-of-care devices (POCDs) for environmental and clinical applications. These sensors operate with shorter analysis times and are more economic than the labelled ones. Here, four completely label-free biosensors without electron transfer mediators were developed for hepatitis B virus (HBV) detection. The approach consisted in (i) the modification of gold surfaces with cysteamine (CT) or cysteine (CS) linkers, (ii) the subsequent antibody (Ab) immobilization, either directly by hydrogen bonding (HB) interactions or by covalent bonds (CB) using additional reagents, and (iii) measuring the biosensor response by electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The electrode surfaces at each stage of the modification process were characterised by X-ray photo-electron spectroscopy (XPS) and atomic force microscopy (AFM). The combination of Ab immobilization by HB with the DPV analysis displayed improved repeatability, lower interference to serum matrix and similar limits of detection and quantification than the traditional biosensors that immobilize the Ab via CB and use EIS as readout technique. The Ab immobilization by HB is shown as a simple, efficient and low-cost alternative to CB ones, while DPV was faster and showed better performance than EIS. The CT-HB biosensor displayed the lowest limits of detection and quantification of 0.14 and 0.46 ng/mL, respectively, a 0.46–12.5 ng/mL linear analytical range, and 100% of recovery for 1/10 human serum media during HBV surface antigen detection by DPV. Even, it preserved the initial sensing capability after 7 days of its fabrication.Graphical abstract

Electrochemical determination of phenolic antioxidant BHT in cosmetic, food and water samples

BHT, an antioxidant often employed in several industries such as food, cosmetics, and food packaging, has raised public health concerns due to its possible toxicological consequences. These concerns originate from both the inherent properties of BHT itself as a result of its usage as an antioxidant. This research presents a novel sensor that uses a combination of a rare lanthanide element and a metal oxide as substrate modifiers on graphene nanopowder. Three independent electrochemical methods, cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy, were used to analyze the electrode modification process. Excellent linearity in the concentration range of 1.0 × 10−12–1.0 × 10−7 M was obtained under the optimal conditions of the technique, with a detection limit of 3.0 × 10−13 M. Repeatability, reproducibility, and stability studies were performed using the proposed sensor. The RSD value for the reproducibility study was 2.91 %. For the within-day repeatability, the repeatability was determined to be 1.97 % for the sensor. After 7 days, the stability studies indicated a decrease up to a value of 90.89 % of the initial value from the first day of assessment.

Fabrication and characterization of bioresorbable, electroactive and highly regular nanomodulated cell interfaces

Biomaterial-based implantable scaffolds capable of promoting physical and functional reconnection of injured spinal cord and nerves represent the latest frontier in neural tissue engineering. Here, we report the fabrication and characterization of self-standing, biocompatible and bioresorbable substrates endowed with both controlled nanotopography and electroactivity, intended for the design of transient implantable scaffolds for neural tissue engineering. In particular, we obtain conductive and nano-modulated poly(D,L-lactic acid) (PLA) and poly(lactic-co-glycolic acid) free-standing films by simply iterating a replica moulding process and coating the polymer with a thin layer of poly(3,4-ethylendioxythiophene) polystyrene sulfonate. The capability of the substrates to retain both surface patterning and electrical properties when exposed to a liquid environment has been evaluated by atomic force microscopy, electrochemical impedance spectroscopy and thermal characterizations. In particular, we show that PLA-based films maintain their surface nano-modulation for up to three weeks of exposure to a liquid environment, a time sufficient for promoting axonal anisotropic sprouting and growth during neuronal cell differentiation. In conclusion, the developed substrates represent a novel and easily-tunable platform to design bioresorbable implantable devices featuring both topographic and electrical cues.

Corrosion kinetics of carbon steel in hydrochloric acid and its inhibition by recycling Salbutamol extracted from expired Farcolin drug

ABSTRACT Salbutamol, which has nontoxic properties, was effectively extracted from expired Farcolin and was evaluated as an inhibitor against carbon steel (CSt) dissolution in 1.0 M HCl solution. Some technologies were applied to determine the inhibition efficacy of Salbutamol such as weight loss (WL), potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Also, FTIR, 1HNMR, and mass spectroscopy were used to clarify the structure of Salbutamol. The findings indicate that CSt can profit significantly from the recycling of Farcolin medicine and that Salbutamol may be extracted and employed as a CSt corrosion inhibitor. The efficiency of the inhibition improved with an increase in the dosage of salbutamol, polarization resistance and lowering corrosion current density, WL, and temperature. It’s reached 89.65% at a dose of 200 ppm using the EIS technology. The inhibition impact of Salbutamol was interpreted due to its spontaneous adsorption on the CSt/electrolyte interface, in accordance with Langmuir isotherm. Salbutamol was classified as a mixed inhibitor. In addition, how temperature affects the corrosion rate is considered by calculating and discussing some thermodynamic parameters.

Electrochemical Behavior of Tantalum Nitride Protective Layers for PEMFC Application

Proton Exchange Membrane Fuel Cells (PEMFCs) are promising technology to convert chemical energy from dihydrogen in electrical energy. HT-PEMFCs are working at high temperatures (above 120 °C) and with doped orthophosphoric acid H3PO4 PBI membranes. In such devices, bipolar metallic plates are used to provide reactive gas inside the fuel cell and collect the electrical current. The metallic elements used as bipolar plates, end plates, and interconnectors in acid electrolyte and gaseous fuel cells are severely damaged by a combination of oxidation (due in particular to the use of oxygen, whether pure or contained in the air) and corrosion (due in particular to acid effluents from the electrolyte). This degradation rapidly leads to the loss of the electrical conductivity of the metallic elements and today requires the use of very specific alloys, possibly coated with pure gold. The solution investigated in the present study is the use of a protective coating based on single-phase nitrides obtained by reactive magnetron sputtering or reactive HiPIMS (High-Power Impulse Magnetron Sputtering). The influence of the microstructure on the physical–chemical properties was studied. The electrochemical properties were quantified following two approaches. First, the corrosion current of the developed coatings was measured at room temperature and at higher temperatures using the Linear Sweep Voltammetry (LSV) technique. Then, Electrochemical Impedance Spectroscopy (EIS) measurements were performed to better identify and evaluate their corrosion-resistance performances.

Two-Dimensional TiS2 Nanosheet- and Conjugated Polymer Nanoparticle-Based Composites for Sensing Applications.

The assessment of phenolic compounds in food samples, environmental samples, and medical applications has gained importance recently. Here, we present research on novel conjugated polymer nanoparticles (P-PimBzBt NPs) and their composites with two-dimensional titanium disulfide nanosheets (2D-TiS2) for electrochemical tyrosinase (TYR)-based catechol detection. P-PimBzBt NPs are decorated with 2D-TiS2 to enhance the electrochemical performance for biosensing. In addition, the interaction of P-PimBzBt NPs with TiS2 was investigated at the molecular level by employing van der Waals (vdW) dispersion-corrected density functional theory (DFT) calculations and classical all-atom molecular dynamics simulations. According to the theoretical studies, the presence of the TiS2 layer increases the interfacial interaction with the conjugated polymer via electrostatic interactions. Using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDS) analyses, the production of SPE/TiS2@P-PimBzBt NPs/TYR nanobiosensors was examined. With a detection range of 3.0-27.5 μM, 0.33 μM LOD, and 3.89 μA/μM·cm2 sensitivity values, the sensing layer based on the TiS2@P-PimBzBt NP composites has a targeting ability toward catechol. Its selectivity was investigated using commonly used interfering ions and compounds such as citric acid, urea, glucose, uric acid, KCl, and NaCl. Application of nanobiosensors to actual samples (tap water and black tea) was carried out with high accuracy. The fabricated biosensing platform demonstrates that P-PimBzBt NPs with 2D-TiS2 nanomaterial functionalization are appropriate as electrode materials and could be used to create an inexpensive, fast-response, and highly selective electrochemical biosensor for the detection of catechol in actual samples.

Enhanced photoelectrochemical CO2 reduction activity towards selective generation of alcohols over CuxO/SrTiO3 heterojunction photocathodes

Photoelectrochemical reduction (PECR) of CO2 to value-added chemicals and fuels will reduce the dependency on fossil fuels, also it will solve environmental issues that arise due to greenhouse gases. A heterojunction of CuxO/SrTiO3 with varying post-annealing temperature ranges from 300 to 600 °C (CS300-600) was synthesized by overlying the spin-coated SrTiO3 on electrodeposited Cu2O over the FTO glass substrate. The synthesized photoelectrode's crystallinity and phase formation significantly varied by varying the post-annealing temperature, which was characterized via XRD and Raman spectroscopy. Optical, morphological, type of heterojunction formation and elemental surface oxidation states of photoelectrodes were studied through UV–visible DRS spectrum, FE-SEM, and XPS analysis respectively. Electrocatalytic analysis such as Linear Sweep Voltammetry (LSV), and Electrochemical Impedance Spectrometry (EIS) was employed, thus it conforms to the highest photocurrent density (−1.38 mA/cm2 at −0.6V vs. Ag/AgCl), and low charge transfer resistance (RCT=0.412 kΩ) at the electrode-electrolyte interfaces for CS500 photoelectrode as compared to others photoelectrodes. PECR of CO2 to liquid product formation was evaluated by applying different potential ranges (0 to −0.6 V vs. Ag/AgCl). Highest methanol formation of 48.69 μmol.cm−2hr−1, which is approximately 9 times enhanced as compared to the pure Cu2O (5.62 μmol.cm−2hr−1) photoelectrode at 0 V vs Ag/AgCl for CS500 heterojunction. Optimization of overlaying SrTiO3 synthesis temperature for crystallization formation on Cu2O and applied photoelectrode potential findings could pave the way for designing other new heterojunction types for selective liquid alcohol production.

Fluorescent Protein PEGylation for Stable Photon Manipulation in Deep‐Red Light‐Emitting Devices

AbstractPEGylation is a classic strategy to reduce denaturation and immunogenicity in therapeutic proteins, bioimaging, and drug delivery. However, this concept has not been applied to incorporate biogenic materials as functional components in optoelectronics. Herein, PEGylation is rationalized as an effective tool to stabilize fluorescent proteins in solid‐state photon manipulation down‐converters integrated into bio‐hybrid light‐emitting diodes. In short, the archetypal red‐emitting protein mCherry is nonspecifically PEGylated with methoxypolyethylene glycols (mPEG) chains of different lengths (mPEG‐350/‐750/‐2000). These derivatives hold the same photoluminescence figures‐of‐merit of mCherry, but an improved resistance against organic solvents, pH, temperature, and polymers (in solution/dry‐coatings) upon increasing the mPEG length. Indeed, the best‐performing mCherry‐mPEG‐2000 adduct leads to deep‐red devices with threefold enhanced color stability (>300 h) under harsh operation conditions (150 mW cm−2) over the prior art. Different device architectures along with spectroscopic, thermocycling, and electrochemical impedance spectroscopy studies of the prepared coatings aid in rationalizing that PEGylation successfully reduces i) nonreversible thermal denaturation, ii) aggregation in solid‐state, and iii) photo‐induced oxidation and H+‐transfer deactivation of the chromophore, since oxygen diffusivity and H+‐reorganization across the protein skeleton are slowed down by strong H+‐bonding/hydrophobic mCherry‐mPEG interactions. Hence, this simple supramolecular modification is of utmost relevance for future advances in protein‐based optoelectronics.

Cobalt‐Based Ferrite Modified Carbon Nanotubes Fibers for Flexible and Disposable Microelectrode Toward Electrochemical Glucose Sensing

ABSTRACTGlucose detection is critical in clinical health and the food industry, particularly in the diagnosis of blood sugar levels. Carbon‐based fiber materials have recently featured prominently as non‐enzymatic electrochemical glucose detectors. Herein, cobalt‐based ferrite (CoFe2O4) in the form of nanoparticles has been successfully fabricated over the carbon nanotubes (CNTs) fiber via a simple hydrothermal process. Fabricated microelectrode (CoFe2O4@CNTs) was investigated as an electrocatalyst toward the non‐enzymatic electrochemical glucose sensors. The structure and morphology of the modified fiber were studied by scanning electron microscopy including energy‐dispersive X‐ray spectroscopy. The electrochemical capability of the microelectrode was analyzed by using different electrochemical techniques including cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy (EIS). The proposed sensors exhibited a superb sensitivity of 0.21 µAcm−2 mM−1, a good linear range from 1 to 9 mM, and a lower detection limit of 1.7 mM. Further investigation via EIS indicated the low charge transfer resistance as compared to the bare CNTs‐based fiber. Outcomes revealed that the material can potentially prove promising for the disposable microelectrode toward electrochemical glucose sensing.

Effect of Zr addition on the corrosion resistance of Ti-Mo alloy in the H2O2-containing inflammatory environment

Reactive oxygen species (ROS), produced by immune cells during inflammatory reaction, are known to promote corrosion of standard biomedical materials such as CP-Ti and Ti-6Al-4V. Electrochemical corrosion in the ROS environment can be further accelerated in the vicinity of fretting regions, where titanium can be polarized towards negative potentials. This study considers both of these aspects and presents corrosion analysis under complex inflammatory conditions for Ti-Mo and Ti-Mo-Zr alloys, which offer exceptional strain-hardening behavior and ductility. Combining electrochemical impedance spectroscopy (EIS) and atomic emission spectroelectrochemistry (AESEC) allowed us to understand the origin of ROS-induced corrosion. At free corrosion conditions, Zr was found to suppress oxide layer growth without any significant effect on the dissolution process. On the other hand, Zr suppressed dissolution rate under cathodic potentials. Although applying cathodic potential resulted in a rapid increase of dissolution rate, cross-section transmission electron microscopy (TEM) analysis did not reveal significant influence of the short cathodic polarization on the oxide film growth during further prolonged exposure at free corrosion conditions.

Synthesis, characterization, electrochemical impedance spectroscopy performance and photodegradation of methylene blue: Mesoporous PEG/TiO2 by sol-gel electrospinning

Sol-gel and electrospinning methods successfully prepared porous TiO2 fibers. The samples were calcined at temperatures of 450 °C and 550 °C and characterized using different techniques. XRD analysis also revealed crystalline anatase and rutile phases of mp-TiO2 observed at calcining temperatures of 450 °C and 550 °C, whereas as-prepared showed an amorphous-like structure. Relatively higher surface area and photocatalytic efficiency were increased with a decrease in crystallite size. All samples absorb UV region. The Rs value of TiO2 calcined at 550 °C was 16.6 Ω, which is much lower than those of the 450 °C calcined TiO2 powder electrode (52.7 Ω) and as-prepared TiO2 electrode (95.3 Ω). In addition, the Rp resistance of TiO2 calcined at 550 °C electrode (5.85 kΩ) was also lower than those of 450 °C calcined TiO2 powder (39.0 kΩ) and as-prepared TiO2 electrode (68.9 kΩ), revealing better electronic and ionic conduction of TiO2 calcined at 550 °C electrode.