Search

As a model of passivation at a micro or nanoparticle, we have modelled a passivating reaction at a microelectrode of hemispherical geometry. The reaction is considered to lead to either the formation of a surface-bound species or diffusion of product into bulk solution. A dimensionless parameter, p, of value 0 to 1.0 can be used to describe the balance between the two processes. We have simulated the first two linear sweep voltammograms (LSV) under different values of p and have simulated the peak width of the first LSV under different values of scan rate and p. These simulations were used to relate the peak width to the value of p. The results were compared to the characteristics of passivation at a microdisk electrode. The equation was used to analyse the oxidation of dopamine at hemispherical Ga electrodes, fabricated by the deposition of liquid phase Ga onto Pt microdisks. [ABSTRACT FROM AUTHOR]

In the present work, we have synthesised ZIF-8-derived ZnO clusters using simple approach. The ZIF-8-derived ZnO clusters have been employed as an electrochemical sensor for the detection of furazolidone (FZE), a prevalent antibacterial drug. The as-synthesized ZnO clusters have been investigated for its physical and chemical properties using X-ray diffractometer (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX) analysis. The characterization study reveals the successful phase pure synthesis of the ZnO without any other impurities. The as-synthesized nanoparticles were further used to modify glassy carbon electrode for the electrochemical detection of the furazolidone (FZE) using cyclic voltammetry (CV) and linear sweep voltammetry (LSV) techniques. The results reveal the modified ZnO to be a potent electrochemical sensor with efficiently high sensitivity, selectivity, stability and reproducibility. The observed limit of detection (LOD) was 0.7 µM with 1.36 µA µM−1 cm−2 sensitivity. [ABSTRACT FROM AUTHOR]

La1 –xSrxCoO3 (x = 0.1, 0.2, 0.3, 0.4, and 0.5) were prepared by the alginic acid sol–gel route and characterized by thermo gravimetric analysis (TGA), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), and scanning electron microscope (SEM) techniques. The electrocatalytic activity of fabricated oxide electrodes (Ni/oxide) was studied for oxygen evolution reaction (OER) in an alkaline medium. The cyclic voltammetry of oxide electrodes shows a pair of redox couple at anodic peak potential (Epa) = 400 ± 6 mV and cathodic peak potential (Epc) = 296 ± 8 mV. The observed values of electrode kinetic parameters such as the Tafel slope (b) lie between 91 and 126 mV dec–1 and current density (j) lie between 17.0–73.1 mA cm–2 at 0.85 V. The Sr-substitution in lanthanum cobaltate matrix improve electrocatalytic activity for OER in an alkaline medium and maximum improvement was observed in the case of 0.4 mol Sr-substituted oxide. The order of reaction (p) with respect to the concentration of [OH–] is found unity and the highly negative value of entropy of the reaction indicated the oxygen evolution follows the same mechanism and involves the adsorption of the reaction intermediate. [ABSTRACT FROM AUTHOR]

Search for a Platinum metal-free catalyst for Proton Exchange Membrane Fuel Cells (PEMFCs) is a concern to scientists as the Pt-catalyzed electrode comprises about 45% of the entire fuel cell stack cost. Due to layered structure, Two-dimensional (2D) MoS2 nanostructured materials have recently drawn attention as effective catalysts for oxygen reduction reaction (ORR). The 1T-phase of MoS2 (1T-MoS2) has higher electronic conductivity than the 2H-phase (2H-MoS2); high surface area 1T-MoS2 can have high electrocatalytic activity towards PEFFCs. Here, we report hydrothermally synthesized 2H-MoS2 and solvothermally synthesized mixed 1T/2H-MoS2 phases as a catalyst for ORR in PEM Fuel Cells. Owing to the high BET-specific surface area, hybrid 1T/2H-MoS2 showed better ORR activity than 2H-MoS2. The limiting current density of the 1T/2H-MoS2 hybrid structure is ‒7.1 mA cm−2 compared to Pt/C (‒8.2 mA cm−2) at 1600 rpm. The Tafel slope values of 2H-MoS2, 1T/2H-MoS2, and Pt/C are 92.7 mV dec−1, 57.5 mV dec−1, and 39.3 mV dec−1, respectively. The electron transferred during ORR are 3.8 and 1.8, respectively, for 1T/2H-MoS2 and 2H-MoS2 (in 0.1 M KOH) ; suggesting less formation of undesirable peroxide formation than 2H-MoS2. The 1T/2H-MoS2 displays better electrochemical durability compared to 2H-MoS2 (after 2000 CV cycles). [ABSTRACT FROM AUTHOR]

In this study, Nernst growth model equations are used to explain the anodic biofilm (ABF) modeling, linear sweep voltammetry (LSV) at various growth stages of biofilm, and polarization curve modeling for its electron generation behavior in a miniaturized single-chambered microbial fuel cell (SMFC). Kinetic constants of various growth model equations were determined using non-linear regression analysis. Maximum specific growth rate (μmax) at anodic surface is observed 0.016 h−1 at a glucose concentration of 12 g L−1, whereas retardation in μmax is observed 14 g L−1 or more in SMFC. LSV results showed maximum current density of 6720.56 mA m−2. Anode performance in SMFC is examined through polarization curve resulting maximum open-circuit voltage (OCV), minimum charge transfer loss, and ohmic loss for NWG (NiWO4 impregnated on rGO), NiWO4, rGO, and plain CC (carbon cloth) anode. These results demonstrate significant enhancement in performance of MFC to lead towards model-based process controlling for significant scale-up in future. [ABSTRACT FROM AUTHOR]

The electrode is a key component in a microbial electrolysis cell (MEC) that needs significant improvement for practical implementation. Accurate and reproducible analytical methods are substantial for the effective development of electrode technology. Linear sweep voltammetry (LSV) is an essential analytical method for evaluating electrode performance. In this study, inoculated carbon brush (IB), abiotic brush (AB), Pt wire (PtW), stainless steel wire (SSW), and mesh (SSM) were tested to find the most suitable counter electrode under different medium conditions. The coefficient of variation (Cv) of maximum current (Imax) was the most decisive indicator of the reproducibility test. This study shows that (i) the electrode used in operation is an appropriate counter electrode in an acetate-added condition, (ii) the anode LSV test should avoid the use of Pt wire as counter electrodes, and (iii) PtW is an appropriate counter electrode in cathode LSV in all conditions. [ABSTRACT FROM AUTHOR]

In the present work, graphene oxide covalently functionalized with l-lysine (LSN@GO)-based electrochemical sensor has been developed for the ultrasensitive individual as well as the first ever simultaneous detection of Rifampicin (RIFA) and Acetaminophen (APAP) drugs. The synthesized LSN@GO composite, as well as its precursors LSN and GO, were characterized using FT-IR, XRD, TGA, XPS, SEM and EDAX. The electrochemical studies were performed using Cyclic Voltammetry (CV), Linear Sweep Voltammetry (LSV), and Electrochemical Impedance Spectroscopy (EIS). The fabricated LSN@GO/GCE electro-sensor's interface exhibited efficient electrical activity for the analysis of RIFA and APAP under the optimized conditions, owing to its substantial electrochemically active surface area and exceptional electron transport capabilities. The detection of RIFA and APAP in various pH environments entailed a proton-dependent mechanistic approach. The sensor displayed a robust linear correlation over a broad range (0.5 to 10 µM) for both RIFA and APAP, with low detection limits of 4.3 nM for RIFA and 5.8 nM for APAP (S/N = 3), along with quantification limits of 14.6 nM for RIFA and 19.4 nM for APAP (S/N = 10) for their individual detection. For simultaneous detection, the detection limit of 4.2 nM for RIFA and 6.0 nM for APAP were observed. We successfully detected spiked RIFA and APAP in real drug and urine samples without pre-treatment, demonstrating significant detection limits and no notable interference from excipients with satisfactory recovery data. The developed sensing platform demonstrated exceptional electrochemical performance for the detection of RIFA and APAP, showcasing significant potential for applications in clinical diagnosis and pharmaceuticals. [ABSTRACT FROM AUTHOR]

In this investigation, the leaf extract of Olea ferruginea royle was utilized to fabricate organic complexes of Ni (CH3CO2)24H2O, ZrO(CH3COO)2, and Mn (CH3CO2)24H2O, subsequently facilitating the successful preparation of nano-composites comprising NiO, ZrO2, and Mn3O4. Various spectroscopic methodologies were employed to meticulously characterize the synthesized nano-composites. Subsequently, the electrocatalytic prowess of the material for the oxygen evolution process (OER) was assessed. With an onset potential of 1.71V vs. the reversible hydrogen electrode (RHE) and a remarkably low Tafel value of 81mV/dec, the observed performance closely mirrored that of chemically synthesized metal oxide-based catalysts. Extraordinary electro-catalytic activity is attributed to the combined action of the mixed metal oxides and the organic capping agents, which speed up charge transfer and increase the number of active sites. The present work offers valuable perspectives on environmentally friendly synthesis methods for producing high-performance electrode materials for water electrolysis. By employing plant-derived extracts and organic capping agents, this more ecologically friendly synthesis technique has potential for durable and efficient electrocatalysts in a range of energy conversion applications. [ABSTRACT FROM AUTHOR]

In this study, we report the electrochemical detection of sunset yellow (SY) at the surface of a carbon paste electrode (CPE) modified with CuCo2O4 nanorods (NRs) and an ionic liquid (IL). The electrochemical behavior of sunset yellow at the modified electrode was investigated using linear sweep voltammetry, differential pulse voltammetry and chrono­amperometry techniques. The CuCo2O4 NRs/IL/CPE sensor exhibited good performance and favorable electrochemical response for the electrochemical reaction of SY in a 0.1 M phosphate buffer solution at pH 7.0. The results showed a linear electrochemical response to SY within the concentration range of 0.2 to 160.0 μM, with a detection limit of 0.06 μM. In addition, The CuCo2O4 NRs/IL/CPE sensor demonstrated good ability for SY determination in real samples.

In this study, linear sweep voltammetry (LSV) was implemented for the sensitive detection of 2-nitrophenol (2-NP) in phosphate buffer solution (PBS) at pH 7.00 with lab-made nanocomposite materials for environmental remediation. Initially, a flat glassy carbon electrode (GCE) modified using the inorganic-organic binary Au-NPs@ZnO/CTSN(Chitosan) nanocomposites (NCs) was used as a working electrode (WE). The NCs of Au NPs@ZnO/CTSN were basically prepared by an ultra-sonochemical process and fabricated on a GCE using conducting coating binder such as PEDOT:PSS. Before the electrochemical examination, the Au NPs@ZnO/CTSN NC was fully characterized by Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray Spectroscopy (EDS), Brunauer-Emmett-Teller (BET), X-Ray Diffraction analysis (XRD), High-Resolution Transmission Electron Microscopy (HRTEM), and X-Ray Photoelectron Spectroscopy (XPS) to analyze the functional, morphological, structural, elemental, surface area, crystallinity, and binding energy analyses. A linear concentration range (LDR) of 2-NP from 15⁓150 μM was evaluated by LSV in room conditions. From the slope of the calibration curve, the sensor sensitivity was calculated and found to be 20.9905 μAμM−1cm−2. At signal/noise ratio of 3, the lower limit of detection (LOD) is obtained as 0.45 ± 0.023 μM. Additionally, pH optimization, sensor-probe characterization, stability, and validity are fully analyzed in identical conditions by LSV. Besides this, the assembled 2-NP sensor probe as Au NPs@ZnO/CTSN NCs/PEDOT:PSS/GCE for validity test was performed elaborately and found the reliable and satisfactory results. This is a new approach to the development of electrochemical sensors for environmental chemical analysis using an electrochemical process with gold-nanoparticle decorated ZnO-chitosan for the safety of environmental and healthcare fields on a broad scale.

To study the nucleation and growth mechanism of Ni/SiC composite coatings, electrodeposition was conducted in the Ni bath containing SiC particles with different sizes. Compared to the Ni coating electrodeposited from the bare Ni bath, the Ni/SiC composite coatings exhibited similar grain size but rougher surface morphology due to the incorporation of SiC particles. By means of chronoamperometry (CA) and linear sweep voltammetry (LSV) techniques, it was found that the introduction of SiC particles did not change the nucleation mode of Ni: the Scharifker-Hills three-dimensional instantaneous nucleation mode. However, the nucleation sites on the cathode were reduced due to the inert surface and low conductivity of SiC particles. At a step potential of −0.94 V, Ni presented the maximum nucleation density (N0) of 3.09 × 107 cm−2, which was reduced by one order of magnitude for the Ni/SiC. Furthermore, SiC particles in the bath would extend the diffusion path of Ni2+ ions, resulting in the decrease in diffusion coefficient from 1.04 × 10−7 cm2 s−1 (Ni) to 9.91 × 10−9 cm2 s−1 (Ni/50 nm SiC), 1.83 × 10−8 cm2 s−1 (Ni/500 nm SiC) and 2.29 × 10−8 cm2 s−1 (Ni/5 μm SiC), suggesting the “Blocking effect”. COMSOL simulation further confirmed the “Blocking effect”. The “Blocking effect” would lead to excessive interface gaps around 5 μm SiC particles due to the uneven electrodeposition of Ni. To address the issue, we proposed that adding non-ionic surfactants into the bath to lower the electrochemical reaction rate of Ni2+ ions and accordingly gained composite coatings with fine continuity.

Cu-doped polyaniline (Cu–PA) was prepared by chemical oxidation aniline in the presence of Cu ions. By cyclic voltammetry (CV), the electrochemical behavior of glassy carbon electrode modified with Cu–PA was studied in NaOH solution. Since the hydrolysis of glucose occurs in an alkaline solution and the redox peak of Cu–PA depends on the concentration of OH– concentration, here, a new and cost-effective strategy for the non-enzymatic determination of glucose was proposed based on the inhibitory effect of glucose on the electrical activity of the Cu–PA composite. The cathodic current decreased directly after the addition of glucose and demonstrated that the Cu–PA was sensitive to glucose in an alkaline medium. Using linear sweep voltammetry and under optimal condition, the sensor exhibited a linear calibration graph in the concentration range of 0.11–1.66 mM with a limit of detection (LOD) of 0.044 mM (S/N = 3). In addition, the sensor showed desirably accurate selectivity for detecting and recovering glucose in humans serum samples, good reproducibility, and good stability. [ABSTRACT FROM AUTHOR]

The corrosion behavior of a hybrid laminate consisting of laser-structured aluminum EN AW-6082 ∪ carbon fiber-reinforced polymer was investigated. Specimens were corroded in aqueous NaCl electrolyte (0.1 mol/L) over a period of up to 31 days and characterized continuously by means of scanning electron and light microscopy, supplemented by energy dispersive X-ray spectroscopy. Comparative linear sweep voltammetry was employed on the first and seventh day of the corrosion experiment. The influence of different laser morphologies and production process parameters on corrosion behavior was compared. The corrosion reaction mainly arises from the aluminum component and shows distinct differences in long-term corrosion morphology between pure EN AW-6082 and the hybrid laminate. Compared to short-term investigations, a strong influence of galvanic corrosion on the interface is assumed. No distinct influences of different laser structuring and process parameters on the corrosion behavior were detected. Weight measurements suggest a continuous loss of mass attributed to the detachment of corrosion products. [ABSTRACT FROM AUTHOR]

The magnetic chitosan beads (MCB) were synthesized using a co-precipitation method and made to react with epichlorohydrin (ECH) to get the cross-linked derivative (ECH-MCB). In the FTIR spectrum of chitosan (CS) and magnetic chitosan beads, band appeared at 606 cm−1 attributed to Fe–O group in case of MCB. The strong adsorption band at 3438 cm−1, due to –OH stretching vibration, indicates that the hydroxyl groups in chitosan molecules were involved in the cross-linking of ECH-MCB. The surface of magnetic chitosan beads is smooth as compared to the rough surface of cross-linked beads as established by scanning electron microscopy (SEM) proving the better adsorption. The EDX of epichlorohydrin cross-linked magnetic chitosan beads gives the composition of elements present in terms of weight and atomic percentages. Thermal gravimetric analysis (TGA) establishes its three-stage degradation for MCB and ECH-MCB. Two endothermic peaks were observed at 96.28 °C for MCB and at 99.61 °C for ECH-MCB using differential scanning calorimetry (DSC). It is found that zinc metal ion sorption efficiency in terms of adsorption capacity of ECH-MCB (qmax is 0.059 mg/g) is significantly higher than MCB (qmax 0.0488 mg/g). Various factors affecting the uptake behavior of metal ions such as pH, adsorbent dosage, contact time and temperature effects were investigated. The correlation coefficient R2 values lie between 0.9 and 1.0 and fitted well with the Langmuir and Freundlich isotherms. The equilibrium parameter RL values support that the adsorption (0 < RL < 1) is a favorable and spontaneous process. The thermodynamic parameters confirm that it is an endothermic reaction which results in an increase in the randomness of the adsorption process. The beads were regenerated by using easily available, economical chelating agent, ethylenediaminetetraacetic acid (EDTA) which forms considerably stable five-membered complex with Zn+2 ions on desorption. These beads prove as promising materials for the removal of pollutants from industrial wastewater. In the case of Hindon water sample, the Zn(II) level was within permissible limits of 1.01 mg L−1 from initial concentration of 4.34 mg L−1 after 20 min of adsorption, and for Yamuna water samples, it was 1.00 mg L−1 from 9.69 mg L−1 after 40 min of adsorption. [ABSTRACT FROM AUTHOR]

Increased evidence has documented a direct association between Ciprofloxacin (CFX) intake and significant disruption to the normal functions of connective tissues, leading to severe health conditions (such as tendonitis, tendon rupture and retinal detachment). Additionally, CFX is recognized as a potential emerging pollutant, as it seems to impact both animal and human food chains, resulting in severe health implications. Consequently, there is a compelling need for the precise, swift and selective detection of this fluoroquinolone-class antibiotic. Herein, we present a novel graphene-based electrochemical sensor designed for Ciprofloxacin (CFX) detection and discuss its practical utility. The graphene material was synthesized using a relatively straightforward and cost-effective approach involving the electrochemical exfoliation of graphite, through a pulsing current, in 0.05 M sodium sulphate (Na2SO4), 0.05 M boric acid (H3BO3) and 0.05 M sodium chloride (NaCl) solution. The resulting material underwent systematic characterization using scanning electron microscopy/energy dispersive X-ray analysis, X-ray powder diffraction and Raman spectroscopy. Subsequently, it was employed in the fabrication of modified glassy carbon surfaces (EGr/GC). Linear Sweep Voltammetry studies revealed that CFX experiences an irreversible oxidation process on the sensor surface at approximately 1.05 V. Under optimal conditions, the limit of quantification was found to be 0.33 × 10−8 M, with a corresponding limit of detection of 0.1 × 10−8 M. Additionally, the developed sensor's practical suitability was assessed using commercially available pharmaceutical products. [ABSTRACT FROM AUTHOR]

In this study, well-defined tungsten oxide (WO3) nanowall (NW) thin films were synthesized via a controlled hot filament chemical vapor deposition (HFCVD) technique and applied for electrochemical detection of methylamine toxic substances. Herein, for the thin-film growth by HFCVD, the temperature of tungsten (W) wire was held constant at ~1450 °C and gasification was performed by heating of W wire using varied substrate temperatures ranging from 350 °C to 450 °C. At an optimized growth temperature of 400 °C, well-defined and extremely dense WO3 nanowall-like structures were developed on a Si substrate. Structural, crystallographic, and compositional characterizations confirmed that the deposited WO3 thin films possessed monoclinic crystal structures of high crystal quality. For electrochemical sensing applications, WO3 NW thin film was used as an electrode, and cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were measured with a wide concentration range of 20 μM~1 mM of methylamine. The fabricated electrochemical sensor achieved a sensitivity of ~183.65 μA mM−1 cm−2, a limit of detection (LOD) of ~20 μM and a quick response time of 10 s. Thus, the fabricated electrochemical sensor exhibited promising detection of methylamine with considerable stability and reproducibility. [ABSTRACT FROM AUTHOR]

A new hybrid metal oxide (MnO/ZrO2) has been synthesized by an environmentally benign material from the Olea ferruginea royle (OFR)plant leaf extract as a green precursor. The hybrid material has improved oxygen evolution reaction (OER) electrochemical performance. The existence of [OFR-MnO/ZrO2] particles is confirmed by spectroscopic techniques, X-ray photoelectron spectroscopy (XPS), and elemental diffraction spectroscopic (EDS) investigations, emphasizing the role of organic species (N, O and C) during synthesis. To assess the electrode’s electrochemical performance, linear sweep voltametric and impedance measurements were performed. The electrode showed a lower linear sweep measurement of 382 mV and a Tafel value of 79 mV dec−1, suggesting MnO/ZrO2 as an efficient electrocatalytic material. These results demonstrate the potential of MnO/ZrO2 as an excellent, long-term and economical solution for a variety of applications, particularly in the area of water splitting research. [ABSTRACT FROM AUTHOR]

Photoelectrochemical (PEC) technology is a promising approach for converting solar energy into chemical energy, offering significant potential for renewable energy applications. In this work, the CuO thin film was fabricated with different pH value in between 8.5 ± 0.1 and 10.5 ± 0.1 via Successive Ionic Layer Adsorption and Reaction (SILAR) method. The Effect of pH on thickness, structural, morphological, elemental composition and optical properties were investigated by using stylus profilometry, XRD, SEM, TEM, EDX, UV–vis and PL. The XRD results showed that as the pH increased, the crystallite size increased from 19.24 nm to 25.62 nm, with a monoclinic phase along the (111) direction. The CuO film deposited at pH value 10.5 ± 0.1 exhibit well defined identical particle with its size in the range between 200 and 300 nm was confirmed by SEM and TEM analysis. As the pH increased from 8.5 ± 0.1 to 10.5 ± 0.1, the CuO film bandgap (Eg) value reduced from 1.52 eV to 1.42 eV with indirect transition. The CuO photocathode deposited at pH 10.5 ± 0.1 shows maximum photocurrent density of 1.45 mA/cm2 at −0.1 V vs. RHE in 0.5 M Na2SO4 solution. Furthermore, the Electrochemical Impedance Spectroscopy (EIS) analysis shows, the CuO (pH 10.5 ± 0.1) electrode have higher conductivity value of 0.6862 S/cm compared CuO at pH 8.5 ± 0.1 (0.2779 S/cm) and CuO at pH 9.5 ± 0.1 (0.4646 S/cm) electrodes.

Solid biopolymer electrolytes based on potato starch (PS), sodium iodide (NaI), and dispersed with cobalt ferrite (CoFe2O4) as ceramic nanofillers were synthesized via a solution casting technique. These synthesized solid biopolymer electrolytes have been characterized by electrical impedance spectroscopy (EIS), Fourier transform infrared (FTIR) spectroscopy, FTIR deconvolution technique, dielectric studies, linear sweep voltammetry (LSV), and cyclic voltammetry (CV). The highest conductivity is found to be 8.13 × 10–3 S/cm for the system containing 1.0 wt.% of CoFe2O4 nanofillers. The ceramic nanofillers enhance the ion motion inside the polymer matrix, leads to increase the electrolyte's conductivity. FTIR confirmed that the polymer, NaI salt, and ceramic nanofiller interact with each other appreciably, and formed the complexation between the polymer, NaI salt, and ceramic nanofillers. The ion transport parameters such as mobility (µ), carrier density (n), and diffusion coefficient (D) were determined from the deconvolution of FTIR spectra and further used to compute the free ions and contact ion pairs in the solid biopolymer electrolytes. LSV and CV measurements indicate that the synthesized solid biopolymer electrolytes have a great potential in the electrochemical devices. The electrochemical stability window of the material (PNGC-1.0) is 2.5 V, and CV measurement shows the absence of any redox peaks, which may be a promising electrolyte for supercapacitor applications. [ABSTRACT FROM AUTHOR]

This work uses the sonochemical method to represent synthesized cobalt oxide nanoparticles (Co3O4) and analysed using different techniques. The X-ray diffraction analysis (XRD) and Fourier-transform infrared spectroscopy (FTIR) examinations of the synthesized nanoparticles confirmed their cubic structure and average crystallite size of 21.3 nm. The spherical surface shape and presence of components with a particle size of 25.3 nm were revealed. Scanning probe microscopy (SPM) methods analysed the Co3O4 coated plates' surface characteristics, including roughness and topographical ideas. An aqueous electrolyte medium (6 M KOH) was used to investigate the electrochemical corrosion behaviour of Co3O4-coated plates. According to the Tafel plot, coating Zn plates with a high surface area and mesoporous Co3O4 in KOH electrolytes greatly reduced the corrosion of the plates. The coated plates are thermally treated up to 600°. The temperature-dependent anticorrosive properties of Co3O4 NPs are evaluated. [ABSTRACT FROM AUTHOR]

Water-soluble, stable, and monodisperse palladium nanoclusters (PdNCs) were synthesized using NaBH4 as a reductant and lipoic acid as a ligand. PdNCs, measured by high-resolution transmission electron microscopy, showed a round shape and a diameter of 2.49 ± 0.02 nm. It was found that each PdNC contains 550 Pd atoms on average. These PdNCs offer high amplification as a label of biochemical reactions when inductively coupled plasma-mass spectrometry (ICP-MS) is used as a detector. In addition, PdNCs have catalytic activity on electrochemical reactions, allowing detection by linear sweep voltammetry (LSV). As a proof of applicability, a competitive immunoassay based on PdNC labels was developed for the determination of glial fibrillary acidic protein (GFAP) in human serum, comparing ICP-MS and LSV detection. GFAP is a biomarker for differentiating between patients with ischemic stroke (IS) and hemorrhagic stroke (HS). The limit of detection (LoD), corresponding to IC10 (4-parameter logistic curve), was 0.03 pM of GFAP, both by ICP-MS and LSV, being lower than the 0.31 pM LoD provided by the ELISA commercial kit. Using the error profile method, 0.03 pM and 0.11 pM LoDs were obtained respectively by ICP-MS and LSV: LoD is lower by ICP-MS due to the better precision of the measurements. The analyses of human serum samples from IS, HS, and control (CT) donors using PdNC labels and detection by ICP-MS and LSV were validated with a commercial ELISA kit (for CT donors only ICP-MS provided enough sensitivity). Results point out toward the future use of PdNCs as a label in other immunoprobes for the determination of specific proteins requiring very low LoDs as well as the development of electrochemical decentralized methodologies. [ABSTRACT FROM AUTHOR]

This work analyzed the volume fraction of the sigma phase in a superduplex stainless steel UNS S32760. Two electrochemical testing methodologies were applied for this purpose. Firstly the DL-EPR test was performed in three different electrolytic solutions. The LSV-KOH test was also used, a recent methodology proposal for analyzing these alloys. Seven specimens were solution annealed at 1100 °C for 60 min and heat-treated at 850 and 950 °C for 5, 20, and 60 min to promote the formation of different fractions of the sigma phase. The sigma phase volume fraction present in these specimens was determined by quantitative metallography. The DL-EPR analyses in all three conditions proved to be limited in quantifying the sigma phase, especially in specimens heat-treated at 950 °C. On the other hand, from the analyses with the LSV-KOH technique, it was possible to construct a reference curve between the sigma volume fractions and the electrochemical response of the LSV-KOH test (charge density), obtaining a linear regression coefficient of 0.97. This curve can then be applied to quantify the sigma phase. For comparison, the best regression coefficient obtained for DL-EPR was 0.53. Accompanied by the quantitative analysis, a qualitative analysis of the sigma phase can be made from a deeper analysis of the LSV-KOH voltammograms. In these analyses, it was possible to infer whether the sigma phase morphology is lamellar or in blocks. From the results obtained, it was possible to show that the LSV-KOH test is more precise in quantifying the sigma phase and allows a morphological analysis.

Molten salts such as 2LiF-BeF2 (FLiBe) have been proposed as coolants for advanced nuclear fission and fusion reactors. Critical to the design, licensing and operation of these reactors is characterization and understanding of the chemical behavior and mass transport of activation and fission products, corrosion products, and other solutes in the coolant. Electrochemical techniques are a powerful suite of tools for probing these phenomena. The design of an experimental cell for molten salt electrochemistry is described herein. As a demonstration of this design, details of the experimental methods used to conduct electrochemical experiments with molten FLiBe with addition of LiH are provided. Decommissioning of the cell is considered from the point of view of decontamination and waste generated. Main features of the cell include:•Suitable for operation up to 800 °C; suitable for operation inside and outside of a glovebox.•Enables sweep gas, gas sampling and analysis; enables addition of solid and liquid materials during operation.•Supports a variety of electrode materials and arrangements.

Abstract Ursodeoxycholic acid (UDCA) is not only safer than chenodeoxycholic acid in the treatment of hepatobiliary diseases, but also has a wide range of applications in Acute Kidney Injury and Parkinson’s Disease. The purpose of this experiment is to improve the conversion rate of 7-ketocholic acid (7K-LCA) and the yield of ursodeoxycholic acid in aprotic solvents during electrochemical reduction process. Three aprotic solvents were investigated as electrolytes. 1,3-Dimethyl-2-imidazolidinone (DMI) has a stable five-membered ring structure, and 7K-LCA has undergone two nucleophilic reactions and “Walden” inversion, the 7K-LCK was stereoselectively reduced to UDCA. Hexamethylphosphoramide (HMPA) and 1,3-methyl-3,4,5,6-Tetrahydro-2(1H)-pyrimidinone (DMPU) can be attacked by chloride ions to produce by-products. Molecular orbital theory-based simulations were conducted to study the reducibility of three aprotic solvents [hexamethylphosphoramide (HMPA), 1,3-methyl-3,4,5,6-Tetrahydro-2(1H)-pyrimidinone (DMPU), and 1,3-Dimethyl-2-imidazolidinone (DMI)] in combination with experiments. Choose the best solvent based on the simulation results, the electrolysis reaction can be carried out by applying current and voltage when lithium chloride is used as electrolytes. Calculations using Materials Studio showed that Cu, Pb, Hg–Cu, and Ni exhibited the highest binding energies to the substrate in this system. Using Cu as the electrode when the solvent is a 1:1 mix of DMI and HMPA, the conversion rate of 7-ketocholic acid (could reach 98%, the yield of ursodeoxycholic acid was up to 80%. Under the same conditions, linear voltammetry was performed on the electrochemical workstation to study the electrolysis behavior, and the obtained results were consistent with the experiment. Graphical Abstract

Ultrathin three-dimensional (3D) interconnected porous carbon nanosheets (PCNs) derived from Moringa oleifera barks (commonly known as the drumstick tree) with electrochemical (EC) sensor performance was employed as the carbon precursor. In this study, we described a simple one-step pyrolysis technique to generate hierarchical PCN using a high-temperature pyrolysis and KOH activation procedure. Using the microwave-solvothermal approach, platinum–nickel bimetallic octahedral nanoparticles were decorated on ultrathin 3D PCN (referred to as Pt–Ni@PCN). The morphological, structural, and EC properties of the Pt–Ni@PCN nanocomposite were well characterized. Using cyclic voltammetry and linear sweep voltammetry, the dihydroxybenzene (DHB) isomers hydroquinone, catechol, and resorcinol were identified individually as well as simultaneously. The screen-printed carbon electrode-modified nanocomposite [Pt–Ni@PCN/screen-printed carbon electrode (SPCE)] served as an outstanding electron (e–)-transfer mediator for DHB isomer oxidation, yielding limits of detection of 0.0093, 0.0263, and 0.0529 μM, respectively. Also, the Pt–Ni@PCN/SPCE sensor has exceptional selectivity, long-term durability, reproducibility, repeatability, and anti-interference. Furthermore, the proposed sensor can be exploited to detect simultaneously environmental pollutants in river, lake, and tap water samples with good recovery rates. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The electrode is a key component in a microbial electrolysis cell (MEC) that needs significant improvement for practical implementation. Accurate and reproducible analytical methods are substantial for the effective development of electrode technology. Linear sweep voltammetry (LSV) is an essential analytical method for evaluating electrode performance. In this study, inoculated carbon brush (IB), abiotic brush (AB), Pt wire (PtW), stainless steel wire (SSW), and mesh (SSM) were tested to find the most suitable counter electrode under different medium conditions. The coefficient of variation (Cv) of maximum current (Imax) was the most decisive indicator of the reproducibility test. This study shows that (i) the electrode used in operation is an appropriate counter electrode in an acetate-added condition, (ii) the anode LSV test should avoid the use of Pt wire as counter electrodes, and (iii) PtW is an appropriate counter electrode in cathode LSV in all conditions.

Herein, we reported carbon paste electrode modified with graphitic carbon nitride (g–C3N4–CPE) to determine of tryptophan (Trp) using voltametric techniques. Various spectroscopic and electrochemical techniques were used to characterize the as-synthesized g-C3N4 and the assembled electrodes. The transfer coefficient, rate constant and the diffusion coefficient of Trp in this system were found to be 0.28, 1.9 × 104 M−1s−1 and 3.2 × 10−5 cm2s−1, respectively. The linear range was obtained for the detection of Trp using LSV is from 0.1 μM to 120 μM at pH 5. The limit of detection (LOD) (3σ/m) was 0.085 μM. The demonstrated modified CPE was also effectively used for the detection of Trp in milk with percentage recovery of 98 %–105.2 %. Furthermore, the modified CPE exhibited good repeatability, reproducibility and appropriate selectivity.

In this research, we have designed a phosphorous-doped tungsten trioxide nanosheet (P-WO3 NS) for highly sensitive electrochemical sensors using the probe ultrasonication method. The synthesized P-WO3 NS was characterized by a variety of instruments to understand their physicochemical and morphological properties. Subsequently, a glassy carbon electrode (GCE) modified with P-WO3 NS/GCE was developed to investigate a highly sensitive detection of serotonin (ST) via electrochemical methods. The interaction between heteroatom P and WO3 NS greatly increases the active sites, electrical conductivity properties, and electrocatalytic activity. The synergistic effect of the modified P-WO3 NS/GCE exhibited excellent electrochemical performance, excellent catalytic activity, anti-fouling effect, high selectivity, and reproducibility for repeated ST detection. Also, ST is detected by linear sweep voltammetry with a very low detection limit of 60 nM (S/N = 3), good sensitivity of 0.2 μA μM–1 cm–2, and a wide linear dynamic range from 10 nM to 100 μM. Furthermore, the practicability of the sensor was assessed in ST detection in spiked biological fluid samples, and good recovery results were achieved. [ABSTRACT FROM AUTHOR]

Ursodeoxycholic acid (UDCA) is not only safer than chenodeoxycholic acid in the treatment of hepatobiliary diseases, but also has a wide range of applications in Acute Kidney Injury and Parkinson's Disease. The purpose of this experiment is to improve the conversion rate of 7-ketocholic acid (7K-LCA) and the yield of ursodeoxycholic acid in aprotic solvents during electrochemical reduction process. Three aprotic solvents were investigated as electrolytes. 1,3-Dimethyl-2-imidazolidinone (DMI) has a stable five-membered ring structure, and 7K-LCA has undergone two nucleophilic reactions and "Walden" inversion, the 7K-LCK was stereoselectively reduced to UDCA. Hexamethylphosphoramide (HMPA) and 1,3-methyl-3,4,5,6-Tetrahydro-2(1H)-pyrimidinone (DMPU) can be attacked by chloride ions to produce by-products. Molecular orbital theory-based simulations were conducted to study the reducibility of three aprotic solvents [hexamethylphosphoramide (HMPA), 1,3-methyl-3,4,5,6-Tetrahydro-2(1H)-pyrimidinone (DMPU), and 1,3-Dimethyl-2-imidazolidinone (DMI)] in combination with experiments. Choose the best solvent based on the simulation results, the electrolysis reaction can be carried out by applying current and voltage when lithium chloride is used as electrolytes. Calculations using Materials Studio showed that Cu, Pb, Hg–Cu, and Ni exhibited the highest binding energies to the substrate in this system. Using Cu as the electrode when the solvent is a 1:1 mix of DMI and HMPA, the conversion rate of 7-ketocholic acid (could reach 98%, the yield of ursodeoxycholic acid was up to 80%. Under the same conditions, linear voltammetry was performed on the electrochemical workstation to study the electrolysis behavior, and the obtained results were consistent with the experiment. [ABSTRACT FROM AUTHOR]

In this research work the electrochemical oxidation of ortho-aminophenol (oAP) is studied using modified reduced graphene oxide/indium tin oxide (rGO/ITO) glass electrode in acetonitrile medium, tetrabutyl ammonium perchlorate (TBAP) supporting electrolyte. Cyclic voltammetry (CV) and linear-sweep voltammetry (LSV) techniques were used to study the redox behavior of oAP. The graphene oxide-initiated auto-oxidized 2-aminophenoxazine-3-one is irreversibly reduced by modified rGO/ITO glass electrode at −0.048 V (versus Ag–AgCl electrode). LSV response shows that the cathodic peak current increases notably compared to that of bare rGO/ITO glass electrode and with the increasing concentration of oAP. The oxidized product of oAP was characterized by UV–Visible and FT-IR spectroscopy. The redox behavior of oAP of modified rGO/ITO glass electrode was compared with the electrochemical behavior of oAP at bare glassy carbon electrode. Reduced graphene oxide (rGO) modified ITO glass electrode in acetonitrile medium was used to electrochemically oxidize ortho-aminophenol (OAP). The results of modified rGO/ITO glass electrode were also compared with the bare glassy carbon electrode. Linear sweep voltammetry results showed an increase in cathodic current for rGO/ITO glass electrode compared to bare glassy carbon electrode. [ABSTRACT FROM AUTHOR]

We have described the use of a microelectrode to simulate a passivating reaction taking place at a micro or nanoparticle. Reaction at the microelectrode is considered to lead to either diffusion of the product back into solution or the formation of a surface-bound species. A kinetic parameter describes the balance between the two processes. Linear sweep voltammograms were simulated for the first and second scan under different values of the kinetic parameter. These simulations were used to derive an empirical equation relating the change in peak height to the passivation kinetics. The equation was used to examine the oxidation of NADH, phenol and ascorbic acid at a Pt microelectrode, and the oxidation of phenol at alloy microelectrodes of different Pt:Rh content. [ABSTRACT FROM AUTHOR]

Heterostructured TiO2@MXene rich in oxygen vacancies defects (VO-TiO2@MXene) has been developed to construct an electrochemical sensing platform for imidacloprid (IMI) determination. For the material design, TiO2 nanoparticles were firstly in situ grown on MXene and used as a scaffolding to prevent the stack of MXene nanosheets. The obtained TiO2@MXene heterostructure displays excellent layered structure and large specific surface area. After that, electrochemical activation is utilized to treat TiO2@MXene, which greatly increases the concentration of surface oxygen vacancies (VOs), thereby remarkably enhancing the conductivity and adsorption capacity of the composite. Accordingly, the prepared VO-TiO2@MXene displays excellent electrocatalytic activity toward the reduction of IMI. Under optimum conditions, cyclic voltammetry and linear sweep voltammetry techniques were utilized to investigate the electrochemical behavior of IMI at the VO-TiO2@MXene/GCE. The proposed sensor based on VO-TiO2@MXene presents an obvious reduction peak at -1.05 V(vs. Hg|Hg2Cl2) with two linear ranges from 0.07 - 10.0 μM and 10.0 - 70.0 μM with a detection limit of 23.3 nM (S/N= 3). Furthermore, the sensor provides a reliable result for detecting IMI in fruit and vegetable samples with a recovery of 97.9-103% and RSD≤ 4.3%. [ABSTRACT FROM AUTHOR]

The highly effective alk-Ti3C2/bimetallic Co, Zn embedded N-doped carbon (Co-Zn-NC) composite was fabricated by a convenient self-assembled method strategy and applied to the reduction of 4-nitrophenol(4-NP). Co-Zn-NC nanocage was synthesized by using designed core–shell ZIF-8@ZIF-67 as sacrificial template. The Co-Zn-NC was prepared by pyrolysis of ZIF-8@ZIF-67 at 900 °C with high-specific surface area and hollow structure, which facilitates the dispersion of Co species and produces abundant Co-Nx active sites. In addition, the electrochemical property and specific surface area of Ti3C2 were improved by alkaline treatment. As a result, compared with alk-Ti3C2 and Co-Zn-NC, the alk-Ti3C2/Co-Zn-NC sensor showed higher activity and stability in detecting 4-NP. The alk-Ti3C2/Co-Zn-NC sensor has a wide determination range of 2–500 μM and a low detection limit of 0.23 μM for 4-NP. In addition, the newly developed alk-Ti3C2/Co-Zn-NC sensor displayed satisfactory reproducibility and good stability in detecting 4-NP in aqueous samples. [ABSTRACT FROM AUTHOR]

An electrochemical sensor has been developed, by modifying screen-printed carbon devices (SPCE) with photochemically synthesized gold nanoparticles (AuNP), to determine benzyl alcohol, a preservative widely used in the cosmetic industry. To obtain the AuNP with the best properties for electrochemical sensing applications, the photochemical synthesis was optimized using chemometric tools. A response surface methodology based on central composite design was used to optimize the synthesis conditions, as irradiation time, and the concentrations of metal precursor and the capping/reducing agent (poly(diallyldimethylammonium) chloride, PDDA). The anodic current of benzyl alcohol on SPCE modified with the AuNP was used as response of the system. The best electrochemical responses were obtained using the AuNP generated by irradiating for 18 min a 7.20 × 10−4 mol L−1 AuCl4−-1.7% PDDA solution. The AuNP were characterized by transmission electron microscopy, cyclic voltammetry and dynamic light scattering. The nanocomposite-based sensor formed by the optimal AuNP (AuNP@PDDA/SPCE) was used to determine benzyl alcohol by linear sweep voltammetry in 0.10 mol L−1 KOH. The anodic current at + 0.017 ± 0.003 V (vs. AgCl) was used as analytical signal. Detection limit obtained under these conditions was 2.8 µg mL−1. The AuNP@PDDA/SPCE was applied to determine benzyl alcohol in cosmetic samples. [ABSTRACT FROM AUTHOR]

Herein, a fast, inexpensive, and sensitive electrochemical approach for the quantification of 6-gingerol in the ginger samples was established. Au nanoparticles-ZnO-reduced graphene oxide (AuNPs-ZnO-rGO) nanocomposites were fabricated and employed as electrode-modified materials to improve the sensitivity of the determination. UV–visible (UV–vis), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) characterization elucidated the successful fabrication of AuNPs-ZnO-rGO nanocomposites. Voltammetry investigation demonstrated the excellent electrocatalytic activity of AuNPs-ZnO-rGO nanocomposites toward the redox reaction of 6-gingerol. Using the best experimental conditions (pH: 2.0 BR; the amount of AuNPs-ZnO-rGO suspension: 6 μL; accumulation time: 120 s), the linearity of the peak currents relied on the concentration of 6-gingerol from 0.1 to 100 μM with a detection limit of 0.03 μM (S/N = 3). The developed approach was successfully implemented for the quantification of 6-gingerol in ginger samples, with recoveries of 99.07‒102.1%. [ABSTRACT FROM AUTHOR]

Screen‐printed carbon electrode (SPCE) has various crucial applications as biosensors. The binders used in the ink formulation of the SPCEs reduce the electron transfer from an electrolyte to it. In this study, we used an argon atmospheric pressure plasma jet (APPJ), a cost‐effective device, to modify the SPCE surface. Scanning electron microscopy and X‐ray photoelectron spectroscopy results show binder removal and oxidation of the APPJ‐treated SPCE surface. Due to binder removal and exposure of graphitic surface, the hydrophilicity of the APPJ‐treated SPCE surface enhances significantly. Moreover, oxidation makes the electrode more suitable for dopamine adsorption, resulting in enhanced sensitivity. The detection limit for the APPJ‐treated electrode is 1 μm, as observed in this study. Cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy have been performed on APPJ‐treated and untreated SPCEs. [ABSTRACT FROM AUTHOR]

Sluggish oxygen reduction reaction (ORR) of electrodes is one of the main challenges in fuel cell systems. This study explored the kinetics of the ORR reaction mechanism, which enables us to understand clearly the electrochemical activity of the electrode. In this research, electrocatalysts were synthesized from platinum (Pt) catalyst with multi-walled carbon nanotubes (MWCNTs) coated by three polymers (polybenzimidazole (PBI), sulfonated tetrafluoroethylene (Nafion), and polytetrafluoroethylene (PTFE)) as the supporting materials by the polyol method while hexachloroplatinic acid (H2PtCl6) was used as a catalyst precursor. The oxygen reduction current of the synthesized electrocatalysts increased that endorsed by linear sweep voltammetry (LSV) curves while increasing the rotation rates of the disk electrode. Additionally, MWCNT-PBI-Pt was attributed to the maximum oxygen reduction current densities at −1.45 mA/cm2 while the minimum oxygen reduction current densities of MWCNT-Pt were obtained at −0.96 mAcm2. However, the ring current densities increased steadily from potential 0.6 V to 0.0 V due to their encounter with the hydrogen peroxide species generated by the oxygen reduction reactions. The kinetic limiting current densities (JK) increased gradually with the applied potential from 1.0 V to 0.0 V. It recommends that the ORR consists of a single step that refers to the first-order reaction. In addition, modified MWCNT-supported Pt electrocatalysts exhibited high electrochemically active surface areas (ECSA) at 24.31 m2/g of MWCNT-PBI-Pt, 22.48 m2/g of MWCNT-Nafion-Pt, and 20.85 m2/g of MWCNT-PTFE-Pt, compared to pristine MWCNT-Pt (17.66 m2/g). Therefore, it can be concluded that the additional ionomer phase conducting the ionic species to oxygen reduction in the catalyst layer could be favorable for the ORR reaction. [ABSTRACT FROM AUTHOR]

Recently, the active surface modification of glassy carbon electrodes (GCE) has received much attention for the development of electrochemical sensors. Nanomaterials are widely explored as surface-modifying materials. Herein, we have reported the hydrothermal synthesis of molybdenum disulfide (MoS2) and its electro-catalytic properties for the fabrication of a resorcinol sensor. Structural properties such as surface morphology of the prepared MoS2 was investigated by scanning electron microscopy and phase purity was examined by employing the powder X-ray diffraction technique. The presence of Mo and S elements in the obtained MoS2 was confirmed by energy-dispersive X-ray spectroscopy. Finally, the active surface of the glassy carbon electrode was modified with MoS2. This MoS2-modified glassy carbon electrode (MGC) was explored as a potential candidate for the determination of resorcinol. The fabricated MGC showed a good sensitivity of 0.79 µA/µMcm2 and a detection limit of 1.13 µM for the determination of resorcinol. This fabricated MGC also demonstrated good selectivity, and stability towards the detection of resorcinol. [ABSTRACT FROM AUTHOR]

An optimised electrochemical technique, linear sweep voltammetry (LSV) in KOH solution (LSV-KOH) was confronted with the double loop electrochemical Potentiokinetic reactivation (DL-EPR) to verify which is the best technique to quantify deleterious phases (DP) in a UNS S32750 super duplex stainless steel. DL-EPR presented an error in determination of deleterious phases in the range of 6.9–100%. LSV-KOH show a better accuracy in quantification of deleterious phases volume fractions, the error range for LSV-KOH was 2.4–26.2%. When the morphology of sigma changes from lamellar to divorced, was observed modifications on LSV-KOH voltammograms. In specimens where lamellar morphology is present, the voltammograms show two peaks curve. Meanwhile, in specimens where occurred also divorced precipitation of sigma the voltammograms changes to a 3 peaks curve. This feature is due to the dissolution of sigma phase boundaries which has different compositions according to the form of sigma precipitation. [ABSTRACT FROM AUTHOR]

The ion transport properties across the membrane under conditions of different membrane types, solution concentrations, flow rates and temperatures were investigated in a four-compartment reactor. By combining linear sweep voltammetry and chronopotentiometry, the limiting current density (Ilim), the ion transition time (τ) and the difference between ion transport numbers in the membrane and the solution (tm–ts) were determined. And the diffusion boundary layer thickness (δ) of the membrane-solution system at steady-state conditions was measured by electrochemical impedance spectroscopy. The results show that the use of Selemion membrane and the increase of solution concentration, flow rate and temperature, Ilim and τ increase, tm–ts and δ decrease. This means the concentration polarization of the system is weaker and complete concentration polarization is more difficult to occur. At the same time, Ilim, τ and tm–ts are strongly related to solution concentration and temperature, while the diffusion boundary layer thickness is mainly affected by solution concentration and flow rate. Additionally, Ilim of anion exchange membranes is larger than that of cation exchange membranes due to the difference in migration rates of anion and cation. [ABSTRACT FROM AUTHOR]

Due to its hazardous nature, the determination of hydrazine is of great significance. This study designed and fabricated a hydrazine electrochemical sensor. Two-dimensional (2-D) molybdenum diselenide (MoSe2) has been synthesized by using the sol-gel method. The phase purity and formation of MoSe2 was determined by a powder X-ray diffractometer. The surface morphological characteristics of the MoSe2 were studied by scanning electron microscopy. The presence of Mo and Se elements in the synthesized MoSe2 was checked by energy dispersive X-ray spectroscopy. The glassy carbon (GC) electrode (3 mm) was modified with the prepared MoSe2 via a drop-cast approach. This MoSe2-glassy carbon (MoSe2-GC) electrode was used as the working electrode for the hydrazine sensing application. The electrochemical sensing properties of the fabricated MoSe2-GC were analyzed by linear sweep voltammetry and cyclic voltammetry. The MoSe2-GC has shown a sensitivity of 0.68 µA/µMcm2 and a detection limit of 0.091 µM. In addition, MoSe2-GC also has good selectivity toward hydrazine determination in the presence of various interfering compounds. The excellent electro-catalytic behavior of MoSe2 is solely responsible for this enhanced sensing performance of MoSe2-GC. [ABSTRACT FROM AUTHOR]

A nanosensor comprising of gold nanostars (Au-Nstars)-graphitic carbon nitride (g-C3N4) nanocomposite layered on a glassy carbon electrode (GCE) to detect serotonin (ST) in various body fluids has been fabricated. The nanocomposite and the sensing platform have been thoroughly characterized with UV–visible spectroscopy (UV–vis), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray photoelectron spectroscopy (EDX), and electrochemical techniques such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The designed ST detection probe has achieved a linear dynamic range (LDR) in the range 5 × 10−7 and 1 × 10−3 M with a limit of detection (LOD) of 15.1 nM (RSD < 3.3%). The ST detection capability of the fabricated sensor ranges between the normal and several abnormal pathophysiological situations. The sensor effectively detects ST in real matrices such as urine and blood serum, thus, showing its direct diagnostic applicability. Additionally, the sensor has been tested in the microenvironment of human embryonic kidney (HEK) cells to assess the possibility of ST secretion in cell lines. Interferences because of co-existing molecules have been evaluated, and the shelf-life of the fabricated sensor has been obtained as 8 weeks. [ABSTRACT FROM AUTHOR]

Supercapacitors are a boon in today's modern world. The role of a supercapacitor is important in providing electrical energy in the most efficient way for the usefulness of the society. Herein, co-precipitation technique was adapted to prepare electrodes for energy storage and water-splitting purposes. Role of ammonia at different concentrations was deliberated. Better 269 and 364 F/g capacitance was attained for best electrode from cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) curves, respectively. The capacitive and diffusion contribution of all electrodes were estimated and found to be 91.88 and 8.12 for the best sample. A better diffusion contribution of the higher-concentration ammonia sample revealed a higher specific capacitance. In this study, 91.33% capacitive retention and 90.38% columbic efficiency were calculated after 5000 cycles of charge and discharge. Further electrochemical method like linear sweep voltammetry (LSV) and chronoamperometry (CA) was explored for water-splitting applications and 367 mA/g current density with 264 mV overpotential was achieved in the LSV plot. CA test was carried out for 10 h to reveal 189 mA/g current density and delivered 74% stability. Therefore, the present study describes different technique to extend electrochemical supercapacitor and water-splitting purposes. • A simple co-precipitation method used to synthesis CoSn(OH) 6 nanoparticles. • Higher ammonia additive revealed 269 F/g, 364 F/g from CV and GCD. • Higher ammonia additive revealed 8.12% capacitive and 91.88% diffusive contributions. • 91.33% capacitive retention, 90.38% columbic efficiency was calculated over 5000 cycles. • 367 mA/g current density with 264 mV over potential was achieved in LSV. [ABSTRACT FROM AUTHOR]