Effect Of Scan Rate Research Articles

Combustion synthesis of Pr6O11 nanoparticles as an effective and sensitive sensor for detection of vanillin in the presence of uric acid

This research work describes a simple, sensitive, and disposable modified carbon paste electrode that has been constructed using praseodymium oxide nanoparticles (Pr6O11 NPs) as a modifier. These Pr6O11 NPs were prepared by combustion method and their characteristic features were studied by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDX). The prepared modified carbon paste electrode (Pr6O11/CPE) was explored by voltammetric techniques such as cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and electron impedance spectroscopy (EIS). The electrochemical oxidation of vanillin (VN) with uric acid (UA) in 0.1 M PBS (pH 7.0), the modified Pr6O11/CPE provides a significant current enhancement over the bare carbon paste electrode (BCPE). Some variable parameters, such as electroactive surface area, effect of modifier concentration, scan rate effect, effect of pH, and electron transfer kinetics have been investigated using the modified electrode. The electrooxidation of VN shows a diffusion-controlled process at modified Pr6O11/CPE. The detection limit of VN was found to be 0.57 µM in the range of 1-4 µM was studied by DPV method. The proposed modified sensor was fruitfully employed to measure the ingredient of VN in real sample. The stability, sensitivity, and limit of detection for VN study demonstrated the feasibility of the modified Pr6O11/CPE.

Exploiting Pr0.66(MoO4)-rGO nanocomposite for effective energy storage and electrochemical sensing applications

The multi-functional composites derived from rare-earth-based materials offer favorable properties for numerous applications. Given this, here we explore the energy storage and the sensing application of praseodymium molybdate-reduced graphene oxide [Pr0.66(MoO4)-rGO] nanocomposite for silibinin (SIL) for the first time. The [Pr0.66(MoO4)-rGO] composite was prepared hydrothermally and examined by XRD, SEM with EDX, FT-IR, AFM, particle size analyzer, zeta potential, and thermal methods. Detailed electrochemical properties of the Pr0.66(MoO4)-rGO nanocomposite over nickel foam (NF) were explored for energy storage applications. As a supercapacitor, the Pr0.66(MoO4)-rGO/NF electrode exhibited an impressive specific discharge capacitance value of 684.25 F g−1 with significant cycle stability of over 2000 cycles. Furthermore, Pr0.66(MoO4)-rGO/glassy carbon electrode (GCE) was fabricated for the electrochemical sensing of an anticancer drug, SIL, employed to treat a wide range of cancers. The peak current of SIL was enhanced by 38 – folds at Pr0.66(MoO4)-rGO/GCE compared to that at bare GCE. The effect of pH, scan rate, accumulation time and amount of suspension of Pr0.66(MoO4)-rGO on the electrochemical behavior of SIL was studied. SIL exhibited well-defined peaks in phosphate buffer of pH 3.0. Linearity between the peak current and concentration of SIL was noticed in the range of 2.04–44.89 μM for square wave voltammetric and 3.0–50 μM for differential pulse voltammetric methods. The developed methods were successfully applied for the determination of SIL in pharmaceutical formulations and biological samples. The accuracy and precision of the developed electrochemical methods were evident by higher percentage recovery and lower relative standard deviation (RSD) values.

Electrochemical Behavior and Ultrasensitive, Simple and Effective Voltammetric Determination of Acetaminophen Using Modified Glassy Carbon Electrode Based on 4‐Hydroxyquinoline‐3‐carboxylic Acid

AbstractAn electrochemical oxidation of acetaminophen (ACOP) has been successfully performed by using glassy carbon electrode covered with 4‐hydroxyquinoline‐3‐carboxylic acid (4HQ3CA) to reinforce electrode's feature. To characterize the modified electrode (4HQ3CA/GC), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and Fourier transform infrared spectroscopy (FT‐IR) techniques were used. The finding optimum conditions (supporting electrolyte, pH) and the electrochemical determination studies were performed with differential pulse voltammetry (DPV). It was decided that the supporting electrolyte medium suitable for ACOP determination was Britton‐Robinson (BR) buffer and the effect of pH change on the oxidation peak of ACOP in this media was investigated. The effect of changing scan rate on the oxidation peak of ACOP was examined and this study showed that the oxidation process of ACOP on the 4HQ3CA/GC modified electrode surface was diffusion and adsorption controlled process. A wide concentration range from 0.0025 μM to 141 μM with a limit of detection (LOD) of 5.98×10−10 M (3 s/m) was obtained. This prepared sensor was carried out for the determination of ACOP in pharmaceutical sample.

A dynamic current hysteresis model for IGZO-TFT

This paper proposes a dynamic current hysteresis model for the Indium Gallium Zinc Oxide Thin Film Transistor (IGZO-TFT). Based on the Shockley-Read-Hall (SRH) theory, a kinetic equation that accurately describes the interface trap’s capture/emission behaviour is presented, which can incorporate the effect of interface trap density, trap energy level and scan rate dependency. Further, the kinetic equation is solved using a sub-circuit approach, combined with a calibrated TFT static current model, to achieve an accurate simulation of the current hysteresis of IGZO-TFT. This model has been validated with numerical TCAD simulations and has been shown to precisely reflect the effect of trap energy level, trap density and scan rate on the current hysteresis characteristics.

One-step direct desulfurization of cuprous sulfide for copper recovery via electrolysis in deep eutectic solvent

Cuprous sulfide (Cu2S) is the main composition of chalcocite and widely used in the catalyst. Deep eutectic solvents (DESs) are eco-friendly electrolytes for the separation and recycling of metals and their compounds in addition to environmental protection. In this work, choline chloride-ethylene glycol (ChCl-EG) DES is innovatively used towards one-step desulfurize cuprous sulfide to recycle copper for the first time. Cyclic voltammetry is employed to investigate the effect of initial potential, scan rate and temperature on the electrochemical behavior of Cu(I) in ChCl-EG DES. The effect of essential parameters (applied voltage, temperature and NH4HCO3 ratio) on the chemical composition and microstructure of the product are discussed. Pure polycrystalline nano-Cu with an average size of ≈16.15 nm can be obtained with the current efficiency of 96.58% at the optimized parameters of 2.5 V, 353 K, 40% NH4HCO3 and 10 h. The structure of Ch+ is unbroken and the main existence form of Cu(I) is CuCl2− in the electrolyte. Mechanism analysis indicates the reduction of Cu2S to Cu is step-by-step with the feasible process of Cu2S→Cu1.96S→Cu7.2S4…→Cu. The S element is possibly converted and stabilized as the sulfate (SO42−) in the DES. All these findings are expected to provide new feasibility for the direct extraction and recycling of Cu from Cu2S with high current efficiency and less hazardous.

An electrochemical sensor based on multiferroic NdFeO3 particles modified electrode for the detection of H2O2

The high dielectric constant and lower dielectric loss make NdFeO 3 materials ideal for potential use in many several applications. Specifically, NdFeO 3 is a promising candidate for electrochemical sensing applications owing to its high thermal stability, and non-toxicity. In this present study, multiferroic NdFeO 3 particles are synthesized using a solid-state reaction at a higher temperature. Structural studies confirm that NdFeO 3 crystallizes in an orthorhombic symmetry. Elemental color mapping of the NdFeO 3 sample reveals there is no impurity, and that the sample comprises Nd, Fe, and O elements. In addition, the Nyquist plot suggests the contribution of grain and grain boundary effect towards the resistive and capacitive characteristics of NdFeO 3 . Magnetic measurements at room temperature indicated an antiferromagnetic nature of the sample with a weak ferromagnetic component arising due to the canted nature of Fe 3+ . The non-collinear magnetic structure of NdFeO 3 promotes the ferroelectric loop. Single-phase room temperature NdFeO 3 multiferroics were coated upon the glassy carbon electrode with the aim of sensing hydrogen peroxide (H 2 O 2 ) using a three-electrode electrochemical setup. The cyclic voltammetry technique showed an increase in the peak current with an upsurge in the concentration of H 2 O 2 between 1 mM and 10 mM. The limit of detection, the limit of quantification, and sensitivity was calculated to be 0.87 µM, 2.92 µM, and 52.6 µA mM −1 cm −2 respectively. The correlation coefficient R 2 was found to be 0.9792. The value of linearity with regression coefficient was calculated to be R 2 = 0.9922 from the effect of scan rate. NdFeO 3 showed an excellent selectivity towards H 2 O 2 in the presence of H 2 SO 4 , KCl, HCl, and NaOH, and good sensitivity for monitoring H 2 O 2 in a real milk sample. The sensitivity of modified Glassy carbon electrode (GCE) in milk was calculated to be 46.58 µA mM −1 cm −2 . • Solid state reaction of single phase multiferroic particles NdFeO 3 . • Extensive studies of electrical, impedance, X-ray photoelectron spectroscopy. • Weak ferroelectric and antiferromagnetic with weak ferromagnetic behavior are observed. • Electrochemical sensing of the hydrogen peroxide in real milk samples.

Miniaturized 3D printed electrochemical platform with optimized Fibrous carbon electrode for non-interfering hypochlorite sensing.

3D printing technology based electrochemical device can provide ease of fabrication, cost effectiveness, rapid detection and lower limit of detection. Herein, a novel, customized, portable and inexpensive 3D printed electrochemical device, has been presented. Fibrous carbon Toray paper, deposited with gold nanoparticles through electrodeposition, used as a working electrode which Further device was tested with 1mM sodium hypochlorite using cyclic voltammetry (CV) and square wave voltammetry (SWV) in 0.1M PBS. Hypochlorite has a pivotal role in supporting the growing chemical and paper industries and finds diverse uses in several clinical applications. It is primarily used for disinfecting food, water and surfaces. The scan rate study was carried out from 20mVs-1 to 250mVs-1 using cyclic voltammetry technique. The diffusion coefficient obtained from scan rate effect was 1.39×10-6 cm2s-1. The concentration range was evaluated with SWV technique, in a linear range of 0.6μM-40μM, with a detection limit of 0.7μM. The device was further analyzed to ensure non-interference from co-existing chemicals like sodium chloride, potassium nitrate, sodium carbonate, sodium nitrite. Real sample analysis was done with sea, artificial sea and tap water with impressive recovery values. In summary, the developed working electrode can be customized and modified based on testing analyte; thus, the proposed device can be used for various other biochemical analytes.

Electrochemical Sensor for Meropenem Therapeutic Monitoring in Human Plasma Based on Carbon Nanotubes Modified Basal Pyrolytic Graphite Electrode

Sensitive, precise, and fast differential pulse voltammetric (DPV) method has been developed for determination of meropenem (MER) in pure form, pharmaceutical dosage form, and human plasma. The fabricated sensors are based on basal-plane pyrolytic graphite electrode (BPPGE) substrates that was modified by coating the surface with carbon nanotubes. The modified electrode showed detectable enhancement of the anodic peak current of meropenem from 25.8 to 35.7 μA. Effect of both pH and scan rate on peak current and potential were studied, optimum conditions were found to be at pH = 3.0 and scan rate of 100 mV.s−1. A linear response was obtained over the concentration range of 3.0 × 10−7 to 7.0 × 10−5 M MER in aqueous buffer solution. The suggested sensor is highly sensitive, has short response time, capable of MER detection as low concentration as 1.5 × 10−6 M in human plasma. The proposed sensors shows a great potential towards future fabrication of a point-of-care device to monitor MER level in patients’ plasma to ensure drug safety and efficacy for patients in intensive care unit.

Electrochemically tracking interactions between molecular ions of sodium dodecyl sulphate and the selected amino acid at the electrode-electrolyte interface

Surfactant assisted electrode–electrolyte (E-E) interface is a fascinating research topic that has been employed in different fields such as biosensing, energy devices, surface technology, etc. This work explores the electrochemical properties of sodium dodecyl sulphate (SDS) in the presence of essential amino acid (AA) i.e., l-Threonine (THR), dl-Methionine (MET), and l-Phenylalanine (PHE) at the E-E interface through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). For the electrochemical study of SDS at its premicellar and post micellar concentration in presence of AA ions, the three-electrode configuration consisting of glassy carbon (GC) as the working electrode, Ag/AgCl as reference electrode, and Pt wire as the counter electrode, have been used. Briton Robinson buffer (pH, 2) was utilized as the supporting electrolyte. The effect of AA ions on faradic properties of electroactive ions in the SDS system was studied by CV measurement. The scan rate effect was used to calculate the kinetic parameters such as maximum surface adsorbed concentration (Г, mol/cm2), diffusion coefficient (D, cm2/s), and capacitance of electrode surface (C, F/cm2). EIS measurements were applied to study the capacitive and resistive properties of the electric double layer (EDL) that developed at the E-E interface. The double-layer capacitance (Cdl) of EDL was extracted from the equivalent circuit diagram. The results from electrochemical measurements suggested that the electrochemical properties of SDS such as the faradaic process of electroactive ions and their kinetics through the SDS channel and charge storage performance of electrified surface were strongly affected by AA ions at the E-E interface through electrostatic interactions between oppositely charged ions. This work contributed to the understanding of the electrochemical interaction of biomolecular ions at the surfactant-assisted E-E interface. It will diversify the application of surface-active agents in biology and biotechnology.

An effective, novel, and cheap carbon paste electrode for naproxen estimation

AbstractHerein, a carbon paste electrode (CPE) modified with poly(reduced-o-nitrobenzoic acid [r-o-NBA]) supported in graphene quantum dots (GQDs) was fabricated for the first time. The fabricated electrode’s surface morphology and composition were characterised by scanning electron microscope and transmission electron microscope. The poly(r-o-NBA)/GQDs/CPE showed high electrocatalytic activity towards the oxidation of naproxen (NPX) using cyclic and differential pulse voltammetric methods. The effect of scan rate on the oxidation peak of NPX suggests that the electrode process was typically diffusion-controlled. In addition, the effect of pH reflects the participation of protons in the oxidation process of NPX. The peak current is linearly proportional to the concentration of NPX ranging from 1.0 to 100.0 µM, with the correlation coefficient (R2), sensitivity, limit of detection (3σ), and limit of quantification (10σ) being 0.9995, 0.419 µA·µM−1·cm−2, 0.672, and 2.241 µM, respectively. Using chronoamperometry, the diffusion coefficient of NPX at the poly(r-o-NBA)/GQDs/CPE was estimated to be 5.36 × 10−6 cm2·s−1. The proposed electrode has good reproducibility, stability, and high selectivity for NPX oxidation. The obtained recovery range (96.7–102.0%) means that the proposed sensor performed satisfactorily when applied for the detection of NPX in its pharmaceutical formulations.

Electrochemical detection of bisphenol A in presence of catechol and hydroquinone at copper oxide modified carbon paste electrode

Utilizing co-precipitation method copper oxide (CuO) nanomaterials are prepared and analyzed using X-ray diffraction (XRD), Scanning electron microscope (SEM), and Energy-dispersive X-ray Analysis (EDAX) technique. Copper oxide modified carbon paste electrode (CuOMCPE) were used as electrochemical sensor for the study of catechol, bisphenol A and hydroquinone using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The analyte species shows high reproducibility in voltammetric response because of his enhancement. The CuOMCPE exhibits the better electrocatalytic property for the oxidation of BPA, CC and HQ. Parameters like scan rate and concentration of Bisphenol A (BPA), catechol (CC) and hydroquinone (HQ) were studied by CuOMCPE. The effect of scan rate on CuOMCPE was studied individually for BPA, CC, and HQ and shows that the electrode process was adsorption-controlled. The modifier exhibits good limit of detection (LOD) and limit of quantification (LOQ) values are found at 2.48 μM and 8.26 μM for BPA, 3.22 μM and 10.73 μM for CC, 4.94 and 16.48 μM for HQ respectively. The CuOMCPE shows high stability and reproducibility compared to BCPE. DPV were studied using CuOMCPE gives three well defined peaks located at 0.4406(BPA), 0.1043 V (CC) and 0.0075 V (HQ) respectively. The simultaneous and interference study of analytes were studied using CuOMCPE. Hence, the modifier exhibits good selectivity and sensitivity for the study of BPA, HQ and CC.

Voltammetric Behaviour of Rhodamine B at a Screen-Printed Carbon Electrode and Its Trace Determination in Environmental Water Samples

The voltammetric behaviour of Rhodamine B was studied at a screen-printed carbon electrode (SPCE), by cyclic and differential pulse voltammetry. Cyclic voltammograms exhibited two reduction peaks (designated R1 and R2) generated from the reduction of the parent compound through, first, one electron reduction (R1) to give a radical species, and then a further one-electron, one-proton reduction to give a neutral molecule (R2). On the reverse positive-going scan, two oxidation peaks were observed. The first, O1, resulted from the oxidation of the species generated at R2, and the second, O2, through the one-electron oxidation of the amine group. The nature of the redox reactions was further investigated by observing the effect of scan rate and pH on the voltammetric behaviour. The developed SPCE method was evaluated by carrying out Rhodamine B determinations on a spiked and unspiked environmental water sample. A mean recovery of 94.3% with an associated coefficient of variation of 2.9% was obtained. The performance characteristics indicated that reliable data may be obtained for Rhodamine B measurements in environmental water samples using this approach.

EDTA salt modified carbon paste electrode for square wave voltammetric determination of theophylline in pharmaceutical tablet formulation.

In this study, a square wave voltammetric method for determination of theophylline in tablet formulation based on EDTA salt modified carbon paste electrode is presented. CV, FT-IR, and EIS results confirmed modification of the carbon paste with EDTA salt. In contrast to the unmodified carbon paste electrode, the modified carbon paste electrode showed irreversible oxidation of theophylline with considerable current enhancement. Investigation of the effect of scan rate on the Ip and Ep response of the modified electrode for theophylline revealed predominantly diffusion controlled oxidation kinetics. Under the optimized conditions, square wave oxidative peak current of theophylline in pH 7.0 PBS showed linear dependence on concentration in the range 10–200 μM with determination coefficient (R2), limit of detection, and limit of quantification of 0.99782, 0.0257 μM, and 0.0857 μM, respectively. Detection of an amount of theophylline in the analyzed tablet formulation with 1.85% error from its nominal content (120 mg/tablet) confirmed the accuracy of the developed method. Spike and interference recovery results of 98.59%, and 95.7–100%, respectively validated the applicability of the developed method for determination of theophylline content in tablet samples.

Voltammetric Determination of Hg2+, Zn2+, and Pb2+ Ions Using a PEDOT/NTA-Modified Electrode.

A novel electrochemical sensor for determining trace levels of Hg2+, Pb2+, and Zn2+ ions in water using square wave voltammetry (SWV) is reported. The sensor is based on a platinum electrode (Pt) modified by poly(3,4-ethylenedioxythiophene) and Nα,Nα-bis-(carboxymethyl)-l-lysine hydrate (NTA lysine) PEDOT/NTA. The modified electrode surface (PEDOT/NTA) was prepared via the introduction of the lysine-NTA group to a PEDOT/N-hydroxyphthalimide NHP electrode. The (PEDOT/NTA) was characterized via cyclic voltammetry (CV), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The effects of scan rates on the electrochemical properties of the polymer electrode were also investigated. The electrochemical results were used to estimate the coverage of the electrode polymer surface and its electrostability in background electrolyte solutions. Several analytical parameters, such as polymer film thickness, metal deposition time, and pH of the electrolyte, were examined. Linear responses to Hg2+, Pb2+, and Zn2+ ions in the concentration range of 5–100 μg L–1 were obtained. The limits of detection (LODs) for the determination of Hg2+, Pb2+, and Zn2+ ions were 1.73, 2.33, and 1.99 μg L–1, respectively. These promising results revealed that modified PEDOT/NTA films might well represent an important addition to existing electrochemical sensor technologies.

The electrochemical evaluation of antipsychotic drug (promethazine) in biological and environmental samples through samarium cobalt oxide nanoparticles

In this work, we developed a perovskite structured samarium cobalt oxide nanoparticles (SmCoO3 NPs) with the aid of the co-precipitation method. The rare earth metal (Sm) and cobalt oxide combined to form a perovskite lattice structure. One-pot route synthesized SmCoO3 NPs were scrutinized successfully through various physicochemical techniques. Concerning its effective thermal stability and electrical properties, the synthesized SmCoO3 NPs have been effectively implemented in the electrochemical evaluation of promethazine hydrochloride (PHY) using cyclic voltammetry. The electrochemical detection of PHY was performed through SmCoO3 NPs-modified glassy carbon electrode (GCE) and unmodified GCE. The electron transfer kinetics, effect of scan rate, the influence of pH, electroactive surface area, selectivity, and sensitivity have been studied. The electron charge transfer rate (Rct) and electrolyte resistance (Rs) were calculated to be 105.59 (Ω) and 150 (Ω) in the ferricyanide probe, indicating great facilitation of the electron transfer between PHY and SmCoO3 NPs deposited on the electrode surface. Further, the optimized SmCoO3-modified GCE exemplifies excellent selectivity, storage stability, reproducibility, repeatability, detection limit (5 nM), sensitivity (0.594 μA μM−1 cm−2), and wide consecutive linear ranges, respectively. Besides, the proposed method has been effectively employed for the detection of PHY in the various real samples which reveals good recoveries of 95.40–99.17%.

Electro-Oxidation and Determination of Ciprofloxacin at f-MWCNT@Poly-Aniline Glassy Carbon Electrode

A simple and sensitive electrochemical sensor was developed to quantify ciprofloxacin by restricted electro-polymerization of aniline on GCE followed by drop coating functionalized MWCNTs. Electro-catalytic activity of modified electrodes was investigated by EIS and CV revealed decrease in electrode’s charge transfer resistance and increase in electron transfer kinetics. Effect of pH and scan rate suggests a mixed adsorption-diffusion process. Tafel slope (plot of ln∣j a ∣ or ln∣I a ∣ against E) with linear relationship of potential vs logarithm of current on the linear sweep voltammogram determined the electron transfer coefficient (α). Using the value of (α), number of electrons (n) involved in the rate determining step was obtained. Surface coverage of analyte molecules adsorbed, and diffusion coefficient of ciprofloxacin were estimated from the Laviron and Randles Sevcik equations respectively. Peak current obtained by LSV for various concentrations of ciprofloxacin exhibited two linear ranges, 0.1 μM to 1 μM and 1 μM to 20 μM, with limit of detection 0.08 μM (RSD = 2.4%, S/N = 3). Presence of species existing abundantly in the sample matrix do not affect the sensor signal. Proposed ciprofloxacin sensor demonstrated high reproducibility, long-term stability and fast reaction. The fabricated sensor successfully determined ciprofloxacin in pharmaceutical formulations with recoveries between 92 to 104%.

2-Aminoantrakinon ile Modifiye Edilmiş Camsı Karbon Elektrot Kullanılarak Nitrobenzenin Elektrokimyasal Tayini

PAAQ (Poly(2-amino-anthraquinone)) films were prepared through electrochemical oxidation of 2-amino-anthraquinone monomer in anhydrous acetonitrile using the supporting electrolyte tetrabutylammonium perchlorate. The effects of scan rate, cycle number, and monomer concentration on polymer film formation were investigated. Electrochemical detection of nitrobenzene (NB) on PAAQ modified glassy carbon electrode was examined with voltammetry and differential pulse voltammetry. The polymer-modified electrode exhibited excellent reducing ability towards NB compared to the unmodified electrode. The NB sensor developed on the polymer-modified electrode showed a wide linear response range of 0.0625 - 8 mM and a low detection limit of 2.294 mM.

An electrochemical study of the binding interaction between chitosan and MPA-CdSe QDs for the development of biocompatible theranostic nanoprobe

The strength and stability of biopolymer-modified quantum dots (QDs) for designing biocompatible nanoprobes depends on the interaction between QDs and coating of interest. Hence, the quantitative determination of interaction parameters has a crucial role in their development. This paper focuses on an electrochemical approach to determine interaction and binding parameters between the chitosan and hydrophilic Mercaptopropionic acid (MPA) - CdSe QDs. MPA- CdSe QDs were synthesized by the hot injection method and characterized by several techniques. The cyclic voltammetry study revealed the reduction in oxidation peak current of redox solution with the addition of MPA- CdSe QDs (50 × 10−12 M to 350 × 10−12 M); however, the peak current was increased with the addition of chitosan (1 × 10−13 M to 50 × 10−13 M), without any change in the oxidation potential. This may be due to the interaction of the amino group of chitosan with the carboxylate group of MPA-CdSe QDs. The interaction was analyzed in terms of binding constant and no. of binding sites, which was 7.3 × 1015 L Mol−1and 1.3, respectively. Effect of scan rate on oxidation and reduction peak current confirms an irreversible electrode reaction. The interaction was further characterized with UV–Vis/Fluorescence spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Biocompatibility of developed nano-biocomposite further evaluated by standard cell viability assay using Adenocarcinoma human alveolar basal epithelial cell line (A549) and Chinese hamster cell line (V79). Confocal microscopic studies and Z stacking were also performed to explore the efficacy of chitosan-coated MPA-CdSe QDs as a fluorescent agent for cell imaging.

Enhanced Electrochemical Sensor for Electrocatalytic Glucose Analysis in Orange Juices and Milk by the Integration of the Electron-Withdrawing Substituents on Graphene/Glassy Carbon Electrode.

In this work, a novel electrochemical sensor was developed by electron-withdrawing substituent modification of 1-phenyl-3-methyl-4-(4-fluorobenzoyl)-5-pyrazolone on a graphene-modified glassy carbon electrode (HPMpFP-graphene/GCE) for glucose detection. The results of characterizations using a scanning electron microscope, Fourier transform infrared spectroscopy, Raman spectroscopy, and nuclear magnetic resonance spectroscopy showed the successful fabrication of HPMpFP-graphene nanocomposite, which served as an electroactive probe for glucose detection. The electron transfer ability of HPMpFBP-graphene/GCE has been successfully revealed using cyclic voltammetry and electrochemical impedance spectroscopy results. The good electrochemical performance was shown by well-defined peak currents of square wave voltammetry under various parameters, including pH, HPMpFP and graphene composition, and scan rate effect. A high electrochemically evaluated surface area using chronoamperometry suggested that the present glucose detection response was intensified. The chronoamperometry results at a work potential of 0.4 V presented a wide linear range of 1 × 103–90 µM and 88–1 µM with 0.74 µM (S/N = 3) as the detection limit. An acceptable recovery has been revealed in the real sample analysis. The electrochemical sensing behaviour of the composite indicates that it may be a promising candidate for a glucose sensor and it significantly extends the range of applications in the electrochemical field.

An Electrochemical Investigation of Methanol Oxidation on Thin Films of Nickel Oxide and Its Composites with Zirconium and Yttrium Oxides

The present work is focused on the fabrication of NiO-ZrO2/FTO and NiO-Y2O3/FTO thin films via a simple dip-coating method. The films are deposited from precursor solutions of Ni(CH3COO)2·2H2O, Zr(CH3COO)4, Y(CH3COO)3·H2O in methanol. The synthesized films, after proper characterization, are employed for electrochemical oxidation of methanol. The analytical techniques such as X-ray diffraction (XRD), Raman, and Infrared (IR) spectroscopy reveal the successful formation of crystalline thin films of mixed metal oxide without any additional impurities. Further, X-ray photoelectron spectroscopy (XPS) results, confirm the composition and oxidation state of all the elements present in thin films. The field emission scanning electron microscopy (FESEM) further aided to identify the uniformity and porous nature of composite thin films while the energy-dispersive X-ray spectroscopy (EDS) confirms the targeted elemental composition of the prepared thin films is in good agreement with precursors. The electrochemical oxidation of methanol results reveals that NiO-Y2O3/FTO and NiO-ZrO2/FTO thin films showed current densities of 6.2 mA/cm2 and 10 mA/cm2 at 0.65 V, respectively, against Ag/AgCl/3M KCl using 0.6 M methanol solution. Furthermore, Chronoamperometric (CA) results show good stability of NiO-ZrO2/FTO and NiO-Y2O3/FTO thin films with observed current decay of 10% and 6.8% of the initial current density, respectively. Moreover, the effect of scan rate and concentration of metals in a catalyst was also investigated. The Electrochemical impedance studies (EIS) further support electrochemical results, where the lower charge transfer resistance (Rct) values are recorded for composite thin films as compared to the pure metal oxide thin films (NiO/FTO, ZrO2/FTO, and Y2O3/FTO).