Cyclic Voltammetry Response Research Articles

Exploiting synergistic interaction in Cu-Zn-Ni alloy oxide films prepared by one-step anodizing for a highly sensitive non-enzymatic glucose sensor

A highly sensitive and precise electrochemical biosensor for glucose detection was developed by coupling synergetic catalysis of Cu-Zn-Ni oxide films. To enhance the catalytic performance of alloy, potentials between −0.5 V and 1.5 V are selected for potentiostatic oxidation. Notably, the oxidation process reveals the influence of Cl− in the electrolyte, leading to electrode surface etching, with increasing etching and grain boundary collapse at higher potentials. The electrochemical performance of the electrode was comprehensively evaluated using cyclic voltammetry (CV) and amperometric response in alkaline conditions. The catalytic electrode has an impressive linear response in the concentration range of 0.1 ∼ 1.0 mM glucose, with a sensitivity of 3775.11 μA·mM−1. Furthermore, the electrode exhibits remarkable stability and anti-interference properties, rendering it suitable for non-enzymatic glucose sensing applications.

Strong Activity Changes Observable during the First Pretreatment Cycles of Trimetallic PtNiMo/C Catalysts

AbstractPt‐based alloy catalysts supported on carbon are commonly characterized for oxygen reduction reaction (ORR) activity using the rotating disk electrode technique (RDE). Within this study, we show exemplarily for PtNiMo/C catalysts that the applied pretreatment influences strongly the determined activity. The classically employed descriptor of unchanged cyclic voltammetry response is insufficient to portrait completed surface restructuring, and gives an incorrect impression that stable activity can be determined. This might be one of the reasons for the strongly deviating activities reported in literature. Following the changes in activity during pretreatment also with in‐situ FTIR and online dissolution measurements gives insights to an up to now largely overseen high activity of the trimetallic catalysts. A maximum activity of 0.57 mA cmPt−2 at 0.95 VRHE is reached quickly during the first six cycles and decreases slowly subsequently. The maximum activity and change of activity over the cycle number is affected by the scan rate and electrolyte refreshing, while the gas atmosphere plays only a minor role. This exemplary study might be important for Pt alloy catalysts in general.

Ultraflexible polyvinylidene fluoride film based amperometric enzyme-free sensor for selective detection of uric acid in a trace level.

The present invention describes a novel flexible nanosensor for the electrochemical detection of uric acid (UA) present in urine. The synthesized graphite-boron nanocomposite with an average thickness of ∼32 nm was grown up on a flexible polyvinylidene fluoride film with an average thickness of ∼50 μm and it acts as a nonenzymatic sensor for UA. The developed flexible sensor showed a prominent reduction peak in cyclic voltammetry and amperometric response with the presence of different concentrations of aqueous UA solution. In the electrochemical study, the redox peak was generated near ∼-0.42 V with a detection limit of around ∼2.09 μM as the bottom level. The high robustness of the developed sensor originated from the polymeric film base and the rapid response time of ∼0.5 s for detecting UA present in human urine. The interference property of the sensor was confirmed in the presence of bilirubin and creatinine as an eventual reference toward selectivity. The phase and morphology of the sensor surface were extensively observed before and after sensing to comprehend the electrochemical interaction between the sensor and target molecules. The generated quantitative results of the integrated system were verified by testing known and unknown concentrations of UA solutions.

Electrochemical reduction and protonation of a biomimetic diiron azadithiolate hexacarbonyl complex: Mechanistic insights

The electrochemical reduction and protonation of [Fe2(adtH)(CO)6] (1, adtH = SCH2N(H)CH2S) and [Fe2(pdt)(CO)6] (2, pdt = SCH2CH2CH2S) in the presence of moderately strong acid in acetonitrile was investigated by cyclic voltammetry (CV), focusing on the catalysis of hydrogen evolution reaction (HER) by a {2e−,2H+} pathway. The turnover frequencies at zero overpotential (TOF0) of the N-protonated product 1(H)+ and 2 for the HER were estimated from simulations of the catalytic CV responses at low acid concentration using a simple ECEC mechanism (two electrochemical and chemical steps). This approach confirmed that 1(H)+ is clearly a better catalyst than 2, pointing to a possible role of the protonable and biologically relevant adtH ligand in the enhancement of the catalytic performances. Density functional theory (DFT) calculations further suggested that, owing to a strong structural rearrangement in the course of the catalytic cycle, the HER catalysis by 1(H)+ only involves the iron center adjacent to the amine group in adtH and not the two iron centers as in 2. Since terminal hydride species (FeFe−H) are known to more easily undergo protonolyse to H2 than their bridging hydride isomers (Fe−H−Fe), this may explain here the enhanced activity of 1(H)+ over 2 for the HER.

Orthovanillin azine ester as a potential functional material for organic electronic devices

The present study reports the synthesis of OVAE, an ester of ortho-vanillin azine, and its structural characterization using spectral and single crystal-XRD studies. Intermolecular interactions of OVAE are investigated using the Hirshfield surface analysis, 3D Hirshfield surface maps, 2D fingerprint plots, and electrostatic energy frameworks. Good thermal stability in thermogravimetric analysis, irreversible redox peaks in electrochemical studies, high carrier concentration and dielectric constant in electrical measurements, uniform films observed upon surface morphology examination, fabrication of a diode, the obtained current-voltage characteristics, dielectric constant and frequency-dependent AC conductivities directed towards the use of OVAE as a potential semiconducting functional material in suitable electronic devices. Based on cyclic voltammetry and AC impedance response, the performance of OVAE as an electrode material is explored by constructing a supercapacitor, which exhibited a specific capacitance of 56 Fg−1 at 10 mV s−1.

Correlation between the electrochemical response and main components structure in solutions for rechargeable Mg batteries based on THF and the reaction products of tBuMgCl and AlCl3

The electrochemical response of ethereal solutions containing magnesium organohaloaluminate complexes has drawn great interest in recent decades owing to their relevance to rechargeable magnesium batteries, as demonstrated with solutions containing complexes formed by reacting R2Mg and AlCl2R moieties in ethers like tetrahydrofuran (THF). However, most of previous reports focused on battery related performances, and less on the structure of the active species. Herein, we focus on (1) identifying electroactive species and (2) correlating the electrochemical properties of their solutions to the preparation modes: either through reactions of their precursors in THF, or by dissolving isolated crystallized products in the ether solvent. Specifically, we explore the products of the reaction of the Grignard reagent t-BuMgCl with AlCl3 (1:1) in THF, and how their presence in solutions affect their electrochemical behavior.We isolated two complex products, one non-soluble and one soluble in THF, which exhibit two distinct single-crystal structures. The molecular structure of the two complexes obtained from the single-crystal X-ray diffraction (SCXRD) and nuclear magnetic resonance (NMR) measurements was correlated with the electrochemical behavior of their solutions in THF, as reflected by their cyclic voltammetry (CV) response. We found that one product (compound I) has the molecular structure [MgCl·THF5]+ [AlCl4]– and it is electrochemically inactive in terms of reversible Mg dissolution/deposition. The molecular structure of the second compound (II), [Mg2(μ-Cl)3·THF6]+ [t-BuAlCl3]–, has not been reported before, and its solutions in THF exhibit reversible Mg dissolution/deposition behavior. Our study clearly demonstrates the possibility of tuning judiciously the electrochemical response of ethereal solutions of magnesium organohaloaluminate complexes through their structural modifications.

Development and Detailed Performance Study of a Carbon Paste Electrode for the Electrochemical Detection of Malachite Green

The present investigation aims to lighten a quick electrochemical detection technique of malachite green (MG) content using an easy and affordable carbon paste electrode (CPE). MG finds a wide area of application for controlling external fungi plus parasites on the fish egg for its antifungal and antiparasitic features. However, MG is noticed to be dreadfully poisonous and unsafe. Hence, the determination of MG in aquaculture is very much necessary. In this current report, the electrochemical behavior of CPE has been studied using a three-electrode system containing a silver-silver chloride (Ag/AgCl) reference electrode and a platinum counter electrode to record the corresponding cyclic voltammetry (CV) and differential pulse voltammetry (DPV) responses. CV plots in the applied potential range from 0.3 V to 1.5 V described a strong indication of MG existence, while DPV results successfully illustrated the quantification of several MG concentrations. The linear range of operation was from 10[Formula: see text][Formula: see text]M to 1000[Formula: see text][Formula: see text]M with the lowest limit of detection (LOD) as 0.78 [Formula: see text]M. Various concentrations like 50, 300, 600, 800, and 1000[Formula: see text][Formula: see text]M were assessed via principal component analysis (PCA) with effective data clustering (separability index (SI) found as 131.08). The prediction estimations of MG content using PLSR (partial least square regression) along with PCR (principal component regression) algorithms were also carried out, resulting in 95.39% and 93.02% prediction accuracies, respectively. Moreover, applying this CPE over natural aqueous sample extracts exhibited a reasonable recovery rate of 94.85–97.3%.

Investigation of Newly Synthesized Bis-Acyl-Thiourea Derivatives of 4-Nitrobenzene-1,2-Diamine for Their DNA Binding, Urease Inhibition, and Anti-Brain-Tumor Activities

Bis-acyl-thiourea derivatives, namely N,N'-(((4-nitro-1,2-phenylene)bis(azanediyl)) bis(carbonothioyl))bis(2,4-dichlorobenzamide) (UP-1), N,N'-(((4-nitro-1,2-phenylene) bis(azanediyl))bis(carbonothioyl))diheptanamide (UP-2), and N,N'-(((4-nitro-1,2-phenylene)bis(azanediyl))bis(carbonothioyl))dibutannamide (UP-3), were synthesized in two steps. The structural characterization of the derivatives was carried out by FTIR, 1H-NMR, and 13C-NMR, and then their DNA binding, anti-urease, and anticancer activities were explored. Both theoretical and experimental results, as obtained by density functional theory, molecular docking, UV-visible spectroscopy, fluorescence (Flu-)spectroscopy, cyclic voltammetry (CV), and viscometry, pointed towards compounds' interactions with DNA. However, the values of binding constant (Kb), binding site size (n), and negative Gibbs free energy change (ΔG) (as evaluated by docking, UV-vis, Flu-, and CV) indicated that all the derivatives exhibited binding interactions with the DNA in the order UP-3 > UP-2 > UP-1. The experimental findings from spectral and electrochemical analysis complemented each other and supported the theoretical analysis. The lower diffusion coefficient (Do) values, as obtained from CV responses of each compound after DNA addition at various scan rates, further confirmed the formation of a bulky compound-DNA complex that caused slow diffusion. The mixed binding mode of interaction as seen in docking was further verified by changes in DNA viscosity with varying compound concentrations. All compounds showed strong anti-urease activity, whereas UP-1 was found to have comparatively better inhibitory efficiency, with an IC50 value of 1.55 ± 0.0288 µM. The dose-dependent cytotoxicity of the synthesized derivatives against glioblastoma MG-U87 cells (a human brain cancer cell line) followed by HEK-293 cells (a normal human embryonic kidney cell line) indicated that UP-1 and UP-3 have greater cytotoxicity against both cancerous and healthy cell lines at 400 µM. However, dose-dependent responses of UP-2 showed cytotoxicity against cancerous cells, while it showed no cytotoxicity on the healthy cell line at a low concentration range of 40-120 µM.

Enhanced electrochemical properties of graphene-based screen-printed carbon electrode by PPy modification: Experimental and DFT investigations

Here, a novel method to enhance the electrochemical properties of graphene-modified screen-printed carbon electrode (G/SPCE) with polypyrrole (PPy) nanosheets is proposed. The mechanism of improving the electrochemical sensitivity of G/SPCE was investigated at the molecular level. G/SPCE was modified with PPy nanosheets synthesized by oxidative polymerization to improve its electrochemical properties. The cyclic voltammetry (CV) and differential pulse voltammetry (DPV) response of PPy-modified G/SPCE (PPy/G/SPCE) to K3[Fe(CN)6] (PF) were tested experimentally. The results show that the oxidation current sensitivity of G/SPCE to PF after PPy nanosheets modification increased from 11.12 μA·mM−1 to 12.91 μA·mM−1 in CV response, and from 8.44 μA·mM−1 to 10.72 μA·mM−1 in DPV response. The effective reaction area of PPy/G/SPCE was found to be increased by scanning electron microscopy. And the functional group CO/CO in PPy/G/SPCE, acting as a catalyst for the redox reaction of PF, was also found to be improved by X-ray photoelectron spectroscopy. Furthermore, the adsorption energy, electron transfer and density of states changes of PF molecule on pure and PPy-modified graphene were analyzed based on density functional theory calculation. The calculation results show that the adsorption energy and electron transfer of PPy-modified graphene to PF molecule are significantly increased. The response sensitivity of graphene to PF molecule is greatly enhanced by the synergistic effect generated of PPy and graphene.

Simultaneous Determination of Ranitidine and Metronidazole at Low Potential Using an Acid‐Activated Glassy Carbon Electrode

AbstractA simple, highly sensitive and inexpensive electrochemical method was established using an activated glassy carbon electrode (AGCE) in an acidic condition for the determination of ranitidine (RT) and metronidazole (MT) simultaneously at a low potential range. The AGCE was characterized using various techniques such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and morphology was studied through field‐emission scanning electron microscope (FE‐SEM). The AGCE exhibited an electrocatalytic behavior towards the reduction of RT and MT in 0.5 M acidic solution. Both CV and DPV responses for the mixture of RT and MT gave well‐resolved peaks at low potential. Analysis of these experiments helps us to predict interactions that took place on the surface of AGCE and RT and MT with each other for having different types of functional groups. Furthermore, AGCE also promoted the electron transfer process. The linear dynamic range of MT and RT was 0.5–580 μM and 0.5–500 μM, respectively with the regression coefficient 0.99. The detection limit (S/N=3) calculated for MT and RT was 0.062 μM and 0.13 μM, respectively. Decent results were obtained from the reproducibility and stability test. The performance of the sensor was evaluated for the possible interferences which show high selectivity. Additionally, the real sample analysis was carried out to understand our sensor‘s applicability in real life.

Facile synthesis of Ag/ZIF-8@ZIF-67 as an electrochemical sensing platform for sensitive detection of halonitrophenols in drinking water.

Halonitrophenols (HNPs) are an emerging type of aromatic disinfection byproduct, with detected concentrations of ∼nmol L-1 in source water and drinking water. Currently, there are no standard methods for identifying HNPs, and most of the reported methods are time-consuming and equipment-dependent. A core-shell metal-organic framework (MOF) based electrochemical sensor (Ag/ZIF-8@ZIF-67) capable of detecting 2,6-dichloro-4-nitrophenol (2,6-DCNP) is reported in this study. The electrochemical sensor obtains the concentration of 2,6-DCNP by detecting the peak current passing through the sensor. In this sensor, Ag nanoparticles (AgNPs) play a key role in electrochemical sensing by reducing nitro groups via electron transfer, and porous structure with a large surface area is offered by ZIF-8@ZIF-67. The cyclic voltammetry (CV) response of Ag/ZIF-8@ZIF-67 was found to be approximately 1.75 times and 2.23 times greater than that of Ag/ZIF-8 and Ag/ZIF-67, respectively, suggesting an ideal synergistic effect of the core-shell structures. The Ag/ZIF-8@ZIF-67 sensor exhibited exceptional sensitivity to 2,6-DCNP, exhibiting a broad linear response range (R2 = 0.992) from 240 nmol L-1 to 288 μmol L-1 and a low detection limit of 20 nmol L-1. Furthermore, the sensor exhibited good anti-interference for isomers and common distractors in water, excellent stability and reproducibility, and high recovery in actual water samples. Our reported sensor gives a novel strategy for sensitive, selective, and in situ detection of 2,6-DCNP in practical analysis.

Nonenzymatic electrochemical lactic acid sensor using CuO nanocomposite

The detection of biochemical performance and health parameters using wearable sensors have gained more attention. Lactic acid (LA) sensor was developed using the simple facile method for electrochemical detection in artificial sweat. The non-enzymatic LA sensing characteristics were assessed using cyclic voltammetry and amperometry response with a three-electrode system. The CuO nanoparticles were applied to a glassy carbon electrode (GCE) as a single-step modification using the Nafion matrix. In order to examine the CuO material used to modify the glassy carbon electrode, various analytical methods were used such as Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–Visible), and X-ray powder diffraction (XRD). The minimum detectable concentration for lactic acid was found to be 0.05 × 103 mol/l. The present investigation provides an excellent pathway for the specific detection of LA biomolecule for medical purposes by a non-enzymatic approach.

Microfluidic electrochemical device for real-time culturing and interference-free detection of Escherichia coli

Bacterial contamination and infection is a major health concern today leading to the significance of its detection. Being lab-based bacterial culturing processes, the present approaches are time consuming and require trained skillset. An economical, and miniaturized lab-on-chip device, capable of simultaneous detection of bacterial growth, could be a benchmarking tool for monitoring the bacterial contamination. Herein, the microfluidic-based electrochemical device for a fast, susceptible, detection of Escherichia coli was developed. The device could aid incubator free bacteria culturing in the ambient atmosphere and simultaneously monitor and detect the growth electrochemically. A three-electrode system, integrated with a reservoir and a portable thermostat temperature controller was fabricated and assembled. To achieve this, three-electrodes were embedded on the microfluidic device by screen-printing carbon paste, and the working electrode was enhanced by graphitized mesoporous carbon. Cyclic voltammetry response was noted as the function of concentration and growth of Escherichia Coli in the reservoir. The device gave a linear bacterial concentration range of 0.336 × 1012 to 40 × 1012 CFU mL−1, detection limit of 0.35 CFU mL−1 and the quantification limit of 1.05 CFU mL−1 which was less than the maximum allowable limit. The developed platform was further used to detect and continuously monitor the bacterial growth in the real sample (mango juice) for a period of 36 h. Finally, the interference from other common bacteria on the electrode selectivity was also investigated. Such approach in being further modified for specific sensing of bacteria in patients suffering from different diseases such as corneal ulcers, Diarrhea, tuberculosis, leprosy, and syphilis.

Deciphering Highly Sensitive Non-Enzymatic Glucose Sensor Based on Nanoscale CuO/PEDOT-MoS2 Electrodes in Chronoamperometry

The present work demonstrates fabrication of a non-enzymatic glucose sensor based on CuO nanoparticles deposited over poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer infiltrated with nanoscale MoS2. Structural, morphological and elemental analyses of the fabricated sensor electrodes were performed via different characterization techniques like X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), elemental dispersive X-ray spectroscopy (EDX), and Fourier transform infra-red spectroscopy (FT-IR). The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies of the hybrid nanoelectrode (CuO/PEDOT-MoS2) exhibited better redox activity and electron transfer kinetics, as compared with the CuO/PEDOT and CuO only systems. Accordingly, the electrochemical parameters of all the systems were determined and compared at large. The CuO/PEDOT-MoS2 hybrid electrode system offered a significant enhancement in the electroactive area (∼1.47 cm2) and rate constant (0.76 s−1) upon oxidizing glucose into gluconic acid. In the CV responses, an augmented activity was monitored at +0.6 V which was considered as the dc bias potential in the chronoamperometric experiment for detecting glucose suitably. The sensor electrode yielded a low LOD of 0.046 μM and with a sensitivity magnitude as high as 829 μA mM−1 cm−2 over a wide linear range, between 30 μM to 1.06 mM of glucose concentration. Deployment of organic-inorganic nanomaterial based non-enzymatic sensor would find immense scope in non-clinical diagnostics and pharmaceutical applications for fast, convenient and smart sensing.

Hydrothermally Enhanced Tungsten-Tungsten Bronze (W-MxWO3) Electrodes for Pseudocapacitive Energy Storage

Hexagonal tungsten bronzes (h-MxWO3) are an emergent class of pseudocapacitive energy storage material: a metastable phase arranged in a hexagonal crystal structure that enhances the oxide’s rapid intercalation mechanism with impressive capacitances of over 200 F/g and excellent cyclability figures reported. A symmetrical pseudocapacitive device composed of h-MxWO3 electrodes negates the need for expensive and problematic rare minerals such as cobalt and lithium instead using low-cost tungsten whilst offering more efficient high-rate energy storage than commercial lithium-ion batteries.Hexagonal tungsten bronze has shown some promising capacitances in literature in conventional electrode configurations, i.e. composite structures with binder support materials which increase electrode mass impacting specific capacitance. If the bronze was instead grown directly upon a current-collecting substrate, this would negate the need for additional electrode components, with the entire electrode mass participating in storing charge. The present work explores this concept of a novel binder-free electrode design where the nanostructured tungsten-bronze (active material) is grown directly upon a tungsten-based substrate (current collector). This simple design offers potentially higher specific capacitances than conventionally fabricated electrodes.Nanostructured W/h-MxWO3 electrodes were fabricated in a twostep process. Firstly, tungsten foil was oxidised in hot nitric acid, forming a seed layer of monoclinic-WO3. A second step saw the hexagonal bronze deposited upon substrates through a hydrothermal dehydration reaction of sodium tungstate (Na2WO4) where the effect of the directing agent (NaCl, Na2SO4, (NH4)2SO4& Rb2SO4) on the deposited nanostructure was investigated. To assess the benefit of the acid pretreatment step, vis-à-vis a pristine untreated tungsten foil, the hydrothermal reaction was completed upon both a pristine tungsten foil and an acid treated foil. The nanostructured surface deposited from the hydrothermal reaction was characterised by SEM, and the crystal phase identified by XRD. The electrochemical behaviour was analysed using a Biologic SP-300 potentiostat in a 3-electrode cell: as-synthesised foils employed as working electrode; Pt Wire as counter electrode; a saturated calomel electrode (SCE) as reference; and 0.5M H2SO4 as electrolyte. The performance of devices fabricated from two symmetrical as-synthesised electrodes was also characterised using both the potentiostat and a NEWARE battery cycling test system in a two-electrode cell configuration.XRD analysis confirmed that hexagonal-tungsten bronzes were successfully deposited upon substrates irrespective of the substrate pretreatment. The acid pretreatment generally resulted in larger masses of bronze being deposited upon the substrate, but this did not necessarily translate to superior electrochemical performance. The choice of directing agent present in hydrothermal synthesis drastically altered the nature of the deposited layer as may be seen in the provided figure of as-synthesised electrodes (figure b-d). Sodium directed samples formed powder-like deposits (figure b), ammonium sulphate produced larger colloidal bronze layers (figure c) and rubidium sulphate developed glossy smooth sheets (figure d). Additionally, the ratio of tungstate ions (WO4 2-) to directing agent cations (M+) was identified as being critical to obtaining the hexagonal phase. The mechanical stability of the deposited bronze proved problematic, with the layer prone to delamination and disintegration from a variety of mechanisms. A bespoke electrode holder, device testing apparatus and handling procedure was therefore developed to enable repeatable electrode characterization.The cyclic voltammetry response of the hydrothermally deposited layers was typical of an intercalation system, though an initial pseudocapacitive behaviour deteriorated to a battery-like response at sweeprates above 20 mV/s. Galvanostatic charge-discharge testing displayed a significant pseudocapacitive response over limited potential windows; moving beyond these limits produced steep non-linear curves indicating a departure from pseudocapacitive charge transfer processes. The charging at current densities above 1 A/g occurred over rapid time scales showing the electrodes’ suitability for high power applications. Preliminary 3-electrode capacitance results are encouraging with specific capacitances of over 100 Fg-1 by dry mass. The tunnelated M+ ion in the bronze is found to greatly influence the electrochemical performance of the electrode.This work reports the first example of hexagonal tungsten bronze being successfully grown directly on tungsten substrates for application as energy storage electrodes. The binder free electrodes were found to deliver promising performance characteristics in both 3-electrode analysis and in a two-electrode symmetrical device. The performance so far is hampered by the mechanical fragility of the electrode structures, while scale-up of the manufacturing process may prove challenging. The observed mechanism of deposition of hexagonal tungsten bronze from solution to substrate is of interest for future work, as is the significance of tunnelated M+ cations to the hexagonal bronze (h-MxWO3) structure, stability, and electrode performance (figure a). Figure 1

High entropy alloy nanoparticle - graphene (HEA:G) composite for non-enzymatic glucose oxidation : optimization for enhanced catalytic performance

High entropy alloy (HEA) metal nanoparticles engineered graphene composites (HEA:G) were produced via green approach involving mechanical milling and sonication assisted exfoliation. Mixture of metal powders and graphite (metal-to-graphite weight ratio: 20%, 50%, 70%, 90%) were ball milled and exfoliated. As produced 20:80, 50:50, 70:30, 90:10 - HEA:G composites electrochemical activity was explored using the redox probe potassium ferricyanide [K3Fe(CN)6] and for the non-enzymatic detection of glucose. From cyclic voltammetry(CV) response, the significant electron transfer kinetics for K3Fe(CN)6 was found for 20:80, 50:50, 70:30 composites, whereas reduced activity was observed with 90:10. Also, 20:80, 50:50, 70:30 composites exhibited notable oxidation of glucose in 0.1 M PBS compared to 90:10. The anodic current indicating oxidation of glucose was found to be increasing linearly with HEA:G composite - 20:80<50:50<70:30. However, DPV measurements indicate better working potential from 0.45 V to 0.4 V followed by saturation in the oxidation currents for 50:50 and 70:30 composites. The sensitivity obtained for HEA:G composites 20:80, 50:50, 70:30 were 12.09 μAmM−1cm−2, 22.99 μAmM−1cm−2, 18.2 μAmM−1cm−2 respectively. Hence, 50:50 and 70:30 are the efficient composites exhibiting excellent catalytic activity indicating the prominence of HEA:Graphene composites and their synergism.

A thin-layer diffusion model-based intelligent cyclic voltammetry analysis method to capture electrochemical parameters in flow batteries

Contrary to the conventional approach that utilizes the planar electrode model to achieve the electrochemical parameters of the electrode in flow batteries, this work proposes an intelligent cyclic voltammetry (CV) analysis method to accurately capture the electrochemical parameters of the carbon-based porous electrode: (i) the transient diffusion process is elaborated by the Fick's second law; (ii) the thin-layer diffusion boundary condition is determined based on the structural characteristics of porous electrodes; (iii) CV response on the porous electrode is obtained by the Bulter-Volmer equation in assocition with the Fick's first law; and (iv) the electrochemical parameters of the porous electrode are automatically extracted from the experimental data via the genetic algorithm. The feasibility of the intelligent CV analysis method is proven by studying the electrochemical parameters including the diffusion coefficient D and the standard rate constant k0 of [Fe(CN)6]4−/[Fe(CN)6]3−. Additionally, this analysis method is applied to investigate the vanadium redox flow battery by providing accurate electrochemical parameters for the 3D multi-physics model to predict the charge/discharge performance at different current densities. The simulation results demonstrate a maximum relative error of 2% in comparison to the experimental data, suggesting the good reliability in developing the advanced model. The proposed intelligent CV analysis method provides a potential application in accurately capturing the electrochemical parameters in other electrochemical energy conversion and storage devices.

Pyrene-based chalcones as functional materials for organic electronics application

Though new generation organic electronic devices have evolved from mere scientific perceptions to real-life marketed applications, considerably less research attention has been focused on n-type or electron transporting small molecule semiconductors. The present study is focused on the exploration of structural, thermal, electrochemical, electrical, and optical properties of two pyrene-based chalcones: PC1 and PC2, synthesized through Claisen Schmidt condensation reaction. The chalcones displayed good thermal stability and wide bandgap n-type semiconducting behaviour with high charge carrier concentration and dielectric constant. The experimental evidences including fluorescence measurements, nanoaggregate size, and morphology analysis, supported by DFT calculations and molecular dynamic simulations advocated the intramolecular charge transfer and aggregation-induced enhanced emission features of the molecules. Successful fabrication of a diode in combination with the current-voltage characteristics established the candidature of PC1 and PC2 for electro-optical devices. The dielectric studies were performed to measure dielectric constant and AC conductivity at different frequency ranges. The cyclic voltammetry and AC impedance response of PC2 differed from PC1 due to the inclusion of a fluorine atom in the molecular scaffold. Further, the functional implication of PC2 as an electrode material was explored by constructing a supercapacitor, which offered a specific capacitance of 220 Fg-1 at a scan rate of 10 mV s−1. Moreover, these chalcone-based organic semiconductors displayed high thermal and charge carrier concentration as well as compatibility with other layers in an OLED device. Hence PC1/PC2 can be further investigated as dopants along with other emissive layers as host materials in OLEDs.

High-resolution patterning of silica nanoparticle-based ionogels by reverse-offset printing and its characterization

In this study, nanoparticle-based, high-resolution patternable ionogels are presented to provide a route for realizing printed solid-state ionic devices. By incorporating an ionic liquid (IL) into a spherical silica nanoparticle suspension, a quasi-solid ionogel layer compatible with reverse-offset printing (ROP) with a spatial resolution of approximately 5 μm was realized. In situ near-infrared (NIR) spectroscopic analysis revealed the drying kinetics of the ionogel ink during printing, and a temporal margin for successful patterning in relation to its dry state was provided. In contrast to polymer-based gels, the present ionogel can be regarded as a porous medium of silica filled with ionic liquids with a certain degree of saturation. By optimizing the ink formulations, ROP patterning was successful for saturation up to 102%, indicating the nanoscale pores between silica nanoparticles can be fully used as an ion-conductive phase in the proposed patternable gel. The conductivity depends drastically on saturation, with a saturation exponent of approximately −7 according to Archie’s law. From a complementary scratch test, an ionogel at a saturated condition still exhibited fragile but solid-like characteristics. As a demonstration, planar micro-supercapacitors fully printed with reverse-offset printable ionogel and carbon inks were fabricated. A comparison with a drop-casted IL showing a similar capacitance indicates a limited ability of the carbon nanoparticle material used here, while a relatively high resistance of the silica-nanoparticle-based ionogel hinders a fast cyclic voltammetry response.

(Digital Presentation) Super Ultra-Fast and Highly-Sensitive Non-Enzymatic Electrochemical Sensor to Detect Uric Acid By Electronic Waste to MoS2 and Functionalised MWCNT/MoS2 Coated High-Performance Aluminium Electrode

Electronic waste also known as (E-waste) includes used computers, televisions, refrigerators, mobile phones, laptops, electric and electronic cables and so on possess a severe threat to the society and the environment. Among the Sustainable Development Goals (SDGs) about six goals are interlinked to tackle the e-waste management stress to understand and focus on the challenge. In the present work, we report the utilization of waste aluminum cables as high-performance modified electrode to detect the uric acid in human urine. The obtained waste PVC wrapped 2mm diameter aluminum cable is peeled off, cleaned and cut in to 7 cm rod to be use as an electrode. MoS2 and Multiwalled Carbon Nanotubes (MWCNTs) doped MoS2 are separately grown on the Al rod through hydrothermal synthesis. The XRD patterns reveal that both the MoS2 and MWCNTs/MoS2 are in 1T phase structures, but the doping of MWCNTs promoted a minor phase shift and transformed to accurate 1T structure. The fundamental modes of vibration and qualitative chemical analysis are obtained from FTIR and Raman analysis. The interlaced nanosheets underlying in flower like morphology of MoS2 and MoS2/MWCNTs are clearly seen from the FESEM images which offered the high sensing ability of the sensor with a detection limit of 1.13 µM and sensitivity of 97.6 nA µM-1 with linear response (R2=0.99) within 2 seconds. The stability and reproducibility of the electrodes were determined by 15 repeated cyclic voltammetry response to 0.1M uric acid. All the detection parameters were studied in comparison with MoS2 and MWCNTs/MoS2 electrode and the later offered the superior results as mentioned. Though there are many publications on uric acid detections through nanomaterials modified standard electrodes, the present work initiates to report the non-enzymatic detection of uric acid in human urine samples by modifying the Al electrode for the e-waste. This work may pave the way towards decreasing the usage of conventional fossil carbon electrodes. The developed MWCNTs/MoS2 electrode offers a super ultra-fast and highly-Sensitive electrode that can be employed in biomedical sensing applications. Keywords: E-waste, Aluminum rod, Modified Electrode, MoS2, MWCNTs doped MoS2 Figure 1