Electrochemical Procedure Research Articles

Rapid Phenotypic Antibiotics Susceptibility Analysis by a 3D Printed Prototype.

One of the most important public health concerns is the increase in antibiotic-resistant pathogens and corresponding treatment of associated infections. Addressing this challenge requires more efficient use of antibiotics, achievable by the use of evidence-based, effective antibiotics identified by antibiotic susceptibility testing (AST). However, the current standard method of phenotypic AST used for this purpose requires 48 h or more from sample collection to result. Until results are available, broad-spectrum antibiotics are used to avoid delaying treatment. The turnaround time must therefore be shortened in order for the results to be available before the second administration of antibiotics. The phenotypic electrochemical AST method presented here identifies effective antibiotics within 5-10 h after sampling. Spiked serum samples, including polymicrobial samples, with clinically relevant pathogens and respective concentrations commonly found in bloodstream infections (Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa) are used. Direct loading of the test with diluted serum eliminates the need for a pre-culture, as required by existing methods. Furthermore, by combining several electrochemical measurement procedures with computational analysis, allowing the method to be used both online and offline, the AST achieves a sensitivity of 94.44% and a specificity of 95.83% considering each replicate individually.

Activated and shorter Laser-Scribed graphene Electrodes: Excellent electrochemical signal amplification for detecting biomarkers

Laser-scribed graphene electrodes (LSGEs) are emerging as powerful transducers in electroanalysis. Surface structure and electrode geometry are the two key properties that heavily influence the characteristics of the resulting biosensors. In this work, we have investigated the sensing abilities of the LSGEs at various electrochemical activation procedures and electrode geometry conditions. We found that electrochemically activated LSGEs with shorter electrode connection lengths outperform corresponding non-activated LSGEs with longer electrode connection lengths. The effects of different pH conditions, supporting electrolytes, polarization potentials, and activation time were studied. X-ray photoelectron spectroscopy, Raman spectroscopy, and voltammetry techniques were used to examine the in-situ formation of porosity, introduction of surface oxygen functionalities, role of defect densities, and electrochemically accessible area. Dopamine is used as a model to study the sensing capabilities of the electrodes. Activated LSGE offered a 5.4-fold enhanced detection limit for dopamine compared to longer and non-activated LSGE. Practicality of the method is validated in human serum and urine samples. In addition, the sensor was demonstrated in monitoring in-situ dopamine released by neuroblastoma SH-SY5Y cells. Additionally, the enhanced sensing performance of the activated LSGEs are also tested by sensing uric acid and paracetamol. Electrochemically activated, shorter LSGEs hold great potential in various electrochemical applications.

Electrocatalytic Epoxidation of Cyclooctene on Surface Modified Ni Foam Using Water as Oxygen Source.

Electrochemical epoxidation of olefins using water as an oxygen atom source is emerging as an alternative approach for an atom economic and sustainable method towards a highly selective synthesis of epoxides. We report an electrochemical procedure for epoxidation of cyclooctene using water as the sole oxygen atom source over a sodium dodecyl sulfonate (SDS) modified nickel hydroxide Ni(OH)2 catalyst directly grown on Ni foam. The SDS modification facilitates the mass transfer of cyclooctene towards the anode, thus achieving a 2.5-fold higher conversion with more than 90 % selectivity towards the corresponding epoxide compared with pure Ni(OH)2 catalyst.

A new streamlined electrochemical assembly procedure to improve conductive polymer-based metal chalcogenide electrodes for innovative energy systems

Reliable, effective, and environmentally friendly supercapacitors still need development despite the progress made in many nanoscale electrode materials. In this area, composite materials made of organic polymers with high electrical conductivity and metal sulfides with various oxidation states were more attractive. This article describes the design and synthesis of zinc sulfide and polyaniline nanocomposites employing a fast and straightforward electrochemical deposition method and their use as electrode materials for supercapacitors. The structural investigation showed clumped spherical for pAni, hexagonal for pure ZnS, and coexisting hexagonal and spherical phases for ZnS@pAni nanocomposites. The ZnS@pAni nanocomposite demonstrated remarkable electrochemical efficiency and faradaic energy storage capabilities with practical reversibility. Also, an impedance inquiry found that the ZnS@pAni composite has better conductivity and a lower charge transfer resistance than its bulk components. ZnS@pAni//AC was used to create a hybrid asymmetric supercapacitor and displayed a large voltage window up to 2.06 V, 235.24 F g−1 specific capacity, and an ultimate energy density of 144.08 Wh kg−1. Also, when energy density drops to 22 Wh kg−1, substantial power delivery is achieved at 6.3 kW kg−1. Moreover, 88.05% of the capacitance was retained after the device completed 5000 cycles, suggesting good ZnS@pAni//AC asymmetric supercapacitor stability.

Dioctylsulfosuccinate Functionalized NiAl-Layered Double Hydroxide for Sensitive Fenuron Electroanalysis Using a Carbon Paste Electrode.

Environmental pollution resulting from the use of pesticides such as fenuron poses significant health risks due to the carcinogenic and teratogenic properties of these compounds. There is an urgent need to develop rapid and cost-effective detection methods for quantifying fenuron. In this study, an inorganic-organic composite material was obtained by intercalating sodium dioctylsulfosuccinate (DSS) within the interlayer space of a nickel-aluminum-layered double hydroxide (NiAl-LDH). The pristine and modified LDHs (NiAl-LDH) were characterized using Fourier transform infrared, X-ray diffraction, and thermogravimetric analysis, confirming the successful intercalation of DSS in the mineral structure. The modified LDH was used to elaborate a sensor for detecting fenuron herbicide via differential pulse voltammetry (DPV) employing a carbon paste electrode (CPE). The electrochemical procedure for fenuron analysis consisted of immersing the working electrode in an electrolytic solution containing the appropriate amount of fenuron, followed by voltammetry detection without any preconcentration step. Compared to CPE modified by pristine LDH, the peak current obtained on the organo-LDH-modified CPE was twice as high. The increase in the fenuron signal was attributed to the high organophilic feature of this composite material induced by DSS modification. To optimize the sensitivity of the organo-LDH modified electrode, the effects of several experimental parameters such as pH of the medium and proportion of the modifier in the paste on the stripping response were examined. Linear calibration curves were obtained for the fenuron concentrations ranging from 0.5 × 10-6 to 1 × 10-6 mol.L-1 and 1 × 10-6 to 5 × 10-6 mol.L-1. The limit of detection (LOD) calculated on the basis of a signal-to-noise ratio of 3 was found to be 1.8 × 10-8 mol.L-1 for the low concentration range with a limit of quantification (LOQ) which was 6 × 10-8 mol.L-1. Furthermore, the interference effect of several inorganic ions and other pesticides potentially affecting fenuron stripping was explored, and the method's applicability was confirmed by determining fenuron levels in a river sample taken from down-town Yaoundé.

Green electrochemical synthesis of graphene oxide for high-performance electromagnetic shields

Controlled exfoliation and oxidation of graphene oxide nanosheets > multi-scale materials design > high performance EMI shields.

Supercapacitor electrode based on graphene covalently functionalized with cross-linking inorganic-organic molecule

This work presents the fabrication of a supercapacitor electrode based on covalently cross‐linked graphene structure. It introduces a simple method to fabricate modified graphene oxides with an inorganic and organic cross-linked agent. The supercapacitive performance of this cross-linked graphene oxide structure (C-GO) is approved by conventional electrochemical procedures, such as cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy. The calculated specific capacitance amounts of 231 F/g and 240 F/g was achieved via CV and GCD curves at ѵ= 10 mVs−1 and I = 0.8 A g−1, respectively. This C-GO based-supercapacitor indicates a 9 % reduction in specific capacitance value after measurement of 3000 continuous cycles in the CV.

Electrochemistry of copper post-CMP cleaning examined in combination with brush-scrubbing in a malonic acid solution

Post-CMP cleaning (PCMPC) is used in the fabrication of integrated circuits to remove unwanted residues of chemical mechanical planarization (CMP) from wafer surfaces. PCMPC combines (electro)chemical surface reactions in a cleaning solution with mechanical scrubbing by a brush. Using tribo-electrochemical protocols, the present work simultaneously probes the (electro)chemical and mechanical functions of PCMPC and determines the corresponding cleaning efficiency. Employing malonic acid as a cost effective, environmentally compatible cleaning solution for copper, it is demonstrated how this electroanalytical approach can facilitate the tasks of developing and evaluating effective PCMPC solutions. The results indicate that malonic acid in a pH neutral environment removes Cu-oxides and their co-adsorbed organic residues of CMP. A detailed electrochemical procedure is illustrated for quantifying the residue removal efficiency of PCMPC, and the role of brush scrubbing in the overall cleaning process is identified.

Determination of Electrochemical Pretreatment Voltage Limits, Scan Rate and Cycle Number

Electrochemical characterisation analyses are performed to determine the electrochemical behaviour of the electrode and electrolyte of vanadium redox battery components. A 3-electrode system which consisted of counter electrode, working electrode and reference electrode is used for electrochemical testing. It is important for the consistency of the proposed idea that the results obtained from the analyses are comparable and repeatable under the same conditions. In order to prepare the working electrode surface for electrochemical reactions, an electrochemical treatment procedure is applied in addition to the polishing procedure [1,2]. In this study, it is aimed to determine the optimum pretreatment conditions of the working electrode. For this purpose, a 3-electrode system consisting of a reference electrode (Saturated KCl, ALS RE-1CP), a working electrode (ALS GCE 3 mm) and a counter electrode (platinum wire) was established. All pretreatment procedure experiments were carried out using 2 M H2SO4. After each pretreatment step, cyclic voltammetry analyses were carried out with 1.6 M VOSO4 + 2 M H2SO4 solution. CV analyses were performed in the range of 0 V - 1.2 V at a scan rate of 20 mV/s. The upper voltage was chanced between 1.5 V and 2.3 V with 0.1 V steps at the constant lower voltage limit. In contrast, the establishment of the lower voltage limit encompassed incremental increases by 0.3 V steps from -0.7 V to 1.4 V at a constant upper voltage limit. Different scan rates (10 mV/s, 20 mV/s, 50 mV/s, 100 mV/s, and 200 mV/s) were explored to identify the optimal scan rate for the pretreatment process. Additionally, experiments were performed across varying cycle numbers (1, 2, 4, 6, 8, 10) under predefined pretreatment conditions.The results of the pretreatment procedure and CV analysis are graphically presented in Figure 1. The upper voltage limit determination and CV analysis results under a lower voltage limit are displayed in Figure 1.a and 1.b. Redox reactions did not occur when the upper voltage limit was 1.5 V-1.8 V. While redox reactions started to occur after 1.9 V, the highest anodic and cathodic peaks values were obtained in the 0-2 V range. Lower limit pretreatment results and CV analysis under constant upper voltage are shown in Figures 1.c and 1.d, respectively. These experiments indicated minimal distinctions between -0.7 V and 0 V CV results, leading to the selection of 0 V as the lower limit. In cases where the lower limit is greater than 0 V, redox reactions were negatively affected by the pretreatment process. There was no significant difference was observed between the CV results of 10 mV/s and 20 mV/s. However, redox reactions were negatively affected at scanning rates of 50 mV/s and higher. The scan rate of the pretreatment process was determined as 20 mV/s. Figures 1.g and 1.h show the results of pretreatment cycle number and CV analysis results at the 0 V-2 V voltage limits and 20 mV/s scan rate. Redox reactions did not occur when pretreatment was applied in 1 and 2 cycles while 4 and higher cycle numbers were obtained. The highest anodic and cathodic peaks were obtained when the cycle numbers were 6 and 8, and these results are very close to each other. The cycle number of the pretreatment process was determined as 6 cycle.It has been shown that the conditions of the pretreatment process have a significant influence on the reaction behaviour of the working electrode. It conclusively establishes the optimum pretreatment process conditions as a voltage range 0 V-2 V, scan rate 20 mV/s and number of cycles 6. Acknowledgements This work supported by the Scientific Research Projects Unit of Erciyes University under contract no: FDK-2020-10376. The first named author MT thanks to The Scientific and Technological Research Council of Turkey (TÜBİTAK) for their scholarships under “2211-C Priority Areas PhD Scholarship Program with the grant number 1649B032000390” and “2214-A International Research Fellowship Program for PhD Students with the grant number 1059B142200567”. References J. Noack et al., J. Energy Chem., 27, 1341–1352 (2018).N. Roznyatovskaya et al., Batteries, 5, 1–16 (2019). Figure 1

WO3 Nanostructures Modified with Carbon and Sulfur Used as Anode for Li-Ion Batteries

Nowadays, energy problems have become one of the biggest challenges in our society and they have drawn worldwide attention. Rechargeable lithium-ion batteries (LiBs) are a good option thanks to their potential applications as power sources for electric vehicles and mobile devices due to their high energy density and good cycle stability. Much effort has recently been devoted to find alternative anode materials and replace graphite in LiBs, like transition metal oxides that are currently being investigated (1).Specifically, tungsten oxide (WO3) has attracted much interest as an anode due to its excellent properties: high electronic conductivity (10–10−6 s cm−1), high intrinsic density (>7 g cm−3), small radius, and correct crystalline phase for rapid ion insertion and superior electrochemical performance (2).In this research, the effects of the morphology and composition of WO3 nanostructures on the charge/discharge behavior for Li-ion batteries are methodically examined.On the one hand, a simple method is used to synthesize crystalline WO3 nanostructures, with a well-defined morphology by means of an electrochemical procedure known as electrochemical adodization. Then, an annealing treatment at 600◦C in air environment for 4 h was carried out. In the second electrode synthesized, a carbon layer was uniformly deposited on WO3 nanostructures to obtain a WO3/C electrode. Finally, WO3/WS2 electrodes were prepared by means of in situ sulfurization of WO3 one-step solid-state synthesis using tungsten trioxide (WO3) and thiourea as precursor material.The different electrodes synthesized have been morphologically characterized by using X-ray photoelectron spectroscopy, X-ray diffraction analysis, transmission electron microscopy, Raman spectra, and field-emission scanning electron microscopy.The performance of the nanostructures applied as anodes for energy storage in Li-ion batteries and their specific capacity was evaluated by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Charge-Discharge curves. Among all the synthesized samples, WO3/C nanostructures reveal the best performance as they exhibit the greatest discharge capacity and cycle performance (820 mA h g−1). Acknowledgments Authors would like to express their gratitude to AEI (PID2019-105844RB-I00/ AEI/10.13039/501100011033) for the financial support. M. Cifre-Herrando thank Ministerio de Universidades for the concession of the pre-doctoral grant (FPU19/02466). G. Roselló-Márquez also thanks the UPV for the concession of a post-doctoral grant (PAID-10-21) and for the grant to promote postdoctoral research at the UPV (PAID.-PD-22). Finally, project co-funded by FEDER operational programme 2014-2020 of Comunitat Valenciana (IDIFEDER/18/044) is acknowledged. References Li P, Li X, Zhao Z, Wang M, Fox T, Zhang Q, et al. Correlations among structure, composition and electrochemical performances of WO3 anode materials for lithium ion batteries. Electrochim Acta. 2016;192:148–57. 2. Lian C, Xiao X, Chen Z, Liu Y, Zhao E, Wang D, et al. Preparation of hexagonal ultrathin WO3 nano-ribbons and their electrochemical performance as an anode material in lithium ion batteries. Nano Res. 2016;9(2):435–41.

Scalable Diastereoselective Electrosynthesis of Spiro[benzofuran-2,2'-furan]-3-ones.

Spirobenzofuran scaffolds, because of their three-dimensional structure, are incorporated into several valuable natural products and drug candidate molecules. Herein, with the assistance of electrosynthesis, we introduce a novel electrochemical approach for achieving spirobenzofurans in a user-friendly and operationally simple undivided cell setup under constant current. This metal-catalyst-free electrochemical procedure afforded spiro[benzofuran-2,2'-furan]-3-ones with high diastereoselectivity. Compatibility with gram-scale synthesis along with the convenient accessibility of reaction instruments and starting materials collectively raised the importance of this protocol compared to previous challenging methods. Furthermore, mechanistic cognizance of this reaction is obtained by the investigation of the cyclic voltammetry spectra of reactants.

A novel and intelligent chemometric-electrochemical-enzymatic biosensing procedure and mimicking a clinical condition environment to trick the red blood cells for counting them under physiological conditions: A new connection among chemometry, electrochemistry and hematology

Here, a novel electrochemical biosensing procedure has been developed for determination of the number of red blood cells (RBCs) under physiochemical conditions based on chemometric modeling of hydrodynamic differential pulse voltammetric (HDPV), and amperometric data as responses of a modified edge plane pyrolytic graphite electrode (EPPGE). In order to obtain a good sensitivity from the EPPGE, its surface was modified with a thin layer of multiwalled carbon nanotubes-ionic liquid (MWCNTs-IL). Catalase (CAT) was immobilized onto the surface of MWCNTs-IL/EPPGE with help of nafion. The response of the biosensor was based on electrochemical reduction of oxygen of the blood samples which was enhanced by a trick based on addition of hydrogen peroxide (H2O2) to blood samples which can be reduced by the CAT to produce extra oxygen. Prior to experiments, the solution in electrochemical cell was bubbled with pure N2 to purge the oxygen in the solution, but in order to increase the selectivity of the biosensor towards detection of the oxygen obtained from the red blood cells, voltammetric responses of the biosensor were modeled by multivariate chemometric calibration methods with the help of radial basis function-partial least squares (RBF-PLS), least squares-support vector machines (LS-SVM), recursive weighted partial least squares (rPLS), ant colony optimization-mathematical pre-processing selection by genetic algorithm-sample selection through a distance-based procedure-partial least squares-1 (ACO-GA-SS-PLS1), and radial basis function-artificial neural networks (RBF-ANN) to select the best method for determination of the number of the RBCs. The results confirmed the amperometric methods modeled by RBF-ANN showed the best performance for supporting the biosensor in determination of the number of the RBCs with a performance which had an excellent compatibility with the results of a hemocytometer. The results of this study as the newest application of chemometric-electrochemical methods can make a strong connection among electrochemists, chemometricians and hematologists to expand their collaborations on determination of blood factors.

Electrochemical Synthesis of Gold-N-Heterocyclic Carbene Complexes.

An electrochemical synthesis of gold(I)-N-heterocyclic carbene (Au-NHC) complexes has been developed. The electrochemical methodology uses only imidazolium salts, gold metal electrodes, and electricity to produce these complexes with hydrogen gas as the only by-product. This high-yielding and operationally simple procedure has been used to produce eight mononuclear and three dinuclear Au-NHC complexes. The electrochemical procedure facilitates a clean reaction with no by-products. As such, Au-NHC complexes can be directly transferred to catalytic reactions without work-up or purification. The Au-NHC complexes were produced on-demand and tested as catalysts in a vinylcyclopropanation reaction. All mononuclear Au-NHC complexes performed similarly to or better than the isolated complexes.

Ultrafast Electrochemical Self-Doping of Anodic Titanium Dioxide Nanotubes for Enhanced Electroanalytical and Photocatalytic Performance

This study explores an ultrarapid electrochemical self-doping procedure applied to anodic titanium dioxide (TiO2) nanotube arrays in an alkaline solution to boost their performance for electroanalytical and photocatalytic applications. The electrochemical self-doping process (i.e., the creation of surface Ti3+ states by applying a negative potential) is recently emerging as a simpler and cleaner way to improve the electronic properties of TiO2 compared to traditional chemical and high-temperature doping strategies. Here, self-doping was carried out through varying voltages and treatment times to identify the most performing materials without compromising their structural stability. Interestingly, cyclic voltammetry characterization revealed that undoped TiO2 shows negligible activity, whereas all self-doped materials demonstrate their suitability as electrode materials: an outstandingly short 10 s self-doping treatment leads to the highest electrochemical activity. The electrochemical detection of hydrogen peroxide was assessed as well, demonstrating a good sensitivity and a linear detection range of 3–200 µM. Additionally, the self-doped TiO2 nanotubes exhibited an enhanced photocatalytic activity compared to the untreated substrate: the degradation potential of methylene blue under UV light exposure increased by 25% in comparison to undoped materials. Overall, this study highlights the potential of ultrafast electrochemical self-doping to unleash and improve TiO2 nanotubes performances for electroanalytical and photocatalytic applications.

Photoelectro-catalytic oxidation of monoethanolamine: From the study of electrooxidation mechanism to the development of high-efficient Ni-based photoelectro-catalysts

Monoethanolamine (MEA) electrooxidation occurring on Ni catalyst has proven to be a viable tactics for simultaneous MEA degradation and energy recovery. However, the excessively large overpotential (1505 mV) on Ni catalyst either causes high electricity consumption when acquiring H2 from MEA-containing electrolyzer or leads to low energy output when extracting electricity from direct MEA fuel cell. In this context, the reaction mechanism of MEA electrooxidation on Ni-based catalyst is deciphered at first by employing a specially designed three-step electrochemical procedure and in-situ Raman spectroscopy. Electrochemical data deconvolutions indicate the indirect electrochemical-chemical reaction path, via Ni(OH)2/NiOOH mediator, occupies ∼2.5 % of the total catalytic current density at 0.55 V vs. Ag/AgCl and the direct oxidation of MEA ranks the rest ∼97.5 %. To decrease the onset potential of MEA oxidation, a photoelectric-catalytic system including high-efficient Ni-based photoelectric-catalyst, where Ni is intimately coated on TiO2 by in-situ photodeposition to achieve the shortest carrier transport channel between Ni(OH)2 and TiO2, is developed. Results show the overpotential of MEA electrooxidation under illumination significantly drops to 255 mV. Such a Ni@TiO2/FTO electrode also exerts excellent durability toward MEA oxidation.

Ionic liquids-mediated recovery of metals from spent batteries

Tremendous efforts are being made toward electrification of the transport sector. Accordingly, next-generation recycling technologies to tackle the large volumes of spent batteries must be urgently innovated. Herein, ionic liquids and the promising ionometallurgy that can overcome some issues of traditional recycling methods are discussed. Ionic liquids-mediated recovery of metals from spent batteries represents a sustainable strategy, featured with new fundamental chemistries. The opportunities for regeneration and reuse of ionic liquids are promising toward a cost-levelized recycling process. The unique chemical environment of ionic liquids also allows the development of coupled electrochemical procedures and upcycling. Future development requires the assessment of continuous operation and holistic process efficiency, technoeconomic and environmental aspects.

Binary Metallic CuCo5 S8 Anode for High Volumetric Sodium-Ion Storage.

With the rapid improvement of compact smart devices, fabricating anode materials with high volumetric capacity has gained substantial interest for future sodium-ion batteries (SIBs) applications. Herein, a novel bimetal sulfide CuCo5 S8 material is proposed with enhanced volumetric capacity due to the intrinsic metallic electronic conductivity of the material and multi-electron transfer during electrochemical procedures. Due to the intrinsic metallic behavior, the conducting additive (CA) could be removed from the electrode fabrication without scarifying the high rate capability. The CA-free CuCo5 S8 electrode can achieve a high volumetric capacity of 1436.4 mA h cm-3 at a current density of 0.2 A g-1 and 100 % capacity retention over 2000 cycles in SIBs, outperforming most metal chalcogenides, owing to the enhanced electrode density. Reversible conversion reactions are revealed by combined measurements for sodium systems. The proposed new strategy offers a viable approach for developing innovative anode materials with high-volumetric capacity.

A nanoporous screen-printed carbon sensor for environmental and clinical monitoring of the antibiotic ciprofloxacin

A very sensitive, fast and simple electrochemical procedure using a nanoporous screen-printed carbon electrode (NPSPCE) was developed for the determination of the fluoroquinolone antibiotic ciprofloxacin (CFX). Changes in the surface morphology and electrochemical properties of the SPCE before and after pre-anodization were examined using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). CV studies also demonstrated unequivocally adsorption controlled and irreversible oxidation of CFX. Using optimized conditions, the developed procedure is characterized by excellent selectivity and high sensitivity, allowing to achieve a very low limit detection (6.3 × 10−11 mol/L). The measurements taken allow us to consider the NPSPCE as a very effective tool for direct determination of CFX in samples with a complex matrix such as sewage and body fluids. The developed environment friendly sensor and procedure meet the requirements of green chemistry (reduction of toxic chemicals/reagents, and generation of minimal waste).

Electrosynthesis and characterization of alloyed CdSxSe1−x ternary quantum dots

CdS, CdSe and CdSxSe1−x (x = 0.15, 0.35, 0.5, 0.65, 0.85) ternary quantum dots (QDs) were electrosynthesized in a cavity cell and aqueous medium, using 3-mercaptopropionic acid (MPA) as stabilizer. The electrochemical procedure was carried out by a paired electrolysis, where elemental sulfur and selenium were reduced in a graphite powder macroelectrode while a sacrificial cadmium rod was oxidized, giving the simultaneous generation of S2-, Se2- and Cd2+ ions for efficient production of the ternary QDs, in the S2-/Se2- ratio of choice. The CdSxSe1−x QDs were characterized by XRD, HRTEM, UV-Vis absorption and emission spectroscopies, and voltammetric analyses. XRD analysis showed lattice parameters of the cubic CdSxSe1−x nanoalloys with a linear drop tendency when the sulfide molar ratio increased in the crystalline structure. HRTEM analysis was used to determine nanoparticle sizes: 3.94 ± 0.70 nm (CdS), 4.23 ± 1.00 nm (CdS0.5Se0.5), and 4.12 ± 0.78 nm (CdSe), with interplanar distances of 0.348 nm, 0.341 nm, and 0.339 nm, respectively. The band gap energy (Eg opt) of the CdSxSe1−x QDs were determined by UV-Vis absorption spectroscopy: 2.42, 2.47, 2.53, 2.66, 2.63, 2.73 and 2.84 eV, respectively, showing a linear increasing according to the S2-/Se2- ratio. The same behavior was observed for the Eg Elect determined by cyclic and linear voltammetry analysis, presenting a nanoalloy nature of the ternary QDs electrosynthesized.

Firstly electrochemical investigetions and determination of anticoagulant drug edoxaban at single-use pencil graphite electrode: an eco-friendly and cost effective voltammetric method.

The anticoagulant drug edoxaban has a blood thinning mechanism of action. In this study, a pencil graphite electrode was electrochemically activated at + 1.4V for 60s. in a Britton-Robinson (pH 9.0) supporting electrolyte solution. A simple, fast, and sensitive electrochemical procedure was developed using cyclic voltammetry and square wave voltammetry techniques. It was observed that edoxaban gave a good oxidation signal with cyclic voltammetry technique at a potential of + 0.98V (vs. Ag/AgCl). This procedure showed a linear response in a Britton-Robinson (pH 9.0) media within the concentration range of 0.2-1.8µM and limit of detection (LOD) and the limit of quantification (LOQ) values were determined to be 0.073μM (0.133μgmL-1) and 0.243μM (0.443μgmL-1), respectively. The method developed in this study was successfully applied to drug and urine samples. The developed voltammetric method was highly selective and gave satisfactory recovery results in urine and pharmaceutical samples. The results of the voltammetric method were compared with the spectroscopic method and it was determined that the results were compatible.