Simple Electrochemical Method Research Articles

Cheap and sensitive polymer/bismuth film modified electrode for simultaneous determination of Pb(II) and Cd(II) ions

Different aminonaphetalenesulphonic acid derivatives like 5-aminonaphthalene-1-sulphonic acid (5AN1SA), 2-aminonaphthalene-1-sulphonic acid (2AN1SA), 8-aminonaphthalene-2-sulphonic acid (8AN2SA) and 4-amino-3-hydroxynaphthalene-1-sulphonic acid (4A3HN1SA) were used to construct polymer/bismuth film modified electrode for simultaneous determination of Pb(II) and Cd(II) ions with the aim of developing a cheaper and sensitive electrode that could possibly replace Nafion. Among the different modified electrodes, poly (8AN2SA)/bismuth film modified electrodes showed the highest electrochemical response for both ions. These electrochemical results were also supported by density functional theory (DFT) calculations. Based on these experimental and theoretical results, poly (8AN2SA)/bismuth film glassy carbon modified electrode was further investigated to develop a simple and sensitive electrochemical method for the simultaneous determination of Pb(II) and Cd(II) ions. After optimizing the different experimental parameters, the proposed method gave a linear range of 1–40 μg/L with the detection limit of 0.38 and 0.08 μg/L for the simultaneous determination of Pb(II) and Cd(II) ions, respectively.

Electrochemical Detection of Celestine Blue Based on Screen Printed Carbon Electrode Modified with Molecular Imprinted Polymer and NiO Nanoparticles

A simple and rapid electrochemical method was developed for the detection of trace amount of Celestine blue (CB) at the surface of modified screen-printed carbon electrode (SPCE) with nickel oxide (NiO) nanoparticles and molecular imprinted polymer (MIP). Various types of electrochemical methods; containing, differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in order to probe the characteristics of the sensor toward CB was employed. The selectivity, real sample analysis (efficiency), the linear concentration range, and the detection limit of CB at the MIP/NiO-NPs/SPCE were evaluated by DPV method. FT-IR spectroscopy was applied in order to characterize the synthesized CB-MIP and non-molecular imprinted polymers (NIP). Scanning electron microscopy (SEM) and BET (Brunauer-Emmett-Teller) techniques were used for surface morphology and porosity properties of CB-MIP and NIP. A linear range was presented by the sensor for CB concentration between 2-150 µM with detection limit (S/N=3) of 0.35 µM. The sensor is able to selectively detect the CB molecules over the potential interferences. The sensor was used to determine CB in the real sample with acceptable results.

Assay of Famotidine in Pure Solutions and Pharmaceutical Preparatives using the Coated- graphite Electrode as a Detector in the FlA System

A simple electrochemical method was developed to estimate famotidine (FMT) in pure solutions and pharmaceutical preparatives by a flow-injection analysis system (FlA). This method includes preparation of a coated graphite electrode using FMT with the Phosphotungstic acid precipitant (PTA), di-butyl phthalate (DBP) and poly vinyl chloride (PVC). The electrode characteristics were examined by studying the optimum conditions, the carrier current, the injected model size, flow rate, the reaction coil length, pH, the range of concentrations, the minimum Nernst response, the response time, the detection limits, and the study also included identifying the electrode selectivity of the toward other interfering ions. The electrode showed that the best Nernst slope for the calibration curve was at 33.82 mv/decade within linear range of (1.0 × 10-6- 1.0 × 10-1M), correlation coefficient (R2) 0.9999, response time 10 seconds, the estimating speed is 90 sample/hour, while the rate of dilution degree (D) is 2.6452. The obtained results confirmed that it is of high accuracy and precision (Err 0.119%), (Rec 100.11%), (RSD 0.1233%). The proposed method was successfully applied to assay of FMT in commercial tablet forms.

Gemcitabine Direct Electrochemical Detection from Pharmaceutical Formulations Using a Boron-Doped Diamond Electrode.

The development of fast and easy-to-use methods for gemcitabine detection is of great interest for pharmaceutical formulation control in both research laboratories and hospitals. In this study, we report a simple, fast and direct electrochemical method for gemcitabine detection using a boron-doped diamond electrode. The electrochemical oxidation of gemcitabine on a boron-doped diamond electrode was found to be irreversible in differential pulse voltammetry, and scan rate influence studies demonstrated that the process is diffusion-controlled. The influence of the pH and supporting electrolytes were also tested, and the optimized differential pulse voltammetry method was linear in the range of 2.5–50 μg/mL, with a detection limit of 0.85 μg/mL in phosphate-buffered saline (pH 7.4; 0.1 M). An amperometric method was also optimized for gemcitabine detection. The linear range of the method was 0.5–65 μg/mL in phosphate-buffered saline of pH 7.4 as well as pH 5.5, the limit of detection being 0.15 μg/mL. The optimized differential pulse voltammetry and amperometric detection strategies were successfully applied to pharmaceutical formulations, and the results were compared to those obtained by high-performance liquid chromatography and UV-Vis spectrophotometry with good correlations.

Electrochemical methods for monitoring the content of polysulfides in environmental objects

Sulfur-containing products (elemental sulfur, polysulfides) used to control agricultural pests (powdery mildew, anthracnose, scab, spider mite) undergo chemical transformations under environmental conditions resulting in formation of toxic soluble and volatile sulfur compounds (hydrogen sulfide, sulfides, polysulfides). A relatively simple electrochemical method for monitoring the content of polysulfides in various objects based on cathodic stripping voltammetry (direct- and alternating-current modes) with a mercury-film electrode in an alkaline supporting electrolyte is proposed in the paper. It was shown that the value of the analytical signal depends linearly on the concentration of S2 2- and S3 2- ions in the range of 1•10−7-1•10−3 M. The method can be used to determine the total content of polysulfides in environmental objects and to calculate the average degree of polysulfidity n for Sn 2- ions.

Electrocatalyst Derived from Waste Cu-Sn Bronze for CO2 Conversion into CO.

To sustainably exist within planetary boundaries, we must greatly curtail our extraction of fuels and materials from the Earth. This requires new technologies based on reuse and repurposing of material already available. Electrochemical conversion of CO2 into valuable chemicals and fuels is a promising alternative to deriving them from fossil fuels. But most metals used for electrocatalysis are either endangered or at serious risk of limitation to their future supply. Here, we demonstrate a combined strategy for repurposing of a waste industrial Cu-Sn bronze as a catalyst material precursor and its application toward CO2 reuse. By a simple electrochemical transfer method, waste bronzes with composition Cu14Sn were anodically dissolved and cathodically redeposited under dynamic hydrogen bubble template conditions to yield mesoporous foams with Cu10Sn surface composition. The bimetal foam electrodes exhibited high CO2 electroreduction selectivity toward CO, achieving greater than 85% faradaic efficiency accompanied by a considerable suppression of the competing H2 evolution reaction. The Cu-Sn foam electrodes showed good durability over several hours of continuous electrolysis without any significant change in the composition, morphology, and selectivity for CO as a target product.

Robust Cu-Au alloy nanowires flexible transparent electrode for asymmetric electrochromic energy storage device

Flexible electrochromic energy storage (EES) systems have attracted tremendous attention because of their combined advantages of color-changing and energy-storing. Although copper nanowires (Cu NWs) flexible transparent electrodes (FTEs) have been considered as one of the most promising candidates for next-generation flexible electronics, its instinct electrochemical instability hindered its application in flexible electrochemical energy system, including EES device. Herein, we proposed a highly conductive electrochemically stable FTE based on Cu-Au alloy NWs network synthesized in a facile and simple electrochemical method. Compared with the pristine Cu NWs network that breaks into disconnected nanorods less than 10 s in 1 M H2SO4 solution during electrochemical anodic corrosion, the Cu-Au NWs network remained stable after 4000 s under the same condition. Furthermore, thanks to the forming of firm joints between the stacked NWs during inducting Au atoms, the optical-electrical performance (a sheet resistance of 23.2 Ohm/sq at a transmittance of 87%) and mechanical flexibility were highly improved. Based on these improvements, anodic PANI and cathodic WO3 layer were successfully deposited onto the Cu-Au NWs FTE by electrochemical method. An asymmetric-EES (AEES) device was assembled utilizing these complementary electrodes, which concurrently exhibited excellent electrochromic (coloration efficiency: 153.77 cm2/C at 633 nm) and energy storage performance (areal capacitance: 2.29 mF/cm2), demonstrating their potential for smart multifunctional flexible electronics.

Mechanical Performance Enhancement of Aluminum Single-Lap Adhesive Joints Due to Organized Alumina Nanotubes Layer Formation on the Aluminum Adherends

The present investigation aims to take a step forward for the transfer of a simple laboratory electrochemical method of surface nano-treatment of aluminum to industrial applications. The electrochemical method has been applied to process 1050A aluminum. Surface nano-structuring has been achieved and resulted in the formation of an organized alumina nanotubes layer on commercial aluminum plates used as adherends for the manufacturing of aluminum single-lap adhesive joints. The mechanical properties of single-lap aluminum adhesive joints constructed with both non-anodized and anodized adherends were investigated and compared. Two types of epoxy resins were used to prove that the anodization of the adherends is equally effective, independently of the adhesives’ type. Furthermore, three overlap lengths were used (7, 10, and 25 mm) to study the effect of the overlap length on the overall joint mechanical response. Results of both three-point bending and tensile–shear testing showed that there is a considerable improvement of the joints’ mechanical performance with the addition of the nanostructures, for all the overlap lengths. It was found that the anodization method greatly contributes to the strengthening of the joints, leading to a strength increase of up to 176% and 148% for the shear and three-point bending strength, respectively.

The initial stages of the dissolution of chalcopyrite in chloride solutions: Validity of mixed potential model and comparison with sulfate solutions

A relatively simple electrochemical method has been used to obtain accurate data on the rates of oxidative dissolution of chalcopyrite from well defined surface areas under ambient conditions using iron(III) or copper(II) (in chloride solutions) as the oxidants. The initial rates are approximately constant for extended (6 h) periods in chloride solutions but decrease with time in sulfate solutions.The rates of dissolution are not strongly dependent on the nature of the solution except in solutions of high chloride concentration for which the rates are higher. The rate is also slightly higher with copper(II) or with iron(III) + copper(II) as the oxidant. A limited study has shown the importance of temperature with an activation energy of 57 kJ mol−1 for dissolution in chloride solution.The chalcopyrite mixed potentials measured during dissolution vary over a limited range (less than 200 mV) depending on the conditions. Potentiostatic measurements in solutions without oxidants have shown that the rates calculated from the current densities at the mixed potentials agree quantitatively with those obtained from the chemical dissolution measurements. This correspondence confirms the validity of the mixed potential model for oxidative dissolution. Comparisons have been made with previously published data largely at elevated temperatures.

Confining invasion directions of Li+ to achieve efficient Si anode material for lithium-ion batteries

Tremendous volume expansion of silicon anode during cycling limits its further application. Here, a novel silicon nano-ribbon (SiNR) with (110) crystal plane is proposed as anode for the Lithium-ion batteries. The SiNRs with (110) crystal plane have been synthesized by a simple electrochemical micromachining method. Both invasion direction of the lithium-ions and expansion directions of the lithiated silicon are limited to the <110> crystal direction. Recrystallization of SiNR induced by the retention of silicon atomic chains after delithiation is verified experimentally and theoretically. Such SiNR, without necessary surface coating treatment, exhibits high ionic conductivity, high stable solid electrolyte interphase (SEI) and long cycling stability, retaining a specific capacity of 1721.3 mAh g−1 (∼80% capacity retention) after 2000 cycles with an initial coulombic efficiency (CE) of 83%. The rational design of nanostructured battery materials and electrodes in this work also opens a new dimension in material design for other batteries.

To Love and to Kill: Accurate and Selective Colorimetry for Both Chloride and Mercury Ions Regulated by Electro-Synthesized Oxidase-like SnTe Nanobelts

Herein, SnTe nanobelts (NBs) with efficient oxidase-mimetic activity were synthesized by the simple electrochemical exfoliation method. A specific inhibition effect of Cl- on the enzymatic behavior of the pure SnTe NBs was discovered, which was accordingly used for establishing a highly feasible, sensitive, selective, and stable Cl- colorimetric assay. The detection concentration range was 50 nM to 1 mM, and the lowest detection limit was 20 nM for Cl-. In addition, a signal on-off-on route based on the SnTe NB nanozyme was designed to realize the reliable and specific detection of Hg2+. Therein, the SnTe NBs were grafted with gold nanoparticles to form a hybrid of SnTe/Au, resulting in the depression of the oxidase-like activity, which can then be recovered in the presence of the Hg2+ due to the formation of a gold amalgam. Especially, it was found that the high concentration of Cl- over 3 mM could again exert suppression influence toward the enzymatic activity of the SnTe/Au-Hg system. Based on the to-love-and-to-kill interaction between Cl- and Hg2+, the detection range for Cl- can be extended to 40 to 250 mM. In return, the assays of Cl- could avoid in advance its interference toward the accurate Hg2+ assays. We systematically clarified the oxidase-like catalytic mechanism of the SnTe-derived nanozyme systems. The as-proposed colorimetry can be successfully applied in practical samples including the sweat, human serum, or seawater/tap water, relating to cystic fibrosis, hyper-/hypochloremia, or environmental control, respectively.

A simple strategy to improve the electrochemical performance of rechargeable aqueous Al-graphite battery

We report here the improved performance of a rechargeable Al-graphite cell in aqueous electrolyte which is achieved by a modification of the graphite electrode. A simple electrochemical method was adopted to exfoliate the graphite electrode which was further treated at 800 °C to obtain thermally exfoliated graphite. The thermal treatment resulted in formation of high surface area nanosized graphite flakes. This thermally exfoliated graphite shows a discharge capacity of 100–120 mAhg−1, whereas exfoliated graphite shows only 50–60 mAhg−1 at current rate of 0.5 Ag−1. The improvement is due to lesser charge transfer resistance at the electrode–electrolyte interface. The influence of ‘water-in-salt’ electrolyte in the electrochemical performance was also investigated.

Development of a simple and rapid screening method for the detection of 1-(3-chlorophenyl)piperazine in forensic samples

1-(3-chlorophenyl) piperazine (mCPP) is a synthetic drug with hallucinogenic effects that has often been found in seized samples. In this context, easy to use point-of-care tests can be of great value in preliminary forensic analysis. Herein, we proposed a simple, fast, and portable electrochemical method for the detection of mCPP in seized samples. The method is based on the use of disposable screen-printed carbon electrodes (SPCE) and rapid screening procedures by square-wave voltammetry using minimal sample sizes (100 μL). mCPP showed an irreversible electrochemical oxidation process at +0.65 V on SPCE (vs Ag) using 0.04 mol L−1 Britton Robinson (BR) buffer solution (pH 7) as the supporting electrolyte. The proposed method exhibited a linear correlation (r = 0.998) between peak current and mCPP concentration in the range of 1–30 μmol L−1 (LOD = 0.1 μmol L−1). Interference studies were performed for adulterants and other classes of drugs of abuse, which can also be found in seized samples containing mCPP, such as caffeine, amphetamine, methamphetamine, 1-benzylpiperazine, 3,4-methylenedioxymethamphetamine, methylone, mephedrone, ethylone and 3, 4-methylenedioxypyrovalerone. The developed method presents great potential as a rapid and simple screening tool to detect mCPP in forensic samples.

Simple and rapid electrochemical detection of 1-benzylpiperazine on carbon screen-printed electrode

1-Benzylpiperazine (BZP) is an illegal synthetic drug commonly used in combination with alcoholic beverages for recreational purposes due to its amphetamine-like stimulant and hallucinogenic effects. In this work, we described a simple, portable and low-cost electrochemical method for BZP determination in beverage (vodka, whisky and white wine) and seized street samples. The electrochemical behavior of BZP was investigated by differential pulse voltammetry (DPV) and cyclic voltammetry (CV) using a screen-printed carbon electrode (SPCE), where a single irreversible oxidation processes was presented at around +0.7 V (vs. Ag pseudo reference). An electrochemical mechanism for BZP oxidation at SPCE was proposed. The quantification of BZP in beverage samples was optimized by the DPV technique in 0.12 mol L−1 Britton Robison buffer solution (pH = 5.0) using a drop-casting method of small sample volume (~100 μL) on SPCE. The proposed method showed a good linear range for BZP determination from 1 to 75 μmol L−1 with a low limit of detection (0.3 μmol L−1) and recovery values between 90 and 102%. Additionally, interference studies for other synthetic drugs from piperazine class and for other drugs commonly found in combination with BZP, such as 3,4-methylenedioxymethamphetamine (ecstasy), caffeine and synthetic cathinones, were performed. The analytical performance of the SPCE for detection of BZP in beverage and seized samples presents great potential for a simple and rapid screening method in forensic analysis.

Electrochemical synthesis of binder-free interconnected nanosheets of Mn-doped Co3O4 on Ni foam for high-performance electrochemical energy storage application

• Simple electrochemical CV method for the synthesis of different nanostructures by tuning the scan rate. • Binder free preparation of different nanostructures of Mn-doped Co 3 O 4 on Ni foam. • Superior electrochemical performance of interconnected nanosheets exhibiting maximum specific capacitance of 1005F g −1 in KOH. • Aqueous asymmetric supercapacitor assembly with activated carbon showed enhanced electrochemical performance. In this study, various nanostructures of Mn-doped Co 3 O 4 were synthesized on Ni foam using binder-free electrochemical technology for electrochemical energy storage applications. Using the cyclic voltammetry method with different scan rates, diverse nanostructures, i.e., irregularly oriented nanooctahedra, interconnected standing nanosheets, and nanopetals of Mn-doped Co 3 O 4 , were obtained. The standing interconnected nanosheets on the Ni foam exhibited remarkable supercapacitive performance due to the void space between the sheets and mesoporous structure, which provided additional active sites for faradic transitions. The nanosheets exhibited excellent electrochemical performance with a maximum specific capacitance of 1005F g −1 and a cyclic stability of 88% during 5000 charge–discharge cycles. Moreover, an asymmetric supercapacitor was assembled comprising activated carbon on Ni foam and interconnected nanosheets of Mn-doped Co 3 O 4 on Ni foam as negative and positive electrodes, respectively. This assembled device exhibited an improved potential of 1.6 V, a maximum specific energy of 20.6 Wh kg −1 , and a maximum specific power of 16 kW kg −1 with 80.6% capacity retention after 2000 charge–discharge cycles, which is superior for SC devices.

Molecularly imprinted photoelectrochemical sensor for aflatoxin B1 detection based on organic/inorganic hybrid nanorod arrays

In this work, an organic/inorganic hybrid nanorod array (P(33DT-co-3TPCA)/[BMIM]Cl-ZnO NRAs) composed of poly(3,3'-dithiophene-co-3-thiophenecarboxylic acid) (P(33DT-co-3TPCA)), 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) and zinc oxide (ZnO) was synthesized by simple electrochemical method through in-situ growing on indium tin oxide (ITO). Due to the introduction of molecularly imprinted conducting polymer (MICP) with good recognition ability and the use of ionic liquid [BMIM]Cl instead of KCl during ZnO growth to regulate and control its micromorphology and photoelectrochemical property, the developed photoelectrochemical (PEC) sensor exhibited good PEC performance for aflatoxin B1 (AFB1) detection. Under the optimized conditions, the MICP-PEC sensor could linearly response to the target molecule AFB1 in the range of 0.10 ng mL−1-10 ng mL−1 with a detection limit of 0.058 ng mL−1 (S/N = 3). Furthermore, the practicability of the developed MICP-PEC sensor was demonstrated by determining AFB1 in rice and peanut samples. This work provided a new promising organic/inorganic hybrid MICP-PEC sensing platform for toxic small molecule detection.

Direct electrochemical synthesis of the copper based metal-organic framework on/in the heteroatoms doped graphene/pencil graphite electrode: Highly sensitive and selective electrochemical sensor for sertraline hydrochloride

Abstract In this study, a simple and innovative electrochemical method was utilized for the synthesis of the copper based metal-organic framework (Cu-MOF)/sulfur and nitrogen co-doped graphene (SNDGr) nanocomposite on the pencil graphite electrode (PGE) and developing of an electrochemical sensor for determination of sertraline hydrochloride (STLHC); an antidepressant drug. Firstly, the SNDGr was simply synthesized through the electrochemical exfoliation of PGE by using potentiostatic procedure in the mixture solution of melamine and ammonium sulfate. Thereafter, the Cu-MOF was also electrochemically deposited on/in SNDGr/PGE using chronoamperometry technique. The as-fabricated modified electrode (Cu-MOF/SNDGr/PGE) was characterized through relevant instrumental methods (scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction, and electrochemical techniques). The designed modified electrode exhibited excellent electrocatalytic activity for the oxidation of STLHC compared with bare PGE, SNDGr/PGE and Cu-MOF/PGE due to its high specific surface area, high conductivity and fast charge transfer ability of the nanocomposite. The experimental results demonstrated that the present modified electrode has a promising potential as a stable and efficient electrochemical sensor for determination of STLHC. Under the optimized experimental condition, the designed sensor responds efficiently to STLHC over the concentration range of 0.05 to 2.67 µM with a low detection limit (0.038 μM), high selectivity, good sensitivity (0.4557 μA/μM cm2) and repeatability. Further, the suggested sensor was successfully employed for the determination of STLHC in real samples with suitable recovery values.

Formate Dehydrogenases Reduce CO2 Rather than HCO3- : An Electrochemical Demonstration.

Mo/W formate dehydrogenases catalyze the reversible reduction of CO2 species to formate. It is thought that the substrate is CO2 and not a hydrated species like HCO3- , but there is still no indisputable evidence for this, in spite of the extreme importance of the nature of the substrate for mechanistic studies. We devised a simple electrochemical method to definitively demonstrate that the substrate of formate dehydrogenases is indeed CO2 .

Formate Dehydrogenases Reduce CO2 Rather than HCO3−: An Electrochemical Demonstration

AbstractMo/W formate dehydrogenases catalyze the reversible reduction of CO2 species to formate. It is thought that the substrate is CO2 and not a hydrated species like HCO3−, but there is still no indisputable evidence for this, in spite of the extreme importance of the nature of the substrate for mechanistic studies. We devised a simple electrochemical method to definitively demonstrate that the substrate of formate dehydrogenases is indeed CO2.

Facile Electrochemical Method for the Fabrication of Stable Corrosion-Resistant Superhydrophobic Surfaces on Zr-Based Bulk Metallic Glasses.

Both surface microstructure and low surface energy modification play a vital role in the preparation of superhydrophobic surfaces. In this study, a safe and simple electrochemical method was developed to fabricate superhydrophobic surfaces of Zr-based metallic glasses with high corrosion resistance. First, micro–nano composite structures were generated on the surface of Zr-based metallic glasses by electrochemical etching in NaCl solution. Next, stearic acid was used to decrease surface energy. The effects of electrochemical etching time on surface morphology and wettability were also investigated through scanning electron microscopy and contact angle measurements. Furthermore, the influence of micro–nano composite structures and roughness on the wettability of Zr-based metallic glasses was analysed on the basis of the Cassie–Baxter model. The water contact angle of the surface was 154.3° ± 2.2°, and the sliding angle was <5°, indicating good superhydrophobicity. Moreover, the potentiodynamic polarisation test and electrochemical impedance spectroscopy suggested excellent corrosion resistance performance, and the inhibition efficiency of the superhydrophobic surface reached 99.6%. Finally, the prepared superhydrophobic surface revealed excellent temperature-resistant and self-cleaning properties.