Surface Morphology Of Electrode Research Articles

High-performance Li-organic battery based on thiophene-containing porous organic polymers with different morphology and surface area as the anode materials

It is the hot issue for Li-organic battery that whether the higher specific surface area of the porous organic polymers as the electrode materials can benefit to the better battery performance. In this article, the conjugated polymer based on star-shaped benzene-thiophene structure (pBHT) and benzene-ethynyl-thiophene structure (pBAT and pBABT) were designed and successfully prepared. The pBHT polymer exhibits the unique stacked hollow tube morphology and possesses the high surface area (~1139 m2/g), while the polymers pBAT and pBABT both display the macroporous morphology with the low surface area (32.5 m2/g and 12.5 m2/g). Being explored for the battery performance as anode materials, the pBHT electrode exhibits a very low discharge capacity (<100 mAh g−1) and poor cycle’s stability. In contrast, the pBABT electrode with very low surface area of only 12.5 m2/g displays the higher discharge capacity (442 mAh g−1 at 500 mA/g of the second cycle), excellent stability (401 mAh g−1 at 500 mA/g of the 1000 cycles) and higher rate capabilities. These uncommon electrochemical properties may be attributed to the unique hollow tube morphology for the polymer pBHT, which limit the lithium ion released and might form “dead lithium”, thus resulting in the collapse of polymer structures and difficult solid electrolyte interface formation, as well as the fast capacity fading and extremely low capacity according to the electrochemical behaviors and SEM measurements. EIS also confirm the uncommon electrochemical properties with the three polymer electrodes from the kinetics for charge carrier insertion/extraction. Our findings may offer a clue to explore the effect of specific surface area and morphology of polymer electrodes on the performance of LIBs when designing the high-performance electrode materials.

Hole Accumulation at the Grain Boundary Enhances Water Oxidation at α-Fe2O3 Electrodes under a Microwave Electric Field

We studied the effects of surface morphology and carrier distribution of α-Fe2O3 electrodes on the enhancement of water electrolysis under microwave (MW) irradiation. We deposited α-Fe2O3 electrodes with various morphologies on Nb-doped rutile TiO2 (100) substrates. α-Fe2O3 films with rough and flat surfaces were deposited using electrodeposition (ED) and pulsed laser deposition (PLD), respectively. The ED α-Fe2O3 film showed a larger response to the MW electric field applied to the electrodes than did the PLD film. In addition, the response was linearly correlated with the MW electric field intensity. Using scanning MW microscopy, we found that the local MW susceptibility of the α-Fe2O3 electrode was enhanced at the grain boundary of the ED α-Fe2O3 film. Analysis of the surface band structure of both ED and PLD α-Fe2O3 films using electrochemical impedance spectroscopy showed that the ED α-Fe2O3 film had a wider depleted layer, indicating increased accumulation of holes on the surface of the electrode to enhance water oxidation. We concluded that the accumulation of holes at the grain boundary of the ED α-Fe2O3 film determines the enhancement of water oxidation under an MW electric field.

Treatment of Methyl Blue Wastewater by Steel Slag Particle Three-Dimensional Electrode System

The particle electrode was prepared by using industrial waste slag as raw material, and the surface morphology of the particle electrode was characterized by scanning electron microscopy. The comparison experiments showed that under the same experimental conditions, the efficiency of removing the methyl blue from the three-dimensional electrode of the steel slag particles was 23.48% higher than that of the two-dimensional electrode, and the energy consumption was reduced by 36.2%. The results showed that the primary and secondary factors affecting the methyl blue wastewater of steel slag particles are electrolyte concentration, voltage, initial waste concentration and particle volume. Under the optimal combination of pH 3, voltage 12 V, initial methyl blue concentration of 15 mg/L and electrolyte concentration of 0.3 mol/L, the removal rate of methyl blue reached 91.41%.

Study on the corrosion resistance performance of PbO2-ZrO2 nanocomposite electrode in NaCl electrolyte solution

Purpose This paper aims to improve the corrosion resistance performance and stability of PbO2 electrodes in chloride wastewater. Design/methodology/approach The morphology of PbO2-ZrO2 nanocomposite electrodes was observed by scanning electron microscopy (SEM). The open circuit potential (OCP) curves, anodic polarization curves, electrochemical impedance spectra, accelerated life tests, weight-loss tests and reusability tests were used to study the corrosion resistance properties and stability of PbO2-ZrO2 nanocomposite electrodes in NaCl solution. Findings SEM showed that the surface morphology of PbO2-ZrO2 nanocomposite electrodes became compacted and smooth. Electrochemical tests showed that ZrO2 nanoparticles could increase the OCP, corrosion potential and charge transfer resistance, and decrease the corrosion current density in 3.5 Wt. per cent NaCl electrolyte solution. Besides, PbO2-ZrO2 nanocomposite electrodes showed high reusability for acetamiprid degradation, the accelerated service life could reach 146 h, which was almost 3.3 times longer than that of PbO2 electrodes (44 h), weight-loss tests showed that the corrosion resistance for PbO2-ZrO2 nanocomposite electrodes was 2.3 times as compared to PbO2 electrodes. Originality/value By the codeposition of ZrO2 nanoparticles, the corrosion resistance performance and stability of PbO2 electrodes in NaCl electrolyte were improved.

Selective and ultrasensitive electrochemical immunosensing of NSE cancer biomarker in human serum using epoxy-substituted poly(pyrrole) polymer modified disposable ITO electrode

An ultrasensitive, specific and label-free immunosensor was developed to determine the lowest alteration of neuron specific enolase antigen (NSE), the standard biomarker of lung cancer patients. This immunosensor was the first biosensor which was fabricated by utilizing epoxy-substituted-polypyrrole P(Pyr-Epx) polymer as an immobilization platform. The fabrication steps of the immunosensor were followed by using electrochemical studies (electrochemical impedance spectroscopy and cyclic voltammetry) and these techniques were applied to characterize the binding interactions. Scanning electron microscopy and atomic force microscopy analyses were performed to investigate the changes formed on the indium tin oxide electrode surface morphology and electrode surface structure. The optimization of the experimental parameters and the analytical performance of the proposed immunosensor were widely evaluated. Under optimum experimental conditions, the change in impedimetric signal was determined to follow the specific biointeraction between anti-NSE antibody and NSE antigen. The sensing ability of the proposed immunosensor for NSE detection showed a wide linear detection range of 0.02–7.5 pg/mL, with a low detection limit of 6.1 fg/mL. This impedimetric immunosensor also demonstrated highly repeatable and reproducible responses, and reliable results in the analysis of human serum samples with recoveries between 98.29 % and 102.81 %. In addition, the designed immunosensor could be used for detection of lung cancer biomarkers after simple dilution of serum samples with phosphate buffer.

In Situ AFM Imaging of Platinum Electrode Surface during Oxidation–Reduction Cycles in Alkaline Electrolyte

The development of energy conversion systems depends strongly on our fundamental understanding of the electrochemical interface of the electrocatalyst. Here, we study the changes in the surface morphology of a platinum polycrystalline electrode during oxidation-reduction cycles in a wide potential window (0.05-2.0 V) in sodium hydroxide by in situ atomic force microscopy. Platinum nanoparticles are observed on the surface after cycling due to the redeposition of dissolved platinum ions. The influence of scan rate on platinum redeposition is studied by applying asymmetric potential sweep programs. The negative-going scan rate is the key factor here, as it controls the reduction of platinum oxide, as well as the redeposition of platinum. Moreover, it is found that chloride ions in the electrolyte impede the redeposition by complexing with platinum. This investigation enables us to reveal the surface roughening processes on platinum electrode in alkaline electrolyte and assists in understanding the fundamentals of the stability of platinum-containing energy conversion systems.

Carbon electrodes derived from polyacrylonitrile-polyethylene glycol blend for high-performance supercapcitor

Continuous and evenly distributed porous carbon electrodes are prepared from electrospun nanofibers of Polyacrylonitrile (PAN) and Polyethylene glycol (PEG) blend with different weight ratio. Structure and surface morphology of carbon electrodes are characterized by x-ray diffraction, Raman spectroscopy, scanning electron microscopy and Brunauer–Emmett–Teller method. The electrochemical performances of porous nanofiberous electrodes are studied by cyclic voltametry, galavanostatic charge-discharge and electrochemical impedance spectroscopy. The carbon electrodes derived from nanofibers of PAN/PEG blend with 15 wt% loadings of PEG shows excellent electrochemical properties with a high specific capacitance of 272.05 F g−1 at the current density of 0.5 A g−1 in 6 mol l−1 aqueous potassium hydroxide electrolyte. These electrodes show 92% capacity retention after 1000 charge/discharge cycles at the current density of 1 A g−1 .

Sensitive monitoring of riboflavin in commercial multivitamins using poly (chitosan)-based nanocomposite.

The rapid and sensitive determination of riboflavin (RF) is important for the treatment of seborrheic and glossitis dermatitis, sunlight sensitivity, mucosal, and skin disorders. In this work, an electrochemical sensor was developed by electrodes modification using poly (chitosan) to sensitive detection of RF in commercial multivitamin. Electrodeposition of chitosan on the surface of glass carbon electrode was performed using cyclic voltammetry technique in the range of -1 to +1 V. The modified electrode surface morphology was characterized using a high-resolution field emission scanning electron microscope. The modified electrode was used as an effective electrical interface for the detection of RF using cyclic, differential pulse, and square wave voltammetry techniques. Finally, the sensor was applied to determine RF in commercial multivitamins. In optimum conditions, the linear range for the standard sample of RF and commercial multivitamins 94 to 333μM and 24.6 to 176μM were obtained, respectively. Low limit of quantification (LLOQ) were obtained as 24.6μM.

Surface modification of superparamagnetic iron oxide nanoparticles and methyl methacrylate molecularly imprinted polymer for gluten detection

Gluten is a protein found in cereal grain such as wheat, barley, and rye. A small amount of gluten causes an autoimmune disease that leads to damage in the digestive system as well as a skin body system. The detection of gluten in food attracts tremendous attention. Surface modification by molecularly imprinted polymers electrode has been studied for specific detection of gluten using electrochemical superparamagnetic iron oxide nanoparticles trapped into a polymer matrix to improve gluten sensitivity with a magnetic property. A gold screen-printed electrode was modified by the magnetic molecularly imprinted polymers using surface polymerization of methyl methacrylate as monomer and gluten as a template. The magnetic iron oxide with a particle size less than 100 nm was modified and characterized using VSM, DLS and TEM techniques. SEM techniques confirmed the surface morphology of gold screen-printed electrodes modified with the MMIP. Finally, MMIP electrodes were used to detect gluten by an electrochemical method.

Electrochemical Behavior Investigation of Cysteine on Nickel Corrosion in Acidic Medium

The corrosion inhibition of nickel in 0.5 M H2SO4 by cysteine was investigated with various electrochemical methods and surface observations by SEM. The cyclic voltammetry revealed that the current density is the highest in absence of the cysteine and decreases with increasing inhibitor concentration. The cysteine is an anodic inhibitor. The polarization and electrochemical impedance spectroscopy showed that the cysteine has a poor inhibitive effect. The surface observation by scanning electron microscope corroborates the addition of cysteine has no significant improvement of the surface morphology of nickel electrode in 0.5 M H2SO4. Results obtained by different methods corroborate each other.

Highly sensitive determination of gallic acid on poly (l-Methionine)-carbon nanotube composite electrode

In this work, composite electrode was prepared with poly l-methionine and carbon nanotube (PLM/MWCNT) onto glassy carbon electrode. The composite electrode surface morphology and electrical properties were characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). Electrochemical response of Gallic acid (GA) on PLM/MWCNT/GCE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry. The results demonstrated that PLM/MWCNT/GCE exhibit a favorable application for the determination of GA in pH 2.2 Britton-Robinson buffer solution. The prepared composite electrode offered two linear segments for GA in DPV over the range of 4.0 nmoL L−1-1.1μmol L−1 and 1.7 μmol L−1 – 20.0 μmol L−1 with a detection limit of 3.1 nmol L−1 (S/N = 3). The amperometric detection was also used for improving as lower detection limit compare with DPV. The detection limit was calculated from the amperometric studies found as 0.5 nmol L−1. Through the synergistic effect of PLM and MWCNT, the composite electrode exhibits good catalytic effect, selectivity, stability and reproducibility for GA. The proposed method was verified by successful determination of GA in green tea, black tea and wine samples.

Electrochemical detection of flutamide with gold electrode as an anticancer drug

In this research, the Gold electrode was used to investigate the electrochemical behavior of the Flutamide by cyclic voltammetry and differential pulse voltammetry method. In addition, the morphology of the gold electrode surface was demonstrated with field emission scanning electron microscope (FESEM). Some of the effective parameters such as pH, scan rates, and Flutamide concentration were optimized. The pH 7 was selected as optimal pH. The currents of peak according to Flutamide concentration from 6 to 60 μM and 100–600 μM were linear, and the limit of detection was calculated 1.8 μM. This electrochemical sensor could detect Flutamide selectable in the presence of some interferents. • FESEM, CV, and DPV methods were used to study the electrochemical behavior of Flutamide. • The electrode was successfully detected Flutamide in presence of some interferents, with high selectivity.

High-performance tin-titanium thin-film anodes prepared by magnetron co-sputtering for lithium-ion microbatteries

A new anode material of Sn-Ti thin film was successfully prepared by magnetron co-sputtering of two separate targets at the atmosphere of Ar at normal temperature. The structure, surface morphology, and electrochemical performance of the Sn-Ti thin film electrodes are examined by X-ray diffraction spectroscopy, scanning electron microscopy, and electrochemical tests. Furthermore, the effects on the electrochemical performance of the Ti content in the Sn-Ti thin films are studied. Results show that increasing the power of Ti target can improve the cyclic performance of Sn-Ti thin film electrodes. It is very interesting that no any cracks or material pulverization are observed on these Sn-Ti thin films, which indicate that the Ti can improve the stability of Sn-based anode materials. Such improved electrochemical properties benefit from the good mechanical support by Ti and uniform Ti doping.

Low-Overpotential Electrochemical Reduction of CO2 to Formic Acid on Surface-Modified Doped Tin Oxide Pellets

Gas sensors fabricated with antimony doped tin oxide (ATO) nanomaterials exhibit remarkable sensitivity for detecting oxidizing and reducing gases. This study highlights the enhanced selectivity and stability of the porous ATO nanomaterial electrode made for electrochemical reduction of CO2 in aqueous media. During electrochemical reduction, these electrodes prepared from compressed powders tend to crumble within a few hours in aqueous media. To overcome this electrode disintegration effect, we modified the surface of the doped tin-Oxide nanoparticles and nanowires with Nafion and a dipodal silane (1,2-Bis(triethoxysilyl)ethane). The electrode characterization studies include Cyclic Voltammetry (CV), and Electrochemical Impedance Spectroscopy (EIS). Scanning electron microscopic investigation of electrode surface morphology and roughness before and after electrochemical CO2 reduction for derivatized and underivatized electrode revealed lower surface roughness for former than the latter. The derivatized electrodes allowed CO2 electrochemical reduction at low overpotentials and high current density without any electrode crumbling over more than 24 hours of continuous operation. Formate/formic acid and methanol were the major products of reduction at electrode potentials ranging from -0.4 to -1.0V vs. RHE in the CO2 saturated 0.1M KHCO3 electrolyte. Higher current density and Faradaic Efficiency of formic acid was observed when compared to planar tin electrode materials and tin oxide nanoparticles deposited on FTO glass.

Preparation of novel Ti-based MnOx electrodes by spraying method for electrochemical oxidation of Acid Red B.

At different calcination conditions, titanium-based manganese oxides (MnOx) electrodes were fabricated by spraying method without adhesive. The MnOx/Ti electrodes were applied in electrochemical oxidation of wastewater treatment for the first time. The surface morphologies of electrodes were tested by scanning electron microscopy. The formation of different manganese oxidation states on electrodes was confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The electrochemical properties of the electrodes have been performed by means of cyclic voltammetry and electrochemical impedance spectroscopy. The characterizations revealed that the MnOx/Ti-350(20) electrode, prepared at calcination temperature of 350 °C for 20 min, exhibited fewer cracks on the electrode surface, larger electrochemically effective surface area and lower charge transfer resistance than electrodes prepared at other calcination conditions. Moreover, Acid Red B was used as target pollutant to test the electrode activity via monitoring the concentration changes by UV spectrophotometer. The results showed that the MnOx/Ti-350(20) electrode presented the best performance on decolorization of Acid Red B with the lowest cell potential during the process of electrochemical oxidation, and the chemical oxygen demand (COD) conversion was 50.7%. Furthermore, the changes of Acid Red B during the electrochemical oxidation process were proposed by the UV-vis spectra.

Characterization and theoretical studies of synthesized (E)-2((3-methylbenzilidene) amino) phenol complexes for the fabrication of novel electrochemical sensor for determination of Pb2+ and Hg2+ ions

A Schiff base (E)-2((3-methylbenzilidene) amino) phenol (EMBAP)/multi-walled carbon nanotube modified carbon paste electrode was applied to the selective and accurate determination of Hg2+ and Pb2+ ions by voltammetric methods. The morphology of electrodes surface was characterized, and a density functional theory (DFT) based on the interaction of target ions with EMBAP was investigated. The theoretical binding energies, entropies, free energies and formation constants were calculated. The results indicated that complexes are stable, and formation is spontaneous. The synergistic advantages of EMBAP and MWNTs caused higher sensitivity, fast electron transfer, well reproducibility, long time stability, and well anti-interference capability. The theoretical studies showed that the most important interaction is the electron-donating O lone pair to the contacting LP* of metal ions. Under optimum conditions, the peak current was linear in 0.1–200 μmol L−1 and 0.1–250 μmol L−1 concentration of Hg2+ and Pb2+ with limits of detection (S/N = 3) of 28 nmol L−1 and 41 nmol L−1 for Hg2+ and Pb2+, respectively. The current method was applied for the simultaneous determination of Hg2+ and Pb2+ in algae samples with comparable accuracy and precision respect to reference methods.

Investigating the Relationship between the Conditions of Polythiophene Electrosynthesis and the Pseudocapacitive Properties of Polythiophene-Based Electrodes

Thin polythiophene films are electrochemically deposited onto different types of substrates. We investigate the effects the conditions of polythiophene (PT) synthesis have on the pseudocapacitive (charge accumulation) properties of fabricated electrodes and identify the optimal synthesis conditions. Composite electrodes with a polyacrylamide (PAM) sublayer modified with trifluoromethanesulfonic acid exhibit the largest specific capacity (up to 550 F g−1). With a PAM sublayer, polythiophene-based electrodes exhibit lesser (by 19%) losses of the initial capacitance compared to their PAM-free counterparts. The surface morphology of electrodes fabricated using steel support is studied by scanning electron microscopy and low-temperature nitrogen adsorption.

Mode of electrochemical deposition on the structure and morphology of bimetallic electrodes and its effect on nitrate reduction toward nitrogen selectivity

This work investigates the effect of electrode preparation on nitrate reduction reaction with a focus on increasing nitrogen yield. Results indicated that stainless steel (SS) supported tin-palladium (SS/Sn-Pd) electrodes synthesized via multi-step electrodeposition at low voltage (<10 V) substantially influenced the performance of nitrate transformation and nitrogen selectivity. Different electrodeposition programs, in terms of charging step and batch of metal solution, affected the crystallite size and surface morphology, i.e., roughness, and thus impacted nitrate reduction capability. Of the most significance, electrode prepared with one batch of solution containing both SnCl2 and PdCl2 at molar ratio of 4 to 1 exhibited the best performance in nearly 100% nitrate reduction and 81% nitrogen yield. The proposed low voltage electrochemical deposition process enables a new route to control the reactivity and selectivity of the reduction of oxyanions such as nitrate in water by manipulating electrode surface morphology.

Molecularly Imprinted Polyresorcinol Based Capacitive Sensor for Sulphanilamide Detection

AbstractA molecularly imprinted polymer (MIP) based capacitive sensor for antibiotic detection in drinking water and milk has been developed on a gold coated silicon electrode (Au Electrode). The electrode was fabricated by electropolymerizing monomer resorcinol (RN) on Au surface in presence of sulphanilamide (SN) as a template molecule, to get insulated RN polymer antibiotic composite. The insulation of the polymer film was improved by incubation of electrode in 1‐Dodecanethiol solution. Subsequently MIP sensor was obtained by extraction of SN in ethanol and acetic acid solution. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements were performed for characterization of the developed MIP electrode at different steps of fabrication. The surface morphology of MIP electrode was characterized using atomic force microscopy (AFM), X‐ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x‐ray spectroscopy (EDS). Performance of MIP sensor was evaluated by measuring change in capacitance against varying concentration of SN using EIS. A linear response in the range 1 to 200 μg L−1 SN was recorded for MIP sensor with a detection limit of 0.1 μg L−1. The developed MIP sensor exhibited good selectivity towards SN in water and milk with recoveries in the range 92 % to 105 %. The obtained results suggest the usability of MIP based sensor for SN estimation in water and milk samples.

Electrochemical removal of metribuzin in aqueous solution by a novel PbO2/WO3 composite anode: Characterization, influencing parameters and degradation pathways

Abstract In this work, we fabricated PbO2/WO3 composite electrode through composite electrodeposition method and employed it in electrocatalytic degradation of metribuzin. The effects of WO3 particles on surface morphology, structure and electrochemical characters of PbO2 electrodes were investigated. Different from PbO2 electrodes, the PbO2/WO3 composite electrodes owned higher oxygen evolution overpotential, longer service life and higher hydroxyl radicals generation performance. The effect of key operating parameters, for instance, current density, initial metribuzin concentration, initial pH values, and supporting electrolyte concentration, upon electrochemical removal process of metribuzin were studied. The current density and initial metribuzin concentration exerted prominent effects on electrochemical degradation of metribuzin. Kinetic analysis indicated that the electrochemical decomposition of metribuzin was a pseudo-first-order reaction. The byproducts during metribuzin degradation process were identified, several aromatic products and inorganic ions were generated along with the reaction time. Finally, the electrochemical pathways of metribuzin degradation at the PbO2/WO3 composite electrode were proposed based on the identified reaction byproducts, which were separated into three parallel sub-pathways according to the different degradation reactions by hydroxyl radicals, and quantities of hydroxylation, oxidation, demethylation, deamination, and addition reactions’ products were generated. All the byproducts were finally decomposed into inorganic H2O, CO2, NO3−, and NH4+.