Electrochemical Properties and Ex Situ Study of Sodium Intercalation Cathode P2/P3-NaNi1/3Mn1/3Co1/3O2

In recent work, P2/P3-NaNi1/3Mn1/3Co1/3O2 (NaNMC) was obtained by the sol-gel process followed by calcination of the precursor at 900°C for 12 h. The electrochemical properties of NaNMC were investigated in the voltage range of 2.0–4.0 V. The material exhibited an initial discharge capacity of 107 mAh·g−1 and good capacity retention of 82.2% after 100 cycles. Ex situ XRD performance showed that the P3-phase transformed from the P3- to O1-phase and vice versa, while the P2-phase remained stable during the sodium intercalation. The kinetic of sodium intercalation of NaNMC upon reversible Na+ insertion/deinsertion was evaluated via a Galvanostatic Intermittence Titration Technique (GITT) and Electrochemical impedance spectroscopy (EIS). The diffusion coefficients of Na+ ion deduced from the GITT curve have a broad distribution ranging from 10−10 to 10−11 cm2·s−1 for the charging/discharging process. Besides, the evolution of diffusion coefficient and charge transfer resistance is consistent with the complex phase transition generally observed in sodium layered oxides.

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Improved Electrochemical Performance of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 Cathode Material Synthesized by the Polyvinyl Alcohol Auxiliary Sol-Gel Process for Lithium-Ion Batteries

Advances in Condensed Matter Physics ◽

10.1155/2018/1217639 ◽

2018 ◽

Vol 2018 ◽

pp. 1-7

Author(s):

He Wang ◽

Mingning Chang ◽

Yonglei Zheng ◽

Ningning Li ◽

Siheng Chen ◽

...

Keyword(s):

Polyvinyl Alcohol ◽

Cathode Material ◽

Discharge Capacity ◽

Electrochemical Impedance ◽

Coulombic Efficiency ◽

Sol Gel ◽

Rate Capability ◽

Lithium Ion ◽

Transfer Resistance ◽

Sol Gel Process

A lithium-rich manganese-based cathode material, Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2, was prepared using a polyvinyl alcohol (PVA)-auxiliary sol-gel process using MnO2 as a template. The effect of the PVA content (0.0–15.0 wt%) on the electrochemical properties and morphology of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 was investigated. Analysis of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 X-ray diffraction patterns by RIETAN-FP program confirmed the layered α-NaFeO2 structure. The discharge capacity and coulombic efficiency of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 in the first cycle were improved with increasing PVA content. In particular, the best material reached a first discharge capacity of 206.0 mAhg−1 and best rate capability (74.8 mAhg−1 at 5 C). Meanwhile, the highest capacity retention was 87.7% for 50 cycles. Finally, electrochemical impedance spectroscopy shows that as the PVA content increases, the charge-transfer resistance decreases.

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Electrochemical Characterization of CVD-Grown Graphene for Designing Electrode/Biomolecule Interfaces

Crystals ◽

10.3390/cryst10040241 ◽

2020 ◽

Vol 10 (4) ◽

pp. 241

Author(s):

Keishu Miki ◽

Takeshi Watanabe ◽

Shinji Koh

Keyword(s):

Electrochemical Properties ◽

Electrode Materials ◽

Electrochemical Impedance ◽

Chemical Vapor ◽

Charge Transfer Resistance ◽

Monolayer Graphene ◽

Transfer Resistance ◽

Graphene Electrode ◽

Before And After ◽

Modified Graphene

In research on enzyme-based biofuel cells, covalent or noncovalent molecular modifications of carbon-based electrode materials are generally used as a method for immobilizing enzymes and/or mediators. However, the influence of these molecular modifications on the electrochemical properties of electrode materials has not been clarified. In this study, we present the electrochemical properties of chemical vapor deposition (CVD)-grown monolayer graphene electrodes before and after molecular modification. The electrochemical properties of graphene electrodes were evaluated by cyclic voltammetry and electrochemical impedance measurements. A covalently modified graphene electrode showed an approximately 25-fold higher charge transfer resistance than before modification. In comparison, the electrochemical properties of a noncovalently modified graphene electrode were not degraded by the modification.

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Study of Insulating Properties of Alkanethiol Self-Assembled Monolayers Formed Under Prolonged Incubation Using Electrochemical Impedance Spectroscopy

Journal of Nanotechnology in Engineering and Medicine ◽

10.1115/1.4007698 ◽

2012 ◽

Vol 3 (3) ◽

Cited By ~ 8

Author(s):

Damena D. Agonafer ◽

Edward Chainani ◽

Muhammed E. Oruc ◽

Ki Sung Lee ◽

Mark A. Shannon

Keyword(s):

Electrochemical Impedance Spectroscopy ◽

Impedance Spectroscopy ◽

Electrochemical Impedance ◽

Charge Transfer Resistance ◽

Critical Voltage ◽

Transfer Resistance ◽

Low Frequencies ◽

Prolonged Incubation ◽

Voltage Range ◽

Self Assembled

The electrochemical interfacial properties of a well-ordered self-assembled monolayer (SAM) of 1-undecanethiol (UDT) on evaporated gold surface have been investigated by electrochemical impedance spectroscopy (EIS) in electrolytes without a redox couple. Using a constant-phase element (CPE) series resistance model, prolonged incubation times (up to 120 h) show decreasing monolayer capacitance approaching the theoretical value for 1-undecanethiol. Using the CPE exponent α as a measure of ideality, it was found that the monolayer approaches an ideal dielectric (α = 0.992) under prolonged incubation, which is attributed to the reduction of pinholes and defects in the monolayer during coalescence and annealing of SAM chains. The SAMs behave as insulators until a critical potential, Vc, is exceeded in both cathodic and anodic regimes, where electrolyte ions are believed to penetrate the monolayers. Using a Randles circuit model for these cases, the variation of the capacitance and charge transfer resistance with applied dc potential shows decreased permeability to ionic species with prolonged incubation time. The EIS data show that UDT (methylene chain length n = 10), incubated for 120 h, forms a monolayer whose critical voltage range extends from −0.3 to 0.5 V versus Ag/AgCl, previously attained only for alkanethiol at n = 15. At low frequencies where ion diffusion occurs, almost pure capacitive phase (−89 deg) was attained with lengthy incubation.

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Synthesis and Electrochemical Properties of Polypyrrole Conducting Polymer in Sheath like Nanotube Arrays Structured over TiO2 for Supercapacitor Energy Storage Devices

MRS Proceedings ◽

10.1557/opl.2015.78 ◽

2015 ◽

Vol 1749 ◽

Author(s):

Navjot K. Sidhu ◽

A.C. Rastogi

Keyword(s):

Energy Storage ◽

Electrochemical Properties ◽

Electrochemical Impedance ◽

Charge Transfer Resistance ◽

Nanotube Arrays ◽

Energy Storage Devices ◽

Transfer Resistance ◽

Capacitance Density ◽

Electrically Conducting ◽

Supercapacitor Energy Storage

ABSTRACTThe vertical TiO2 nanotube arrays constituting the core of 3-D nanoscale electrode architecture were synthesized over Ti sheet by anodization. Such formed TiO2 nanotubes are electrically conducting and amorphous as confirmed by XRD studies. Nanotube morphology is affected by water content and in the present study, close-packed 3-4 μm long TiO2 nanotube arrays of 45-50 nm diameter are formed with 2% water as revealed by the transmission and scanning electron microscopy. The redox active polypyrrole sheath is created by ultra-short pulsed current electropolymerization. Electrochemical properties of the 3-D nanoscaled TiO2 nanotube core-polypyrrole sheath electrodes relevant to the energy storage were investigated using cyclic voltammetry (CV) plots, electrochemical impedance spectroscopy (EIS), Charge discharge (CD) tests. High areal capacitance density of 48 mF cm-2 and low charge transfer resistance 12 Ω cm-2 with least ion diffusion limitation are realized at optimized polypyrrole sheath thickness. The Raman spectra studies reveal anion at specific chain locations involve in the redox process.

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Influence of Fe and Ni Doped CuO Nanomaterials for High Performance Supercapacitors

Asian Journal of Chemistry ◽

10.14233/ajchem.2020.22845 ◽

2020 ◽

Vol 32 (11) ◽

pp. 2763-2772

Author(s):

Palanisamy Revathi ◽

Venkatachalam Ma nikandan ◽

Panneerselvam Ezhilmathi ◽

Veerasamy Uma Shankar ◽

Palani Suganya ◽

...

Keyword(s):

High Performance ◽

Electrochemical Impedance ◽

Sol Gel ◽

Charge Transfer Resistance ◽

Cyclic Voltammograms ◽

Transfer Resistance ◽

Galvanostatic Discharge ◽

Low Charge ◽

Supercapacitor Applications ◽

Eis Analysis

This paper focuses on the synthesis of doped and undoped CuO nanoparticles using the sol-gel method, which has been prepared and described. Supercapacitor applications of as-synthesized nanomaterials were analyzed using cyclic voltammetry (CV), galvanostatic discharge (GCD) and electrochemical impedance spectroscopic (EIS) analysis. The cyclic voltammograms illustrated the quasi-rectangular shape which depicted the pseudocapacitance nature of the samples. The calculated specific capacitance of the prepared samples was 180, 253 and 303 (F/g) corresponding to CuO, Fe-CuO and Ni-CuO, respectively at the low current density and the EIS spectra show that the prepared Ni-CuO electrode exhibits low charge transfer resistance.

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Effects of Ni Electroless Plating on Electrochemical Properties of Mg2 Ni Hydrogen Storage Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.488-489.681 ◽

2005 ◽

Vol 488-489 ◽

pp. 681-684

Author(s):

Yougen Tang ◽

Yijun Xu ◽

Zhuguang Lu ◽

Bo Yun Huang

Keyword(s):

Hydrogen Storage ◽

Electrochemical Properties ◽

Electrochemical Impedance ◽

Charge Transfer Resistance ◽

Diffusion Resistance ◽

Cyclic Voltammogram ◽

Hydrogen Storage Alloys ◽

Transfer Resistance ◽

Atom Diffusion ◽

Surface Morphologies

Effects of nickel coating on electrochemical properties of Mg2Ni hydrogen storage alloys were presented in this paper. X-ray diffraction ( XRD) and scanning electron microscope (SEM) were employed to examine the crystal structure and surface morphologies of the as-obtained bare and Ni-coated Mg2Ni alloys and their electrochemical properties were characterized by cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS). Results showed that Ni coating not only decreased charge transfer resistance, but also decreased H atom diffusion resistance for Mg2Ni alloys. It was also found that Ni coating effectively improved the discharge capacity.

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Synthesis and Characterization of Electrophoretically Deposited Nanostructured LiCoPO4 for Rechargeable Lithium Ion Batteries

ISRN Nanotechnology ◽

10.1155/2013/653237 ◽

2013 ◽

Vol 2013 ◽

pp. 1-5

Author(s):

S. Priya Nair ◽

U. Jyothsna ◽

P. Praveen ◽

A. Balakrishnan ◽

K. R. V. Subramanian ◽

...

Keyword(s):

Cathode Material ◽

Electrochemical Properties ◽

Electrophoretic Deposition ◽

Sol Gel ◽

Specific Capacity ◽

Lithium Ion ◽

Deposition Process ◽

Charge Transfer Resistance ◽

Transfer Resistance ◽

Charge Discharge

Nanosized LiCoPO4 (LCP) was prepared using a simple sol-gel method. For the first time, electrophoretic deposition process was employed to fabricate a LiCoPO4 cathode material in order to improve the electrochemical performance. The prepared powder was deposited on titanium plate by electrophoretic deposition and their electrochemical properties were studied. The electrochemical properties were analyzed by using cyclic voltagramm studies, impedance studies, and charge/discharge tests. The thickness of the prepared cathode material was found to be 11-12 µm by using scanning electron microscope. The initial specific capacity and the charge transfer resistance (Rct) of the prepared cathode was 103 mAh/g and 851 Ω, respectively. The charge/discharge profiles showed moderate columbic efficiency of 70%.

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Morphological, chemical, and electrochemical properties of Ti/(TiO2 + IrO2) electrodes

Canadian Journal of Chemistry ◽

10.1139/v97-178 ◽

1997 ◽

Vol 75 (11) ◽

pp. 1483-1493 ◽

Cited By ~ 44

Author(s):

L.A. da Silva ◽

V.A. Alves ◽

M.A.P. da Silva ◽

S. Trasatti ◽

J.F.C. Boodts

Keyword(s):

Electrochemical Impedance Spectroscopy ◽

Impedance Spectroscopy ◽

Electrochemical Impedance ◽

Charge Transfer Resistance ◽

Ex Situ ◽

Electronic Effects ◽

Transfer Resistance ◽

Oxide Composition ◽

Tafel Slopes ◽

Impedance Parameters

Electrodes of general composition IrxTi(1−x)O2 with 0.2 ≤ x ≤ 1.0 were prepared on a Ti support by calcination of the chlorides at 450 °C. Ex situ and in situ characterization included the use of techniques such as scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). EDX showed a surface enrichment with Ti. The voltammetric charge was found to go through a maximum at 60% IrO2. O2 evolution was studied in 1.0 mol dm−3 HClO4 by determining Tafel slopes and impedance parameters. Tafel slopes were found to vary between 40 and 60 mV depending on the overpotential range and the oxide composition. Solution and film resistance, film and double layer capacitance, and charge transfer resistance were determined as a function of potential and oxide composition. A reaction mechanism has been proposed. Separation of geometric and electronic effects has been attempted. Keywords: oxygen evolution, oxide electrode, electrocatalysis, electrochemical impedance spectroscopy, iridium dioxide.

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Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

10.26434/chemrxiv.7991129 ◽

2019 ◽

Author(s):

Charlys Bezerra ◽

Géssica Santos ◽

Marilia Pupo ◽

Maria Gomes ◽

Ronaldo Silva ◽

...

Keyword(s):

Thermal Decomposition ◽

Polyvinyl Alcohol ◽

High Efficiency ◽

Electrochemical Impedance ◽

Pechini Method ◽

Low Cost ◽

Charge Transfer Resistance ◽

Transfer Resistance ◽

Calcination Temperatures ◽

Service Lifetime

Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO2–IrO2 anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO2 and IrO2 have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO2–IrO2 anodes with improved properties that can be further extended to synthesise other MMO compositions.

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Electrochemical Immunosensor for the Quantification of S100B at Clinically Relevant Levels Using a Cysteamine Modified Surface

Sensors ◽

10.3390/s21061929 ◽

2021 ◽

Vol 21 (6) ◽

pp. 1929

Author(s):

Alexander Rodríguez ◽

Francisco Burgos-Flórez ◽

José D. Posada ◽

Eliana Cervera ◽

Valtencir Zucolotto ◽

...

Keyword(s):

Frequency Analysis ◽

Surface Characterization ◽

Electrochemical Impedance ◽

Limit Of Detection ◽

Neuronal Damage ◽

Charge Transfer Resistance ◽

Single Frequency ◽

Response Analysis ◽

Transfer Resistance ◽

Therapeutic Decisions

Neuronal damage secondary to traumatic brain injury (TBI) is a rapidly evolving condition, which requires therapeutic decisions based on the timely identification of clinical deterioration. Changes in S100B biomarker levels are associated with TBI severity and patient outcome. The S100B quantification is often difficult since standard immunoassays are time-consuming, costly, and require extensive expertise. A zero-length cross-linking approach on a cysteamine self-assembled monolayer (SAM) was performed to immobilize anti-S100B monoclonal antibodies onto both planar (AuEs) and interdigitated (AuIDEs) gold electrodes via carbonyl-bond. Surface characterization was performed by atomic force microscopy (AFM) and specular-reflectance FTIR for each functionalization step. Biosensor response was studied using the change in charge-transfer resistance (Rct) from electrochemical impedance spectroscopy (EIS) in potassium ferrocyanide, with [S100B] ranging 10–1000 pg/mL. A single-frequency analysis for capacitances was also performed in AuIDEs. Full factorial designs were applied to assess biosensor sensitivity, specificity, and limit-of-detection (LOD). Higher Rct values were found with increased S100B concentration in both platforms. LODs were 18 pg/mL(AuES) and 6 pg/mL(AuIDEs). AuIDEs provide a simpler manufacturing protocol, with reduced fabrication time and possibly costs, simpler electrochemical response analysis, and could be used for single-frequency analysis for monitoring capacitance changes related to S100B levels.

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