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

Crystals ◽  
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.

Effect of Plating Solutions on Supercapacitor Characteristics of MnO2 Films

2010 ◽  
Vol 113-116 ◽  
pp. 1810-1813
Author(s):  
Fang Xiao ◽  
You Long Xu
Keyword(s):  
Electrode Materials ◽  
Electrochemical Impedance ◽  
Equivalent Circuit Model ◽  
Active Surface ◽  
Charge Transfer Resistance ◽  
Electrochemical Impedance Spectrum ◽  
Active Surface Area ◽  
Cyclic Voltammograms ◽  
Supercapacitor Electrode ◽  
Transfer Resistance

MnO2 films were electrodeposited on the Ti substrates by galvanostatic method in various plating solutions, which was MnCl2, Mn(NO3)2, MnSO4 and Mn(CH3COO)2 solutions, respectively. On X-ray diffraction test, Crystal structures of all MnO2 films were associated to α-MnO2 of tetragonal crystal system. Scanning electron microscopy results show that morphologies of MnO2 films were clearly different. Among them, MnO2 film prepared in Mn(CH3COO)2 solution presented a lot of cracks and holes. According to electrochemical impedance spectrum analysis, this MnO2 film presents the lowest charge-transfer resistance. Additionally, electrochemical active surface areas of MnO2 films were calculated on the basis of equivalent circuit model for impedance data. The result was found that MnO2 film prepared in Mn(CH3COO)2 solution showed the biggest electrochemical active surface area, which was about 382 cm2. Cyclic voltammograms were carried out for all the samples. MnO2 film formed in Mn(CH3COO)2 solution showed the highest special capacitance of 230 F g-1. The results suggest that Mn(CH3COO)2 solution is suitable for electrodepositing MnO2 film using supercapacitor electrode materials.

Electrochemical behavior of hydrogen precipitated Zircaloy-4

2015 ◽  
Vol 29 (32) ◽  
pp. 1550200 ◽  
Author(s):  
Mohsin Rafique ◽  
Naveed Afzal ◽  
K. M. Deen ◽  
Yong-Soo Kim
Keyword(s):  
Hydrogen Concentration ◽  
Electrochemical Behavior ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
X Ray Diffraction ◽  
Transfer Resistance ◽  
Corrosion Kinetics ◽  
Before And After ◽  
Potentiodynamic Anodic Polarization ◽  
Kinetics Of

This work investigates the hydrogen precipitation effects on the electrochemical behavior of Zircaloy-4 in acidic saline media. The specimens of Zircaloy-4 were hydrogen charged at 200, 400 and 600 ppm concentrations for 30 min at 400[Formula: see text]C. X-ray diffraction (XRD) studies confirmed the formation of delta hydrides in the material. Scanning electron microscopy (SEM) results also indicated the presence of elongated hydrides whose density and thickness increased with the increase of hydrogen concentration in the alloy. The corrosion kinetics of the specimens were explored before and after hydrogen precipitation using potentiodynamic anodic polarization (PAP) and electrochemical impedance spectroscopy (EIS) techniques. The results showed that hydrogen precipitation shifts the corrosion potential towards more positive and thus improves the corrosion resistance of the alloy. The charge transfer resistance [Formula: see text] of the alloy was found to increase with increasing hydrogen concentration. This indicates an increased polarization tendency of the Zircaloy-4 surface with a limited dissolution tendency in the presence of delta hydrides.

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

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.

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

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.

scholarly journals Fabrication, characterization, and photocatalytic performance of ternary cadmium chalcogenides CdIn2S4 and Cd7.23Zn2.77S10-ZnS thin films

2020 ◽  
Vol 44 (1) ◽  
pp. 39-50
Author(s):  
Umar Daraz ◽  
Tariq Mahmood Ansari ◽  
Shafique Ahmad Arain ◽  
Muhammad Adil Mansoor ◽  
Muhammad Mazhar ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Impedance ◽  
Chemical Vapor ◽  
Linear Sweep Voltammetry ◽  
Photocurrent Density ◽  
Charge Transfer Resistance ◽  
Single Step ◽  
Transfer Resistance ◽  
X Ray ◽  
Dual Source

Abstract Dithiocarbamate complexes [Cd(S2CNCy2)2(py)] (1), [In(S2CNCy2)3]·2py (2) and [Zn(S2CNCy2)2(py)] (3) were synthesized and toluene solution of (1) and (2) was used as dual source precursor for the synthesis of CdIn2S4 (CIS), while that of (1) and (3) was applied for the deposition of Cd7.23Zn2.77S10–ZnS composite (CZS-ZS) thin film photoan-odes by employing single step aerosol assisted chemical vapor deposition (AACVD) technique. Deposition experiments were performed at 500°C under an inert ambient of argon gas. The structural properties of deposited films were evaluated by using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The field emission scanning electron microscopy (FESEM) exposed surface morphologies while UV-Visible spectrophotometry revealed that CIS is low band gap photoanode in comparison to CZS-ZS. The comparison of photoelectrochemical (PEC) responses measured in identical conditions in terms of linear sweep voltammetry (LSV) depicts photocurrent density of 4.4 mA /cm2 and 2.9 mA/cm2 at applied potential of 0.7 V under solar light intensity of 100 mW/cm2 for CIS and CZS-ZS respectively. Further, electrochemical impedance spectroscopy (EIS) confirms that PEC properties of CIS are superior to CZS-ZS photoanode as the former offer less charge transfer resistance (Rct) 0.03 MΩ in comparison to CZS-ZS having Rct value of 0.06 MΩ.

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

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Minh Le Nguyen ◽  
Hoang Van Nguyen ◽  
Man Van Tran ◽  
Phung My Loan Le
Keyword(s):  
Electrochemical Properties ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Charge Transfer Resistance ◽  
Ex Situ ◽  
Layered Oxides ◽  
Transfer Resistance ◽  
Complex Phase ◽  
Voltage Range ◽  
Sol Gel Process

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.

scholarly journals Enhanced Activity of Hierarchical Nanostructural Birnessite-MnO2-Based Materials Deposited onto Nickel Foam for Efficient Supercapacitor Electrodes

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1933
Author(s):  
Shang-Chao Hung ◽  
Yi-Rong Chou ◽  
Cheng-Di Dong ◽  
Kuang-Chung Tsai ◽  
Wein-Duo Yang
Keyword(s):  
Electrochemical Performance ◽  
Electrode Materials ◽  
Electrochemical Impedance ◽  
Nickel Foam ◽  
Rate Capability ◽  
Multiwall Carbon Nanotubes ◽  
Charge Transfer Resistance ◽  
Transfer Resistance ◽  
Pore Size Distributions ◽  
Hierarchical Porous

Hierarchical porous birnessite-MnO2-based nanostructure composite materials were prepared on a nickel foam substrate by a successive ionic layer adsorption and reaction method (SILAR). Following composition with reduced graphene oxide (rGO) and multiwall carbon nanotubes (MWCNTs), the as-obtained MnO2, MnO2/rGO and MnO2/rGO-MWCNT materials exhibited pore size distributions of 2–8 nm, 5–15 nm and 2–75 nm, respectively. For the MnO2/rGO-MWCNT material in particular, the addition of MWCNT and rGO enhanced the superb distribution of micropores, mesopores and macropores and greatly improved the electrochemical performance. The as-obtained MnO2/rGO-MWCNT/NF electrode showed a specific capacitance that reached as high as 416 F·g−1 at 1 A·g−1 in 1 M Na2SO4 aqueous electrolyte and also an excellent rate capability and high cycling stability, with a capacitance retention of 85.6% after 10,000 cycles. Electrochemical impedance spectroscopy (EIS) analyses showed a low resistance charge transfer resistance for the as-prepared MnO2/rGO-MWCNT/NF nanostructures. Therefore, MnO2/rGO-MWCNT/NF composites were successfully synthesized and displayed enhanced electrochemical performance as potential electrode materials for supercapacitors.

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

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

<p>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/RuO<sub>2</sub>–IrO<sub>2</sub> 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 RuO<sub>2</sub> and IrO<sub>2</sub> 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/RuO<sub>2</sub>–IrO<sub>2</sub> anodes with improved properties that can be further extended to synthesise other MMO compositions.</p>

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

Sensors ◽  
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.

scholarly journals Influence of HAP on the Morpho-Structural Properties and Corrosion Resistance of ZrO2-Based Composites for Biomedical Applications

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 202
Author(s):  
Réka Barabás ◽  
Carmen Ioana Fort ◽  
Graziella Liana Turdean ◽  
Liliana Bizo
Keyword(s):  
Electrochemical Impedance ◽  
Artificial Saliva ◽  
Synergetic Effect ◽  
Composite Layer ◽  
Charge Transfer Resistance ◽  
Processing Route ◽  
Dental Alloys ◽  
Metallic Electrode ◽  
Transfer Resistance ◽  
X Ray

In the present work, ZrO2-based composites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP) to the inert zirconia. The composites were synthesized by the conventional ceramic processing route and morpho-structurally analyzed by X-ray powder diffraction (XRPD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two metallic dental alloys (i.e., Ni–Cr and Co–Cr) coated with a chitosan (Chit) membrane containing the prepared composites were exposed to aerated artificial saliva solutions of different pHs (i.e., 4.3, 5, 6) and the corrosion resistances were investigated by electrochemical impedance spectroscopy technique. The obtained results using the two investigated metallic dental alloys shown quasi-similar anticorrosive properties, having quasi-similar charge transfer resistance, when coated with different ZrO2-based composites. This behavior could be explained by the synergetic effect between the diffusion process through the Chit-composite layer and the roughness of the metallic electrode surface.

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