scholarly journals Alternate layer by layered self assembly of conjugated and unconjugated Salen based nanowires as capacitive pseudo supercapacitor

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Mahdi Doroodmand ◽  
Sina Owji
Keyword(s):  
Self Assembly ◽  
Electrochemical Impedance ◽  
Supporting Electrolyte ◽  
Organometallic Compounds ◽  
Electrode System ◽  
Discharge Process ◽  
Organometallic Complex ◽  
Counter Electrodes ◽  
Acetone Water ◽  
Alternate Layer

AbstractA novel electrosynthetic method has been introduced based on alternate layer-by-layered self-assembly of conjugated/unconjugated Salen-based nanowires as a capacitive pseudo-supercapacitor. For this purpose, a three-electrode system consisted of a glassy carbon (GC), Ag/AgCl (Sat’d Cl−) and a Pt rod as working, reference, and counter electrodes, respectively. The electrolyte included the same molar concentration (0.040 mol L−1) of each Salen monomer (as initial precursor), and KCl solution (as supporting electrolyte), besides using KOH solution (0.01 mol L−1, as basic-controlling reagent) inside acetone/water (4:1, V/V) as a solvent. The formation of this self-assembly nanowire was attributed to the control of the electrical conductivity of this polymer during formation of an organometallic complex with K+ as responsible complex forming agent. This novel nanowire then played role as a capacitive pseudo-supercapacitor. Based on the chrono—potentiometry, reproducible charge/discharge process for at least 5000 cycles was observed at a potential between − 2.00 and + 1.75 V (vs. Ag/AgCl). The capacity behavior of the polymer was also evidenced using electrochemical impedance spectroscopy. This synthesized polymeric nanowire was adopted as the acceptable pseudo-supercapacitor with real capacity equals to 3110 ± 6 (n = 3) C g−1. This study was considered as the first report at which the self—assembly of organometallic compounds as an efficient pseudo—supercapacitor was introduced.

scholarly journals Label-free Electrochemical Impedance Spectroscopy Aptasensor for Ultrasensitive Detection of Lung Cancer Biomarker Carcinoembryonic Antigen

2021 ◽  
Vol 9 ◽  
Author(s):  
Yawei Wang ◽  
Lei Chen ◽  
Tiantian Xuan ◽  
Jian Wang ◽  
Xiuwen Wang
Keyword(s):  
Carcinoembryonic Antigen ◽  
Self Assembly ◽  
Electrochemical Impedance ◽  
Reference Electrode ◽  
Electrode System ◽  
Impedance Change ◽  
Label Free ◽  
Working Electrode ◽  
Label Free Detection ◽  
Assembly Technique

In this work, an integrated electrode system consisting of a graphene working electrode, a carbon counter electrode and an Ag/AgCl reference electrode was fabricated on an FR-4 glass fiber plate by a polyethylene self-adhesive mask stencil method combined with a manual screen printing technique. The integrated graphene electrode was used as the base electrode, and AuNPs were deposited on the working electrode surface by cyclic voltammetry. Then, the carcinoembryonic antigen aptamer was immobilized using the sulfhydryl self-assembly technique. The sensor uses [Fe(CN)6]3−/4− as a redox probe for label free detection of carcinoembryonic antigen based on the impedance change caused by the difference in electron transfer rate before and after the binding of carcinoembryonic antigen aptamer and the target carcinoembryonic antigen. The results showed a good linear relationship when the CEA concentration is in the range of 0.2–15.0 ng/ml. The detection limit was calculated to be 0.085 ng/ml (S/N = 3).

An Experimental Research on Electrochemical Impedance Spectra of New High-Specific Energy EDLC

2011 ◽  
Vol 675-677 ◽  
pp. 65-68 ◽  
Author(s):  
Zi Lei Liang ◽  
Chong Kuan Cheng ◽  
Ji Bo Liu ◽  
Guo Min Mi
Keyword(s):  
Specific Energy ◽  
Electrochemical Impedance ◽  
Discharge Process ◽  
Electrochemical Impedance Spectra ◽  
Charge Voltage ◽  
Electrochemical Double Layer Capacitors ◽  
Complex Capacitance ◽  
Electrochemical Double Layer ◽  
High Specific Energy ◽  
Double Layer Capacitors

The real times Electrochemical Impedance Spectroscopy (EIS) analysis which corresponds to the charge and discharge process was reported in order to evaluate the relationships between impedance and potential for new high specific energy electrochemical double-layer capacitors (EDLC). Also the Niquist plots were presented and the impedance of the EDLC was discussed in terms of complex capacitance. It was found that the high frequency impedance changed with its potential in charging or discharging process, the medium frequency impedance Rct belonged to the resistance of ions diffusion into micro pore or the inner of electrode material decreased with increasing charge voltage and had a certain capacitance of about 1F.

From hollow lignin microsphere preparation to simultaneous preparation of urea encapsulation for controlled release using industrial kraft lignin via slow and exhaustive acetone-water evaporation

Holzforschung ◽  
2019 ◽  
Vol 74 (1) ◽  
pp. 77-87 ◽  
Author(s):  
Miao Wang ◽  
Yadong Zhao ◽  
Jiebing Li
Keyword(s):  
Controlled Release ◽  
Self Assembly ◽  
Average Diameter ◽  
Kraft Lignin ◽  
Water Evaporation ◽  
Shell Wall ◽  
Straightforward Method ◽  
Acetone Water ◽  
Direct Preparation ◽  
Microsphere Preparation

AbstractLignin nano/microparticles have recently attracted growing interest for various value-additive applications of lignin, especially encapsulation. In this study, in order to establish a highly efficient and highly productive preparation process to effectively utilize technical lignin, a brand-new, slow and exhaustive solution evaporation process following a simple, self-assembly principle was developed using industrial softwood kraft lignin (SKL) from a starting acetone-water (80/20, v/v) solution to recover 100% of the lignin as homogeneous and well-shaped microspheres. The prepared microspheres had a typical average diameter of 0.81 ± 0.15 μm and were hollow with very thin shells (of nanoscale thickness). Based on this developed technique, encapsulation of urea by these lignin microspheres was directly achieved using the same process as hollow lignin microspheres with urea attached to the outside and entrapped inside of the wall. Two distinct urea release rates were observed for the urea-encapsulated microspheres: a fast release of the urea outside the shell wall and a slow (controlled) release of the urea inside the shell wall. The encapsulation efficiency was as high as 46% of the trapped urea as encapsulated inside the lignin microspheres. The slow and exhaustive solution evaporation procedure reported here is a simple and straightforward method for the valorization of industrial kraft lignin as hollow microspheres with controllable, homogeneous and desired morphologies, and especially for the direct preparation of lignin-based encapsulating fertilizers for controlled release.

scholarly journals Lithium-Rich Cobalt-Free Manganese-Based Layered Cathode Materials for Li-Ion Batteries: Suppressing the Voltage Fading

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3487
Author(s):  
Ashraf Abdel-Ghany ◽  
Ahmed M. Hashem ◽  
Alain Mauger ◽  
Christian M. Julien
Keyword(s):  
Layered Structure ◽  
Performance Enhancement ◽  
Electrochemical Impedance ◽  
Discharge Process ◽  
High Porosity ◽  
Li Ion Batteries ◽  
Hydrothermal Route ◽  
Li Ion ◽  
Fading Rate ◽  
Charge Discharge

Lithium-rich layered oxides are recognized as promising materials for Li-ion batteries, owing to higher capacity than the currently available commercialized cathode, for their lower cost. However, their voltage decay and cycling instability during the charge/discharge process are problems that need to be solved before their practical application can be envisioned. These problems are mainly associated with a phase transition of the surface layer from the layered structure to the spinel structure. In this paper, we report the AlF3-coating of the Li-rich Co-free layered Li1.2Ni0.2Mn0.6O2 (LLNMO) oxide as an effective strategy to solve these problems. The samples were synthesized via the hydrothermal route that insures a very good crystallization in the layered structure, probed by XRD, energy-dispersive X-ray (EDX) spectroscopy, and Raman spectroscopy. The hydrothermally synthesized samples before and after AlF3 coating are well crystallized in the layered structure with particle sizes of about 180 nm (crystallites of ~65 nm), with high porosity (pore size 5 nm) determined by Brunauer–Emmett–Teller (BET) specific surface area method. Subsequent improvements in discharge capacity are obtained with a ~5-nm thick coating layer. AlF3-coated Li1.2Ni0.2Mn0.6O2 delivers a capacity of 248 mAh g−1 stable over the 100 cycles, and it exhibits a voltage fading rate of 1.40 mV per cycle. According to the analysis from galvanostatic charge-discharge and electrochemical impedance spectroscopy, the electrochemical performance enhancement is discussed and compared with literature data. Post-mortem analysis confirms that the AlF3 coating is a very efficient surface modification to improve the stability of the layered phase of the Li-rich material, at the origin of the significant improvement of the electrochemical properties.

scholarly journals Egg Albumin-Assisted Hydrothermal Synthesis of Co3O4 Quasi-Cubes as Superior Electrode Material for Supercapacitors with Excellent Performances

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Jiale Sun ◽  
Ya Wang ◽  
Yanfei Zhang ◽  
Chunju Xu ◽  
Huiyu Chen
Keyword(s):  
Electrode Material ◽  
Aqueous Electrolyte ◽  
Hydrothermal Reaction ◽  
Electrode System ◽  
Electrochemical Performances ◽  
Discharge Process ◽  
Rate Performance ◽  
Egg Albumin ◽  
Size And Morphology ◽  
Total Specific Surface Area

Abstract Novel Co3O4 quasi-cubes with layered structure were obtained via two-step synthetic procedures. The precursors were initially prepared via hydrothermal reaction in the presence of egg albumin, and then the precursors were directly annealed at 300 °C in air to be converted into pure Co3O4 powders. It was found that the size and morphology of final Co3O4 products were greatly influenced by the amount of egg albumin and hydrothermal durations, respectively. Such layered Co3O4 cubes possessed a mesoporous nature with a mean pore size of 5.58 nm and total specific surface area of 80.3 m2/g. A three-electrode system and 2 M of KOH aqueous electrolyte were employed to evaluate the electrochemical properties of these Co3O4 cubes. The results indicated that a specific capacitance of 754 F g−1 at 1 A g−1 was achieved. In addition, the Co3O4 cubes-modified electrode exhibited an excellent rate performance of 77% at 10 A g−1 and superior cycling durability with 86.7% capacitance retention during 4000 repeated charge-discharge process at 5 A g−1. Such high electrochemical performances suggest that these mesoporous Co3O4 quasi-cubes can serve as an important electrode material for the next-generation advanced supercapacitors in the future.

A heterometallic Cd/Ag/Se complex incorporating 3-ferrocenyl-5-(2-pyridyl)pyrazolato (fcpp) ligands: synthesis and structure of [Cd2{Ag(SePh)}2(μ3-OH2)2(μ2,η3-fcpp)4]·2C3H6O

2019 ◽  
Vol 74 (6) ◽  
pp. 527-531
Author(s):  
Zhe Qian ◽  
Ai-Quan Jia ◽  
Feng Hu ◽  
Cai-Xia Zhang ◽  
Qian-Feng Zhang
Keyword(s):  
Self Assembly ◽  
Selenium Atom ◽  
Water Molecules ◽  
Heterometallic Complex ◽  
Coordination Environment ◽  
Water Solvent ◽  
Acetone Water ◽  
Distorted Octahedral ◽  
Distorted Tetrahedral Coordination ◽  
Distorted Octahedral Coordination Environment

AbstractA self-assembly reaction of Cd(NO3)2 · 4H2O, 3-ferrocenyl-5-(2-pyridyl)-pyrazole (Hfcpp), [Ag(SePh)]n, and Et3N in a mixed acetone-water solvent resulted in the formation of a heterometallic complex [Cd2{Ag(SePh)}2 (μ3-OH2)2(μ2,η3-fcpp)4] · 2C3H6O (1) with a phenylselenolate ligand. The two cadmium and two silver centers are linked by four [μ2,η3-fcpp]− ligands and two μ3-OH2 water molecules. Each Cd atom is in a slightly distorted octahedral coordination environment, while each Ag atom shows a distorted tetrahedral coordination geometry, which is composed of two pyrazolyl nitrogen atoms, one selenium atom, and one oxygen atom.

Effect of Anode Surface Roughness on Power Generation in Microbial Fuel Cells

2012 ◽  
Author(s):  
Zhou Ye ◽  
Junbo Hou ◽  
Michael W. Ellis ◽  
Bahareh Behkam
Keyword(s):  
Surface Roughness ◽  
Fuel Cells ◽  
Glassy Carbon ◽  
Microbial Fuel Cells ◽  
Electrochemical Impedance ◽  
Charge Transfer Resistance ◽  
Electrode System ◽  
Anode Surface ◽  
Transfer Resistance ◽  
Rough Electrode

A three-electrode system was used to study the effect of anode surface roughness on the performance of microbial fuel cells (MFCs). Two glassy carbon plates were polished to uniform roughness of the orders of magnitude of 10s of nm and 100s of nm. Atomic force microscopy (AFM) was used to quantify the roughness as well as the 3D topography of the surfaces. Multiple electrochemical methods including potentiostatic tests, potentiodynamic tests, and electrochemical impedance spectroscopy (EIS) were utilized to monitor the performance of the glassy carbon electrodes. After 275 hours of experimentation, the current density generated by the rough electrode was much higher than that generated by the smooth one. Furthermore, the charge-transfer resistance of the rough electrode was lower than that of the smooth one. The better electrochemical performance of the rough surface may be due to denser biofilm grown on the surface, which was observed by scanning electron microscopy (SEM).

scholarly journals Electrochemistry Study of Permselectivity and Interfacial Electron Transfers of a Branch-Tailed Fluorosurfactant Self-Assembled Monolayer on Gold

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2998 ◽  
Author(s):  
Shanshan Li ◽  
Qingying Luo ◽  
Zhiqing Zhang ◽  
Guanghui Shen ◽  
Hejun Wu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Electrochemical Impedance ◽  
Click Reaction ◽  
Hydration Shell ◽  
Self Assembled Monolayer ◽  
Tunneling Mechanism ◽  
Assembly Technique ◽  
Hydration Resistance ◽  
Self Assembled ◽  
Electron Transfers

We investigated the permselectivity and interfacial electron transfers of an amphiphilic branch-tailed fluorosurfactant self-assembled monolayer (FS-SAM) on a gold electrode by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The FS-SAM was prepared by a self-assembly technique and a “click” reaction. The barrier property and interfacial electron transfers of the FS-SAM were also evaluated using various probes with different features. The FS-SAM allowed a higher degree of permeation by small hydrophilic (Cl− and F−) electrolyte ions than large hydrophobic (ClO4− and PF6−) ones. Meanwhile, the redox reaction of the Fe(CN)63− couple was nearly completely blocked by the FS-SAM, whereas the electron transfer of Ru(NH3)63+ was easier than that of Fe(CN)63−, which may be due to the underlying tunneling mechanism. For hydrophobic dopamine, the hydrophobic bonding between the FS-SAM exterior fluoroalkyl moieties and the hydrophobic probes, as well as the hydration resistance from the interior hydration shell around the oligo (ethylene glycol) moieties, hindered the transport of hydrophobic probes into the FS-SAM. These results may have profound implications for understanding the permselectivity and electron transfers of amphiphilic surfaces consisting of molecules containing aromatic groups and branch-tailed fluorosurfactants in their structures.

A Study of Hot Corrosion of Fe-Cr Alloys Induced by a Thin Film of Fused (Na,K)2SO4 by Electrochemical Impedance Spectroscopy

2013 ◽  
Vol 32 (5) ◽  
pp. 493-501
Author(s):  
S.N. Liu ◽  
W. Su ◽  
W.Y. Lu ◽  
Z.F. Wei ◽  
C.L. Zeng
Keyword(s):  
Thin Film ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Hot Corrosion ◽  
Electrochemical Impedance ◽  
Diffusion Flux ◽  
Electrode System ◽  
Corrosion Mechanism ◽  
Low Frequencies ◽  
Nyquist Plots

AbstractTo understand the hot corrosion mechanism of materials it is of significance to establish electrochemical measurements under a thin film of fused salts. In this paper, the hot corrosion behavior of Fe-Cr alloys containing 5, 10 and 25wt% Cr, respectively, in the presence of a fused film of 0.9Na2SO4-0.1K2SO4 (mole fraction) at 1173 K in air has been investigated by electrochemical impedance spectroscopy using a two-electrode system. The Nyquist plots for the corrosion of both Fe-5Cr and Fe-10Cr are composed of a very small semicircle at high frequencies and a line at low frequencies indicating that the corrosion is controlled by the diffusion of oxidants in the fused salt film. The alloys were severely corroded, forming a thick porous corrosion layer containing large amounts of non-protective precipitated Fe oxide particles. Conversely, the Nyquist plots for the corrosion of Fe-25Cr are composed of double capacitive loops, with significantly larger impedance values, which are associated with the formation of a protective Cr2O3 scale. Based on the experimental diffusion impedance results and the theoretic solubility and diffusion coefficient of oxygen in molten salts, respectively, a theoretical value of the diffusion flux of molecular O2 has been calculated.

Sign in / Sign up

Export Citation Format

Share Document