scholarly journals Degradation Phenomena of Bismuth-Modified Felt Electrodes in VRFB Studied by Electrochemical Impedance Spectroscopy

Batteries ◽  
2019 ◽  
Vol 5 (1) ◽  
pp. 16 ◽  
Author(s):  
Jonathan Schneider ◽  
Eduard Bulczak ◽  
Gumaa El-Nagar ◽  
Marcus Gebhard ◽  
Paul Kubella ◽  
...  
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Modified Electrodes ◽  
Impregnation Method ◽  
Carbon Felt ◽  
Half Cell ◽  
Negative Side ◽  
Prolonged Contact ◽  
Before And After

The performance of all-V redox flow batteries (VRFB) will decrease when they are exposed to dynamic electrochemical cycling, but also when they are in prolonged contact with the acidic electrolyte. These phenomena are especially severe at the negative side, where the parasitic hydrogen evolution reaction (HER) will be increasingly favored over the reduction of V(III) with ongoing degradation of the carbon felt electrode. Bismuth, either added to the electrolyte or deposited onto the felt, has been reported to suppress the HER and therefore to enhance the kinetics of the V(II)/V(III) redox reaction. This study is the first to investigate degradation effects on bismuth-modified electrodes in the negative half-cell of a VRFB. By means of a simple impregnation method, a commercially available carbon felt was decorated with Bi 2 O 3 , which is supposedly present as Bi(0) under the working conditions at the negative side. Modified and unmodified felts were characterized electrochemically using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in a three-electrode setup. Surface morphology of the electrodes and composition of the negative half-cell electrolyte were probed using scanning electron microscopy (SEM) and X-ray fluorescence spectroscopy (TXRF), respectively. This was done before and after the electrodes were subjected to 50 charge-discharge cycles in a battery test bench. Our results suggest that not only the bismuth catalyst is dissolved from the electrode during battery operation, but also that the presence of bismuth in the system has a strong accelerating effect on electrode degradation.

The influence of gold nanoparticles on the electroactivity of nickel tetrasulfonated phthalocyanine

2014 ◽  
Vol 18 (08n09) ◽  
pp. 642-651 ◽  
Author(s):  
Audacity Maringa ◽  
Tebello Nyokong
Keyword(s):  
Gold Nanoparticles ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Glassy Carbon ◽  
Electrochemical Impedance ◽  
Modified Electrodes ◽  
Enhancement Effect ◽  
Carbon Electrode ◽  
Cathodic Peak ◽  
Peak Separation

We report on the electrodeposition of gold nanoparticles ( AuNPs ) on a glassy carbon electrode (GCE) followed by deposition of nickel tetrasulfonated phthalocyanine ( NiTSPc ) film by electropolymerization (poly- NiTSPc -GCE) to form Poly- NiTSPc / AuNPs -GCE. The presence of the gold nanoparticles caused a lowering of the anodic and cathodic peak separation (ΔE p ) of ferricyanide from 126 mV on poly- NiTSPc to 110 mV on poly- NiTSPc / AuNPs . The electrooxidation of nitrite improved on modified electrodes compared to GCE, with the latter giving E p = 0.78 V and the modified electrodes gave E p = 0.62 V or 0.61 V. Poly- NiTSPc / AuNPs -GCE had higher currents compared to poly- NiTSPc -GCE. This indicates the enhancement effect caused by the AuNPs . Electrochemical impedance spectroscopy and chronoamperometric studies also showed that poly- NiTSPc / AuNPs -GCE was a better electrocatalyst than poly- NiTSPc -GCE or AuNPs -GCE.

scholarly journals In situ drug release measuring in α-TCP cement by electrochemical impedance spectroscopy

2021 ◽  
Vol 32 (4) ◽  
Author(s):  
Júnio Augusto Rodrigues Pasqual ◽  
Lucas C. Freisleben ◽  
Júlio Cesar Colpo ◽  
Jose Ramón Jurado Egea ◽  
Luis Alberto Loureiro dos Santos ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Drug Application ◽  
Chemical Mechanism ◽  
Before And After ◽  
Good Technique ◽  
The Right ◽  
Non Destructive

AbstractThe use of drug delivery systems is a good technique to leave the right quantity of medicine in the patient’s body in a suitable dose, because the drug application is delivered directly to the affected region. The current techniques such as HPLC and UV–Vis for the drug delivery calculation has some disadvantages, as the accuracy and the loss of the sample after characterization. With the aim of reducing the amount of material used during the characterization and have a non-destructive test with instantaneous results, the present paper shows the possibility of using electrochemical impedance spectroscopy (EIS) to have a drug delivery measurement during the release phenomena for a calcium phosphate cement (CFC) delivery system with gentamicin sulfate (GS) and lidocaine hydrochloride (LH), at a ratio of 1% and 2%, respectively. The equivalent circuit and the chemical mechanism involved during the measurements have been proposed as a tool to determine the drug delivery profile. The method has been compared with the UV–Vis technique. XRD was realized to verify conditions, before and after release. It was possible to verify the potential for using EIS as an instant technique to quantify drug delivery.

Study on the Surface Fractures of Nanoparticle Silicon Anode for Lithium-Ion Batteries

2015 ◽  
Vol 1092-1093 ◽  
pp. 216-219
Author(s):  
Pan Li Ren ◽  
Xu Ma ◽  
Ling Long Kong
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Lithium Ion Batteries ◽  
Electrochemical Impedance ◽  
Specific Capacity ◽  
Lithium Ion ◽  
Silicon Anode ◽  
Cyclic Voltammograms ◽  
Capacity Curves ◽  
Before And After

In this paper the fractures appeared in the surface of nanoparticle silicon anode for lithium-ion batteries was explored. The changes of nanoparticle silicon anode before and after cycling were charactered using SEM, XRD,Cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS). The result indicates that the electrode cracking occured in the cycling process , the CV, EIS and discharge specific capacity curves proved the fractures could lead to the degradation of the electrochemical performance.

Steel Corrosion and Control in Concrete Made with Seawater

2020 ◽  
Vol 10 (1) ◽  
pp. 58-67
Author(s):  
Arpit Goyal ◽  
S.R. Karade
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Corrosion Resistance ◽  
Electrochemical Impedance Spectroscopy ◽  
Fly Ash ◽  
Impedance Spectroscopy ◽  
Potable Water ◽  
Electrochemical Impedance ◽  
Half Cell ◽  
Cell Potential

Background: Water scarcity is amongst the biggest problems the world is facing in the 21st century. To reduce the consumption of Potable Water (PW) in construction industries and to make concrete construction more sustainable, its replacement with Seawater (SW) has been explored. Technical literature on this subject is not widely available. Such investigations are necessary for determining suitable remedial measures for the effective utilization of seawater for making sustainable concrete. Objective: In the present study, use of Seawater (SW) has been explored as both mixing and curing water in concrete. To counter the adverse effects of seawater on strength and corrosion resistance, use of Fly Ash (FA) and Red Mud (RM) as cement replacements in the seawater concrete had been investigated. Methods: The possibility of the use of seawater in making concrete has been explored by literature and experimental investigations. The obtained results are discussed in light of the information available in the literature. Various tests were performed such as compressive strength, Half-cell potential, electrochemical impedance spectroscopy and microstructural analysis using SEM and XRD. Result: Results showed higher compressive strength and improved corrosion resistance for Seawater Concrete (SWC) with FA & RM as compared to Potable Water Concrete (PWC) specimens. SWC specimens without supplementary cementitious materials show lower electrical resistivity and potential more negative than -450 mV indicating severe corrosion. 30% FA and 5% RM is identified as the optimum combination for the most favorable response in terms of mechanical strength and electrical resistivity of seawater concrete. After 90 days, the compressive strength of 35.77 MPa was achieved. Conclusion: Combination of both FA and RM in SWC reduces chloride migration and increases chloride binding by the formation of Friedel’s salt. Half-cell potential (HCP) and Electrochemical Impedance Spectroscopy (EIS) results confirmed a reduction in corrosion rate in SWC specimens with fly ash and red mud.

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