Polyaniline: Influence of Polymerization Current Density

1994 ◽  
Vol 369 ◽  
Author(s):  
Steen Skaarup ◽  
L.M.W.K. Gunaratne ◽  
Keld West ◽  
Birgit Zachau-Christiansen
Keyword(s):  
Cyclic Voltammetry ◽  
Current Density ◽  
High Current Density ◽  
Electrochemical Polymerization ◽  
Regular Structure ◽  
Spectral Lines ◽  
Complex Nature ◽  
Cyclic Voltammograms ◽  
Layer By Layer ◽  
Current Densities

AbstractPolyaniline has been synthesized in propylene carbonate by galvanostatic electrochemical polymerization at current densities between 16 and 1000 μA/cm2. Earlier results for polypyrrole have shown that low and high current density films have different properties: The films synthesized at low current density have a higher conjugation length and a more regular structure. The corresponding effect in PANI has been investigated by cyclic voltammetry and UV/visible spectroscopy. Simultaneous measurement of cyclic voltammograms and the absorbtion of selected spectral lines is used because of the complex nature of the PANI system which involves several redox systems as well as forms differing in the degree of protonation and morphology.The main result is that the method of galvanostatic synthesis at low current densities (-16 μA/cm2) produces polyaniline polymers of different, more conjugated and more regular structure than those prepared at higher current densities. The standard method of in situ layer-by-layer polymerization of conducting polymers during cyclic voltammetry often results in uncontrolled and unmeasured current densities of 0.5-2 mA/cm2 which produces a film that probably has a less regular structure containing more deviations from ideality.

scholarly journals Electrochemical synthesis of poly(2-methyl aniline): electrochemical and spectroscopic characterization

2001 ◽  
Vol 66 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Aleksandra Buzarovska ◽  
Irena Arsova ◽  
Ljubomir Arsov
Keyword(s):  
Raman Spectroscopy ◽  
Cyclic Voltammetry ◽  
Redox Reactions ◽  
Electrochemical Polymerization ◽  
Spectroscopic Characterization ◽  
Potential Range ◽  
Cyclic Voltammograms ◽  
Impedance Measurements ◽  
Order Of Magnitude ◽  
Poly Aniline

Poly(2-methyl aniline) or poly(ortho-toluidine), as ring substituted derivative of aniline, has been synthesized electrochemically in various concentrations of H2SO4 and HCl, and then characterized by cyclic voltammetry, as well as by impedance and Raman spectroscopy. The cyclic voltammograms of poly(o-toluidine) and poly(aniline) show that the electrochemical polymerization of these two polymers proceeds by almost identical mechanisms. The Raman spectroscopical measurements suggest that the redox reactions of poly(aniline) and poly(o-toluidine) are similar in the potential range between -0.2 and 0.7V vs. SCE. The impedance measurements showed that the conductivity of poly(o-toluidine) is an order of magnitude lower than that of the corresponding poly(aniline) form.

scholarly journals Unexpected Genomic Features of High Current Density-Producing Geobacter sulfurreducens strain YM18

2021 ◽  
Author(s):  
Takashi Fujikawa ◽  
Yoshitoshi Ogura ◽  
Koki Ishigami ◽  
Yoshihiro Kawano ◽  
Miyuki Nagamine ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Current Density ◽  
Iron Reduction ◽  
High Current Density ◽  
Model Organism ◽  
Geobacter Sulfurreducens ◽  
Extracellular Electron Transfer ◽  
High Current ◽  
Current Production ◽  
Current Densities

Abstract Geobacter sulfurreducens produces high current densities and it has been used as a model organism for extracellular electron transfer studies. Nine G. sulfurreducens strains were isolated from biofilms formed on an anode poised at –0.2 V (vs. SHE) in a bioelectrochemical system in which river sediment was used as an inoculum. The maximum current density of an isolate, strain YM18 (9.29 A/m2), was higher than that of the strains PCA (5.72 A/m2), the type strain of G. sulfurreducens, and comparable to strain KN400 (8.38 A/m2), which is another high current producing strain of G. sulfurreducens. Genomic comparison of strains PCA, KN400, and YM18 revealed that omcB, xapD, spc, and ompJ, which are known to be important genes for iron reduction and current production in PCA, were not present in YM18. In the PCA and KN400 genomes, two and one region (s) encoding CRISPR/Cas systems were identified, respectively, but they were missing in the YM18 genome. These results indicate that there is genetic variation in the key components involved in extracellular electron transfer among G. sulfurreducens strains.

Selective Conversion of Carbon Dioxide to Formate with High Current Densities

2021 ◽  
pp. 2150001
Author(s):  
Xiulin Yang ◽  
Defei Liu ◽  
Shenghong Zhong ◽  
Xiaofeng Zhou ◽  
Kuo-Wei Huang ◽  
...  
Keyword(s):  
Current Density ◽  
Hollow Fiber ◽  
Active Sites ◽  
Large Scale ◽  
High Current Density ◽  
High Current ◽  
Faradaic Efficiency ◽  
Practical Applications ◽  
Selective Conversion ◽  
Current Densities

Selective conversion of CO2 to formate with high current densities is highly desirable but still challenging. Copper hollow fibers with interconnected pore structures were fabricated via a facile method and used as a stand-alone cathode for highly efficient electrochemical reduction of CO2 to formate. Our studies revealed that delivering the reactant CO2 gas to the inner space of the hollow fiber could build up a higher CO2 partial pressure in the pores and presumably reduce the concentration of H[Formula: see text] from the electrolyte to effectively suppress the major competing reaction, hydrogen evolution reaction (HER), from 46.9% faradaic efficiency (FE) to 15.0%. A high selectivity for CO2 reduction to formate with a maximum FE of 77.1% was achieved with a high current density of 34.7[Formula: see text]mA cm[Formula: see text], which is one of the highest FEs on Cu-based materials. Mechanistic studies suggest that the abundant active sites along with the unique crystal facets induced by the high pressure of CO2 at the pore surface in the “gas in” mode are attributed to the superior electroactivity and selectivity for the CO2 reduction to formate. The Cu hollow fiber electrodes exhibit an outstanding long-term stability at high current density, showing great potential for large-scale practical applications.

scholarly journals The spectrum of carbon arcs in air at high current densities

1927 ◽  
Vol 117 (776) ◽  
pp. 164-182 ◽  
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Short Note ◽  
Direct Vision ◽  
Ground Glass ◽  
Total Radiation ◽  
High Current ◽  
Carbon Arc ◽  
Current Densities ◽  
Made In

Although the spectrum of the ordinary carbon arc has been studied in great detail during the last 70 years, there seems to have been no similar study of the “High Current Density” arc which was introduced by Beck in 1914. Spectrophotometrical measurements have been made in connection with the development of this type of arc for searchlights, and photographs of the spectra obtained from the total radiation from the arc have been published. The only account, however, of the spectrum from individual parts of the arc appears in a short note by Bell and Bassett. They examined an image of the arc on a ground glass screen with a direct vision spectroscope and reported that in the arc stream 15 lines appeared when the current exceeded 100 amperes. They attributed 7 of these to helium and 2 to hydrogen.

Texture Evolution along the Layer Thickness in a Fe-3%Si Steel under Electropulsing Treatment

2011 ◽  
Vol 702-703 ◽  
pp. 943-946 ◽  
Author(s):  
Xin Li Wang ◽  
Hong Ming Zhao ◽  
Wen Bin Dai ◽  
Xiang Zhao
Keyword(s):  
Layer Thickness ◽  
Current Density ◽  
High Current Density ◽  
Texture Evolution ◽  
Specimen Thickness ◽  
Evolution Analysis ◽  
Orientation Density ◽  
Current Densities ◽  
The Difference ◽  
Electropulsing Treatment

Effects of electric current densities on recrystallization texture evolution in cold-rolled Fe-3%Si steel were investigated by using a high current density electropulsing treatment. Results showed that the orientation density of α fiber and  fiber varied with the specimen thickness during current passing. However, with the current density increasing, the difference from layer thickness almost vanished. In addition, Goss component texture was the final sharper one but no relation with the specimen thickness at 9.96kAmm-2. By the texture evolution analysis, it was found that the preferred nucleation always occurred in the surface layer due to the high storied energy coursed by previous cold rolling. Combined with the corresponding microstructures, it could be found that though there was an apparent texture evolution along specimen thickness, the microstructure had no change with thickness. In addition, due to the application of electropulsing, the recrystallization nucleation was greatly increased.

Texture and Microstructural Evolution under Electric Current Pulses in a Fe-3%Si Steel

2011 ◽  
Vol 197-198 ◽  
pp. 1104-1108 ◽  
Author(s):  
Xin Li Wang ◽  
Hong Ming Zhao ◽  
Wen Bin Dai ◽  
Xiang Zhao
Keyword(s):  
Electric Current ◽  
Microstructural Evolution ◽  
Current Density ◽  
High Current Density ◽  
Current Direction ◽  
Direction Parallel ◽  
Current Pulses ◽  
Electric Current Pulses ◽  
Current Densities ◽  
Cold Rolled

The evolution of the recrystallization texture under high current density electric current pulses (ECP) was investigated in a cold-rolled Fe-3%Si steel sheet. Results showed that the preferred nucleation always occurred in the direction parallel to the current direction at the primary stage of recrytallization. With the increment of the current density, the effect of current direction on texture and microstructural evolution was decreased. Due to the different texture component along the layer depth under different current densities, it was also found that the recrystallization nucleation was much easier to occur from the top surface.

Layer-structured FeCo bihydroxide as an ultra-stable bifunctional electrocatalyst for water splitting at high current densities

2021 ◽  
Author(s):  
Chaoyang Sun ◽  
Hui Wang ◽  
Shan Ji ◽  
Xuyun Wang ◽  
Vladimir Linkov ◽  
...  
Keyword(s):  
Water Splitting ◽  
Current Density ◽  
High Stability ◽  
High Current Density ◽  
High Current ◽  
Bifunctional Electrocatalyst ◽  
Current Densities ◽  
Double Hydroxide

A layered FeCo double hydroxide bifunctional water cracking electrocatalyst with ultra-high stability at high current density was developed.

Stable high current density operation of La0.6Sr0.4Co0.2Fe0.8O3−δ oxygen electrodes

2019 ◽  
Vol 7 (22) ◽  
pp. 13531-13539 ◽  
Author(s):  
Matthew Y. Lu ◽  
Justin G. Railsback ◽  
Hongqian Wang ◽  
Qinyuan Liu ◽  
Yvonne A. Chart ◽  
...  
Keyword(s):  
High Temperatures ◽  
Current Density ◽  
High Current Density ◽  
Solid Oxide ◽  
Stable Operation ◽  
Electrochemical Cells ◽  
High Current ◽  
Oxygen Electrodes ◽  
Current Densities

Stable operation of LSCF oxygen electrodes with high current densities at high temperatures for solid oxide electrochemical cells.

scholarly journals Alcohols electrooxidation coupled with H2 production at high current densities promoted by a cooperative catalyst

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Zhenhua Li ◽  
Yifan Yan ◽  
Si-Min Xu ◽  
Hua Zhou ◽  
Ming Xu ◽  
...  
Keyword(s):  
Benzyl Alcohol ◽  
Current Density ◽  
High Current Density ◽  
H2 Production ◽  
Open Circuit ◽  
High Current ◽  
Cell Potential ◽  
Current Densities ◽  
Electrode Membrane

AbstractElectrochemical alcohols oxidation offers a promising approach to produce valuable chemicals and facilitate coupled H2 production. However, the corresponding current density is very low at moderate cell potential that substantially limits the overall productivity. Here we report the electrooxidation of benzyl alcohol coupled with H2 production at high current density (540 mA cm−2 at 1.5 V vs. RHE) over a cooperative catalyst of Au nanoparticles supported on cobalt oxyhydroxide nanosheets (Au/CoOOH). The absolute current can further reach 4.8 A at 2.0 V in a more realistic two-electrode membrane-free flow electrolyzer. Experimental combined with theoretical results indicate that the benzyl alcohol can be enriched at Au/CoOOH interface and oxidized by the electrophilic oxygen species (OH*) generated on CoOOH, leading to higher activity than pure Au. Based on the finding that the catalyst can be reversibly oxidized/reduced at anodic potential/open circuit, we design an intermittent potential (IP) strategy for long-term alcohol electrooxidation that achieves high current density (>250 mA cm−2) over 24 h with promoted productivity and decreased energy consumption.

In-Situ Scanning Electron Microscope Observations of Strain-Confined Lithium Nucleation at Electrode/Electrolyte Interfaces in All-Solid-State-Lithium Battery

2015 ◽  
Vol 1754 ◽  
pp. 25-30
Author(s):  
Munekazu Motoyama ◽  
Makoto Ejiri ◽  
Yasutoshi Iriyama
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Amorphous Solid ◽  
Number Density ◽  
Cu Film ◽  
Small Cracks ◽  
Current Densities ◽  
A Current ◽  
Scanning Electron

ABSTRACTWe have studied electrochemical Li deposition/dissolution processes at amorphous solid electrolyte (LiPON) interfaces with 30-nm-thick-Cu-current collectors at different current densities by in-situ scanning electron microscopy (SEM). When the current density is smaller than 300 μA cm−2, Li islands continue to grow under a Cu film without coalescing with their neighbors. Consequently, they produce small cracks in the Cu film leading to isolated Li rod growth from the cracks. On the other hand, a current density of 1.0 mA cm−2 provokes the nucleation of Li islands with a higher number density. They rapidly coalesce under a Cu film in all lateral directions before cracking the Cu film. High current density conditions therefore suppress Li rod growths.

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