Studies in hydrogen overvoltage at high current densities: Part I—The influence of electrode material, current density, and time, in aqueous solution

1940 ◽  
Vol 36 (0) ◽  
pp. 1226-1235 ◽  
Author(s):  
A. Hickling ◽  
F. W. Salt
Keyword(s):  
Aqueous Solution ◽  
Current Density ◽  
Electrode Material ◽  
High Current ◽  
Hydrogen Overvoltage ◽  
Current Densities

Integrative Chemistry-Based Generation of Novel Three Dimensional Macrocellular Carbonaceous Biofuel Cell

2014 ◽  
Vol 1641 ◽  
Author(s):  
Victoria Flexer ◽  
Nicolas Brun ◽  
Mathieu Destribats ◽  
Rénal Backov ◽  
Nicolas Mano
Keyword(s):  
Current Density ◽  
Electrode Material ◽  
Three Dimensional ◽  
Modified Electrodes ◽  
Biofuel Cell ◽  
High Current ◽  
Active Components ◽  
Synthetic Pathway ◽  
Current Densities ◽  
The Right

ABSTRACTHere we report the first membrane-less biofuel cell made by using three-dimensional carbonaceous foam electrodes. We first developed a new synthetic pathway to produce a new carbonaceous foam electrode material with increased porosity both in the meso and macroporous scale. We proved that by increasing the porosity of our three-dimensional foams we could increase the current density of our modified electrodes. Then, by choosing the right combination of enzyme and mediator, and the right loading of active components, we achieved unprecedentedly high current densities for an anodic system. Finally, we combined the improved cathode and anode to build a new membrane-less hybrid enzymatic biofuel cell consisting of a mediated anode and a mediator-less cathode.

scholarly journals Effect of deposition current density and annealing temperature on the microstructure and magnetic properties of nanostructured Ni-Fe-W-Cu alloys

2019 ◽  
Vol 51 (2) ◽  
pp. 209-221 ◽  
Author(s):  
Milica Spasojevic ◽  
Dusan Markovic ◽  
Miroslav Spasojevic ◽  
Zoran Vukovic ◽  
Aleksa Maricic ◽  
...  
Keyword(s):  
Current Density ◽  
Amorphous Matrix ◽  
Ammonium Citrate ◽  
High Current ◽  
Cathodic Polarization Curve ◽  
Cu Alloy ◽  
Powder Particles ◽  
Current Densities ◽  
Deposition Current Density ◽  
Microstructure And Magnetic Properties

Ni-Fe-W-Cu alloy powders were obtained by electrodeposition from an ammonium citrate bath at current densities ranging between 70 and 600 mA cm-2. As the deposition current density increased, the contents of Fe and W in the alloy increased, and those of Ni and Cu decreased. The total cathodic polarization curve was recorded, and partial polarization curves for Ni, Fe and W deposition and hydrogen evolution were determined. The current efficiency of alloy deposition was measured. The powders contained an amorphous matrix and FCC nanocrystals of the solid solution of Fe, W and Cu in Ni. At high current densities, small-sized nanocrystals exhibiting high internal microstrain values were formed. Powder particles were dendrite- and cauliflower-shaped. The dendrites had a large number of secondary branches and higher-order branches containing interconnected globules. The density of branches was higher in particles formed at high current densities. The powders formed at high current densities exhibited higher magnetization. Annealing at temperatures up to 460?C resulted in structural relaxation, accompanied by an increase in magnetization. At temperatures above 460?C, amorphous matrix crystallization and FCC crystal growth took place, accompanied by a decrease in magnetization.

THE ELECTROLYSIS OF SOME ORGANIC COMPOUNDS WITH ALTERNATING CURRENT

1939 ◽  
Vol 17b (5) ◽  
pp. 147-158 ◽  
Author(s):  
J. W. Shipley ◽  
M. T. Rogers
Keyword(s):  
Hydrochloric Acid ◽  
Organic Compounds ◽  
Current Density ◽  
Irreversible Process ◽  
High Current Density ◽  
Current Yield ◽  
High Current ◽  
Hydrogen Overvoltage ◽  
General Relations ◽  
A Current

The a-c. electrolysis of a number of organic compounds was carried out in order to ascertain what products might be obtained, what electrolytic conditions affected the nature and the yield of products, and to discover the general relations governing oxidation and reduction when a.c. is used. Oxidation was found to predominate over reduction, owing, probably, to the relatively low hydrogen overvoltage on the electrodes. The effect of varying the conditions of a-c. electrolysis was in general similar to that observed in d-c. electrolysis. Satisfactory yields were obtained only when a product of an irreversible process was concerned. A good yield of quinhydrone from the a-c. electrolysis of hydroquinone was secured at a relatively high current density. The chlorination of acetone by the a-c. electrolysis of a solution of acetic anhydride in hydrochloric acid gave a current yield of 35% at a current density of 2 amp. per cm2.

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.

THE PRODUCTION OF ETHANE, QUINHYDRONE, AND POTASSIUM CUPRIC CYANIDE BY A-C. ELECTROLYSIS

1939 ◽  
Vol 17b (6) ◽  
pp. 167-177 ◽  
Author(s):  
J. W. Shipley ◽  
M. T. Rogers
Keyword(s):  
Aqueous Solution ◽  
Current Density ◽  
Good Yield ◽  
High Current Density ◽  
Low Frequency ◽  
Space Time ◽  
Distinct Advantage ◽  
Current Yield ◽  
High Current ◽  
Space Time Yield

The quantitative production, of ethane, quinhydrone, and potassium cupric cyanide by a-c. electrolysis was studied in respect to conditions affecting yield. It was found that a good yield (about 90%) of quinhydrone was obtained by a-c. electrolysis, at low frequency and moderately high current density, of an aqueous solution of hydroquinone. This method of preparation has a distinct advantage in respect to space-time yield over the method of d-c. electrolysis. The current yield of potassium cupric cyanide at low current density (0.3 to 1.0 amp. per cm.2) using a.c. was in the neighbourhood of 88%. A-c. electrolysis was not found to indicate any particular advantage over d-c. electrolysis, as far as could be ascertained by comparing the ethane efficiency of the two processes.

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.

EFFECT OF GELATIN ON THE CHANGES IN INITIAL CATHODE POLARIZATION DURING ELECTRODEPOSITION OF COPPER

1954 ◽  
Vol 32 (6) ◽  
pp. 581-590 ◽  
Author(s):  
B. I. Parsons ◽  
C. A. Winkler
Keyword(s):  
Steady State ◽  
Current Density ◽  
Copper Sulphate ◽  
Chloride Concentration ◽  
High Current ◽  
Concentration Increase ◽  
Addition Agent ◽  
Cathode Polarization ◽  
Current Densities ◽  
Gelatin Concentration

In the absence of addition agent, the cathode polarization during initial electrolysis of copper from a solution of acid copper sulphate rose almost instantaneously from zero to approximately the steady state polarization. When gelatin was present in the electrolyte, the polarization generally increased to a maximum, Pmax, (in time tmax) then decreased to a minimum, Pmin, (in-time tmin) beyond which it increased to the steady state value, Ps. Generally, Pmax increased to a steady value with an increase in the time, T0, the electrode was in contact with the electrolyte before electrolysis was begun. At low, moderate, and high current densities respectively, tmax increased continuously, passed through a maximum, and decreased continuously with T0.The behavior of tmin approximately paralleled that of tmax. The polarization was linear in the logarithm of the current density; tmax and tmin decreased with increase in current density. The polarization values increased and tmax decreased, with increase in gelatin concentration. Increase of temperature had approximately the same effect as decrease in current density. With both chloride and gelatin present, Pmax was practically independent of T0 and chloride concentration, while Pmin and Ps showed minimum values at about 2 mgm./l. chloride.

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