The Electrical Double Layer and the Stability of Lyophobic Colloids.

1935 ◽  
Vol 16 (3) ◽  
pp. 363-415 ◽  
Author(s):  
E. J. W. Verwey
Keyword(s):  
Double Layer ◽  
Electrical Double Layer ◽  
The Stability

Increasing the stability of very high potential electrical double layer capacitors by operando passivation

2018 ◽  
Vol 402 ◽  
pp. 53-61 ◽  
Author(s):  
M. Pohl ◽  
I. Tallo ◽  
A. Jänes ◽  
T. Romann ◽  
E. Lust
Keyword(s):  
Double Layer ◽  
Electrical Double Layer ◽  
High Potential ◽  
Electrical Double Layer Capacitors ◽  
The Stability ◽  
Double Layer Capacitors ◽  
Very High

Towards understanding the impact of operating voltage on the stability of adiponitrile-based electrical double-layer capacitors

2021 ◽  
Vol 496 ◽  
pp. 229841
Author(s):  
A. Bothe ◽  
S.E.M. Pourhosseini ◽  
P. Ratajczak ◽  
F. Beguin ◽  
A. Balducci
Keyword(s):  
Double Layer ◽  
Electrical Double Layer ◽  
Operating Voltage ◽  
Electrical Double Layer Capacitors ◽  
The Stability ◽  
The Impact ◽  
Double Layer Capacitors

scholarly journals STABILITY OF SUSPENSIONS OF SOLID PARTICLES OF PROTEINS AND PROTECTIVE ACTION OF COLLOIDS

1923 ◽  
Vol 5 (4) ◽  
pp. 479-504 ◽  
Author(s):  
Jacques Loeb
Keyword(s):  
Double Layer ◽  
Isoelectric Point ◽  
Electrical Double Layer ◽  
Protective Action ◽  
Solid Particles ◽  
Double Layers ◽  
Salting Out ◽  
Egg Albumin ◽  
Gelatin Films ◽  
The Stability

1. It is shown that the concentrations of different salts required to precipitate suspensions of gelatin-coated collodion particles in water are practically identical with the concentrations of the same salts required for the "salting out" of gelatin from aqueous solutions. Neither effect shows any relation to the electrical double layers surrounding the particles. 2. It is shown that at the isoelectric point of gelatin, suspensions of gelatin-coated collodion particles are not stable and it had been shown previously that gelatin is least soluble at the isoelectric point. The addition of salt increases both the solubility of gelatin in water as well as the stability of suspensions of gelatin-coated collodion particles in water, and both effects increase with the valency of one of the ions of the salt. 3. This latter effect is not due to any charges conferred on the gelatin particles by the salts, since the cataphoretic experiments show that salts like NaCl, Na2SO4, or CaCl2, which at the isoelectric point of gelatin increase the solubility of gelatin as well as the stability of suspensions of gelatin-coated collodion particles, leave the particles practically uncharged in the concentrations in which the salts are efficient. 4. It follows from all these facts that the stability of suspensions of gelatin-coated particles in water depends on the solubility of gelatin in water; e.g., on the chemical affinity of certain groups of the gelatin molecule for water. 5. Though crystalline egg albumin is highly soluble in water, the stability of collodion particles coated with crystalline egg albumin does not depend upon the affinity of the albumin molecule for water, but depends practically alone on the electrical double layer surrounding each particle. As soon as the P.D. of this double layer falls below 13 millivolts, the suspension is no longer stable. 6. The critical potential for the stability of suspensions of collodion particles coated with genuine egg albumin is the same as that for particles of boiled (denatured) white of egg. Since through the process of heating, egg albumin loses its solubility in water, it is inferred that egg albumin undergoes the same change when it forms a film around a solid particle like collodion. 7. The influence of electrolytes on the stability of suspensions of collodion particles coated with casein or edestin was similar to that of collodion particles coated with egg albumin. The experiments are, however, complicated by the fact that near the isoelectric point CaCl2 and even NaCl cause a suspension again at concentrations of about M/2 or 1 M, while still higher concentrations may cause a precipitation again. These latter effects have no connection with double layers, but belong probably in the category of solubility phenomena. 8. These experiments permit us to define more definitely the conditions for a general protective action of colloids. Protective colloids must be capable of forming a durable film on the surface of the suspended particles and the molecules constituting the film must have a higher attraction for the molecules of the solvent than for each other; in other words, they must possess true solubility. Only in this case can they prevent the precipitating action of low concentrations of electrolytes on particles which are kept in suspension solely by the high potentials of an electrical double layer. Thus gelatin films, in which the attraction of the molecules for water is preserved, have a general protective action, while crystalline egg albumin, casein, and edestin, which seem to lose their attraction for water when forming a film, have a protective action only under limited conditions stated in the paper.

scholarly journals NiCo2O4-based Hybrid Nanocomposite for High-Performance Pseudocapacitor Electrodes

2019 ◽  
Author(s):  
Mehdi Eskandari ◽  
Rassoul Malekfar ◽  
David Buceta ◽  
Pablo Taboada
Keyword(s):  
Double Layer ◽  
Electrical Double Layer ◽  
High Performance ◽  
Conductive Polymer ◽  
Multiwall Carbon Nanotubes ◽  
Cost Effective ◽  
Hybrid Nanocomposite ◽  
Reduced Graphene ◽  
Potential Applicability ◽  
The Stability

New hybrid nanostructured electrodes for supercapacitors made by combination of electrical double layer and faradaic supercapacitors based-nanomaterials within a single hybrid composite has a great potential on expanding the range of use of these devices and increase their electrochemical performance. In this work, we developed several hybrid nanostructured composites with combinations of such types of materials with potential applicability as electrodes in supercapacitors. In particular, these composites were obtained by easy, cost-effective and scalable procedures, and were composed by NiCo2O4 nanocores as the main faradaic-based nanomaterial and either the conductive polymer polyaniline (PANI), multiwall carbon nanotubes (MWCNTs), or reduced graphene oxide (r-GO) as the electrical double layer-based carbonaceous-based nanomaterials in order to enable the combination of both type of energy storage processes within a single nanostructured device. These constructions allowed us to obtain specific capacitance as large as 1760 F/g, 900 F/g and 734 F/g at a current density of 1 A/g for NiCo2O4/PANI, NiCo2O4/MWCNT, and NiCo2O4/r-GO hybrid nanocomposite electrodes, respectively. Besides, the stability of NiCo2O4/MWCNTs and NiCo2O4/r-GO-based electrodes was outstanding, with capacity losses below 10% after long periods of operation (> 500 cycles).

Modeling the Electrical Double Layer to Understand the Reaction Environment in a CO2 Electrocatalytic System

2019 ◽  
Author(s):  
Divya Bohra ◽  
Jehanzeb Chaudhry ◽  
Thomas Burdyny ◽  
Evgeny Pidko ◽  
wilson smith
Keyword(s):  
Electric Field ◽  
Double Layer ◽  
Electrical Double Layer ◽  
Surface Reaction ◽  
Catalyst Surface ◽  
Local Reaction ◽  
Reaction Diffusion ◽  
Alkali Metal Cations ◽  
Applied Potential ◽  
Critical Aspect

<p>The environment of a CO<sub>2</sub> electroreduction (CO<sub>2</sub>ER) catalyst is intimately coupled with the surface reaction energetics and is therefore a critical aspect of the overall system performance. The immediate reaction environment of the electrocatalyst constitutes the electrical double layer (EDL) which extends a few nanometers into the electrolyte and screens the surface charge density. In this study, we resolve the species concentrations and potential profiles in the EDL of a CO<sub>2</sub>ER system by self-consistently solving the migration, diffusion and reaction phenomena using the generalized modified Poisson-Nernst-Planck (GMPNP) equations which include the effect of volume exclusion due to the solvated size of solution species. We demonstrate that the concentration of solvated cations builds at the outer Helmholtz plane (OHP) with increasing applied potential until the steric limit is reached. The formation of the EDL is expected to have important consequences for the transport of the CO<sub>2</sub> molecule to the catalyst surface. The electric field in the EDL diminishes the pH in the first 5 nm from the OHP, with an accumulation of protons and a concomitant depletion of hydroxide ions. This is a considerable departure from the results obtained using reaction-diffusion models where migration is ignored. Finally, we use the GMPNP model to compare the nature of the EDL for different alkali metal cations to show the effect of solvated size and polarization of water on the resultant electric field. Our results establish the significance of the EDL and electrostatic forces in defining the local reaction environment of CO<sub>2</sub> electrocatalysts.</p>

Electrical Double Layer Formation on Glassy Carbon in Aqueous Solution

2021 ◽  
pp. 138416
Author(s):  
Sofia B. Davey ◽  
Amanda P. Cameron ◽  
Kenneth G. Latham ◽  
Scott W. Donne
Keyword(s):  
Aqueous Solution ◽  
Double Layer ◽  
Glassy Carbon ◽  
Electrical Double Layer ◽  
Layer Formation

scholarly journals Artificial synapses with a sponge-like double-layer porous oxide memristor

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Qin Gao ◽  
Anping Huang ◽  
Jing Zhang ◽  
Yuhang Ji ◽  
Jingjing Zhang ◽  
...  
Keyword(s):  
Double Layer ◽  
Layer Structure ◽  
Learning Experience ◽  
Rapid Development ◽  
Spike Timing ◽  
Synaptic Functions ◽  
Intelligence Studies ◽  
Bionic Structure ◽  
Porous Oxide ◽  
The Stability

AbstractClosely following the rapid development of artificial intelligence, studies of the human brain and neurobiology are focusing on the biological mechanisms of neurons and synapses. Herein, a memory system employing a nanoporous double-layer structure for simulation of synaptic functions is described. The sponge-like double-layer porous (SLDLP) oxide stack of Pt/porous LiCoO2/porous SiO2/Si is designed as presynaptic and postsynaptic membranes. This bionic structure exhibits high ON–OFF ratios up to 108 during the stability test, and data can be maintained for 105 s despite a small read voltage of 0.5 V. Typical synaptic functions, such as nonlinear transmission characteristics, spike-timing-dependent plasticity, and learning-experience behaviors, are achieved simultaneously with this device. Based on the hydrodynamic transport mechanism of water molecules in porous sponges and the principle of water storage, the synaptic behavior of the device is discussed. The SLDLP oxide memristor is very promising due to its excellent synaptic performance and potential in neuromorphic computing.

Enzyme Immobilization Behavior on the Surface of Hydroxyapatite Capsules under Alkaline Condition

2018 ◽  
Vol 782 ◽  
pp. 21-26
Author(s):  
Takeshi Yabutsuka ◽  
Masaya Yamamoto ◽  
Shigeomi Takai ◽  
Takeshi Yao
Keyword(s):  
Enzyme Immobilization ◽  
Double Layer ◽  
Isoelectric Point ◽  
Electrical Double Layer ◽  
Alkaline Condition ◽  
Bicarbonate Buffer

We prepared hydroxyapatite (HA) capsules encapsulating maghemite particles. In order to evaluate enzyme immobilization behavior of the HA capsules under alkaline condition, we immobilized five kinds of enzymes with different isoelectric point in carbonate/bicarbonate buffer (CBB, pH 10.0). When the enzymes in CBB were moderately charged, immobilization efficiency on the HA capsules showed the highest value. It was suggested that immobilization efficiency was affected according to both pI of enzyme and pH of the surrounding solution and that enzyme immobilized on the HA capsules by not only electrical double layer interactions but also ion interaction and other interactions.

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