Overestimation of the stability of the π-delocalized versus the σ-localized configuration in radicals by current density functionals: the case of vinylacyl radicals

2000 ◽  
Vol 104 (6) ◽  
pp. 455-460 ◽  
Author(s):  
Maurizio Guerra
Keyword(s):  
Current Density ◽  
Density Functionals ◽  
The Stability

scholarly journals Superior FexN electrocatalyst derived from 1,1′-diacetylferrocene for oxygen reduction reaction in alkaline and acidic media

2020 ◽  
Vol 9 (1) ◽  
pp. 843-852
Author(s):  
Hunan Jiang ◽  
Jinyang Li ◽  
Mengni Liang ◽  
Hanpeng Deng ◽  
Zuowan Zhou
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Current Density ◽  
Active Sites ◽  
Reduction Reaction ◽  
Alkaline Media ◽  
Acidic Media ◽  
Onset Potential ◽  
Acidic And Alkaline Media ◽  
The Stability

AbstractAlthough Fe–N/C catalysts have received increasing attention in recent years for oxygen reduction reaction (ORR), it is still challenging to precisely control the active sites during the preparation. Herein, we report FexN@RGO catalysts with the size of 2–6 nm derived from the pyrolysis of graphene oxide and 1,1′-diacetylferrocene as C and Fe precursors under the NH3/Ar atmosphere as N source. The 1,1′-diacetylferrocene transforms to Fe3O4 at 600°C and transforms to Fe3N and Fe2N at 700°C and 800°C, respectively. The as-prepared FexN@RGO catalysts exhibited superior electrocatalytic activities in acidic and alkaline media compared with the commercial 10% Pt/C, in terms of electrochemical surface area, onset potential, half-wave potential, number of electrons transferred, kinetic current density, and exchange current density. In addition, the stability of FGN-8 also outperformed commercial 10% Pt/C after 10000 cycles, which demonstrates the as-prepared FexN@RGO as durable and active ORR catalysts in acidic media.

scholarly journals Investigation of the stability of NiFe-(oxy)hydroxide anodes in alkaline water electrolysis under industrially relevant conditions

2020 ◽  
Vol 10 (16) ◽  
pp. 5593-5601 ◽  
Author(s):  
Marco Etzi Coller Pascuzzi ◽  
Alex J. W. Man ◽  
Andrey Goryachev ◽  
Jan P. Hofmann ◽  
Emiel J. M. Hensen
Keyword(s):  
Elevated Temperature ◽  
Current Density ◽  
Anodic Polarization ◽  
High Current Density ◽  
Water Electrolysis ◽  
High Current ◽  
Alkaline Water Electrolysis ◽  
Alkaline Water ◽  
And Performance ◽  
The Stability

Anodic polarization conducted at high current density, elevated temperature, and high KOH concentration impacted the structure and performance of NiFeOxHy and NiOxHy anodes.

Comparison of Current-Induced Migration of Be and C in GaAs/AlGaAs HBTs

1992 ◽  
Vol 262 ◽  
Author(s):  
F. Ren ◽  
T. R. Fullowan ◽  
J. R. Lothian ◽  
P. W. Wisk ◽  
C. R. Abernathy ◽  
...  
Keyword(s):  
Current Density ◽  
Ideality Factor ◽  
Current Gain ◽  
Rapid Degradation ◽  
Enhanced Diffusion ◽  
Aging Conditions ◽  
The Stability ◽  
Dc Current ◽  
A Current ◽  
Base Doping

ABSTRACTWe contrast the stability under bias-aging conditions of GaAs/AlGaAs HBTs utilizing highly Be- or C-doped base layers. Devices with Be doping display a rapid degradation of dc current gain and junction ideality factor. At 200°C, a 2 × 10 μm2 Be-doped device (4 × 1019cm−3 base doping) operated at a current density of 2.5 × 104 A. cm−2 shows a decrease in gain from 16 to 1.5 within 2h. Under the same conditions a C-doped device with even higher base-doping (7 × 1019 cm−3) is stable over periods of 36h, the longest time we tested our structures. The degradation of Be-doped devices is consistent with the mechanism of recombination-enhanced diffusion of interstitials into the adjoining layers. Similar results are obtained with Zn-doped devices. Since C occupies the As sub-lattice rather than the Ga sublattice as with Be and Zn, it is not susceptible to reaction with Ga interstitials injected during growth or bias-aging.

scholarly journals Plasma Stability in a Tokamak with Reactor Technologies Taking into Account the Pressure Pedestal

2021 ◽  
Vol 47 (11) ◽  
pp. 1119-1127
Author(s):  
S. Yu. Medvedev ◽  
A. A. Martynov ◽  
S. V. Konovalov ◽  
V. M. Leonov ◽  
V. E. Lukash ◽  
...  
Keyword(s):  
Current Density ◽  
Stability Limit ◽  
High Plasma ◽  
Quasi Equilibrium ◽  
Plasma Stability ◽  
Density Profiles ◽  
Edge Localized Modes ◽  
Operating Limits ◽  
Plasma Torus ◽  
The Stability

Abstract Studying stationary regimes with high plasma confinement in a tokamak with reactor technologies (TRT) [1] involves calculating the plasma stability taking into account the influence of the current density profiles and pressure gradient in the pedestal near the boundary. At the same time, the operating limits should be determined by the parameters of the pedestal, which, in particular, are set by the stability limit of the peeling–ballooning modes that trigger the peripheral disruption of edge localized modes (ELM). Using simulation of the quasi-equilibrium evolution of the plasma by the ASTRA and DINA codes, as well as a simulator of magnetohydrodynamic (MHD) modes localized at the boundary of the plasma torus based on the KINX code, stability calculations are performed for different plasma scenarios in the TRT with varying plasma density and temperature profiles, as well as the corresponding bootstrap current density in the pedestal region. At the same time, experimental scalings for the width of the pedestal are used. The obtained pressure values are below the limits for an ITER-like plasma due to the lower triangularity and higher aspect ratio of TRT plasma. For the same reason, the reversal of magnetic field shear in the pedestal occurs at a lower current density, which causes the instability of modes with low toroidal wave numbers and reduces the effect of diamagnetic stabilization.

scholarly journals The Effect of Cu Ohmic Contact on Photoelectrochemical Property of S-CuO Thin Film Photocathodes

2019 ◽  
Vol 22 (6) ◽  
pp. 255-262
Author(s):  
Aziz Amrullah ◽  
Gunawan Gunawan ◽  
Nor Basid Adiwibawa Prasetya
Keyword(s):  
Thin Film ◽  
Current Density ◽  
Ohmic Contact ◽  
Photoelectrochemical Properties ◽  
Photoelectrochemical Property ◽  
Onset Potential ◽  
Best Response ◽  
Cyclic Voltammetry Method ◽  
The Stability ◽  
A Current

The development of semiconductor materials as photocathodes that have excellent performance is significant for the photoelectrochemical reaction of hydrogen evolution. The thin film of sulfur-doped Copper (II) oxide (S-CuO)  was successfully synthesized using the cyclic voltammetry method. Investigation of photoelectrochemical properties of S-CuO photocathodes, including current density, onset potential, applied photon to current efficiency (ABPE), and bandgap had been carried out. It was reported that the Cu ohmic contact affected the photoelectrochemical properties and the stability of the thin film. The presence of Cu ohmic contact can improve the performance of S-CuO thin film photocathodes. The S-CuO TU 20 mM thin film has the best response with a current density of -0.923 mA/cm2, an onset potential of 0.59 V, and ABPE of 0.21%. Stability occurred at pH 7 in 0.2M NaH2PO4. The optical analysis showed S-CuO TU 20 mM bandgap of 1.7 eV.

The Stability and the Computed Speed of Application Boundary Element Method to Compute the Electric Potential of One Hundred and Fifty-Needle Electrodes

2013 ◽  
Vol 437 ◽  
pp. 245-248
Author(s):  
An Ling Wang ◽  
Fu Ping Liu
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Current Density ◽  
Electric Potential ◽  
Linear Equations ◽  
Discrete Equations ◽  
Linear Current ◽  
The Stability ◽  
Computing Method ◽  
Element Method

According to the electric potential of one hundred and fifty-needle electrodes (OONE), the discrete equations based on the indetermination linear current density were established by the boundary element integral equations (BEIE) The non-uniform distribution of the current flowing from one hundred and fifty-needle electrodes was imaged by solving a set of linear equations. Then, the electric potential generated by OONE at any point can be determined through the boundary element method (BEM). The time of program running and stability of computing method are examined by an example. It demonstrates that the algorithm possesses a quick speed and the steady computed results. It means that this method has an important referenced significance for computing the potential generated by OONE, which is a fast, effective and accurate computing method.

The Stability and the Computed Speed of the Boundary Element Numerical Method for Electric Potential Generated by Oblique Hundred - Needle Electrodes

2013 ◽  
Vol 415 ◽  
pp. 479-482
Author(s):  
Ming Chang Zhang ◽  
An Ling Wang ◽  
Fu Ping Liu
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Uniform Distribution ◽  
Current Density ◽  
Electric Potential ◽  
Linear Equations ◽  
Discrete Equations ◽  
Linear Current ◽  
The Stability ◽  
Computing Method

Abstract:According to the electric potential of oblique hundred -needle electrodes (OHNE), the discrete equations based on the indetermination linear current density were established by the boundary element integral equations (BEIE) The non-uniform distribution of the current flowing from hundred -needle electrodes was imaged by solving a set of linear equations. Then, the electric potential generated by OHNE at any point can be determined through the boundary element method (BEM). The time of program running and stability of computing method are examined by an example. It demonstrates that the algorithm possesses a quick speed and the steady computed results. It means that this method has an important referenced significance for computing the potential generated by OHNE, which is a fast, effective and accurate computing method.

scholarly journals Enhancing Activity of Pd-Based/rGO Catalysts by Al-Si-Na Addition in Ethanol Electrooxidation in Alkaline Medium

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Minh Dang Nguyen ◽  
Lien Thi Tran ◽  
Quang Minh Nguyen ◽  
Thao Thi Nguyen ◽  
Thu Ha Thi Vu
Keyword(s):  
Alkaline Medium ◽  
Current Density ◽  
Active Phase ◽  
Pd Nanoparticles ◽  
Electrochemical Stability ◽  
Ethanol Electrooxidation ◽  
Peak Current Density ◽  
Direct Ethanol Fuel Cell ◽  
Reduced Graphene ◽  
The Stability

The article presents modified Pd-based catalysts supported on reduced graphene oxide (rGO), used in the electrooxidation reaction of ethanol in alkaline medium. When NaBH4 reducing agent was used, the random presence of Na was found out. According to this result, Na was used as a promoter of Pd-based catalyst. Consequently, the Al-Si-Na addition not only assisted active phase Pd nanoparticles to disperse homogenously on graphene surport, but also contributed to increase catalytic activity in the reaction. This value, 16138 mA·mg−1Pd, is about 1.5 times higer than that of the catalyst modified by Al-Si. Moreover, the stability of the catalyst is enhanced more. The electrochemical stability of PASGN.N catalyst was relatively good: after 500 scanning cycles, the current density diminished 32% compared with the highest peak current density of the 15th cycle, which was chosen as a reference. These significant improvement results in electrooxidation of ethanol have opened up the high potential application of these catalysts in direct-ethanol fuel cell.

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