scholarly journals The Role of the Double Layer for the Pseudocapacitance of the Hydrogen Adsorption on Platinum

2022 ◽  
Author(s):  
Maximilian Schalenbach ◽  
Y. Emre Durmus ◽  
Hermann Tempel ◽  
Hans Kungl ◽  
Rüdiger-A. Eichel
Keyword(s):  
Double Layer ◽  
Hydrogen Adsorption ◽  
Full Range ◽  
Surface States ◽  
Alternative Interpretation ◽  
Kinetics Of Adsorption ◽  
Adsorption Processes ◽  
Kinetics Of ◽  
Cyclic Voltammetry Data

Abstract Pseudocapacitances such as the hydrogen adsorption on platinum (HAoPt) are associated with faradaic chemical processes that appear as capacitive in their potentiodynamic response, which was reported to result from the kinetics of adsorption processes. This study discusses an alternative interpretation of the partly capacitive response of the HAoPt that is based on the proton transport of ad- or desorbed hydrogen in the double layer. Potentiodynamic perturbations of equilibrated surface states of the HAoPt lead to typical double layer responses with the characteristic resistive-capacitive relaxations that overshadow the fast adsorption kinetics. A potential-dependent double layer representation by a dynamic transmission line model incorporates the HAoPt in terms of capacitive contributions and can computationally reconstruct the charge exchanged in full range cyclic voltammetry data. The coupling of charge transfer with double layer dynamics displays a novel physicochemical theory to explain the phenomenon of pseudocapacitance and the mechanisms in thereon based supercapacitors.

scholarly journals The kinetics of adsorption processes

1931 ◽  
Vol 134 (824) ◽  
pp. 512-523 ◽  
Keyword(s):  
Kinetic Theory ◽  
Dynamic Equilibrium ◽  
Accommodation Coefficient ◽  
Kinetic Theory Of Gases ◽  
Adsorption Dynamic ◽  
Adsorbed Molecules ◽  
Kinetics Of Adsorption ◽  
Adsorption Equilibria ◽  
Adsorption Processes ◽  
Kinetics Of

In any process of adsorption, dynamic equilibrium is reached when the number of molecules condensing in unit time on the adsorbing surface is equal to the molecules evaporating. Langmuir obtained the well-known relation between the mass adsorbed and the pressure m = k 1 p /( k 2 p + b ) by writing the number of molecules evaporating as proportional to the number already adsorbed, and the number condensing as equal to na 0 kp , where p is the pressure, n the fraction of the adsorbing space unoccupied, k a constant derived from the kinetic theory of gases, and a 0 an accommodation coefficient, which was supposed to differ very little from unity. Using these assumptions, adsorption equilibria should be reached so rapidly as to be practically instantaneous. If we regard the process of adsorption as analogous to a chemical reaction, involving changes in behaviour of the valency electrons of the adsorbed molecules and the adsorbent, the assumption that a 0 differs little from unity, corresponds with the assumption that every collision is fruitful in a gas reaction. H. S. Taylor has pointed out in a recent paper that for some adsorption processes it is apparently necessary to assume quite large energies of activation. Instead of all the molecules colliding with “unoccupied” spaces being adsorbed, only a fraction e -E/RT of the impinging molecules change over into adsorbed molecules.

Memristor Effect in Sandwich-Type Ni-TiOx-p/Si-Ni Heterojunction

2016 ◽  
Vol 39 ◽  
pp. 114-120 ◽  
Author(s):  
Oleksandr M. Kostiukevych ◽  
Valeriy A. Skryshevsky ◽  
Vasyl V. Lendiel ◽  
Yuriy G. Shulimov ◽  
Anton I. Manilov ◽  
...  
Keyword(s):  
Low Cost ◽  
Surface States ◽  
Hysteretic Behavior ◽  
Voltage Sweep ◽  
Microelectronic Devices ◽  
Non Volatile Memory ◽  
Sandwich Type ◽  
Current Change ◽  
Kinetics Of

I-V, C-V characteristics and current change kinetics of the Ni-TiOx-p/Si-Ni heterojunction were studied under different speeds of voltage sweep, in darkness and under illumination of various spectral regions. It was found that Ni-TiOx-p/Si-Ni heterojunction shows pronounced hysteretic behavior and can act as memristor cell. Results of studies of photosensitivity and current kinetics under abrupt changes of applied voltage and illumination reveal considerable role of surface states recharging in TiOx oxide layer or at TiOx-p/Si interface in the switching effects.The studied Ni-TiOx-p/Si-Ni heterostructure is prospective as a basis for low-cost, CMOS- and SOI-compatible microelectronic devices with non-volatile memory.

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