Modeling Electrochemical Interfaces in Ultrahigh Vacuum:  Molecular Roles of Solvation in Double-Layer Phenomena

1997 ◽  
Vol 101 (49) ◽  
pp. 10166-10177 ◽  
Author(s):  
Ignacio Villegas ◽  
Michael J. Weaver
Keyword(s):  
Double Layer ◽  
Ultrahigh Vacuum ◽  
Electrochemical Interfaces

A theoretical consideration of ion size effects on the electric double layer and voltammetry of nanometer-sized disk electrodes

2016 ◽  
Vol 193 ◽  
pp. 251-263 ◽  
Author(s):  
Yu Gao ◽  
Yuwen Liu ◽  
Shengli Chen
Keyword(s):  
Size Effect ◽  
Double Layer ◽  
Electric Double Layer ◽  
Finite Size ◽  
Finite Size Effect ◽  
The Poisson Equation ◽  
Electrochemical Interface ◽  
Disk Electrodes ◽  
Ion Size ◽  
Electrochemical Interfaces

Considering that an electric-double-layer (EDL) structure may significantly impact on the mass transport and charge transfer kinetics at the interfaces of nanometer-sized electrodes, while EDL structures could be altered by the finite sizes of electrolyte and redox ions, the possible effects of ion sizes on EDL structures and voltammetric responses of nanometer-sized disk (nanodisk) electrodes are investigated. Modified Boltzmann and Nernst–Planck (NP) equations, which include the influence of the finite ion volumes, are combined with the Poisson equation and modified Butler–Volmer equation to gain knowledge on how the finite sizes of ions and the nanometer sizes of electrodes may couple with each other to affect the structures and reactivities of a nanoscale electrochemical interface. Two typical ion radii, 0.38 nm and 0.68 nm, which could represent the sizes of the commonly used aqueous electrolyte ions (e.g., the solvated K+) and the organic electrolyte ions (e.g., the solvated TEA+) respectively, are considered. The finite size of ions can result in decreased screening of electrode charges, therefore magnifying EDL effects on the ion transport and the electron transfer at electrochemical interfaces. This finite size effect of ions becomes more pronounced for larger ions and at smaller electrodes as the electrode radii is larger than 10 nm. For electrodes with radii smaller than 10 nm, however, the ion size effect may be less pronounced with decreasing the electrode size. This can be explained in terms of the increased edge effect of disk electrodes at nanometer scales, which could relax the ion crowding at/near the outer Helmholtz plane. The conditions and situations under which the ion sizes may have a significant effect on the voltammetry of electrodes are discussed.

scholarly journals Electric double layer structure in aqueous electrolyte and its electrocatalytic importance

2021 ◽  
Author(s):  
Seung-Jae Shin ◽  
Dong Hyun Kim ◽  
Geunsu Bae ◽  
Stefan Ringe ◽  
Hansol Choi ◽  
...  
Keyword(s):  
Double Layer ◽  
Electric Double Layer ◽  
Layer Structure ◽  
Structural Phase ◽  
Structural Response ◽  
Cation Complexation ◽  
Reduction Activity ◽  
Complex Structural ◽  
Two Peaks ◽  
Electrochemical Interfaces

Abstract To design electrochemical interfaces for efficient electric-chemical energy interconversion, it is critical to reveal the electric double layer (EDL) structure and relate it with electrochemical activity; nonetheless, this has been a long-standing challenge. Of particular, no molecular-level theories have fully explained the characteristic two peaks arising in the potential-dependence of the EDL capacitance, which is sensitively dependent on the EDL structure. We herein demonstrate that our first-principles-based molecular simulation reproduces the experimental capacitance peaks. The origin of two peaks emerging at anodic and cathodic potentials is unveiled to be an electrosorption of ions and an EDL structural phase transition, respectively. We further find a cation complexation gradually modifies the EDL structure and the field strength, which linearly scales the carbon dioxide reduction activity. This study deciphers the complex structural response of the EDL and highlights its catalytic importance, which bridges the mechanistic gap between the EDL structure and electrocatalysis.

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