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Title: Structure and capacitance of an electric double layer of an asymmetric valency dimer electrolyte: A comparison of the density functional theory with Monte Carlo simulations

Here, the density functional theory is applied to a study of the structure and differential capacitance of a planar electric double layer formed by a valency asymmetric mixture of charged dimers and monomers. The dimer consists of two tangentially tethered hard spheres of equal diameters of which one is charged and the other is neutral, while the monomer is a charged hard sphere of the same size. The dimer electrolyte is next to a uniformly charged, smooth planar electrode. The electrode-particle singlet distributions, the mean electrostatic potential, and the differential capacitance for the model double layer are evaluated for a 2:1/1:2 valency electrolyte at a given concentration. Important consequences of asymmetry in charges and in ion shapes are (i) a finite, non-zero potential of zero charge, and (ii) asymmetric shaped 2:1 and 1:2 capacitance curves which are not mirror images of each other. Comparisons of the density functional results with the corresponding Monte Carlo simulations show the theoretical predictions to be in good agreement with the simulations overall except near zero surface charge.
Authors:
 [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [2]
  1. Brigham Young Univ., Provo, UT (United States)
  2. Univ. of Puerto Rico, San Juan (Puerto Rico)
  3. Adam Mickiewicz Univ. of Poznan, Poznan (Poland)
  4. Univ. of California, Riverside, CA (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Journal of Molecular Liquids
Additional Journal Information:
Journal Volume: 228; Journal Issue: C; Journal ID: ISSN 0167-7322
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Planar electric double layer; Density functional theory; Anisotropic ion shape; Asymmetric valencies
OSTI Identifier:
1399239
Alternate Identifier(s):
OSTI ID: 1413809