On the Properties of a Dimer Electrolyte in a Planar Electric Double Layer A Monte Carlo Simulation Study
Silvestre Alcántara, Whasington
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The precise description of the double layer phenomenon at the interface region between a charged electrode and an ionic solution is nowadays, more than ever, of great importance in areas like capacitors design, metal corrosion, DNA studies, and biomaterial sciences. Most theoretical and computational studies related with this subject have been performed considering basically a spherical approximation for the ions immersed in an electrolyte. A vast amount of experimental results related with the capacitance measurements on this kind of systems have suggested, in contrast, that more realistic models must be considered in order to achieve a better agreement between the simulations/theories and the experimental results. One interesting emerging model is the dimer electrolyte in which the cations are modeled as rigid dumbbells, and the anions as rigid monomer spheres in a dielectric continuum. In this thesis work we explore, using extensive Monte Carlo simulation, the structure and/or capacitance of such novel model. In the first part of the investigation, which was basically focused on the structure of a 2:2 electrolyte and performance of density functional theory, we have found that the theory reproduces well the simulation results, and that the strong electrostatic interaction in 2:2 system leads to pronounced asymmetry due to the dimer neutral tail. In the second part of the investigation, we have continued exploring the dimer electrolyte using simulation, but now the spheres comprising a dimer cation are allowed to fuse into each other. The resulting capacitance tends to evolves from being in the shape of a two asymmetric humps to two symmetric humps as the level of fusion in the dimer increases.