Assessing the concentration effect on hydration radii in aqueous solutions by electroadsorption on a carbon molecular sieve electrode

We report herein on a study of the electrical double layer capacitance of microporous activated carbon fibers electrodes as a function of the concentration of the electrolyte in aqueous solutions. The accessibility of the subnanopores in the electrode-to-ion adsorption decreases as the ionic strength of the solutions decreases, due to the increase in the hydration shell of the ions. Evaluating the concentration effect on the effective size of the ions was possible by the use of highly selective carbon molecular sieve electrodes, produced by the chemical vapor deposition (CVD) of carbon on the ACF surface, which partially closes the entries to the pores. The CVD process was carried out by the pyrolysis of benzene. This study provides a basis for the rigorous evaluation of the size of solvated ions in solutions at different levels of solvation.