On the orientational ordering of water and finite size of molecules in the mean-field description of the electric double layer – a mini review

The distribution of ions in an electrolyte solution close to a charged surface is determined by competition between electrostatic interactions and the entropy of the ions. The diffuse electric double layer (EDL) created influences the overall electrostatic interaction of the charged surface with its environment. Different approaches were introduced through the years to overcome some of the limitations of classical EDL Poisson-Boltzmann models and to better capture the complex phenomena of the EDL. The core of these models is the spatial variation of the relative permittivity, achieved by taking into account the spatial and orientational distribution of water molecules and the excluded volume effect.