关键词: ITIES, 界面双电层, 内层微分电容, 统计力学, 巨正则系综

Abstract: A statistical mechanical treatment for electrical double layer at the interface between two immiscible elecrolyte solution (ITIES) is presented by using grand canonical method based on the MVN model. For the MVN model, the ITIES was represented by that the two space charge regions are separated by an inner layer of the oriented solvent molecules. Assuming that the ions were allowed to penetrated into the solvent compact layer over some distance, then the grand canonical partition function of the inner layer at ITIES can be given. While the mean field approximation is employed to estimate the interactive potential energy of the system, including the dipole dipole, dipole ion and ion ion interaction. A relationship between the differential capacity and the surface charge fluctuation is shown, and the statistical expression of inner layer differential capacity (C 1) is derived. A fitting curve of the C 1 as a function of surface charge density ( σ m ) at water/nitrobenzene interface is given, which is agreed with the generally theoretical inferences.

Key words: ITIES, Electrical double layer, Inner layer differe