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The Electric Double Layer in an Ionic Liquid Incorporated with Water Molecules: Atomic Force Microscopy Force Curve Study
Author(s) -
Zhong Yunxin,
Yan Jiawei,
Li Miangang,
Chen Li,
Mao Bingwei
Publication year - 2016
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201600177
Subject(s) - layering , molecule , adsorption , chemistry , ionic bonding , electrochemistry , chemical physics , layer (electronics) , ion , analytical chemistry (journal) , materials science , electrode , nanotechnology , chromatography , botany , organic chemistry , biology
Electrochemical techniques and atomic force microscopy based force curve measurements under potential control are combined to investigate the effect of small amounts of water on the structure of the electric double layer of an Au(111)/1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) interface. Three to five layering structures, including two charged layers, are observed at the Au(111)/BMPTFSA interface at potentials more negative than the point of zero charge. With an increase in the water concentration, the stiffness values for both the first and second layers decrease, which demonstrates that more water molecules adsorb on the Au(111) surface or interact with the ionic liquid, and thus weaken the interactions between cations, anions, and the electrode surface and lower the stability of the layering structures. The thicknesses of the charged interior layers (the first and second layers in this system) increase with an increase in the water concentration and the thicknesses of neutral exterior layers (the next one to three layers in this system) remain almost unchanged. The structure of the first layer of the interface varies dramatically with the change in the water concentration.