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Au(111)-离子液体界面层状结构与温度关联的原位AFM力曲线研究

ISSN号：1006-3471
期刊名称：电化学
时间：2014.8.28
页码：295-301
分类：O646[理学—物理化学;理学—化学]
作者机构：[1]厦门大学固体表面物理化学国家重点实验室,化学化工学院,福建厦门361005
相关基金：国家重点基础研究发展计划（No.2012CB932902）国家自然科学基金项目（No.21033007,No.21021002,No.20973144）资助
相关项目：离子液体表面电化学的微探针和激光－拉曼研究新方法

关键词：电化学界面, 离子液体, Au(111), 双电层, 层状结构, AFM力曲线, 温度影响, interface electrochemistry, ionic liquids, Au（111）, electric double layer structure, layering structure, AFM force curves, temperature dependence

中文摘要：

本文针对BMIPF6和OMIPF6两种离子液体,在电极表面远离零电荷电位且以负电荷表面电位下,运用AFM力曲线详细地研究了其与Au（111）单晶电极界面所形成的层状结构与温度的关联.在15~40oC的温度范围内,温度越低其离子液体层状结构越稳定.温度对OMIPF6离子液体层状结构的稳定性和数目的影响较BMIPF6缓和：温度变化5oC,OMIPF6靠近表面第一层层状结构的力值变化仅为1~2 nN,而BMIPF6第一层层状结构的力值变化为3~5 nN;较低温下,BMIPF6中层状结构的数目有所增加,而OMIPF6的层状数目始终保持两层,且随温度的变化并不敏感.这可归因于两种离子液体的阳离子尺寸以及与电极表面的作用方式和强度不同;同时,OMIPF6较粘稠,其热运动受温度的影响不甚敏感.

英文摘要：

By utilizing in-situ AFM force curve measurements systematic investigations have been carried out on Au（111）-ionic liquid interface in BMIPF6 and OMIPF6 of imidazolium-based ionic liquids with different lengths of alkyl side chains. The temperature dependence of the number, thickness and stability of the layered structures of each system are studied by performing AFM force curve measurements at potentials far negative of the PZC. The layered structures at Au（111 ）/BMIPF6 interface are composed of two charged interior layers and two neutral exterior layers at -1.0 V, while those at Au（111）/OMIPF6 interface only one charged interior layer and one neutral exterior layer at -1.6 V. But there contains only one neutral exterior layer and one charged interior layer. Temperature influence on the layering behaviors of the two kinds of ionic liquid systems is investigated. It is shown that within the temperature range of 15 to 40 ℃, the stability of the layered structures in both BMI＋ and OMI＋ systems increases as temperature decreases because of the reduced thermal perturbation. However, the temperature influence is greater for BMI＋ than for OMI＋ system. Variation of temperature by 5 ℃, the rupture force of the first layer in OMIPF6 changes only 1 - 2 nN at -1.6 V, while that in BMIPF6 changes 1 - 6 nN at -1.0 V. In addition, at low temperatures, the number of the BMIPF6 layered structures increase, while that of OMIPF6 layer structure maintains the same. This difference may be associated with the different molecular sizes that lead to different intermolecular interactions and interactions between the molecule and electrode surface. Meanwhile, OMIPF6 is more viscous than BMIPF6 so that the former could be less sensitive to temperature perturbation.