Resolving fine structures of the electric double layer of electrochemical interfaces in ionic liquids with an AFM tip modification strategy

Yun-Xin Zhong; Jia-Wei Yan; Mian-Gang Li; Xiao Zhang; Ding-Wen He; Bing-Wei Mao

doi:10.1021/ja508222m

Resolving fine structures of the electric double layer of electrochemical interfaces in ionic liquids with an AFM tip modification strategy

J Am Chem Soc. 2014 Oct 22;136(42):14682-5. doi: 10.1021/ja508222m. Epub 2014 Oct 10.

Authors

Yun-Xin Zhong¹, Jia-Wei Yan, Mian-Gang Li, Xiao Zhang, Ding-Wen He, Bing-Wei Mao

Affiliation

¹ State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen 361005, China.

PMID: 25291430
DOI: 10.1021/ja508222m

Abstract

We report enhanced force detection selectivity based on Coulombic interactions through AFM tip modification for probing fine structures of the electric double layer (EDL) in ionic liquids. When AFM tips anchored with alkylthiol molecular layers having end groups with different charge states (e.g., -CH3, -COO(-), and -NH3(+)) are employed, Coulombic interactions between the tip and a specified layering structure are intensified or diminished depending on the polarities of the tip and the layering species. Systematic potential-dependent measurements of force curves with careful inspection of layered features and thickness analysis allows the fine structure of the EDL at the Au(111)-OMIPF6 interface to be resolved at the subionic level. The enhanced force detection selectivity provides a basis for thoroughly understanding the EDL in ionic liquids.