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Probing Electrified Ionic Liquid-Solid Interface Using Long-Needle AFM

Pengcheng Nie^1,2, Xikai Jiang¹, Xu Zheng¹, Dongshi Guan^1,2,*

1 State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190, China
2 School of Engineering Science, University of Chinese Academy of Sciences, Beijing, 100049, China

* Corresponding Author: Dongshi Guan. Email:

The International Conference on Computational & Experimental Engineering and Sciences 2023, 25(1), 1-2. https://doi.org/10.32604/icces.2023.09838

Abstract

“How can we measure interface phenomena on the microscopic level” is a fundamental question that has been with us for many years and is also listed in recent Science 125 question. It is even harder to explore the electrified interface. In this work, we report atomic-force-microscope measurements of interfacial dynamics of an electrified room-temperature ionic liquid (RTIL)-solid interface. RTILs are intriguing fluids that have drawn much attention in applications ranging from tribology and catalysis to energy storage. With strong electrostatic interaction between ions, their interfacial behaviors can be modulated by controlling energetics of the electrified interface. Using a unique long-needle AFM technique [1-4], we measure contact angle hysteresis (CAH) of a circular contact line formed on a micron-sized fiber, which is coated with a thin layer of conductive film and intersects a RTIL-air interface. The measured CAH shows a distinct transition by increasing the voltage applied on the fiber surface. Molecular dynamics simulations were performed to illustrate variations of the solid-like layer in the RTIL adsorbed at the electrified interface. The integrated experiments and computations demonstrate a new mechanism to manipulate the CAH by rearrangement of interfacial layers of RTILs induced by the surface energetics.

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