Cihan Ebru, Janiszewska Natalia, Awsiuk Kamil, Gao Qingwei, An Rong, Berkovich Ronen, Gnecco Enrico
Institute for Materials Science and Max Bergmann Center for Biomaterials, TU Dresden, Dresden 01069, Germany.
Marian Smoluchowski Institute of Physics, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Krakow 30348, Poland.
Langmuir. 2025 Jun 10;41(22):13793-13799. doi: 10.1021/acs.langmuir.5c00163. Epub 2025 May 30.
We have investigated the evolution of freshly cleaved NaCl(100) and KCl(100) surfaces exposed to the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF) and repeatedly scraped using atomic force microscopy (AFM). The response of the two surfaces to the IL is completely different. On NaCl, the cleavage step edges are slightly eroded, and the surface is progressively smoothed by the AFM tip. These changes are accompanied by a continuous increase in the friction force. On KCl, a dramatic dissolution of the surface is observed immediately after bringing it into contact with the IL. The surface is then smeared along the fast scan direction in the area scratched by the tip and even beyond. An increase in the friction force is also observed but only in the beginning of the surface modification process. Crystallites (∼100-200 nm in size) are observed all over the unscratched areas of KCl but not of NaCl. This result is supported by molecular dynamics simulations and Raman spectroscopy, which indicate a much stronger interaction of the IL with the KCl surface and, respectively, the formation of a BMIM-PF solid phase on it. The analysis performed on the model systems presented here could be extended to other ionic crystal surfaces in contact with ILs, the possible degradation of which must be evaluated in view of their use in catalysis and energy storage applications.
我们研究了新解理的NaCl(100)和KCl(100)表面在暴露于离子液体（IL）1-丁基-3-甲基咪唑六氟磷酸盐（BMIM-PF）并使用原子力显微镜（AFM）反复刮擦后的演变情况。这两种表面对离子液体的响应完全不同。在NaCl上，解理台阶边缘略有侵蚀，并且表面被AFM针尖逐渐平滑。这些变化伴随着摩擦力的持续增加。在KCl上，与离子液体接触后立即观察到表面的剧烈溶解。然后，在针尖刮擦的区域甚至更远的区域，表面沿快速扫描方向被涂抹。也观察到摩擦力增加，但仅在表面改性过程开始时。在KCl的未刮擦区域到处都观察到微晶（尺寸约为100-200 nm），而在NaCl上则没有。分子动力学模拟和拉曼光谱支持了这一结果，这表明离子液体与KCl表面的相互作用更强，并且分别在其上形成了BMIM-PF固相。在此呈现的模型系统上进行的分析可以扩展到与离子液体接触的其他离子晶体表面，鉴于它们在催化和能量存储应用中的使用，必须评估其可能的降解情况。
