Breakdown of the Nernst-Einstein relation in carbon nanotube porins

Zhongwu Li; Rahul Prasanna Misra; Yuhao Li; Yun-Chiao Yao; Sidi Zhao; Yuliang Zhang; Yunfei Chen; Daniel Blankschtein; Aleksandr Noy

doi:10.1038/s41565-022-01276-0

Breakdown of the Nernst-Einstein relation in carbon nanotube porins

Nat Nanotechnol. 2023 Feb;18(2):177-183. doi: 10.1038/s41565-022-01276-0. Epub 2022 Dec 30.

Authors

Zhongwu Li^#^{1

2

3}, Rahul Prasanna Misra^#⁴, Yuhao Li¹, Yun-Chiao Yao^{1

5}, Sidi Zhao^{1

6}, Yuliang Zhang¹, Yunfei Chen², Daniel Blankschtein⁷, Aleksandr Noy^{8

9}

Affiliations

¹ Materials Science Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA.
² Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing, China.
³ School of Mechatronic Engineering, China University of Mining and Technology, Xuzhou, China.
⁴ Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
⁵ School of Natural Sciences, University of California Merced, Merced, CA, USA.
⁶ School of Engineering, University of California Merced, Merced, CA, USA.
⁷ Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA. dblank@mit.edu.
⁸ Materials Science Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA. noy1@llnl.gov.
⁹ School of Natural Sciences, University of California Merced, Merced, CA, USA. noy1@llnl.gov.

^# Contributed equally.

PMID: 36585518
DOI: 10.1038/s41565-022-01276-0

Abstract

For over 100 years, the Nernst-Einstein relation has linked a charged particle's electrophoretic mobility and diffusion coefficient. Here we report experimental measurements of diffusion and electromigration of K⁺ ions in narrow 0.8-nm-diameter single-walled carbon nanotube porins (CNTPs) and demonstrate that the Nernst-Einstein relation in these channels breaks down by more than three orders of magnitude. Molecular dynamics simulations using polarizable force fields show that K⁺ ion diffusion in CNTPs in the presence of a single-file water chain is three orders of magnitude slower than bulk diffusion. Intriguingly, the simulations also reveal a disintegration of the water chain upon application of electric fields, resulting in the formation of distinct K⁺-water clusters, which then traverse the CNTP at high velocity. Finally, we show that although individual ion-water clusters still obey the Nernst-Einstein relation, the overall relation breaks down because of two distinct mechanisms for ion diffusion and electromigration.

Abstract

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