Aprotic solvent accumulation amplifies ion current rectification in conical nanopores Emer Farrell, Dominik Duleba, Robert P. Johnson University College Dublin, Ireland Electrochemical phenomena in asymmetric glass nanopores, including ion current rectification (ICR), are highly reported in aqueous electrochemical systems and sensors, 1, 2 but lack exploration in organic systems, due to the additional complexity introduced through the use of aprotic solvents. ICR in aprotic electrolyte reportedly arises due to the formation of an effective positive surface charge, through solvent dipole alignment on the nanopore surface. 3, 4 Inspired by prior reports, we present a detailed experimental and theoretical study on rectification ratio (RR) as a function of electrolyte concentration in highly polar and mildly polar organic electrolyte. 5 To explain our surprising experimental results, we present a novel phenomenon: the formation of a double-junction diode inside the nanopore due to solvent enrichment/depletion effects. 5 Understanding the complex ion transport processes that arise in aprotic nanopore systems is essential in the development of nanopore sensors which can operate in organic solvents, facilitating a wider range of industrial applications than that for which such aqueous sensors are currently developed. 2
References 1. D. Duleba, P. Dutta, S. Denuga and R. P. Johnson, ACS Meas. Sci. Au , 2022, 2 , 271-277. 2. D. Duleba and R. P. Johnson, Curr. Opin. Electrochem. , 2022, 34 , 100989.
3. T. Plett, W. Q. Shi, Y. H. Zeng, W. Mann, I. Vlassiouk, L. A. Baker and Z. S. Siwy, Nanoscale , 2015, 7 , 19080-19091. 4. X. H. Yin, S. D. Zhang, Y. T. Dong, S. J. Liu, J. Gu, Y. Chen, X. Zhang, X. H. Zhang and Y. H. Shao, Anal. Chem. , 2015, 87 , 9070-9077. 5. E. B. Farrell, D. Duleba and R. P. Johnson, J. Phys. Chem. B , 2022, 126 , 5689-5694.
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