Chaotropic Monovalent Anion‐Induced Rectification Inversion at Nanopipettes Modified by Polyimidazolium Brushes |
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| Authors: | Dr Xiulan He Kailin Zhang Yang Liu Dr Fei Wu Prof Ping Yu Prof Lanqun Mao |
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| Institution: | 1. Beijing National Laboratory for Molecular Sciences, Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, the Chinese Academy of Sciences (CAS), Beijing, China;2. University of Chinese Academy of Sciences, Beijing, China |
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| Abstract: | A nonintuitive observation of monovalent anion‐induced ion current rectification inversion at polyimidazolium brush (PimB)‐modified nanopipettes is presented. The rectification inversion degree is strongly dependent on the concentration and species of monovalent anions. For chaotropic anions (for example, ClO4?), the rectification inversion is easily observed at a low concentration (5 mm ), while there is no rectification inversion observed for kosmotropic anions (Cl?) even at a high concentration (1 m ). Moreover, at the specific concentration (for example, 10 mm ), the variation of rectification ratio on the type of anions is ranged by Hofmeister series (Cl?≥NO3?>BF4?>ClO4?>PF6?>Tf2N?). Estimation of the electrokinetic charge density (σek) demonstrates that rectification inversion originates from the charge inversion owing to the over‐adsorption of chaotropic monovalent anion. To qualitatively understand this phenomenon, a concentration‐dependent adsorption mechanism is proposed. |
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| Keywords: | Hofmeister series ionic transport polyelectrolyte brushes rectification inversion solid nanochannels |
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