Fig. 3. (a) The I–V curves of the nanochannel modified with C4DY; (b) I–V curves of the C4CE nanochannel in an electrolyte of 0.1 M KCl and 0.05 M Tris–HCl (pH = 7.0) in the presence of 1 mM F–, Cl–, Br–, I–, HSO3–, OAC–, NO2–, HCO3–, and ClO4–; (c) histogram of the ionic current change ratios ((I – I0)/I0) at –2 V after adding the above ions to the original channel, the C4DY channel, and the C4CE channel; (d) the change in R-/+ of the C4CE channel in the presence of different concentrations of the respective ions. These results indicated that the C4CE nanochannel was selectively responsive to F–.
