Fig. 4: Ion selectivity measurements.
From: High proton conductivity through angstrom-porous titania
a Examples of I–V characteristics for HCl, KCl and LiCl (color coded). Bottom inset, zoom-in. Top inset, schematic of the experimental setup. b Example of I–V characteristics in the drift-diffusion experiments using HCl in concentrations 0.1 and 1 M as illustrated in the bottom inset. The blue arrow indicates the membrane potential of ~59 mV that corresponds to the perfect proton selectivity with respect to Cl ions. c Concentration dependences using HCl dissolved in H2O and DCl in D2O (color coded). Symbols, data taken in 5 different measurements with the error bars indicating SD (shown if larger than the symbols). Solid lines, best linear fits at high concentrations. Also shown are σ for LiCl and KCl solutions at different concentrations and for deionized water (color coded). d Conductivities for various 0.1 M salt solutions (color coded; SD were less than 40% of all the solutions). The gray areas in (c, d) mark our detection limit because of leakage currents. Blue areas, σ measured using deionized water.
