Ion current rectification in combination with ion current saturation.

Over the decades, nanochannels have been widely used for single molecule detection, smart sensors, and energy transfer and storage based on its unique ion transport properties. Although various ion transport phenomena of nanochannels have been reported, the discovery of new ion transport phenomena is still of great significance for understanding material transport of nanochannels and development of nanodevices with unique working capabilities. This article reports a novel nanochannel ion transport phenomenon - ion current rectification in combination with ion current saturation (ICR-S), which arised from a mesoporous titania conical microplug generated in situ in the glass micropipette tip cavity by space confinement evaporation. The ion current of forward voltage is greater than that of reverse voltage, and the saturation currents appear in both the forward and reverse voltages, the ratio of forward and reverse saturation current can reaches to 10. In addition, the influence of pH, ionic strength, and micropipette angle on ICR-S is also investigated.