Ionic Current Rectification in Nanopores: Effects of Nanopore Material, Electrolyte and Surface Treatment

Ionic Current Rectification (ICR) can appear in nanopores, causing a diode-like behavior that originates from different efficiency of ion transport through the pore channel with respect to the applied voltage bias polarity. This effect is particularly interesting for nanopores with a short channel length, that is smaller than 500 nm, because then the dependence of the ion current on the direction along which the ions pass through the channel is determined by the geometry and material of the nanopore, and by the ion concentration in the electrolyte. Surface charges can play an important role, and therefore nanopores consisting of multiple materials can induce ICR because of different charge distributions at the nanopore-electrolyte interface for the different material sections. In this work, we study four solid-state nanopore designs considering different geometries of charge distributions along the inner and outer surfaces of nanopores, and evaluate their impact on ICR with six different electrolytes. The direct comparison between experimental data and modeling enables to understand how the different surface charge configurations impact the ICR.