Engineering of Asymmetric Iontronic Nanopores by Electroporation for Blue Energy Generation

Abstract

Here, we report a comprehensive study on the electroporation mechanism—electric-field assisted perforation of the barrier oxide layer (BOL)—of blind-hole NAA membranes produced under different electrolytes, anodization regimes and potentials. We harness the characteristic iontronic signals of these model systems to establish a rationale for the design of electroporation conditions (i.e., type and concentration of electrolytes, electroporation voltage, etc.) to achieve ~100% electroporation efficiency. Analysis of dynamic ionic current density signals associated with the hopping of cations and anions from the electrolyte across the BOL during electroporation provide valuable insights into the ion-induced breakdown mechanism of the BOL. The resultant NAA membranes with electroporated nanopores are demonstrated as osmotic energy generators when subjected to a salinity gradient, generating a remarkable power output of ~2.9 W m–2 that makes this new class of membranes with unique nanopore architecture a competitive alternative to other state-of-the-art membrane systems. The findings reported here contribute to the fundamental understanding of electroporation in electrolyte–insulator–electrolyte, which has potential to be further extended to similar systems. The unique structural and chemical features of electroporated NAA membranes make them highly attractive for a broad range of applications such as chemo- and biosensing, nanofabrication, energy generation, fluidic computing, and separation processes.

Keywords: Nanoporous Anodic Alumina, Barrier Oxide Layer, Ionic Current Rectification, electroporation, blue Energy