Ionic transport through nanoscale geometries such as nanopore clusters and nanochannels has been intensively studied in recent decades. Ionic current rectification is a representative example of transport characteristic induced by nanoscale effects. In ion current rectification, the current for voltages of one polarity are higher compared to that for voltages of the same amplitude but opposite polarity. A high current ionic diode is achieved using an asymmetric anodic aluminum oxide membrane constructed by square pulse anodization. The asymmetric anodic aluminum oxide membrane exhibits high rectified currents without losing a rectification ratio because of its ionic selectivity gradient and differentiated electrical conductance. Asymmetric ionic transport is analyzed with diode-like I−V curves, which is closely correlated with ionic selectivity and ion distribution according to variation of anodic aluminum oxide membrane geometries. The ionic current and rectification ratio could be tuned easily by changing the geometry of the AAOM via square pulse anodization. We believe that much higher ionic currents and rectification ratios can be achieved easily by selecting the proper geometry of the nanochannels. These results have the potential to be extended to exciting applications such as energy conversion, filtration, desalination.

Asymmetric anodic aluminum oxide membrane with high ionic rectification and high currents

2019 Spring National Meeting

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