(232z) Fabrication of pH-Sensitive Ionic Diodes in Highly Ordered Alumina Nanochannel Arrays

Fabrication of current rectification ionic diodes to mimic biological ion channels in cell membranes is of circular significance in the biomimetic application technology. In this study, we fabricate a novel ionic diode device, which comprises highly ordered nanochannels of anodic alumina membrane with heterogeneous surface charge properties by patterning the carboxyl functional groups on one side of nanochannels through silanization process. Several factors key to the system under consideration, such as pH, salt concentration, and pH gradient, were experimentally examined for their influences on the ion current rectification. We find that the magnitude of current rectification depends not only on the solution pH and salt concentration but also on the pHs at different sides of reservoirs. In general, the present ionic diode device exhibits high rectification behavior when the nanochannels have bipolar charges. The findings are informative and provide necessary information for further applications such as nanoscale energy conversion.