(232ad) Ionic Conductance in Alumina Nanochannels: Temperature and pH Effects

Inspired by biological ion channels, nanochannels embedded in a thin alumina membrane have captured much attention of scientists due to their promising applications in energy conversion, ionic diodes, and biosensors. The working principle of these emerging applications is highly related to their ionic current (or conductance) behaviors, which depend on the surface charge property of nanochannels. It is known that the surface charge property of alumina nanochannels is exquisitely dependent on the surface chemistry reaction of dissociable functional groups (e.g., Al-OH) on the channel wall and, therefore, the variation in solution temperature might play a role. Although the relevant studies on the ion transport in alumina nanochannels are ample, the influence of solution temperature has not been discussed so far. Herein, we experimentally investigate the temperature effect on the ionic conductance in alumina nanochannels, which were fabricated by the electrochemical anodic oxidation process. SEM images reveal that the diameter of cylindrical alumina nanochannels we fabricated is about 20-30 nm. Results obtained show that temperature sensitive of nanochannel conductance depends apparently on the levels of pH and salt concentration, which provides useful information for the design of ionic devices used in temperature sensitive applications such as ionic diodes and gates.