posted on 2020-03-24, 17:03authored byPo-Hsien Peng, Hsing-Chiao Ou Yang, Pei-Ching Tsai, Li-Hsien Yeh
Mesoscale ionic diodes,
which can rectify ionic current at conditions
at which their pore size is larger than 100 nm and thus over 100 times
larger than the Debye length, have been recently discovered with potential
applications in ionic circuits as well as osmotic power generation.
Compared with the conventional nanoscale ionic diodes, the mesoscale
ionic diodes can offer much higher conductance, ionic current resolution,
and power generated. However, the thermal response, which has been
proven playing a crucial role in nanofluidic devices, of the mesoscale
ionic diode remains significantly unexplored. Here, we report the
thermal dependence of the mesoscale ionic diode comprising a conical
pore with a tip opening diameter of ∼400 nm. To capture its
underlying physics more accurately, our model takes into account the
practical equilibrium chemistry reaction of functional carboxyl groups
on the pore surface. Modeling results predict that in the mesoscale
ionic diode prepared currents increase but the performance decreases
with the increase of temperature, which is consistent with our experimental
data and indicates that the ion transport properties apparently depend
on the presence of highly mobile hydroxide ions. The results gathered
can provide important guidance for the design of new mesoscale ionic
diodes, enriching their applications in thermoelectric power and thermoresponsive
chemical sensors.