Enhanced ion transport in densified CNT arrays

We investigate ion transport behavior through a densified vertically aligned carbon nanotube (CNT) array. An electrowetting effect induced by applying a voltage across densified CNT arrays (DCNTAs) leads to an increase in the wettability of a high surface tension liquid both in the intertube channels and inner channels of hydrophobic CNTs. We present evidence from thermal gravimetric analysis (TGA) and transmission electron microscopy (TEM), which shows that this electric activation treatment greatly promotes the formation of water channels in DCNTAs. Moreover, the formation of water channels is of importance in improving the overall ion transport rate through DCNTAs. We find that an enhancement in the overall ion transport rate through electrically activated DCNTAs gives rise to a reduction of electrolyte transfer resistance, and the capacitive performance of CNT-based devices is greatly improved as compared to untreated DCNTAs.