We use 2D sheets as a material platform to study how ions behave under confinement, and how they can be manipulated by coupling other properties of the sheets.
Electrolytes exhibit drastically different properties when confined in nanochannels. For example, in bulk solution, cations and anions simultaneously move along opposite directions to generate ionic current. However, in channels narrower than the Debye length of the electrolyte, the surface charges on the inner walls repel ions of the same charge and attract the counterions, making them the dominating charge carriers. Such unipolar ionic transport can enhance ionic conductivity up to several orders of magnitudes. Nanofluidic materials and devices provide a platform for the manipulation of confined ions and electrolytes. Such studies provide insights for applications including electrochemical energy conversion and storage, biosensing, and water purification.
Unipolar ionic transport through a nanofluidic channel