PME Thesis Defense: Eli Hoenig- Liu Group

Ionic and Molecular Transport in 2D Material Membranes

Two-dimensional materials represent a new class of membranes for water-ion and ion-ion separations. With careful tuning, two-dimensional materials can form the basis of highly selective and efficient membranes for water decontamination, energy generation, and even biological sensing. Here we present two new devices, based on the two-dimensional material molybdenum disulfide (MoS2) that allow us to control ionic and molecular transport at the nanometer scale. We both demonstrate that MoS2 membranes are practical ionic and molecular sieves, as well as reveal new transport phenomena for aqueous systems under nanometer-scale confinement. First, we present a method to control the interlayer spacing of layered MoS2 membranes. By covalently functionalizing monolayers with small molecular pillars, we expand the height of the interlayer gallery, allowing penetration of small molecular and ionic species. We show how the size and chemistry of the functional group determines membrane structure. Next, we present a new procedure for the fabrication of (sub)nm pores in few-layer MoS2 membranes in-situ, and show how these pores act as ionic sieves, differentiating ions based on size and charge. By comparing transport measurements to molecular dynamics simulations, we show how water dynamics, along with other factors, underlie the separation mechanism.

Zoom: https://uchicago.zoom.us/j/95707774205?pwd=czBjTUpvc0JRaUJxS2VTT1lHMEp4QT09