@article{Molecular:10125,
      recid = {10125},
      author = {Hoenig, Eli},
      title = {Ionic and Molecular Transport in 2D Material Membranes},
      publisher = {University of Chicago},
      school = {Ph.D.},
      address = {2023-12},
      pages = {116},
      abstract = {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. Nanofluidic devices made from two-dimensional  materials are also excellent testing grounds for complex  models of interfacial water structure and confined ionic  and molecular transport; they have lead to striking  advances in our understanding of solid liquid interactions.  Here we present two new devices, based on the  two-dimensional material molybdenum disulfide (MoS2), that  allow us to achieve Å-scale control of ionic and molecular  transport. 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. 

We divide our work into four  chapters: in Chapter 2, we present a method to control the  interlayer spacing of layered MoS2 membranes. By covalently  functionalizing MoS2 monolayers with small molecular  pillars, we expand the height of the interlayer gallery  from effectively 0 to ∼ 0.6 Å. We show how not only the  size but also the chemistry of the functional group  determines membrane structure. In Chapter 3, we show how  these films can be used to sieve ions from water, and even  one ion from another. Using molecular dynamics simulations,  we reveal the effect of water layering on the structure of  the membranes. In Chapter 4, we present a new procedure for  the fabrication (sub)nm pores in few-layer MoS2 membranes  in situ. We find that the grain-boundaries in  polycrystalline films are excellent nucleation points for  electrochemical pore creation. Finally, in Chapter 5, we  show how these pores act as ionic sieves, and can  differentiate not only monovalent from divalent ions, but  also monovalent ions from other from monovalent ions. By  comparing transport measurements to molecular dynamics  simulations, we show how water dynamics, along with other  factors, underlie the separation mechanism.},
      url = {http://knowledge.uchicago.edu/record/10125},
      doi = {https://doi.org/10.6082/uchicago.10125},
}