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Selective Ionic Transport through Tunable Subnanometer Pores in Single-Layer Graphene Membranes

2014; American Chemical Society; Volume: 14; Issue: 3 Linguagem: Inglês

10.1021/nl404118f

1530-6992

Sean C. O’Hern, Michael S. H. Boutilier, Juan Carlos Idrobo, Yi Song, Jing Kong, Tahar Laoui, Muataz Ali Atieh, Rohit Karnik,

Membrane Separation Technologies

We report selective ionic transport through controlled, high-density, subnanometer diameter pores in macroscopic single-layer graphene membranes. Isolated, reactive defects were first introduced into the graphene lattice through ion bombardment and subsequently enlarged by oxidative etching into permeable pores with diameters of 0.40 ± 0.24 nm and densities exceeding 10(12) cm(-2), while retaining structural integrity of the graphene. Transport measurements across ion-irradiated graphene membranes subjected to in situ etching revealed that the created pores were cation-selective at short oxidation times, consistent with electrostatic repulsion from negatively charged functional groups terminating the pore edges. At longer oxidation times, the pores allowed transport of salt but prevented the transport of a larger organic molecule, indicative of steric size exclusion. The ability to tune the selectivity of graphene through controlled generation of subnanometer pores addresses a significant challenge in the development of advanced nanoporous graphene membranes for nanofiltration, desalination, gas separation, and other applications.