FIG. 3. Selectivity of graphene pores.

The selectivity, I_K/I_Cl, is at an applied bias of 1 V, although the permeation rates should follow similar trends. Selectivity increases as pore radius decreases and when the number of layers increases. Trilayer graphene with r_p = 0.34 nm gives a similar selectivity as monolayer graphene with r_p = 0.21 nm. Moreover, if only ion filtration is of interest, then these two pore sizes can be exchanged. For bi- and tri-layer graphene, we use Eq. 4 for r_p = 0.21 nm, as the currents are too small to reliably determine computationally. Those points have a dashed line connecting them to the remaining plot. The error bars are ± 1 block standard error (BSE).