Permeability and Selectivity of Silicon-Passivated Graphene Nanopores

Graphene has the appearance of an atomically thin filter, but it has been shown to be highly impermeable by even single atoms in its perfect form. Selective permeability can be achieved by introducing multivacancy defects. Recent experiments used silicon atoms to stabilize large multivacancies, fabricating “silicon-passivated graphene nanopores”. In this work, we investigated the permeability and selectivity of the defect V₁₀-Si₄ (10 carbon vacancies, 4 silicon atoms), using density-functional theory to calculate energy barriers for the transport of atoms and molecules through the center of the defect. We found a transport mechanism for lithium ions (barrier: 1.35 eV) and determined that H₂ would pass through (barrier: 1.51 eV) while other molecules that may be created during H₂ formation, like CO, would not. The energy barriers are high enough that transport of lithium ions and H₂ will only occur at 200-300 °C temperatures.

This work was performed as an NSF summer REU project.