Fast water transport and ionic sieving in ultrathin stacked nanoporous 2D membranes.

Atomically thin nanoporous 2D membranes, featuring unique sieving characteristics for molecules and ions, have significant potential for seawater desalination. However, they face a common trade-off between permeability and selectivity. Here, we report an ultrathin stacked nanoporous graphene membrane (SNGM) created by layering atomically thin graphene nanomesh. This design achieves highly efficient and selective sieving of water molecules and ions. The SNGMs showcase in-plane nanopores for optimal size-exclusive water input and output, and interlayer 2D nanochannels between adjacent graphene nanomesh membranes for rapid water transport and precise ion/molecular sieving. The resulting SNGMs effectively address the trade-off between water permeability and ion selectivity in conventional desalination membranes, delivering a water permeability of ∼ 1-2 orders of magnitude higher than that of commercial membranes, while maintaining a comparable ion rejection ratio (>95% for NaCl). This advance marks a significant leap forward in adopting 2D nanoporous membranes for desalination technology.