Thermally Reduced Nanoporous Graphene Oxide Membrane for Desalination

Abstract

Graphene-based laminar membranes open new avenues for water treatment; in particular, reduced graphene oxide (rGO) membranes with high stability in aqueous solutions are gaining increased attention for desalination. However, the low water permeability of these membranes significantly limits their applications. In this study, the water permeability of thermally reduced GO membrane was increased by a factor of 26 times by creating in-plane nanopores with an average diameter of ∼3 nm and a high density of 2.89 × 10¹⁵ m^-2 via H₂O₂ oxidation. These in-plane nanopores provide additional transport channels and shorten the transport distance for water molecules. Meanwhile, salt rejection of this membrane is dominated by both the Donnan effect and the size exclusion of the interspaces. Besides, the water permeability and salt rejection of the thermally reduced nanoporous GO membrane can also be simply tuned by adjusting the thermal treatment time and membrane thickness. Additionally, the fabricated membrane exhibited a relatively stable rejection of Na₂SO₄ during the long-term testing. This work demonstrates a novel and effective strategy for fabricating high-performance laminar rGO membranes for desalination applications.