“Network-trapped engineering” of graphene oxide membrane with stable structure

Graphene oxide (GO) membranes are considered ideal candidates for efficient water treatment due to their unique two-dimensional structure and excellent sieving properties. However, the swelling of graphene oxide in aqueous solutions makes it still challenging for practical application. Inspired by the spider web, in this work, we developed a “network-trapped engineering” strategy to stabilize the interlayer spacings of GO membranes, which are defined as GS-Sr membranes. The sodium alginate (SA) and Sr²⁺ were successfully fixed as the “network” and “rivets” in-between the GO nanosheets, respectively. Benefiting from the design of the network structure, the GS-Sr membranes exhibited excellent interlayer spacing stability. Meanwhile, this evenly distributed network structure in the GO laminates can further optimize the stacking of nanosheets, forming more orderly 2D confined nanochannels. As a result, the membranes exhibited superior salt/dye sieving performance, with a separation factor up to 179.13 for Na₂SO₄/CR, while still maintaining an outstanding water permeance of 70.14 L m⁻² h⁻¹ bar⁻¹. Furthermore, the GS-Sr membrane demonstrated stable separation performance in the long-term test, and the mechanical stability has also been enhanced in the mechanical test. Overall, compared with traditional simple cross-linking strategies, this strategy offers a new insight into fine-construction of two-dimensional nanochannels.