"Network-Trapped Enginnering" of Graphene Oxide Membrane with Stable Structure

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Abstract
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 62.61 L m-2 h-1 bar-1 over 72 h (3 days). Furthermore, the enhanced thermal and mechanical stability of GS-Sr membrane was confirmed. Compared with traditional simple cross-linking strategies, this strategy offers a new insight into fine- construction of two-dimensional nanochannels.