Structure-Based Selective Adsorption of Graphene on a Gel Surface: Toward Improving the Quality of Graphene Nanosheets

Abstract

Top-down graphene production via exfoliation from graphite produces a mass of graphene with structural variation in terms of the number of layers, sheet size, edge type, and defect density. All of these characteristics affect its electronic structure. To develop useful applications of graphene, structural separation of graphene is necessary. In this study, we investigate the adsorption behavior of different types of graphene fragments using a multicolumn gel chromatography system with a view to developing an efficient method for separating high-quality graphene. The graphene was dispersed in an aqueous sodium dodecyl sulfate (SDS) surfactant solution and flown through allyl-dextran-based gel columns connected in series. In the chromatographic operation, we observed that the small-sized or oxidized graphene fragments tended to bind to the gel and the relatively large-sized graphene with a low oxygen content eluted from the gel column. In this system, the adsorbed SDS molecules on the graphitic surface prevented graphitic materials from binding to the gel and the oxygen functional groups on the graphene oxide or at the abundant edge of small-sized graphene hindered SDS adsorption. We hypothesize that the reduced SDS adsorption density results in the preferential adsorption of small-sized or oxidized graphene fragments on the gel. This type of chromatographic separation is a cost-effective and scalable method for sorting nanomaterials. The structural separation of graphene based on the adsorption priority found in this study will improve the quality of graphene nanosheets on an industrial scale.

Graphene: A future science material for water treatment

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Layer-Controlled Synthesis of a Silanol–Graphene Oxide Nanosheet Composite Forward Osmosis Membrane by Surface Self-Assembly

“…Graphene, owing to its unique two-dimensional monolayer structure, has attracted the attention of researchers and exhibits many interesting potential applications. In particular, graphene oxide (GO) nanosheets bearing carboxyl, hydroxyl, and other oxygen-containing groups offer extraordinary potential for preparing functional nanocomposite materials with strong hydrophilicities and excellent retention performance of organic dyes. − Due to these advantages, graphene has great possible applications in the field of water treatment. Some researchers found that the nanometer-scale pores in a single-layer freestanding graphene could effectively filter NaCl salt from water, and that ability was critically dependent on the pore diameter, with adequately sized pores allowing water molecules to pass while blocking ions. , It was found that by controlling the pore sizes and functional groups on the nanopores, a monolayer graphene membrane is extraordinarily useful for desalination .…”