Abstract
Membranes with atomic level pores or constrictions are valuable for separation and catalysis. We report a graphene-based membrane with an interlayer spacing of 3.7 angstrom (Å). When graphene oxide nanoplates are functionalized and then reduced, the laminated reduced graphene oxide (rGO) nanoplates or functionalized rGO membrane is little affected by an intercalated fluid, and the interlayer spacing of 3.7 Å increases only to 4.4 Å in wetted state, in contrast to the graphene oxide (GO) membrane whose interlayer spacing increases from 9 Å to 13 Å in wetted state. When applied to ion separation, this membrane reduced the permeation rate of small ions such as K+ and Na+ by three orders of magnitude compared to the GO membrane.
Highlights
With the advent of laminates of graphene oxide (GO) nanoplates as membranes or GO membranes[11,12], membranes of angstrom-range constrictions have become readily accessible and useful because of easy fabrication of the membrane and its robust nature in terms of mechanical strength and flexibility even for submicron-thick films
This GO functionalized by the silylation (EDTA-GO) is reduced with hydrazine to prepare the functionalized reduced graphene oxide (rGO) nanoplates (EDTA-rGO)
These plates of EDTA-GO and EDTA-rGO were dispersed in water (Supplementary Fig. 1), filtered, and vacuum dried on polytetrafluoroethylene (PTFE) membrane, which was used as a support layer, to prepare EDTA-GO and EDTA-rGO membrane, respectively (Supplementary Fig. 2)
Summary
Nanoplates with Angstrom-Level received: February 2016 accepted: May 2016 Published: 16 June 2016. Membranes with angstrom-level pores or constrictions are of particular interest for water purification including desalination[1], for separation of organic mixtures[2] and hydrogen[3], and for genetic and medical diagnostics[4]. We present a membrane based on GO with the interlayer spacing of 3.7 Å that is little affected by intercalated water and demonstrate the utility of the membrane for ion sieving. The relatively high interlayer spacing of GO laminates is mainly due to the presence of functional groups on the basal plane of the nanoplate and on its periphery. The membrane of laminated reduced graphene oxide (rGO) nanoplates or rGO membrane is known to be practically impermeable to water[19]. Be reduced for the purpose of decreasing the interlayer spacing, thereby reducing the spacing while retaining water permeability
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