Graphene Oxide Nanoribbon Hydrogel: Viscoelastic Behavior and Use as a Molecular Separation Membrane

Abstract

The preparation of carbon materials based hydrogels and their viscoelastic properties are essential for their broad application and scale-up. However, existing studies are mainly focused on graphene derivatives and carbon nanotubes, and the behavior of graphene nanoribbon (GNR), a narrow strip of graphene, remains elusive. Herein, we demonstrate the concentration-driven gelation of oxidized GNR (graphene oxide nanoribbon, GONR) in aqueous solvents. Exfoliated individual GONRs sequentially assemble into strings (∼1 mg/mL), nanoplates (∼20 mg/mL), and a macroporous scaffold (50 mg/mL) with increasing concentration. The GONR hydrogels exhibit viscoelastic shear-thinning behavior and can be shear-coated to form large-area GONR films on substrates. The entangled and stacked structure of the GONR film contributed to outstanding nanofiltration performance under high pressure, cross-flow, and long-term filtration, while the precise molecular separation with 100% rejection rate was maintained for sub-nanometer molecules.

Tuning the hierarchical pore structure of graphene oxide through dual thermal activation for high-performance supercapacitor

“…Graphite (particle size 20 μm, 99% pure) was purchased from Sigma Aldrich and used as-received without purification. It was oxidized using a modified Hummer's method 32,33 . The ratio of graphite and KMnO 4 was fixed at 3.5 for all GO preparation procedures.…”

Fabrication Techniques for Graphene Oxide-Based Molecular Separation Membranes: Towards Industrial Application

“…The group in a separate study tested the membrane for OSN application and produced a new scale factor linking permeance to the solvent's viscosity [44]. Choi et al were also able to prepare GONR gels for membrane fabrication through bar coating (Figure 8b) [17]. The GONR gels exceeding 50 mg/mL concentration started to form scaffolds by self-assembly.…”

“…These membranes were used for ion rejection tests and showed high retention of multivalent ions, namely Pb, Ni, Cu, and Mg. [16]. Copyright 2016 Nature Publishing Group; (b) GONR hydrogel membrane fabrication for nanofiltration [17]. Copyright 2020 American Chemical Society; (c) crosslinked, freestanding GO membranes for ion rejection [47].…”

“…The membranes' performance was tested under cross-flow filtration, which marked a rejection rate of 99% for sub-nanometer dye molecules with a high water flux of 30 LMH/bar. Slot-die coaters are unique because well- [17]. Copyright 2020 American Chemical Society; (c) crosslinked, freestanding GO membranes for ion rejection [47].…”

“…This apparent disparity of reported and required preparation processes captures the barrier between GO membranes and their industrial acceptance. Fortunately, there has been a growing consensus on the topic within the field [15][16][17]. As such, recent efforts fueled several investigations utilizing bar-coating, spray coating, and slot-die coating, which are known scalable processes.…”