A Controllable Self‐Assembly Method for Large‐Scale Synthesis of Graphene Sponges and Free‐Standing Graphene Films

Abstract

A simple method to prepare large‐scale graphene sponges and free‐standing graphene films using a speed vacuum concentrator is presented. During the centrifugal evaporation process, the graphene oxide (GO) sheets in the aqueous suspension are assembled to generate network‐linked GO sponges or a series of multilayer GO films, depending on the temperature of a centrifugal vacuum chamber. While sponge‐like bulk GO materials (GO sponges) are produced at 40 °C, uniform free‐standing GO films of size up to 9 cm2 are generated at 80 °C. The thickness of GO films can be controlled from 200 nm to 1 µm based on the concentration of the GO colloidal suspension and evaporation temperature. The synthesized GO films exhibit excellent transparency, typical fluorescent emission signal, and high flexibility with a smooth surface and condensed density. Reduced GO sponges and films with less than 5 wt% oxygen are produced through a thermal annealing process at 800 °C with H2/Ar flow. The structural flexibility of the reduced GO sponges, which have a highly porous, interconnected, 3D network, as well as excellent electrochemical properties of the reduced GO film with respect to electrode kinetics for the [Fe(CN)6]3−/4− redox system, are demonstrated.

Graphene–Biomineral Hybrid Materials

“…The formation of CaCO 3 vaterite microspheres in the presence of GO sheets is attributed to the residing functional groups of GO sheets, such as hydroxyl, epoxy, carboxylic acid, and other carbonyl groups, [27][28][29] that can favorably interact with Ca 2 + in vaterite and further prevent the dissolution of vaterite and its recrystallization to calcite. In particular, carboxylic moieties and hydroxyl groups of GO sheets should induce the formation of the vaterite phase, as their ionization results in a negatively charged surface [ 30 ] that can associate with Ca 2 + by electrostatic interaction, which should further hinder the dissolution-recrystallization process of vaterite to calcite.…”

Self‐Assembly and Embedding of Nanoparticles by In Situ Reduced Graphene for Preparation of a 3D Graphene/Nanoparticle Aerogel

“…[3][4][5] It is believed that developing 3D structures of graphene will further expand its signifi cance in applications. [6][7][8][9] The methods for the preparation of 3D graphene structure have attracted much attention and some of them are the compositions of graphene and polymers [10][11][12][13] or carbon nanotubes. [ 14 , 15 ] Recently, we developed a simple method to prepare an all-graphene hydrogel via in situ self-assembly of graphene prepared by a mild chemical reduction at 95 ° C under atmospheric pressure without stirring.…”

The New Graphene Family Materials: Synthesis and Applications in Oxygen Reduction Reaction

“…Moreover, the mass production of GO can be achieved by the modification of Hummers' method from inexpensive graphite. Ample techniques, such as chemical reduction [84], electrochemical reduction [85], hydrothermal reduction [29], the dip coating method [30], the sol-gel method [31], the metal ion induced self-assembly process [86] and vacuum centrifugation [87], could be used to build 3D-G. Generally, the assembly of GO contains the following procedures. First, GO is uniformly dispersed in aqueous solution due to the electrostatic repulsion effect and hydrophilicity; then, GOs were treated with various reduction procedures to become more hydrophobic.…”