Ice-templated hybrid graphene oxide—graphene nanoplatelet lamellar architectures: tuning mechanical and electrical properties

Abstract

The traditional freeze-casting route for processing graphene-based aerogels is generally restricted to aqueously dispersed flakes of graphene oxide (GO) and post-processing reduction treatments, which brings restrictions to the aerogels electrical properties. In this work, we report a versatile aqueous processing route that uses the ability of GO todisperse graphene nanoplatelets (GNP) to produce rGO-GNP lamellar aerogels via unidirectional freeze-casting. In order to optimise the properties of the aerogel, GO-GNP dispersions were partially reduced by L-ascorbic acid prior to freeze-casting to tune the carbon and oxygen (C/O) ratio. The aerogels were then heat treated after casting to fully reduce the GO. The chemical reduction time was found to control the microstructure of the resulting aeorgels and thus to tune their electrical and mechanical properties. An rGO-GNP lamellar aerogel with density of 20.8±0.8 mg cm −3 reducing using a reduction of 60 min achieved an electrical conductivity of 42.3 S m −1 . On the other hand, an optimal reduction time of 35 min led to an aerogel with compressive modulus of 0.51 ±0.06 MPa at a density of 23.2±0.7 mg cm −3 , revealing a compromise between the tuning of electrical and mechanical properties. We show the present processing route can also be easily applied to produce lamellar aerogels on other graphene-based materials such as electrochemically exfoliated graphene.

Analysis of Thermoelectric Energy Harvesting with Graphene Aerogel-Supported Form-Stable Phase Change Materials

“…To enhance both the thermal conductivity and mechanical property of the graphene aerogel, graphene nano-platelet (GNP) is selected as a filler to construct a three-dimensional hybrid porous skeleton. Graphene aerogel is obtained by the reduction of graphene oxide (GO) aerogel and GO aerogel is produced by the freeze-drying method, which evaporates the whole solvent of the GO aqueous solution [ 41 , 42 ]. According to the mass ratio between GO and GNP, reduced-graphene oxide aerogels (rGO/GNP structures)-supported PCM composites exhibit higher thermal conductivities.…”