Large-range Control of the Microstructures and Properties of Three-dimensional Porous Graphene

Abstract

Graphene-based three-dimensional porous macrostructures are believed of great importance in various applications, e.g. supercapacitors, photovoltaic cells, sensors and high-efficiency sorbents. However, to precisely control the microstructures and properties of this material to meet different application requirements in industrial practice remains challenging. We herein propose a facile and highly effective strategy for large-range tailoring the porous architecture and its properties by a modified freeze casting process. The pore sizes and wall thicknesses of the porous graphene can be gradually tuned by 80 times (from 10 to 800 μm) and 4000 times (from 20 nm to 80 μm), respectively. The property experiences the changing from hydrophilic to hydrophobic, with the Young's Modulus varying by 15 times. The fundamental principle of the porous microstructure evolution is discussed in detail. Our results demonstrate a very convenient and general protocol to finely tailor the structure and further benefit the various applications of porous graphene.

Three-dimensionally bonded spongy graphene material with super compressive elasticity and near-zero Poisson’s ratio

“…1a). Following a slow exchange of ethanol with water, the sponge is freeze-dried and then annealed under inert atmosphere at 400°C to obtain the final graphene sponge 15 (Fig. 1b).…”

Recent Progress in Multifunctional Graphene Aerogels

“…Importantly, GAs dried using the former technique support more weight, having larger surface area and pore volume, and higher electrical conductivity than those of freeze-dried GAs. Actually, the ice crystals formed during the freezing process are responsible for reducing the properties of GAs, although freezing temperature is also a significant parameter in controlling the porous structures and properties of GAs (Xie et al, 2013).…”

“…The morphology and mechanism of the formation of super-elastic GA, along with compressive stress-strain curves and change to resistance upon 50% compression, are shown in Figure 8. Using the concept of directional freeze-drying of partially reduced graphene oxide (PrGO) aqueous suspension, several GAs have been prepared (He et al, 2013a,b;Xie et al, 2013).…”

Three-Dimensional Porous Architectures of Carbon Nanotubes and Graphene Sheets for Energy Applications

“…Direct gelation of GO dispersion into porous bulk structures can be achieved by freeze-drying and hydrothermal methods (Jiang et al, 2010;Xu et al, 2010;Sun et al, 2014). Recently, Xie et al (2013) devised a modified freeze casting process. They found that the microstructures and properties of the resulting porous graphene aerogel can be widely adjusted by the freezing temperature.…”

“…Liquid nitrogen freezing confers the as-synthesized aerogel an isotopic and highly elastic structure. Wan et al covalently cross-linked GO sheets into a monolith by conjugating the epoxy groups on GO with amine groups of a gelating polymer via ring opening reaction (Xie et al, 2013). The obtained GO hydrogel is highly elastic and can be easily converted into reduced GO (rGO) hydrogel via thermal treatment.…”