Biomimetic Architectured Graphene Aerogel with Exceptional Strength and Resilience

Abstract

Materials combining lightweight, robust mechanical performances, and multifunctionality are highly desirable for engineering applications. Graphene aerogels have emerged as attractive candidates. Despite recent progresses, the bottleneck remains how to simultaneously achieve both strength and resilience. While multiscale architecture designs may offer a possible route, the difficulty lies in the lack of design guidelines and how to experimentally achieve the necessary structure control over multiple length scales. The latter is even more challenging when manufacturing scalability is taken into account. The Thalia dealbata stem is a naturally porous material that is lightweight, strong, and resilient, owing to its architecture with three-dimensional (3D) interconnected lamellar layers. Inspired by such, we assemble graphene oxide (GO) sheets into a similar architecture using a bidirectional freezing technique. Subsequent freeze-drying and thermal reduction results in graphene aerogels with highly tunable 3D architectures, consequently an unusual combination of strength and resilience. With their additional electrical conductivity, these graphene aerogels are potentially useful for mechanically switchable electronics. Beyond such, our study establishes bidirectional freezing as a general method to achieve multiscale architectural control in a scalable manner that can be extended to many other material systems.

Preparation and characterization of partially reduced graphene oxide aerogels doped with transition metal ions

“…The freeze-drying process used here depends on freezing the gel with the remaining liquid and following this process sublimation, which is controlled by decreased pressure above the sample. The prior freezing process can determine the pore structure [23][24][25][26], which will further influence the specific surface area, adsorption [27], mechanical strength, electrical conductivity and magnetic properties [28,29]. Figure 2a presents prGO hydrogels obtained via sol-gel technique.…”

Well‐Aligned Hierarchical Graphene‐Based Electrodes for Pseudocapacitors with Outstanding Low‐Temperature Stability

“…The mold was placed on the surface of liquid nitrogen for 30 min; hence the GO mixture was subjected to two temperature gradients perpendicular to the copper surfaces of the mold (i. e., horizontal and vertical directions). Then ice crystals grew along the temperature gradients and GO sheets accumulated between the ice crystals to form aligned networks . After the GO suspension was completely frozen, the sample was tapped out of the mold and freeze‐dried for 24 h (−80 °C, 10 Pa).…”

“…Then ice crystals grew along the temperature gradients and GO sheets accumulated between the ice crystals to form aligned networks. [43,44,66,67] After the GO suspension was completely frozen, the sample was tapped out of the mold and freeze-dried for 24 h (À 80°C, 10 Pa). The resulting sample was thermally annealed at 200°C for 1 h and 900°C for 2 h under argon atmosphere (500 mL min À 1 ) to obtain GN.…”

Smart Nacre‐inspired Nanocomposites

“…The resultant graphene‐based aerogel shows a porous structure (Figure D) and possesses the capability to translate the strain into change of electrical resistance (Figure E). Yang et al . also reported a graphene aerogel based on bidirectional ice‐templating.…”