Ultra-light and elastic graphene foams with a hierarchical structure and a high oil absorption capacity

Abstract

Graphene foams (GFs) have attracted increasing attention because they combine the unique properties of cellular materials and the excellent performance of graphene. The preparation of GFs depends mainly on the self-assembly of graphene or graphene oxide sheets, and designing and controlling the cell morphology of GFs, which determines their properties, remain a challenge. Here, we report a novel strategy for preparing GFs with a hierarchical porous structure. Our preparation method involves mechanically foaming a graphene oxide dispersion with the assistance of a surfactant, followed by lyophilization and thermal reduction. These novel GFs possess large cells created using the bubbles as templates and small pores around the edges of the cells resulting from the self-assembly of the graphene oxide sheets. Because of their unique cell structure, the GFs exhibit an ultra-low density, high porosity, good electrical conductivity, and excellent elasticity. In particular, these GFs exhibit a very large absorption capacity (600–1500 g g⁻¹) for oils and organic solvents. Our work explores a new strategy for controlling the cell morphology and improving the performance of GFs; the results may shed new light on the relationship between the structure and properties of 3D graphene assemblies.