Preparation of a macroporous flexible three dimensional graphene sponge using an ice-template as the anode material for microbial fuel cells

Abstract

A simple and effective method for the fabrication of a flexible macroporous 3D graphene sponge using an ice template is developed in this work. It was found that the porous structures of the 3D graphene architecture depended on the rate of ice crystal formation. At a low cooling rate, the inner walls of the graphene hydrogel were re-assembled into a hierarchical macroporous structure by the as-formed ice crystals, resulting in the formation of a macroporous graphene sponge after freeze-drying. The as-prepared graphene sponge was flexible and could recover from a 50% deformation. When the graphene sponge was used as the anode of a microbial fuel cell (MFC), the maximum power density reached 427.0 W m⁻³, which was higher than that of the MFC fabricated using carbon felt as the anode material. The macroporous structure of the graphene sponge ensured the microbes more easily diffused and propagated inside the materials, resulting in higher MFC performance.