Novelly developed three-dimensional carbon scaffold anodes from polyacrylonitrile for microbial fuel cells

Performance and cost of anodes are two important aspects limiting the power output of microbial fuel cells (MFCs) for practical applications. Novel three-dimensional (3D) open-celled carbon scaffold (CS and CS-GR) anodes were prepared by carbonizing the microcellular polyacrylonitrile (PAN) and PAN/graphite composites (PAN-GR), which were obtained by means of foaming by using supercritical carbon dioxide (Sc-CO2) as a physical foaming agent. The two anodes as well as the conventional carbon felt anode were assembled in MFCs based on Escherichia coli (E. coli). The improved performance of the CS anode is ascribed to the remaining -C=N group resulting in considerably improved hydrophilicity and biocompatibility after carbonization and the 3D open-celled scaffold structure contributing to the substrate transfer and internal colonization of E. coli bacteria. Meanwhile, the superior performance of the CS-GR anode is mainly attributed to the increased specific surface area and active reaction area resulting from the addition of graphite. This work provides an effective method to develop a 3D open-celled biocompatible CS-GR anode, which facilitates the extracellular electron transfer for high-performance MFCs that are promising for practical applications on a large scale.