l-Cysteine tailored porous graphene aerogel for enhanced power generation in microbial fuel cells

Abstract

Graphene aerogel prepared from a solution is a good candidate for a microbial fuel cell (MFC) anode as it possesses a three dimensional porous structure for high biocatalyst loading. However, the surface modification and pore size adjustment are always required during the synthetic process. In this study, a highly biocompatible porous graphene aerogel is developed using a one-pot synthesis with L-cysteine as the reductant. The addition of L-cysteine not only reduces the graphene oxide at around 80 °C under an inert atmosphere but also tailors the pore size and structure of the aerogel. With the optimized ratio of L-cysteine in the precursor, the obtained graphene aerogel G_III exhibits a highly hydrophilic surface and appropriate pore structure for bacteria moving in and adhesion. Increasing the loading of bacterial cells on the G_III anode enables it to achieve a maximum power density of 679.7 mW m⁻², which is around a 1.6 fold higher than the graphene aerogel prepared using a hydrothermal method. This study provides a new way to prepare three-dimensional porous biocompatible anode materials for improving MFC performance.