Graphene Electrodes in Bioelectrochemical Systems

Abstract

The principle of bioelectrochemical systems (BESs) is that biological elements such as microbes or enzymes interact with an electrode to receive or transfer electrons. BESs have different purposes, including the conversion of organic carbons into electricity or hydrogen via microbial fuel cell (MFC) or microbial electrolysis cell (MEC) and the conversion of electricity and inorganic carbons into valuable products via microbial electrosynthesis (MES). MFC and MEC have been mainly developed for the extraction of bioenergy from wastewaters. MES exploits electricity surpluses or renewable energy sources for the bioconversion of the greenhouse gas carbon dioxide into useful chemical compounds. In general, BESs are sustainable technological approaches that have the potential to be beneficial for the environment. Another type of BES intensively studied is biosensors that combine biological sensing elements with electrodes to detect specific target molecules. When compared with competing technologies, biosensors are highly sensitive and inexpensive. For all these systems, researchers fabricated a wide range of novel electrodes to augment productivity and efficiency. Graphene is a material that possesses characteristics, such as high electrical conductivity, large specific surface area and low-cost that are well-suited for BES electrodes. Multiple examples of the successful integration of graphene into MFCs, MECs, MESs and biosensors are described in the literature. Here, we provide an overview of the graphene-containing electrodes, developed for BES, and their performance.