Nanomaterials to facilitate extracellular electron transfer in microbial electrochemical systems

Since the discovery of extracellular electron transfer (EET) between dissimilatory metal reduction bacteria (DMRB) and metallic minerals, this new metabolic pathway immediately invoked a significant research interest. Microbial EET is intimately involved in various environmental processes, including elemental biogeochemical cycling and energy conversion, and displayed great potential for pollutant removal accompanied by energy harvesting. However, the low efficiency of electron transfer still limits the practical applications of technologies based on EET, such as in microbial electrochemical (MESs), soil remediation, and anaerobic reactor systems. Numerous strategies have been developed to facilitate microbial EET efficiency. Nanomaterials with hierarchical structures and large surface areas provide proper space for biofilm accommodation, and the intrinsic electronic properties enable tight contact between microbes and electrodes, thus holding great possibility to improve microbial EET. In this chapter, studies using nanomaterials to enhance EET were systematically summarized, and the multiple functions of nanomaterials in enhancing microbial EET were elaborated.