Graphene Electrodes in Bioelectrochemical Systems

Graphene: An Antibacterial Agent or a Promoter of Bacterial Proliferation?

“…Because of these physical, chemical, structural, and electronic differences, Gr, GO, and rGO will interact differently with bacteria. For BESs, the electronic properties and large SSA of Gr and rGO are particularly advantageous for the fabrication of performant electrodes because they ensure efficient electron transfer with a maximum number of microbial cells ( Tremblay et al, 2020 ). On the other side, reports that may seem somewhat conflicting suggest that Gr or rGO are more efficient at inhibiting bacterial growth than GO because of higher electronic conductivity translating into a greater capacity for oxidizing and unbalancing or degrading intracellular components ( Liu et al., 2011a ; Chen et al., 2013 ).…”

“…Graphene oxide can also be used as the electron acceptor by bacteria for the synthesis of rGO ( Salas et al., 2010 ). In microbial electrosynthesis (MES) reactors, GM coatings on the cathode act as the electron donor for the conversion of electrical energy and the greenhouse gas CO 2 into valuable chemicals ( Tremblay et al, 2020 ). In anaerobic digesters, GMs can be employed simultaneously as the electron donor and the electron acceptor by different bacterial species and thus function as electron bridges for interspecies electron transfer (IET) ( Tian et al., 2017 ).…”

“…Multiple scientific publications are reporting that GMs have antibacterial effects. In parallel, a large number of studies are indicating that GMs can promote bacterial growth and/or biofilm formation ( Hegab et al., 2016 ; Perreault et al., 2015a ; Ruiz et al., 2011 ; ElMekawy et al., 2017 ; Tremblay et al, 2020 ). This suggests that antibacterial mechanisms associated with GMs are active only under specific circumstances and probably required GM with certain physicochemical properties.…”

“…Biocompatible electrodes made of GM composites have been developed for MFC and MES reactors ( ElMekawy et al., 2017 ; Tremblay et al, 2020 ). A common approach reported in the literature is to fabricate an electrode made of a porous or mesh-like conductive material with a large SSA coated with GMs to maximize electron transfer between the electrodes and the microbes ( Zhang et al., 2011b ; Song et al., 2018b ; Aryal et al., 2019 ).…”

“…Because of its physicochemical properties, research groups have investigated the potential of GMs for a plethora of biotechnologies ( Tremblay et al, 2020 ; Zhang et al., 2011b ; Ji et al., 2016 ; Mohammed et al., 2020 ). The study of the interactions of GMs with living cells and more specifically with bacteria has led to discoveries that appear conflicting.…”