Engineering electrodes for microbial electrocatalysis

•Electrodes and microbes are the core elements of bioelectrochemical systems (BESs).•Optimizing microbe–electrode interactions is key to maximize BES performances.•Understanding surface properties is prerequisite to optimize such interactions.•Modifying electrodes at nano-scales and micro-scales impact their large scale prospects.•Tailor-made composite electrodes (metal backbone + carbon coating) seem promising.

Microbial electrocatalysis refers to the use of microorganisms to catalyze electrode reactions. Many processes have been developed on this principle, ranging from power generation to CO2 conversion using bioelectrochemical systems. The nature of the interface between the microorganisms and the electrodes determines the functioning and efficiency of these systems. This interface can be manipulated in terms of chemical and topographical features to better understand the interaction at nanometer and micrometer scales. Here we discuss how the electrode surface topography and chemistry impact the microorganism–electrode interaction both for direct and indirect electron transfer mechanisms. It appears that composite materials that combine high conductivity with excellent biocompatibility are most attractive towards application. In most cases this implies a combination of a metallic backbone with a carbon coating with a defined topography and chemistry.

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