The electrochemical perspective of bioelectrocatalytic activities in microbial electrolysis and microbial fuel cells

Transforming organic waste directly into electricity or indirectly into sources of hydrogen fuel is credible through exoelectrogen microorganisms grown on the anode or cathode that catalyze electrochemical reactions. In this review, we discuss the origin of the electrochemical kinetic in both microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) that are utilized to produce energy from waste through either directly by producing electric energy, or indirectly through hydrogen gas production, respectively. The concept of utilizing electrochemical techniques of cyclic voltammetry, chronoamperometric and derivative cyclic voltammetry to study the interfacial kinetics of exoelectrogenic bacteria and characterize biofilms are described. Additionally, we discuss the influence of various parts of electrochemical cells on bioelectrocatalytic processes, i.e, system design, electrolyte properties, anode and cathode materials. Thus, the necessity of optimizing parameters impacting the efficiency, rate, bacteria enrichment, and system implementations for improved biofilm performance are briefly discussed along with the figures of merit. (C) 2019 The Authors. Published by Elsevier Ltd.