Enhanced performance of microbial electrochemical systems prepared with in situ electropolymerization of L-arginine-modified carbon cloth

Microbial electrochemical systems (MESs) are an emerging technology that utilizes electrochemically active bacteria (EAB) to accomplish the transformation between chemical energy and electricity. Electrode modification is expected to promote EAB biofilm formation and increase MES performance. However, typical methods for MES electrode modification depend on harsh reaction conditions, toxic agents, or complex operations. In the study, a green and simple method was established with in situ L-arginine electropolymerization. Results demonstrate L-arginine electrooxidation is the primary step of in situ L-arginine electropolymerization, and the optimal potential range is [+0.5; +2] V. The N content on the electrode surface is increased from 1.4 ± 0.2% to 11.8 ± 1.5% with electropolymerized L-arginine (PLA) formation, and the zeta potential is increased from −29.3 ± 4.6 mV to −6.7 ± 5.2 mV. Better electropositivity increases the electrostatic attraction between EAB and working electrode, resulting in a 60% increase in biofilm biomass. Higher biomass enhances MES performance, and the current generation is increased by 76%. These results demonstrate that PLA modification is capable to increase electrode electropositivity, promote biofilm formation, and increase MES performance. The study illuminates the feasibility of MES electrode modification with in situ amino acid electropolymerization, and provides a new prospect to improve MES performance.